Keyword: experiment
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MOZGBD1 Towards Full Performance Operation of SwissFEL FEL, photon, electron, laser 24
 
  • T. Schietinger
    PSI, Villigen PSI, Switzerland
 
  SwissFEL is the new X-ray free-electron laser facility at the Paul Scherrer Institute (PSI) in Switzerland. It was inaugurated in December 2016 and saw its first pilot experiments at the end of 2017. We describe the commissioning steps leading to the first phase of pilot experiments and outline the plans towards reaching nominal performance levels in 2018.  
slides icon Slides MOZGBD1 [11.395 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD1  
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MOZGBE5 Results on the FCC-hh Beam Screen at the KIT Electron Storage Ring KARA photon, electron, radiation, vacuum 55
 
  • L.A. Gonzalez, V. Baglin, P. Chiggiato, C. Garion, M. Gil Costa, R. Kersevan
    CERN, Geneva, Switzerland
  • I. Bellafont, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • S. Casalbuoni, E. Huttel
    KIT, Eggenstein-Leopoldshafen, Germany
 
  Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305.
In the framework of the EuroCirCol collaboration* (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of 3 FCC-hh beam-screen (BS) prototypes has been carried out with the aim of testing them at room temperature at the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator). The 3 BS prototypes will be tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power, match the one foreseen for the 50+50 TeV FCC-hh proton collider. Each of the 3 BS prototypes, 2 m in length, implement a different design feature: 1) baseline design (BD), with electro-deposited copper and no electron-cloud (EC) mitigation features; 2) BD with set of distributed cold-sprayed anti-EC clearing electrodes; 3) BD with laser-ablated anti-EC surface texturing. We present here the results obtained so far at BESTEX and the comparison with extensive montecarlo simulations of the expected outgassing behavior under synchrotron radiation.
The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information.
 
slides icon Slides MOZGBE5 [4.323 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE5  
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MOZGBF3 40 Years of Electron Cooling at CERN electron, proton, antiproton, gun 69
 
  • G. Tranquille
    CERN, Geneva, Switzerland
 
  For nearly 40 years electron cooling has been used extensively on the storage rings of the CERN accelerator complex for the accumulation of ions or for the improvement of beam quality for precision experiments. Since the first cooling experiments on ICE the coolers have evolved to incorporate the latest advances in electron cooling technology and many unique experiments have also been performed when the coolers are not used for everyday operation. The trapping of anti-hydrogen atoms and more recently lead-lead and proton-lead ion collisions in the LHC have been made possible thanks to cooling in the AD and cooling and accumulation of lead ions in the LEIR respectively. The next cooler to be built at CERN will be installed on ELENA and will operate at electron energies below 350 eV. Many challenges lie ahead in operating at such a low energy with minimum perturbation to the storage ring. The present AD cooler, which has already seen two re-incarnations, will also be replaced with a new state-of-the-art device operating at higher energies in order to improve the quality of the antiproton beam in this ring.  
slides icon Slides MOZGBF3 [14.907 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF3  
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MOPMF006 Test of Stepwise Electron Bunch Replacement in eRHIC Using an Electron Lens in RHIC electron, emittance, proton, simulation 95
 
  • W. Fischer, M.R. Costanzo, A.V. Fedotov, X. Gu, A. Marusic, M.G. Minty, C. Montag, Y. Tan, P. Thieberger
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
The electron-ion collider eRHIC requires an electron bunch replacement about every second to maintain both high luminosity and polarization. If the bunch can be replaced in several steps, the requirements for both the electron gun and the electron accelerator are greatly reduced due to the reduced bunch charge. However, a stepwise replacement of electron bunches in eRHIC will give rise to transient effects from the beam-beam interaction that will lead to emittance growth. Such a scheme was tested using one of the RHIC electron lenses with a multiple step increase of the electron current. The test provides an order-of-magnitude estimate of the effect without any further mitigating measures.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF006  
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MOPMF010 Measurement and Simulation of Betatron Coupling Beam Transfer Function in RHIC coupling, betatron, simulation, quadrupole 99
 
  • Y. Luo, W. Fischer, A. Marusic, M.G. Minty
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Transfer function measurements are important for characterizing betatron tunes, betatron coupling, and beam spectrum in the routine operation of the Relativistic Heavy Ion Collider (RHIC). To counteract the linear betatron coupling, we developed a technique to continuously measure the betatron coupling coefficient with a base band phase lock loop tune meter in 2006. Based on this technique, we demonstrated and built a robust tune/coupling feedback in RHIC. In this article, we revisit the BTF measurement with betatron coupling to benchmark our BTF simulation code. We also compared the values of eigenmode projection ratios from BTF with those calculated with the single particle model.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF010  
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MOPMF039 First Xenon-Xenon Collisions in the LHC luminosity, proton, injection, emittance 180
 
  • M. Schaumann, R. Alemany-Fernández, P. Baudrenghien, T. Bohl, C. Bracco, R. Bruce, N. Fuster-Martínez, M.A. Jebramcik, J.M. Jowett, T. Mertens, D. Mirarchi, S. Redaelli, B. Salvachua, M. Solfaroli, H. Timko, J. Wenninger
    CERN, Geneva, Switzerland
 
  In 2017, the CERN accelerator complex once again demonstrated its flexibility by producing beams of a new ion species, xenon, that were successfully injected into LHC. On 12 October, collisions of fully stripped xenon nuclei were recorded for the first time in the LHC at a centre-of-mass energy per colliding nucleon pair of 5.44 TeV. Physics data taking started 9.5 h after the first injection of xenon beams and lasted a total of 6 h. The integrated luminosity delivered to the four LHC experiments was sufficient that new physics results can be expected soon. We provide a general overview of this Xe-Xe pilot run before focussing on beam data at injection energy and at flat-top.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF039  
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MOPMF040 Crossing Angle Anti-Leveling at the LHC in 2017 luminosity, operation, proton, simulation 184
 
  • N. Karastathis, K. Fuchsberger, M. Hostettler, Y. Papaphilippou, D. Pellegrini
    CERN, Geneva, Switzerland
 
  In 2017, LHC incorporated in operation an anti-leveling procedure of adapting in steps the crossing angle of the colliding beams to increase the integrated luminosity. In this paper, we present the Dynamic Aperture simulations that were employed to identify the operational margins, and therefore define the leveling steps. The results are complemented by observations from nominal operation and projections for the 2018 operation. Additional anti-leveling techniques, investigated in dedicated machine studies are also discussed  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF040  
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MOPMF041 Refining the HL-LHC Operational Settings with Inputs From Dynamic Aperture Simulations: A Progress Report luminosity, octupole, operation, dynamic-aperture 188
 
  • N. Karastathis, R. De Maria, S.D. Fartoukh, Y. Papaphilippou, D. Pellegrini
    CERN, Geneva, Switzerland
 
  Recent Dynamic Aperture (DA) simulations aimed at providing guidance for the latest updates of the operational scenario for the High Luminosity upgrade of the LHC. The impact of the increased chromaticity and octupole current has been assessed considering the latest updates of the optics. Additional means to improve the lifetime, such as tune optimization, have been identified and deployed. We also briefly discuss the impact of delivering high luminosity to the LHCb experiment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF041  
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MOPMF051 LHC Operational Scenarios During 2017 Run luminosity, proton, optics, hadron 220
 
  • B. Salvachua, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, H. Burkhardt, G.E. Crockford, JCD. Dumont, S.D. Fartoukh, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, J.M. Jowett, Y. Le Borgne, D. Nisbet, M. Pojer, L. Ponce, S. Redaelli, M. Solfaroli, R. Suykerbuyk, D.J. Walsh, J. Wenninger, M. Zerlauth
    CERN, Geneva, Switzerland
 
  During 2017, the Large Hadron Collider LHC delivered luminosity for different physics configuration in addtion to the nominal 6.5 TeV proton-proton run. About 18.5 days were dedicated to commission and to deliver special physics to the experiments. Condifurations with large beta-star of 19 m and 24 m were prepared for luminosity calibration with Van de Meer scans. A proton-proton run at 2.51 TeV took place during the last weeks of November to provide reference data for the heavy ion (Pb-Pb, p-Pb) collisions at the same equivalent nucleon energy . A very short (0.5 days) but effective ion run was scheduled where the LHC saw the first Xe beams collissions and delivered around 3 ub-1 to ATLAS and CMS. The run ended with a low event pile-up run at 6.5TeV. This contribution summarizes the operational aspects and delivered targets for the different configurations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF051  
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MOPMF052 Monitoring and Modeling of the LHC Luminosity Evolution in 2017 luminosity, emittance, operation, monitoring 224
 
  • N. Karastathis, F. Antoniou, I. Efthymiopoulos, M. Hostettler, G. Iadarola, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, B. Salvachua
    CERN, Geneva, Switzerland
 
  In 2017, the Large Hadron Collider (LHC) restarted operation at 6.5 TeV, after an extended end-of-the-year stop, scheduled to deliver 45/fb to the two general-purpose experiments. Continuous monitoring of the key beam parameters and machine configurations that impact the delivered luminosity was introduced, providing fast feedback to operations for further optimisation. The numerical model based on simulations and use of selected machine parameters to estimate the machine luminosity was further developed. The luminosity evolution and comparisons to the model predictions is presented in this paper. The impact of the dynamic variation of the crossing angle, which was incorporated into nominal LHC operation, is also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF052  
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MOPMF060 Safe Disposal of the LHC Beam without Beam Dump - Method and Experimental Verification collimation, emittance, controls, dumping 253
 
  • M. Valette, B. Lindstrom, A. Mereghetti, R. Schmidt, M. Solfaroli, J.A. Uythoven, D. Valuch, J. Wenninger, D. Wollmann, M. Zerlauth
    CERN, Geneva, Switzerland
 
  Funding: Research supported by the HL-LHC project.
In the extremely unlikely event of a non-working beam dumping system in the LHC, the 360 MJ of stored beam energy can be dissipated in the collimation system as a last mitigation measure. In such a situation, it is important to reduce the stored beam energy both quickly and at the same time as smoothly as possible in order to limit the risk of trips of critical systems, to avoid quenches of superconducting magnets (which would lead to changes of the beam trajectory and damage to the accelerator) and ultimately damage to the collimators themselves. Detailed steps and parameters have been developed and validated during two dedicated experiments with beam in the LHC. This paper summarizes the key aspects in view of the preparation of such a procedure for operational use, which will allow for the safe disposal of the full LHC beam by the operation crews.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF060  
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MOPMF061 Emittance Growth in Coast in the SPS at CERN emittance, cavity, scattering, feedback 257
 
  • F. Antoniou, H. Bartosik, T. Bohl, R. Calaga, L.R. Carver, J. Repond, G. Vandoni
    CERN, Geneva, Switzerland
  • A. Alekou
    UMAN, Manchester, United Kingdom
 
  Funding: Research supported by the HL-LHC project.
The HL-LHC prototype crab-cavities are installed in the CERN SPS, which will allow for a comprehensive beam test with high energy protons for the first time. As the time available for experimental beam dynamics studies with the crab cavities installed in the machine will be limited, a very good preparation is required. One of the main concerns is the induced emittance growth, driven by phase amplitude jitter in the crab cavities. In this respect, several machine development (MD) studies were performed during the past years to quantify and characterize the long term emittance evolution of proton beams in the SPS. In these proceedings, the experimental observations from past years are summarized and the MD studies from 2016 and 2017 are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF061  
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MOPMF069 The High Energy LHC Beam-Beam Effects studies octupole, beam-beam-effects, collider, dynamic-aperture 285
 
  • T. Pieloni, J. Barranco García, L. Rivkin, C. Tambasco
    EPFL, Lausanne, Switzerland
  • D. Amorim, S. A. Antipov, X. Buffat, B. Salvant, F. Zimmermann
    CERN, Geneva, Switzerland
 
  Funding: This work is supported by the Swiss State Secretariat for Education, Research and Innovation SERI.
We present in this paper the studies of beam-beam effects for the High Energy Large Hadron Collider. We will describe and review the different aspects of beam-beam interactions (i.e. orbit effects, Landau damping, compensation schemes and operational set-up). An operational scenario for the collider will also be given as a result of the study.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF069  
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MOPMF086 Proposal of an Experimental Test at DAΦNE for the Low Emittance Muon Beam Production From Positrons on Target target, positron, emittance, optics 326
 
  • M. Boscolo, M. Antonelli, O.R. Blanco-García, S. Guiducci, A. Stella
    INFN/LNF, Frascati (Roma), Italy
  • F. Collamati
    INFN-Roma1, Rome, Italy
  • R. Li Voti
    Sapienza University of Rome, Rome, Italy
  • S.M. Liuzzo, P. Raimondi
    ESRF, Grenoble, France
 
  We present in this paper the proposal of an experimental test at DAΦNE of the positron-ring-plus-target scheme foreseen in the Low EMittance Muon Accelerator. This test would be a validation of the on-going studies for LEMMA and it would be synergic with other proposals at DAΦNE after the SIDDHARTA run. We discuss the beam dynamics studies for different targets inserted in a proper location through the ring, i.e. where the beam is focused and dispersion-free. Optimization of beam parameters, thickness and material of target and optics of the target insertion are shown as well. The development of the existent diagnostic needed to test the behavior of the circulating beam is described together with the turn-by-turn measurement systems of charge, lifetime and transverse size. Measurements on the temperature and thermo-mechanical stress on the target are also under study.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF086  
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MOPMF088 Preparation Activity for the Siddharta-2 Run at DAΦNE luminosity, controls, feedback, quadrupole 334
 
  • C. Milardi, D. Alesini, S. Bini, O.R. Blanco-García, M. Boscolo, B. Buonomo, S. Cantarella, S. Caschera, A. D'Uffizi, A. De Santis, G.O. Delle Monache, D.G.C. Di Giulio, G. Di Pirro, A. Drago, L.G. Foggetta, A. Gallo, R. Gargana, A. Ghigo, S. Guiducci, S. Incremona, F. Iungo, C. Ligi, M. Maestri, A. Michelotti, L. Pellegrino, R. Ricci, U. Rotundo, L. Sabbatini, C. Sanelli, G. Sensolini, A. Stecchi, A. Stella, A. Vannozzi, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • G. Castorina
    INFN-Roma1, Rome, Italy
  • J. Chavanne, G. Le Bec, P. Raimondi
    ESRF, Grenoble, France
 
  DAΦNE, the Frascati lepton collider working at the c.m. energy of the F resonance, continues to be a very suitable infrastructure to realize experiments aimed at studying elementary particles and nuclear physics. The motivations of this long lasting interest are related to the DAΦNE ability of increasing its performances in terms of luminosity thanks to the innovative Crab-Waist collision scheme. In this framework, a new run for the SIDDHARTA-2 experiment has been planned in the year 2019. The detector presently installed in the interaction region, KLOE-2, will be removed and a new low-beta session, equipped with new permanent magnets quadrupoles, will be installed. Diagnostics tools will be improved especially the ones used to keep under control the beam-beam interaction. The horizontal feedback in the positron ring will be potentiated in order to achieve a higher positron current. The design and development work done in view of the SIDDHARTA-2 run is presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF088  
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MOPMF089 DAΦNE Luminosity Monitor luminosity, detector, scattering, injection 338
 
  • A. De Santis, C. Bisegni, O.R. Blanco-García, O. Coiro, A. Michelotti, C. Milardi, A. Stecchi
    INFN/LNF, Frascati (Roma), Italy
 
  This work presents a new method to measure the DAΦNE collider instantaneous luminosity. The method is based on the identification of Bhabha scattering events at low polar angle (∼10 degree) around the beam axis by using two small crystal calorimeters shared with the KLOE-2 experiment. A new experimental setup has been designed and realized in order to implement the fast luminosity monitor, also in view of the DAΦNE future physics runs. Besides total instantaneous luminosity the new diagnostic measures also Bunch-by-Bunch (BBB) luminosity. This peculiarity allows to investigate the beam-beam interaction for the Crab- Waist collisions at DAΦNE and luminosity dependence on the bunch train structure.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF089  
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MOPMK014 Resistive-Wall Impedance of Insertions for FCC-hh impedance, insertion, optics, lattice 378
 
  • B. Riemann, S. Khan
    DELTA, Dortmund, Germany
  • S. Arsenyev, D. Schulte
    CERN, Geneva, Switzerland
 
  Funding: This work is supported by the German Ministry of Education & Research (BMBF, funding code 05P15PERB1) and CERN (reference numbers KE3123, EDMS 1606722).
In this work, transverse and longitudinal resistive-wall impedances for beam pipes in the experiment, injection, extraction and RF systems insertion regions of the Future Hadron-Hadron Collider (FCC-hh) are computed based on contributions from different given cross sections of the surrounding (elliptical) chamber parts along the beam path, their temperature-dependent conductivities, and optical functions. An emphasis is placed on the behaviour of transverse impedance in the main experimental regions (A and G), where maximum beta values of 104 to 105 m occur in dependence of the operation mode respectively lattice configuration. Main contributions to the transverse and longitudinal impedance budget are identified, and possibilities of reducing them are discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK014  
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MOPMK017 Transient Beam Loading Due to the Bunch Train Gap and Its Compensation Experiments at BEPC-II and ALS cavity, feedback, beam-loading, luminosity 390
 
  • H. Wang, R.A. Rimmer, S. Wang
    JLab, Newport News, Virginia, USA
  • J.P. Dai, Q. Qin, J. Xing, J.H. Yue, Y. Zhang
    IHEP, Beijing, People's Republic of China
  • D. Teytelman
    Dimtel, San Jose, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Non-uniform bunch fill patterns in storage rings, driven by the need to provide gaps for beam aborting and ion clearing cause a large beam loading change in the RF cavities. The induced turn-periodic transient in the cavity voltage modulates longitudinal beam properties along the train, such as synchronous position and bunch length. In the EIC design, due to the asymmetric bunch train structure between the electron and the ion beam, such modulation results in shifting collision point and leads to reduced luminosity. We have carried out the beam based experiments at BEPC-II and ALS using bunch-by-bunch diagnostic capabilities of the coupled-bunch feedback systems to study this transient effect. A modulated bunch filling pattern with higher charge density around the gap has been demonstrated to be effective in partially compensating this transient modulation. Details of the experimental setups and the data analysis will be presented to this conference.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK017  
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MOPML011 Liquid Cluster Ion Beam Processing of Transition Metal Films vacuum, acceleration, radiation, target 415
 
  • D. Shimizu, H. Ryuto, M. Takeuchi, D. Yamamoto
    Kyoto University, Photonics and Electronics Science and Engineering Center, Kyoto, Japan
 
  The irradiation effects of cluster ion beams are characterized by the high-density collision of molecules that comprise the clusters against a target. According to molecular dynamics calculations, the local temperature of the colliding cluster and the surface of the target are expected to increase to several thousand K. The enhancement of the chemical interactions between the molecules in the colliding clusters and the atoms on the target surface is expected, if polyatomic molecules, such as ethanol and acetone, are used for the source material of the cluster. So, the irradiation effects of the polyatomic liquid cluster ion beams on transition metal films have been studied to examine the possibility of utilizing the liquid cluster ion beam technique for the processing of transition metal films. The transition metal films were formed by magnetron sputtering. The liquid clusters were produced by the adiabatic expansion method and ionized by electron ionization. The sputtering yields of transition metal films induced by liquid cluster ions are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML011  
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MOPML012 Special Collimation System Configuration for the LHC High-Beta Runs background, collimation, simulation, detector 418
 
  • H. Garcia Morales
    Royal Holloway, University of London, Surrey, United Kingdom
  • R. Bruce, H. Burkhardt, M. Deile, S. Jakobsen, A. Mereghetti, S. Redaelli
    CERN, Geneva, Switzerland
 
  Special LHC high-beta optics is required for the forward physics program of TOTEM and ATLAS-ALFA. In this configuration, the beam is de-squeezed (the \beta-function at the collision point is increased) in order to minimize the divergence for measurements at very small scattering angles. In these low beam intensity runs, it is important to place the Roman Pots (RPs) as close as possible to the beam, which demands special collimator settings. During Run I, a significant amount of background was observed in the forward detectors due to particles outscattered from the primary collimator. During Run II, a different collimation configuration was used where a tungsten collimator was used as primary collimator instead of the usual one made of carbon. Using this configuration, a significant reduction of the background at the RPs was observed. In this paper we present a description of the new collimator configuration and the results obtained during the high-beta run carried out in 2016.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML012  
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MOPML023 Very-High Energy Electron (VHEE) Studies at CERN's CLEAR User Facility simulation, electron, scattering, proton 445
 
  • A. Lagzda, R.M. Jones
    UMAN, Manchester, United Kingdom
  • A. Aitkenhead, K. Kirkby, R. MacKay, M. Van Herk
    The Christie NHS Foundation Trust, Manchester, United Kingdom
  • R. Corsini, W. Farabolini
    CERN, Geneva, Switzerland
 
  Funding: Science and Technology Facilities Council (STFC) - United Kingdom
Here we investigate how inserts of various densities (0.001-2.2 g/cm3) affect the dose distribution properties of VHEE beams at ~150 MeV. A range variation comparison was also made with clinical proton beams using TOPAS/GEANT4 Monte Carlo simulations. In addition, we assess the viability of scattering foils for optimizing the size of VHEE beams for radiotherapy purposes. The experiments were conducted at CERN's CLEAR user facility.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML023  
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MOPML028 Accelerator Machines and Experimental Activities in the ENEA Frascati Particle Accelerators and Medical Application Laboratory radiation, proton, electron, linac 460
 
  • M. Vadrucci, A. Ampollini, G. Bazzano, F. Borgognoni, P. Nenzi, L. Picardi, C. Ronsivalle, V. Surrenti, E. Trinca
    ENEA C.R. Frascati, Frascati (Roma), Italy
 
  Funding: Regione Lazio - TOP IMPLART Project
In the ENEA Frascati research center the APAM (Particle Accelerators and Medical Application) laboratory is devoted to the development of particle accelerators for medical applications. Two main facilities are operational. The TOP-IMPLART proton accelerator is a pulsed fully linear machine aimed at active intensity modulated proton therapy with a final energy of 150 MeV. The machine offers two beam extraction points: one at 3-7 MeV, on a vertical line, and the other one at 35 MeV, the maximum energy currently available, with a pulse current up to 35 μA, on the horizontal line. The REX (Removable target Electron X-ray) source consists of an electron standing wave LINAC generating a beam in the energy range of 3 to 5 MeV with a pulsed current of 0.2 A. This source can generate Bremsstrahlung X-ray beams using suitable converters (Pb, W, Ta). This paper describes the experimental results of satellite activities performed in these facilities in the fields of biology, dosimetry, electronics, PIXE spectroscopy and preservation of cultural heritage manufacts.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML028  
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MOPML030 Demonstration of a Tunable Electron Beam Chopper for Application in 200 kV stroboscopic TEM electron, kicker, laser, controls 467
 
  • C.-J. Jing, S.V. Baryshev, A. Kanareykin, A. Liu, Y. Zhao
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • J.W. Lau
    NIST, Gaithersburg, Maryland, USA
  • D. Masiel, B. Reed
    Integrated Dynamic Electron Solutions, Pleasanton, California, USA
  • Y. Zhu
    BNL, Upton, Long Island, New York, USA
 
  Funding: The project is supported by the Office of Basic Energy Science of DOE through a Small Business Innovative Research grant #DE-SC0013121.
For the last several decades, time-resolved transmission electron microscopes (TEM) exploring the sub-microsecond timescale have relied on the photoemission technology to generate the single or train of electron bunches. However, the complexity of additional laser system and the availability of high repitition rate laser limit applications of the laser-driven approach. Lately we have made substantial progress towards pioneering a new kind of time-resolved TEM, complementary to the existing laser-based techniques. Using a tunable RF beam-chopper, we are able to retrofit an exsiting TEM providing a pulsed electron beam at a continuously tunable reptition rate up to 12GHz and a tunable bunch length. In the article we will briefly discuss the working principle and experimental progress to date.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML030  
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MOPML032 Prospects for a Muon Spin Resonace Facility in the Fermilab MuCool Test Area target, linac, timing, resonance 474
 
  • J.A. Johnstone, C. Johnstone
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by Fermi Reserach Alliance, LLC under Contract no. DE-AC02-07CH11359 with the United States Department of Energy.
This paper investigates the feasibility of re-purposing the MuCool Test Area beamline and experimental hall to support a Muon Spin Resonance Facility which would make it the only such facility in the US. This report reviews the basic muon production concepts as studied and operationally implemented at TRIUMF, PSI, and RAL and their application in the context of the MTA facility. Two scenarios were determined feasible. One, an initial minimal-shielding and capital-cost investment stage with a single secondary muon beamline that utilizes an existing primary beam absorber and, another, an upgraded stage, that implements an optimized production target, a proximate high-intensity absorber, and optimized secondary muon lines. A unique approach is proposed which chops or strips a macropulse of H beam into a micropulse substructure - a muon creation timing scheme - which allows Muon Spin Resonance experiments in a linac environment. With this timing scheme, and attention to target design and secondary beam collection, the MTA can host enabling and competitive Muon Spin Resonance experiments.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML032  
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MOPML045 Measurement of Displacement Cross-Section for Structural Materials in High-Power Proton Accelerator Facility proton, target, radiation, cryogenics 499
 
  • S.I. Meigo, S.H. Hasegawa, H.I. Hiroki, H. Hiroki, Y. Iwamoto, F.M. Maekawa
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • T. Ishida, S. Makimura, T. Nakamoto
    KEK, Ibaraki, Japan
  • Y. Makoto
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  As the increase of beam power of hadron accelerators, the damage to target material is essential. For estimation of damage such as target material used at the facility, displacement per atom (DPA), calculated by the particle flux multiplied displacement cross-section with cascade mode, is widely employed as an index of the damage. Although the DPA is employed as the standard, the experimental data of displacement cross-section are scarce for a proton in the energy region above 20 MeV. A recent study reports that the displacement cross section of tungsten has 8 times difference among the calculation models. Therefore, experimental data of the displacement cross-section is crucial. The displacement cross-section can be obtained by observing the change of resistivity of the sample cooled by GM cooler to sustain the damage. The sample is placed in the vacuum chamber placed at upstream of the beam dump for 3 GeV and 30 GeV synchrotrons in J-PARC, where the sample will be irradiated by the proton in the energy range between 0.4 and 30 GeV. In the vast energy range, the displacement cross-section can be obtained for the proton, which will help to improve the damage estimation of the target material.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML045  
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MOPML049 Generation of 1-MeV Quasi-Monochromatic Gamma-Rays for Precise Measurement of Delbrück Scattering by Laser Compton Scattering laser, scattering, electron, photon 508
 
  • H. Zen, T. Kii, H. Ohgaki
    Kyoto University, Kyoto, Japan
  • M. Fujimoto, M. Katoh, E. Salehi
    UVSOR, Okazaki, Japan
  • T. Hayakawa, T. Shizuma
    QST, Tokai, Japan
  • M. Katoh
    Sokendai - Okazaki, Okazaki, Aichi, Japan
  • J. Koga
    National Institutes for Quantum and Radiological Science and Technology, Kyoto, Japan
  • E. Salehi
    AUT, Tehran, Iran
 
  Delbrück scattering is the elastic scattering of photons by the electromagnetic field of an atomic nucleus, as a consequence of vacuum polarization. The isolated measurement of Delbrück scattering has not been performed because of interference with other elastic scattering processes. It was recently discovered that, using linearly polarized photons, Delbrück scattering can be measured nearly independently of the other scattering processes*. In order to perform a proof of principle experiment, a quasi-monochromatic gamma-ray beam with a maximum photon energy of 1 MeV has been generated at the UVSOR facility by colliding a CO2 laser with a 750-MeV electron beam. A preliminary experiment has been performed with 0.5-W laser power and 1-mA electron beam current. As a result, the measured gamma-ray flux was evaluated as 0.0006 photon/eV/mA/W/s around the peak energy of 1 MeV. If we accept 20 percent energy spread, in case of a 100-W CO2 laser colliding with a 300 mA electron beam, approximately 4 x 106-photons/s gamma-rays could be obtained. This flux is sufficiently high for the proof of principle experiment.
*J.K. Koga and T. Hayakawa, Phys. Rev. Lett. 118, 204801 (2017).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML049  
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MOPML051 First Performance Calculations for the Very High Energy Electron Radiation Therapy Experiment at PRAE radiation, electron, proton, photon 516
 
  • A. Faus-Golfe
    LAL, Orsay, France
  • R. Delorme, Y. Prezado
    IMNC, Orsay, France
  • V. Favaudon, C. Fouillade, S. Heinrich, A. Mazal, A. Patriarca, P. Poortmans, P. Verrelle
    Institut Curie - Centre de Protonthérapie d'Orsay, Orsay, France
  • A. Hrybok
    National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev, Ukraine
 
  The Platform for Research and Applications with Electrons (PRAE) project aims at creating a multidisciplinary R&D platform at the Orsay campus, joining various scientific communities involved in radiobiology, subatomic physics, instrumentation, particle accelerators and clinical research around a high-performance electron accelerator with beam energies up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and challenging R&D. In this paper we will report the first optics design and performance evaluations of such a multidisciplinary machine, focusing on Very High Energy Electrons (VHEE) innovative Radiation Therapy (RT) applications in particular by allowing Grid and FLASH methodologies, which are likely to represent a major breakthrough in RT. Functional specifications include beam intensities to produce dose rates from 2 Gy/min to 100Gy/sec, beam sizes with diameters from 0.5 mm to 10 cm or more of homogeneous beams and monitoring devices with accuracy in the order of 1-2% for single or multiple beams and single or multiple fractions in biological and ppreclinical applications. High energies (>140 MeV) would be also needed for GRID therapy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML051  
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MOPML056 Evidence of the Electron-Screened Oppenheimer Philips Reactions 162Er(d, n)163Tm or 162Er(p,γ)163Tm in Deuterated Materials Subjected to a Low-Energy Photon Beam electron, neutron, proton, target 533
 
  • T.L. Benyo, A. Chait, L.P. Forsley, M. Pines, V. Pines, B.M. Steinetz
    NASA Glenn Research Center, Cleveland, USA
 
  NASA GRC has investigated electron-screening of deuterated metals using MV electron linear accelerators (LINACs). GRC found that repeatable sub-threshold nuclear reactions may have occurred resulting in nuclear products observed via witness-material neutron activation using high purity germanium (HPGe) gamma spectroscopy and liquid scintillator spectroscopy. The suspected path of creation may be the result of electron-screened Oppenheimer-Phillips reactions or Mirror Oppenheimer-Phillips reactions. Evidence of 162Er(d, n)163Tm or 162Er(p,γ)163Tm has been shown with the appearance of gamma peaks coinciding with 163Tm with a published ' life of 22 minutes from samples containing deuterated erbium exposed to a photon beam. Both of these reactions are a variation of the Oppenheimer-Phillips nuclear reaction. Evidence of the reactions have been detected by an HPGe gamma detection system and witnessed within gamma spectra collected from deuterated materials subjected to a nominally 1.95 MeV photon beam. This paper describes the theory behind the proposed reactions, the experiments conducted at GRC, and the experimental evidence of the suspected creation of the 163Tm isotope.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML056  
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MOPML062 Accelerator Neutron Source for Boron Neutron Capture Therapy neutron, vacuum, proton, tandem-accelerator 550
 
  • S.Yu. Taskaev, D.A. Kasatov, A.N. Makarov, Y.M. Ostreinov, I.M. Shchudlo, I.N. Sorokin
    BINP SB RAS, Novosibirsk, Russia
  • T.A. Bykov
    Budker INP & NSU, Novosibirsk, Russia
  • Ya.A. Kolesnikov, A.M. Koshkarev, E.O. Sokolova
    NSU, Novosibirsk, Russia
 
  Funding: This study was carried out with a grant from the Russian Science Foundation (project No. 14-32-00006-P) with the support of the Budker Institute of Nuclear Physics and Novosibirsk State University.
A source of epithermal neutrons based on a vacuum-insulated tandem accelerator and a lithium target is developed for the technique of boron neutron capture therapy. A stationary proton beam of 2 MeV with a current of up to 5 mA was obtained in the accelerator. Neutron generation was performed and the flux and neutron spectrum were experimentally measured. A Beam Shaping Assembly was developed and manufactured, which makes it possible to form a therapeutic beam of neutrons to the greatest extent satisfying the requirements of BNCT. It was established that neutron irradiation of tumor cells of human glioma U251 and human glioblastoma T98G, previously incubated in a medium with boron, led to a significant suppression of their viability. Irradiation of mice with grafted human glioblastoma tumor led to their complete cure. In order to increase the beam parameters, the facility was equipped with a wire scanner OWS-30 (D-Pace, Canada; under the license of TRIUMF), a non-contact current sensor NPTC (Bergos, France), a FLIR T650SC infrared camera, an Optris CT Laser 3ML SF pyrometer (Optris, GmbH, Germany), cooled diaphragms with thermistors, telescopic beam receivers with thermoresistors, a new bushing insulator. Two new sources of negative hydrogen ions with a high current are being prepared, one of them is surface-plasma, the other is voluminous. The investigations established the effect of space charge and spherical aberration of lens on the ion beam transport, the dependence of the heating of the diaphragms of the electrodes and the size of the proton beam on the current of the injected beam of negative hydrogen ions and the pressure of the residual gas in the transport channel. The report describes the modernization of the accelerator, discusses the results of research, declares plans.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML062  
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MOPML063 In Situ Observations of Blistering of a Metal Irradiated with 2 MeV Protons proton, neutron, radiation, target 553
 
  • S.Yu. Taskaev, D.A. Kasatov, A.N. Makarov, I.M. Shchudlo
    BINP SB RAS, Novosibirsk, Russia
  • A. Badrutdinov, Y. Higashi, T. Miyazawa
    OIST, Onna-son, Okinawa, Japan
  • T.A. Bykov
    Budker INP & NSU, Novosibirsk, Russia
  • S.A. Gromilov
    Nikolaev IIC, Novosibirsk, Russia
  • Ya.A. Kolesnikov, A.M. Koshkarev, E.O. Sokolova
    NSU, Novosibirsk, Russia
  • H. Sugawara
    KEK, Ibaraki, Japan
 
  Funding: This study was carried out with a grant from the Russian Science Foundation (project No. 14-32-00006-P) with the support of the Budker Institute of Nuclear Physics and Novosibirsk State University.
A vacuum-insulated tandem accelerator was used to observe in situ blistering during 2-MeV proton irradiation of metallic samples to a fluence of up to 6.7 1020 cm2. Samples consisting of copper of different purity, tantalum, and tantalum-copper compounds were placed on the proton beam path and forced to cool. The surface state of the samples was observed using a CCD camera with a remote microscope. Thermistors, a pyrometer, and an infrared camera were applied to measure the temperature of the samples during irradiation. After irradiation, the samples were analyzed on an X-ray diffractometer, laser and electron microscopes. The present study describes the experiment, presents the results obtained and notes their relevance and significance in the development of a lithium target for an accelerator-based neutron source, for use in boron neutron capture therapy of cancer.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML063  
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MOPML066 Ultrafast Mega-electron-volt Gas-Phase Electron Diffraction at SLAC National Accelerator Laboratory electron, gun, vacuum, laser 556
 
  • X. Shen, R.K. Li, X.J. Wang, S.P. Weathersby, J. Yang
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported in part by the U.S. Department of Energy Contract No. DE-AC02-76SF00515, and the SLAC UED/UEM Initiative Program Development Fund.
Ultrashort mega-electron-volt (MeV) electron beams from radio-frequency (rf) photoinjectors have recently attracted strong interests for application in ultrafast gas-phase electron diffraction (UGED). Such high-brightness electron beams are capable of providing 100-fs level temporal resolution and sub-Angstrom level spatial resolution to capture the ultrafast structural dynamics from photoexcited gas molecules. To experimentally demonstrate such an ultrafast electron scattering instrument, a high performance UGED system has been commissioned at SLAC National Accelerator Laboratory. The UGED instrument produces 3.7 MeV electron beams with 2 fC beam charge at 180-Hz repetition rate. The temporal resolution is characterized to be 150 fs full-width-at-half-maximum (FWHM), while the spatial resolution is measured to be 0.76 Å FWHM. The UGED instrument also demonstrates outstanding performance in vacuum, rf, and electron beam pointing stability. Details of the performance of the SLAC MeV UGED system is reported in this paper.
 
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TUXGBD2 Colliding Heavy Ions in the LHC luminosity, heavy-ion, operation, proton 584
 
  • J.M. Jowett
    CERN, Geneva, Switzerland
 
  The Large Hadron Collider at CERN not only collides protons but also heavier nuclei. So far Pb+Pb, Xe-Xe and p+Pb collisions, at multiple energies, have been provided for what was initially conceived as a distinct physics program on the collective behavior of QCD matter at extreme energy density and temperature. However unexpected phenomena observed in p+Pb and p+p collisions at equivalent energies have blurred the distinction. Intense, low-emittance, ion beams are provided by a dedicated source and injector chain setup. When Pb beams collide, new luminosity limits arise from photon-photon and photonuclear interactions but effective mitigations have allowed luminosities over 3 times design. Asymmetric p+Pb collisions introduce new features and beam-dynamical phenomena into operation of the LHC but have also achieved luminosity far beyond expectations. With experimental requirements for multiple changes in energy and data-taking configurations during very short heavy-ion runs, high operational efficiency and reliability are vital. This invited talk discusses performance, future prospects, and technical challenges for the LHC heavy ion program, including injector performance.  
slides icon Slides TUXGBD2 [5.322 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBD2  
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TUXGBE1 Status and Prospects for the AWAKE Experiment electron, plasma, proton, wakefield 595
 
  • M. Turner
    CERN, Geneva, Switzerland
 
  The AWAKE Collaboration is pursuing a demonstration of proton-driven plasma wakefield acceleration of electrons. The AWAKE experiment uses a §I{400}{GeV/c} proton bunch from the CERN SPS, with a rms bunch length of 6-§I{15}{cm}, to drive wakefields in a §I10{m} long rubidium plasma with an electron density of 1014-1015cm-3. Since the drive bunch length is much longer than the plasma wavelength (λpe<§I{3}{mm}) for these plasma densities, AWAKE performed experiments to prove that the long proton bunch self-modulates in the plasma (2017). The next step is to demonstrate acceleration of electrons in the wakefields driven by the self-modulated bunch (2018). We summarize the concept of the self-modulation measurements and describe the plans and challenges for the electron acceleration experiments.  
slides icon Slides TUXGBE1 [8.883 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBE1  
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TUXGBE2 Study of Ultra-High Gradient Acceleration in Carbon Nanotube Arrays plasma, electron, acceleration, wakefield 599
 
  • J. Resta-López, A.S. Alexandrova, V. Rodin, Y. Wei, C.P. Welsch, G.X. Xia
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • Y. M. Li, Y. Zhao
    UMAN, Manchester, United Kingdom
 
  Solid-state based wakefield acceleration of charged particles was previously proposed to obtain extremely high gradients on the order of 1 − 10 TeV/m. In recent years the possibility of using either metallic or carbon nanotube structures is attracting new attention. The use of carbon nanotubes would allow us to accelerate and channel particles overcoming many of the limitations of using natural crystals, e.g. channeling aperture restrictions and thermal-mechanical robustness issues. In this paper, we propose a potential proof of concept experiment using carbon nanotube arrays, assuming the beam parameters and conditions of accelerator facilities already available, such as CLEAR at CERN and CLARA at Daresbury. The acceleration performance of carbon nanotube arrays is investigated by using a 2D Particle-In-Cell (PIC) model based on a multi-hollow plasma. Optimum experimental beam parameters and system layout are discussed.  
slides icon Slides TUXGBE2 [27.296 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBE2  
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TUXGBE3 Status of Plasma-Based Experiments at the SPARC_LAB Test Facility plasma, electron, focusing, emittance 603
 
  • E. Chiadroni, D. Alesini, M.P. Anania, M. Bellaveglia, A. Biagioni, F.G. Bisesto, E. Brentegani, F. Cardelli, G. Costa, M. Croia, D. Di Giovenale, G. Di Pirro, M. Ferrario, F. Filippi, A. Gallo, A. Giribono, A. Marocchino, L. Piersanti, R. Pompili, S. Romeo, J. Scifo, V. Shpakov, A. Stella, C. Vaccarezza, F. Villa
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    INFN-Roma II, Roma, Italy
  • M. Marongiu, A. Mostacci
    Sapienza University of Rome, Rome, Italy
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • A.R. Rossi
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • A. Zigler
    The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel
 
  The current activity of the SPARC LAB test-facility is focused on the realization of plasma-based acceleration experiments with the aim to provide accelerating field of the order of several GV/m while maintaining the overall quality (in terms of energy spread and emittance) of the accelerated electron bunch. The current status of such an activity is presented, together with results related to the applicability of plasmas as focusing lenses in view of a complete plasma-based focusing, accelerating and extraction system.  
slides icon Slides TUXGBE3 [10.262 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBE3  
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TUYGBE3 Recent progress of short pulse dielectric two-beam acceleration acceleration, linear-collider, collider, wakefield 640
 
  • J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, N.R. Neveu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng
    ANL, Argonne, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  Two-Beam Acceleration (TBA) is a structure-based wakefield acceleration method with the potential to meet the luminosity and cost requirements of a TeV class linear collider. The Argonne Wakefield Accelerator (AWA) facility is developing a dielectric-based short pulse TBA scheme with the potential to withstand high acceleration gradients and to achieve low fabrication cost. Recently, the dielectric short pulse TBA technology was successfully demonstrated using K-band 26 GHz structures, achieving 55 MW output power from the power extractor and 28 MeV/m gradient in the accelerator. To improve the generated rf power, an X-band 11.7 GHz power extractor has been developed, which obtained 105 MW in the high power test. In addition, a novel dielectric disk accelerator (DDA) is currently under investigation to significantly increase the efficiency of linear colliders based on short pulse TBA. Details of these research will be presented in this paper.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBE3  
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TUPAF023 The Beamlines of the CERN East Area Renovation Project target, secondary-beams, radiation, operation 717
 
  • J. Bernhard, M. Bonnet, Q. Bouirek, D. Brethoux, B.D. Carlsen, A. Ebn Rahmoun, J. Etheridge, S. Evrard, L. Gatignon, E. Harrouch, M. Lazzaroni, M. Van Dijk, A. Watrigant
    CERN, Geneva, Switzerland
 
  The East Area at the Proton Synchrotron is one of CERN's longest running facilities for experiments, beam tests, and irradiations with a successful history of over 55 years. The facility serves more than 20 user teams for about 200 days of running each year and offers mixed secondary hadron, electron and muon beams of 0.5 GeV/c to 10 GeV/c. In addition, the primary proton beam or ion beam is transported to the irradiation facilities CHARM and IRRAD. Due to the steadily high user demand, the CERN management approved an upgrade and renovation of the facility to meet future beam test and physics requirements. New beam optics will assure a better transmission and purity of the secondary beams, now also with the possibility of highly pure electron, hadron or muon beams. The upgrade includes a pulsed powering scheme with energy recovering power supplies and new magnets, reducing both power and cooling requirements. Together with the building consolidation, this results in a considerably lower energy consumption. The renovation phase is scheduled during the technical stops between 2018 and 2020. We will give an overview of the project scope including upgrades and future beams.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF023  
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TUPAF025 Multi-turn Study in FLUKA for the Design of CERN-PS Internal Beam Dumps dumping, simulation, operation, proton 724
 
  • J.A. Briz Monago, M. Calviani, F. Cerutti, J.J. Esala, S.S. Gilardoni, F.-X. Nuiry, G. Romagnoli, G. Sterbini, V. Vlachoudis
    CERN, Geneva, Switzerland
 
  The CERN Proton-Synchrotron (PS) accelerator is currently equipped with two internal beam dumps in operation since the 1970's. An upgrade is required to be able to withstand the beams that will be produced after the end of the LIU (LHC Injector Upgrade) project. For the design of the new dumps, the interaction and transport of beam and all secondary particles generated has been simulated using FLUKA. The working principle of the internal beam dump in the PS ring is very peculiar with respect to the other dumps in the CERN accelerator complex. A moving dump intercepts the circulating beam during few milliseconds like a fast scraper. The moving dump shaving the beam, the multi-turn transport of beam particles in the PS accelerator and a time-dependent energy deposition in the dump were modeled. The methodology and the results obtained in our studies for the dump core and downstream equipment will be reported in this contribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF025  
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TUPAF032 Beam Transfer Line Design to the SPS Beam Dump Facility target, proton, extraction, quadrupole 751
 
  • Y. Dutheil, J. Bauche, M. Calviani, L.A. Dougherty, M.A. Fraser, B. Goddard, C. Heßler, J. Kurdej, E. Lopez Sola
    CERN, Geneva, Switzerland
 
  Studies for the SPS Beam Dump Facility (BDF) are ongoing within the scope of the Physics Beyond Collider project. The BDF is a proposed fixed target facility to be installed in the SPS North Area, to accommodate the SHiP experiment (Search for Hidden Particles), which is most notably aiming at studying hidden sector particles. This experiment requires a high intensity slowly extracted 400 GeV proton beam with 4·1013 protons per 1 s spill to achieve 4·1019 protons on target per year. The extraction and transport scheme will make use of the first 600 m of the existing North Area extraction line. In this paper, we will present the design of the additional 600 m of transfer line towards BDF branching off from the existing line and discuss the detailed design of the BDF beam line, its components and optics. We present the latest results on the study and design of a new laminated Lambertson splitter magnet to provide fast switch between the current North Area experiments and the BDF. The latest specification of a dipole dilution system used to reduce the local peak power of the beam on the target is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF032  
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TUPAF035 Observations of SPS Slow-Extracted Spill Quality Degradation and Possible Improvements extraction, quadrupole, power-supply, simulation 761
 
  • F.M. Velotti, H. Bartosik, K. Cornelis, M.A. Fraser, B. Goddard, S. Hirlaender, V. Kain, O. Michels, M. Pari
    CERN, Geneva, Switzerland
 
  The SPS delivers slow extracted proton and heavy ion spills of several seconds to the North Area fixed target experiments with a very high duty factor. Reduced machine reproducibility due to magnetic history and power supply ripples on the main circuits lead however to frequent degradation of the spill duty factor. In this paper, the measured effect of the SPS magnetic history on spill quality and principal machine parameters is presented. Another detailed measurement campaign was aimed at characterising the frequency content and response of the spill to noise on the main power supplies ripples. The main findings of this study will also be reported. Finally, simulations of possible improvements based on the data acquired are discussed, as well as an extrapolation to the possible spill quality after the implementation of the improvements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF035  
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TUPAF038 Prototyping Activities for a New Design of CERN's Antiproton Production Target target, proton, antiproton, operation 772
 
  • C. Torregrosa, M.E.J. Butcher, M. Calviani, J.P.C. Espadanal, R. Ferriere, L. Gentini, E. Grenier-Boley, L. Mircea Grec, A. Perillo-Marcone, R. Seidenbinder, N.S. Solieri, M.A. Timmins, E. Urrutia, V. Vlachoudis
    CERN, Geneva, Switzerland
 
  Antiprotons are produced at CERN by impacting intense proton beams of 26 GeV/c onto a high-Z water-cooled target. The current design consists in an Ir core target in a graphite matrix and inserted in a Ti-6Al-4V assembly. A new target design has been foreseen for operation after 2021 aiming at improving the operation robustness and antiproton production yield, triggering several R&D activities during the last years. First, both numerical (use of hydrocodes) and experimental approaches were carried out to study the core material response under extreme dynamic loading when impacted by the primary proton beam. The lessons learnt from these studies have been then applied to further prototyping and testing under proton beam impact at the CERN-HiRadMat facility. A first scaled prototype consisting in Ta rods embedded in an expanded graphite matrix was irradiated in 2017, while in 2018, the PROTAD experiment will test different real-scale AD-Target prototypes, in which the old water-cooled assembly is replaced by a more compact air-cooled one, and different core geometry and material configurations are investigated. This contribution details these prototyping and testing activities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF038  
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TUPAF039 Electron Cooling Simulation and Experimental Benchmarks at LEIR electron, plasma, simulation, solenoid 776
 
  • A. Latina, H. Bartosik, N. Biancacci, R. Corsini, D. Gamba, S. Hirlaender, A. Huschauer
    CERN, Geneva, Switzerland
 
  A fast and accurate simulation of Electron Cooling has recently been implemented in the tracking code RF-Track. The implementation, which is based on a "hybrid kinetic" model, enables the simulation of a large variety of realistic scenarios, including imperfections such as gradients in the electron density, misalignments of electrons / ions / solenoidal fields, both in the static and in the dynamic regimes. Benchmarks of the simulations against measurements performed at LEIR, using Lead and Xenon ions, are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF039  
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TUPAF041 Residual Gas Ions Characterization from the REXEBIS detector, ISOL, rfq, electron 784
 
  • N. Bidault, M.L. Lozano, J.A. Rodriguez
    CERN, Geneva, Switzerland
 
  The Isotope mass Separator On-Line DEvice (ISOLDE) is a user facility located at CERN where Radioactive Ion Beams (RIBs) are produced from proton collisions onto a target, mass separated and transported to user experimental stations either directly at low energy or after being post- accelerated, notably for nuclear physics studies. Prior to acceleration through the REX/HIE-ISOLDE linear acceler- ator, the ion beam is accumulated, bunched and cooled in a Penning trap (REXTRAP) and afterwards charge-bred in an Electron Beam Ion Source (REXEBIS). Multi-charged radioactive species of interest are then selected by a mass-to- charge (A/q) ratio separator dipole in the Low Energy Beam Transfer Line (LEBT). A method is presented to character- ize the Residual Gas Ion (RGI) background contamination for different operational conditions of the REXEBIS. More particularly, a discussion is held about the influence of the confinement time inside the charge-breeder on the residual gas spectrum. Finally, a method to identify sub-pico-Ampere contaminants is demonstrated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF041  
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TUPAF042 Characterization of the Beam Energy Spread at the REX/HIE-ISOLDE Linac cavity, ISOL, linac, detector 787
 
  • M.L. Lozano, N. Bidault, E. Fadakis, M.A. Fraser, E. Matli, J.A. Rodriguez
    CERN, Geneva, Switzerland
 
  ISOLDE is an on-line radioactive isotope separator located at CERN that works by colliding protons accelerated in the PS Booster into a fixed target and by separating the resultant ionized isotopes using a magnetic separator. The completion of the HIE-ISOLDE superconducting linac allows the acceleration of these ions to energy levels that were not reachable before, opening the door to new experiments in different fields. These experiments often have special requirements in terms of beam intensity and purity, transverse emittance or energy spread. A possible way to reduce the energy spread of the beam delivered to the experimental stations is to use one or more of the superconducting cavities as bunchers. The main results of several tests conducted during the last beam commissioning campaign prove that this mode of operation is feasible and will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF042  
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TUPAF043 Testing the Double-Crystal Setup for Physics Beyond Colliders Experiments in the UA9-SPS Experiment proton, detector, collimation, target 790
 
  • S. Montesano
    CERN, Geneva, Switzerland
 
  Funding: on behalf of the UA9 Collaboration
The UA9 experiment is installed in the CERN SPS to study how coherent interaction in crystalline materials can be used to steer particles beams. Recently, new experiments requiring complex beam manipulations by means of crystals have been proposed in the framework of the Physics Beyond Colliders study group at CERN. In particular, it was proposed to use a first crystal to direct protons from the LHC beam halo on a target placed in the beam pipe and to use a second crystal to deflect the particles produced in the target (double-crystal setup), allowing to measure their polarization. The layout of the UA9 experiment in the CERN SPS has been modified to study the feasibility of the proposed scenario and its compatibility with the delicate environment of a superconducting collider. A first set of measurements was performed in 2017 proving that the protons deflected by the first crystal can be intercepted and successfully deflected by a second crystal. A further upgrade of the experiment in 2018 will allow measuring more precisely the combined efficiency of the two crystals and the beam-induced background.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF043  
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TUPAF045 Studies for Future Fixed-Target Experiments at the LHC in the Framework of the CERN Physics Beyond Colliders Study target, collider, proton, luminosity 798
 
  • S. Redaelli, M. Ferro-Luzzi
    CERN, Geneva, Switzerland
  • C. Hadjidakis
    IN2P3-CNRS, Orsay, France
 
  A study on prospects for Physics Beyond Colliders at CERN was launched in September 2016 to assess the capabilities of the existing accelerators complex. Among several other working groups, this initiative triggered the creation of a working group with the scope of studying a few specific proposals to perform fixed-target physics experiments at the Large Hadron Collider (LHC). This includes for example physics experiments with solid or gaseous internal targets, polarized gas targets, and experiments using bent-crystals for halo splitting from beam core for internal targets. The focus of the working group's activities is on the technical feasibility and on implications to the LHC ring. In this paper, the current status of the studies is presented and future plans are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF045  
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TUPAF050 Beam Dynamics Simulations of the Effect of Power Converter Ripple on Slow Extraction at the CERN SPS extraction, quadrupole, emittance, sextupole 818
 
  • J. Prieto, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel, F.M. Velotti
    CERN, Geneva, Switzerland
 
  The SPS provides slowly extracted protons at 400 GeV/c to CERN's North Area Fixed Target experiments over spills of duration from 1-10 seconds. Low frequency ripple on the current in the main magnets originating from their power converters is a common issue that degrades the slow-extracted spill quality. In order to better understand how the stability of the power converters affects losses, beam emittance and spill quality, particle tracking simulations were carried out using MAD-X and compared to measurements, with the impact of each magnet circuit investigated systematically. The implications for the performance of the SPS slow extraction are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF050  
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TUPAF060 Injection and Dump Systems for a 13.5 TeV Hadron Synchrotron HE-LHC kicker, injection, extraction, septum 858
 
  • W. Bartmann, M.J. Barnes, L. Ducimetière, B. Goddard, M. Hofer, T. Kramer, A. Lechner, E. Renner, A. Sanz Ull, V. Senaj, L.S. Stoel, C. Wiesner
    CERN, Geneva, Switzerland
 
  One option for a future circular collider at CERN is to build a 13.5 TeV hadron synchrotron, or High Energy LHC (HE-LHC) in the LHC tunnel. Injection and dump systems will have to be upgraded to cope with the higher beam rigidity and increased damage potential of the beam. The required modifications of the beam transfer hardware are highlighted in view of technology advancements in the field of kicker switch technology. An optimised straight section optics is shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF060  
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TUPAF078 Recent Results of HESR Original Stochastic Cooling Tanks at COSY kicker, pick-up, storage-ring, hardware 913
 
  • R. Stassen, B. Breitkreutz, N. Shurkhno
    FZJ, Jülich, Germany
 
  The High Energy Storage Ring (HESR) of the FAIR project at GSI Darmstadt will be very important for different scientific programs due to the modularized start version of FAIR. Stochastic cooling together with barrier bucket operation will be the key component to fulfill the requirements of the different experiments. First pickup and first kicker of the HESR stochastic cooling system have been installed into the COSY accelerator at FZJ Jülich. COSY is well suited to test the performance of the HESR stochastic cooling hardware at different energies and variable particle numbers. The novel dedicated HESR-structures were already successfully tested at the Nuclotron in Dubna for longitudinal cooling and during a beam time 2017 for transverse cooling at COSY. The results of the last stochastic cooling beam time will be presented as well as the first use of GaN based amplifiers in a stochastic cooling system. The HESR needs fast transmission-lines between PU and KI. Beside air-filled coax-lines, optical hollow fiber-lines are very attractive. First results with such a hollow fiber used for the transverse signal path will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF078  
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TUPAF081 Measurements and Simulations of the Spill Quality of Slowly Extracted Beams from the SIS-18 Synchrotron sextupole, extraction, synchrotron, resonance 924
 
  • S. Sorge, P. Forck, R. Singh
    GSI, Darmstadt, Germany
 
  In this contribution, results of recent measurements of the spill structure of slowly extracted beams out of the GSI heavy ion synchrotron SIS-18 are presented and compared to results of simulations. Aim of the study is the determination of spill structures at several kHz which arise from ripples in the fields of the accelerator magnets due to imperfections of the magnets' power supplies. The goal of the study is to understand how the ripple is transferred from the magnets to the spill and to find possible ways for spill smoothing. For this purpose a comprehensive simulation model for slow extraction is in preparation which will be validated with beam-based measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF081  
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TUPAF083 SIS100 Tunnel Design and Civil Construction Status site, status, radiation, shielding 927
 
  • C. Omet, J. Falenski, H. Kisker, K. Konradt, P.J. Spiller
    GSI, Darmstadt, Germany
  • A. Fischer
    FAIR, Darmstadt, Germany
 
  As the FAIR Project is proceeding, building designs have been frozen and the according work packages tendered. For the future FAIR main driver accelerator, SIS100, the 1.1 km long accelerator tunnel "T110", has been planned 17 m deep under ground. In this article, environmental boundary conditions, the chosen layout and the current status of civil construction is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF083  
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TUPAK005 Upgrade Plan of J-PARC MR - Toward 1.3 MW Beam Power operation, injection, proton, cavity 966
 
  • T. Koseki
    KEK, Ibaraki, Japan
 
  The Main Ring Synchrotron (MR), a 30-GeV slow cycling proton synchrotron, delivers intense proton beam to a long-baseline neutrino oscillation experiment, T2K, by fast extraction and to an experimental facility, which is called hadron hall by slow extraction. The achieved beam intensities for routine operations are 470 kW ( 2.4 x 1014 ppp) for the fast extraction and 44 kW ( 5.1 x 1013 ppp) for the slow extraction. In order to increase the beam intensity, a plan to replace the magnet power supplies are now in progress for operation with a higher repetition rate. After the replacement, the cycle time will be shortened about a half and increase beam intensities two times larger for the fast extraction. In addition, a further upgrade plan for the fast extraction is mainly reinforcement of rf power supplies. The goal of the upgrade plan is reaching 1.3 MW beam power for the neutrino experiment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK005  
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TUPAK007 Simulation of Surface Muon Beamline, Ultra-Slow Muon Production and Extraction for the J-PARC g-2/EDM Experiment simulation, target, laser, proton 970
 
  • M. Otani, N. Kawamura, T. Mibe, T. Yamazaki
    KEK, Tsukuba, Japan
  • K. Ishida
    RIKEN Nishina Center, Wako, Japan
  • G. Marshall
    TRIUMF, Vancouver, Canada
 
  The E34 experiment aims to measure muon anomalous magnetic moment with a precision of 0.1 ppm to cast light on beyond standard model in elementary particle physics. The experiment utilizes a brand new muon beam line in J-PARC (H line), which is designed to have large acceptance to supply an intense muon beam. The surface muons are injected into a silica aerogel target to generate bound state of muon and electron (muonium). Then the muoniums are ionized by lasers and ultra slow (30 meV) muons (USM) are generated. The USM's are extracted by electro-static lens and injected to a muon linac. In this poster, simulation for optics of the surface muon beamline, muonium production and extraction by the electro-static lens, and the estimation of the USM's intensity are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK007  
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TUPAK009 Muon Profile Measurement After Acceleration With a Radio-Frequency Quadrupole Linac simulation, rfq, linac, positron 977
 
  • M. Otani, Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, T. Yamazaki
    KEK, Tsukuba, Japan
  • S. Bae, H. Choi, S. Choi, B. Kim, H.S. Ko
    SNU, Seoul, Republic of Korea
  • K. Hasegawa, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Iijima, Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • H. Iinuma, Y. Nakazawa
    Ibaraki University, Ibaraki, Japan
  • K. Ishida
    RIKEN Nishina Center, Wako, Japan
  • R. Kitamura
    University of Tokyo, Tokyo, Japan
  • S. Li
    The University of Tokyo, Graduate School of Science, Tokyo, Japan
  • G.P. Razuvaev
    Budker INP & NSU, Novosibirsk, Russia
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • E. Won
    Korea University, Seoul, Republic of Korea
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP16H03987, and JP16J07784.
The E34 experiment aims to measure muon anomalous magnetic moment with a precision of 0.1ppm. The experiment utilizes low emittance muon beam with a muon linac to sweep out beam related uncertainties, which limit the g-2 precision in past experiments. A beam matching with precise beam measurements is required to avoid substantial emittance growth and satisfy the experimental requirement on the beam emittance of around 1.5 pi mm mrad. We conduct profile measurement of muon after acceleration with a radio-frequency quadrupole (RFQ) on December 2017 following a first muon acceleration experiment on October. In the experiment of profile measurement, epi-thermal negative muonium ions are generated by injecting surface muons to a thin metal foil. The muonium ions are accelerated to 5 keV. by an electro-static lens and accelerated to 90 keV by the RFQ. Then the muonium ions are transported to a profile detector consisting of a micro-channel plate and a ccd camera via a quadrupole pair and a bending magnet. In this poster, the experimental result and comparison to the simulation are reported.
 
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TUPAK016 Commissioning of the Diagnostic Beam Line for the Muon RF Acceleration with H Ion Beam Derived from the Ultraviolet Light acceleration, quadrupole, diagnostics, MMI 997
 
  • Y. Nakazawa, H. Iinuma
    Ibaraki University, Ibaraki, Japan
  • N. Kawamura, T. Mibe, M. Otani, T. Yamazaki
    KEK, Ibaraki, Japan
  • R. Kitamura
    University of Tokyo, Tokyo, Japan
  • Y. Kondo
    JAEA/J-PARC, Tokai-mura, Japan
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP16H03987, and JP16J07784.
A muon LINAC is under development for a precise measurement of muon g-2 / EDM at J-PARC. We conducted an experiment of a muon RF acceleration on October and December 2017. The surface muon beam is irradiated to a metal degrader to generate slow negative muonium. The slow negative muoniums are accelerated to 90 keV with an electrostatic accelerator and an RFQ. Prior to muon RF acceleration, we conducted a commissioning of the diagnostic beam line consisting of two quadrupole magnets and a bending magnet. The ultraviolet light is irradiated to an aluminum foil and H ion is generated. It simulates a negative muonium and is accelerated with an electrostatic accelerator. This system allowed us to check operation for the diagnostic beam line, which is essential task for transportation and momentum selection of the negative muonium. In this paper, I would like to report the performance evaluation of the diagnostic beam line by H ions.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK016  
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TUPAL002 Numerical Calibration of the Injection Bump Sizes During the Beam Commissioning for CSNS injection, MMI, flattop, neutron 1011
 
  • M.Y. Huang, S. Wang, S.Y. Xu
    IHEP, Beijing, People's Republic of China
 
  In order to control the strong space charge effects, which cause large beam loss during the injection and acceleration processes, phase space painting method was used for injecting a small emittance beam from the linac into the large acceptance of the Rapid Cycling Synchrotron (RCS). During the beam commissioning, in order to control and optimize the painting results, the positions and ranges of the horizontal and vertical painting should be adjusted accurately. Therefore, the numerical calibration of the injection bump sizes was very important and need to be done as soon as possible. In this paper, a method to calibrate the horizontal and vertical bump sizes was presented and applied to China Spallation Neutron Source (CSNS). The numerical calibration results would be given and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL002  
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TUPAL021 Evaluation of Activated Nuclides Due to Secondary Particles Produced in Stripper Foil in J-PARC RCS proton, radiation, neutron, target 1048
 
  • M. Yoshimoto, S. Kato, M. Kinsho, K. Okabe, P.K. Saha, K. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  Multi-turn charge-exchange beam injection is key technique to achieve the high intensity proton beam accelerators. In the J-PARC RCS, 400MeV H beams from the LINAC are converted to H+ beam with the stripper foils, and then injected into the ring. The stripper foil is irradiated by not only the injecting H beams but also the circulating H+ beams. The high energy and high power beam irradiation into the foil induces the nuclear reactions, and generated secondary neutrons and protons. These secondary particles causes high residual does around the stripper foil. Now, to identify species of secondary particles and to identify energies and emission angles, activation analysis method using the sample pieces is considered. In this presentation, we report the result of the evaluation of this activation analysis with PHITS codes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL021  
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TUPAL028 New Feature of the Oscillating Synchrotron Motion Derived from the Hamiltonian Composed of Three Motions synchrotron, betatron, closed-orbit, storage-ring 1060
 
  • K. Jimbo
    Kyoto University, Kyoto, Japan
 
  The equation for the synchrotron motion was derived from the Hamiltonian, which was composed of coasting, betatron and synchrotron motions*. The betatron oscillation is the horizontal oscillation. The synchrotron oscillation is not only an oscillation of the revolution frequency but also an oscillation of the average radius. The synchrotron oscillation is both longitudinal and horizontal oscillations and it is possible to exchange energy with the betatron oscillation. The synchrotron oscillation occurs under a constant particle velocity and the Hamiltonian is conserved.
*K.Jimbo, Physical Review Special Topics - Accelerator and Beams 19, 010102 (2016).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL028  
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TUPAL045 Towards Operational Scalability for H Laser Assisted Charge Exchange laser, cavity, operation, radiation 1110
 
  • S.M. Cousineau, A.V. Aleksandrov, T.V. Gorlov, Y. Liu, M.A. Plum, A. Rakhman, A.P. Shishlo
    ORNL, Oak Ridge, Tennessee, USA
  • D.E. Johnson, S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  • M.J. Kay
    UTK, Knoxville, Tennessee, USA
 
  The experimental development of H laser assisted charge exchange, a.k.a. laser stripping, has been ongoing at the SNS accelerator since 2006 in a three-phase approach. The first two phases associated with proof-of-principle and proof-of-practicality experiments have been successfully completed and demonstrated >95% H stripping efficiency for up to 10 us. The final phase is a proof-of-scalability stage to demonstrate that the method can be deployed for realistic beam duty factors. The experimental component of this effort is centered on achieving high efficiency stripping through the use of a laser power amplification scheme to recycle the macropulse laser light at the interaction point of the H stripping. Such a recycling cavity will be necessary for any future operational laser stripping system with at least millisecond duration H pulses. A second component of the proof-of-scalability phase is to develop a conceptual design for a realistic laser stripping scheme. The status of these efforts and challenges associated with deploying the recycling cavity into the laser stripping experiment will be described in this talk.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL045  
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TUPAL050 Progress Work on a CW Deuteron RFQ with Magnetic Coupling Windows rfq, cavity, coupling, Windows 1123
 
  • Q. Fu, M.J. Easton, P.P. Gan, S.L. Gao, H.P. Li, Y.R. Lu, Q.Y. Tan, Z. Wang, K. Zhu
    PKU, Beijing, People's Republic of China
  • W.P. Dou, Y. He
    IMP/CAS, Lanzhou, People's Republic of China
 
  Funding: This work was supported by the National Basic Research Program of China (Grant No. 2014CB845503).
A new 162.5 MHz RFQ has been built for a joint 973 project between Peking University (PKU) and Institute of Modern Physics (IMP). It is designed to deliver 50-mA deuteron beams to 1 MeV in CW mode, with an inter-voltage of 60 kV and a length of 1.809 m. Due to its window-type structure, the RFQ has compact cross-section, sufficient mode separation and high specific shunt impedance. It consists of two segments fabricated and installed at IMP. The assembling error of the cavity is less than 0.05 mm. The RF measurements show good electrical properties of the resonant cavity with a measured unloaded quality factor equal to 96.4% of the simulated value. After tuning, we obtained the nominal frequency and field unbalance within 1.0%. Preparation of high-power test of this RFQ is underway. This paper will cover the fabrication details and RF measurements, as well as the progress of high-power test.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL050  
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TUPAL054 Experimental Measurements of Resonances near to the ISIS Working Point resonance, synchrotron, controls, space-charge 1132
 
  • P.T. Griffin-Hicks, B. Jones, B.G. Pine, C.M. Warsop, M. Wright
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  ISIS is the pulsed spallation neutron source located at the Rutherford Appleton Laboratory in the UK. Operation is based on a 50 Hz, 800 MeV proton synchrotron, accelerating up to 3·1013 protons per pulse (ppp), which provides beam to two target stations. ISIS is beam loss limited, so to achieve greater beam intensity and optimal operation, losses must be reduced. Some beam loss may be attributed to resonance lines found in betatron tune space. These could be driven by higher order magnet field components, errors or misalignment. This paper describes work measuring losses against tune space around the ISIS working point. Experiments have been carried out to measure beam loss against tune in the ISIS synchrotron. The experiments were done at low intensity to minimise space charge and intensity effects. Resonance lines that cause beam loss can be clearly identified and provide new information about the machine. The experimental process has been automated in order to decrease experiment duration and to reduce systematic human error. MAD-X models that compare the beam envelope at different points in tune space to the beam pipe aperture are used to distinguish between losses caused by increased envelope size and losses induced by driven resonances.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL054  
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TUPAL057 Preliminary Experiments in Caesium Delivery and Gettering on the ISIS Vespa Source ion-source, plasma, operation, site 1144
 
  • T. M. Sarmento, R.E. Abel, D.C. Faircloth, S.R. Lawrie, J.H. Macgregor, M. Whitehead, T. Wood
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  Caesium capture by graphite at various temperatures 20- 300°C in the VESPA ion source test stand was explored in a preliminary experiment. An accompanying experiment was set up to evaluate the control of caesium boiler delivery in the various ISIS penning sources. Results indicate Cs flux fluctuates at constant settings, which must be accounted for to interpret graphite gettering results. Future studies to identify the cause of fluctuations are considered, and a more rigorous experiment to study the use of graphite is introduced.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL057  
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TUPAL067 Accelerators Validating Antimatter Physics proton, antiproton, electron, FEL 1167
 
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 721559.
The Extra Low Energy Antiproton ring (ELENA) will be a critical upgrade to the unique Antiproton Decelerator facility at CERN and is currently being commissioned. ELENA will significantly enhance the achievable beam quality and enable new experiments. To fully exploit the discovery potential of this facility, advances are urgently required in numerical tools that can adequately model beam transport, life time and interaction, beam diagnostics tools and detectors to fully characterize the beam's properties, as well as in novel experiments that exploit the enhanced beam quality that ELENA will provide. These three areas form the scientific work packages of the new pan-European research and training initiative AVA (Accelerators Validating Antimatter physics). The project has received around 4M€ of funding and brings together universities, research centers and industry to train 15 Fellows through research in this area. This contribution presents the research results across AVA's three scientific work packages.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL067  
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TUPAL069 Experimental Demonstration of Ion Beam Cooling with Pulsed Electron Beam electron, synchrotron, simulation, data-analysis 1174
 
  • Y. Zhang, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M. F. Spata, H. Wang, S. Wang, H. Zhang
    JLab, Newport News, Virginia, USA
  • J. Li, X.M. Ma, L.J. Mao, M.T. Tang, J.C. Yang, X.D. Yang, H. Zhao, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Cooling ion beams at high energy is presently considered for several ion colliders, in order to achieve high luminosities by enabling a significant reduction of emittance of hadron beams. Electron beam at cooling channel in a few to tens MeV can be accelerated by a RF/SRF linac, and thus using bunched electrons to cool bunched ions. To study such cooling process, the DC electron gun of EC35 cooler at the storage ring CSRm, IMP was modified by pulsing the grid voltage. A 0.07-3.5 micro-second pulse length with a repetition frequency of less than 250 kHz and synchronized with the ion revolution frequency was obtained. The first experimental demonstration of cooling of a coasting and bunched ion beam by a pulsed electron beam was carried out. Data analysis indicates the bunch length shrinkage and the momentum spread reduction of bunched 12C+6 ion beam as evidence of cooling. A longitudinal grouping effect of the coasting ion beam by the electron pulses has also been observed*. In this paper, we will present experimental results and comparison to the simulation modelling, particularly on the bunched electron cooling data after carefully analyzing the beam diagnostic signals.
* L.J. Mao et al., Experimental Demonstration of Electron Cooling with Bunched Electron Beam, TUP15, Proceedings of COOL2017, Bonn, Germany
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL069  
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TUPAL076 Result of the First Muon Acceleration with Radio Frequency Quadrupole rfq, acceleration, simulation, target 1190
 
  • R. Kitamura
    University of Tokyo, Tokyo, Japan
  • S. Bae, B. Kim
    SNU, Seoul, Republic of Korea
  • Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, T. Yamazaki
    KEK, Tsukuba, Japan
  • K. Hasegawa, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • H. Iinuma, Y. Nakazawa
    Ibaraki University, Ibaraki, Japan
  • G.P. Razuvaev
    Budker INP & NSU, Novosibirsk, Russia
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP16H03987, and JP16J07784.
J-PARC E34 experiment aims to measure the muon g-2/EDM precisely with novel techniques including the muon linear accelerator. Slow muon source by the metal foil method in order to cool the muon beam has been developed for the muon acceleration test with RF accelerator, because the muon beam derived from the proton driver was the tertiary beam and has a large emittance. The first verification test of the muon acceleration with RFQ was carried out at the muon test beam line of J-PARC MLF in October 2017. The incident surface muons were decelerated by the thin metal foil target and produced the negative muonium ions (Mu-), which is the bound stat of a positive muon and two electrons. After Mu- were extracted by a electrostatic accelerator as the injector of the RFQ, they were accelerated with RFQ to 88.6 keV. The accelerated Mu- were identified by the momentum selection with the bending magnet after the RFQ, and the measurement of the Time-Of-Flight. Accelerated Mu- were easily distinguished from penetrated positive muons by the difference of the polarity. The latest analysis result of the world's first muon acceleration with RFQ will be reported in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL076  
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TUPAL077 2D-3D PIC Code Benchmarking/Anchoring Comparisons For a Novel RFQ/RFI LINAC Design rfq, space-charge, simulation, linac 1194
 
  • S.J. Smith, S. Biedron, A. M. N. Elfrgani, E. Schamiloglu
    University of New Mexico, Albuquerque, USA
  • M.S. Curtin, B. Hartman, T. Pressnall, D.A. Swenson
    Ion Linac Systems, Inc., Albuquerque, USA
  • K. Kaneta
    CICS, Tokyo, Japan
 
  Funding: *The study at the University of New Mexico was supported in part by DARPA Grant N66001-16-1-4042 and gift to the University of New Mexico Foundation by ILS.
In this study, comparisons are made between several particle dynamics codes (namely CST Particle Studio, GPT, and upgraded PARMILA codes) in order to benchmark them. The structure used for the simulations is a novel 200 MHz, 2.5 MeV, CW RFQ/RFI LINAC designed by Ion Linac Systems (ILS). The structure design and parameters are provided, simulation techniques are explained, and results from all three code families are presented. These results are then compared with each other, identifying similarities and differences. Numerous parameters for comparison are used, including the transmission efficiency, Q-factor, E-field on axis, and beam properties. Preliminary anchoring between modeling and simulation performance predictions and experimental measurements will be provided.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL077  
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TUZGBE4 Toward High-Power High-Gradient Testing of mm-Wave Standing-Wave Accelerating Structures coupling, cavity, accelerating-gradient, diagnostics 1224
 
  • E.A. Nanni, V.A. Dolgashev, A.A. Haase, J. Neilson, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • S. Jawla, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
  • S. C. Schaub
    MIT, Cambridge, Massachusetts, USA
  • B. Spataro
    INFN/LNF, Frascati (Roma), Italy
 
  Funding: This work is supported in part by Department of Energy contract DE-AC02-76SF00515 (SLAC) and DE-SC0015566 (MIT).
We will preliminary testing results for single-cell accelerating structures intended for high-gradient testing at 110 GHz. The purpose of this work is to study the basic physics of ultrahigh vacuum RF breakdown in high-gradient RF accelerators. The accelerating structures consist of pi-mode standing-wave cavities fed with TM01 circular waveguide mode. We fabricated of two structures one in copper and the other in CuAg alloy. Cold RF tests confirm the design RF performance of the structures. The geometry and field shape of these accelerating structures is as close as practical to single-cell standing-wave X-band accelerating structures more than 40 of which were tested at SLAC. This wealth of X-band data will serve as a baseline for these 110 GHz tests. The structures will be powered with a MW gyrotron oscillator that produces microsecond pulses. One megawatt of RF power from the gyrotron may allow us to reach a peak accelerating gradient of 400 MeV/m.
 
slides icon Slides TUZGBE4 [4.648 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE4  
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TUZGBE5 A Combined Temperature and Magnetic Field Mapping System for SRF Cavities cavity, operation, SRF, niobium 1228
 
  • J.M. Köszegi, K. Alomari, J. Knobloch, O. Kugeler, B. Schmitz
    HZB, Berlin, Germany
 
  In the past decade, a significant improvement of SRF cavity performance has been achieved, yet a number of performance limiting mechanisms, such as magnetic flux trapping, still exist. We present a diagnostics tool which combines flux expulsion measurement during the superconducting phase transition with temperature mapping during operation. This system has a time resolution for both temperature and magnetic field mapping of 2 ms for full cavity coverage, so that short-lived events, including cavity quenches, can easily be resolved.  
slides icon Slides TUZGBE5 [1.363 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE5  
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TUPMF008 Design, Construction, and Magnetic Field Measurements of a Helical Superconducting Undulator for the Advanced Photon Source undulator, photon, storage-ring, electron 1263
 
  • M. Kasa, S.J. Bettenhausen, J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg
    ANL, Argonne, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
A helical superconducting undulator (HSCU) was developed and installed at the Advanced Photon Source (APS). Implementation of a unique design of the helical coil former allowed for a compact turn around scheme of the conductor at the ends of the device during winding. Inherent to the coil winding design was the gradual reduction of the magnitude of the magnetic field at the ends of the device. The coil former design along with the magnetic measurement results will be described.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF008  
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TUPMF016 Application of SVD Analysis to Deflecting Cavitiy Space Harmonics cavity, simulation, timing, data-analysis 1283
 
  • C. Yao, L. Emery, D. Hui, H. Shang, Y.P. Sun
    ANL, Argonne, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Singular value decomposition (SVD) analysis is a powerful tool for identifying different spatial and timing variation patterns in many fields of researches. Recently we applied complex SVD method to space harmonic analysis of a 13-cell defecting cavity that is built and installed in the APS linac injector for beam phase space characterization and emittance exchange experiments. Real and imaginary space harmonics components are extracted from CST simulated data. Fields inside the iris were expressed in analytic forms and produced good agreement. Work is underway to implement the results into elegant simulation model.
 
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TUPMF034 Measuring the Electrical Center and Field Flatness of 704 MHz Deflecting Cavity for LEReC with Wire Stretching System cavity, simulation, diagnostics, pick-up 1320
 
  • T. Xin, J.M. Brennan, J.C.B. Brutus, K. Mernick, K.S. Smith, B. P. Xiao, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • W. Johnson
    SBU, Stony Brook, New York, USA
  • H. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
704 MHz deflecting cavity was designed for the Low Energy RHIC electron Cooling (LEReC) project. The cavity will serve as a major component in diagnostic line. In LEReC project the requirement on the energy spread of the electron beam is extremely high (better than 10-4) and the diagnostic system has to to be designed accordingly. The 704 MHz transverse deflecting cavity provides the vertical kick to the beam after it passes through the dispersion dipole so that we can measure the energy spread of the core of the bunch. Traditional way of determining the electrical center of the cavity involves the needle pulling and integration of the signal which is prone to the cumulative error. We present the measurement result from a wire stretching system that is much more efficient and accurate compared to the bead/needle pulling method. Both simulation and experimental results are shown in this paper and the potential in further application is discussed at the end.
 
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TUPMF035 First Demonstration of the Transparent Fast-to-slow Corrector Current Shift in the NSLS-II Storage Ring feedback, lattice, operation, photon 1323
 
  • X. Yang, V.V. Smaluk, Y. Tian, L. Yu
    BNL, Upton, Long Island, New York, USA
 
  To realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable (a level of 10% beam size). In the circumstances of implementing local bumps, changing ID gaps, and long-term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fast corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm. Especially when the step size of the shift was below 0.012 A, the amount of noise being added to the beam was none.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF035  
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TUPMF065 The Role of Electron-Phonon Scattering in Transverse Momentum Conservation in PbTe(111) Photocathodes electron, scattering, photon, cathode 1414
 
  • J. K. Nangoi, T.A. Arias
    Cornell University, Ithaca, New York, USA
  • S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
  • W.A. Schroeder
    UIC, Chicago, Illinois, USA
 
  Funding: The U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
The state of the art in creating high quality electron beams for particle accelerator applications and next generation ultrafast electron diffraction and microscopy involves laser-generated photoemission. A high quality beam requires that electrons emerge from the surface with low mean transverse energy (MTE). Recent density-functional theory calculations by T. Li and W. A. S. [arXiv:1704.00194v1 [physics.acc-ph] (2017)] suggest that PbTe(111) will produce low-MTE photoelectrons due to the low effective electron mass associated with its electronic band structure. Based on this, we measured the distribution of photoelectrons from PbTe(111) and found the MTE to be about 20x larger than expected. To explain the apparent lack of transverse momentum conservation, we carried out many-body photoemission calculations including electron-phonon scattering. Our results are in far better agreement with the experiment, underscoring the importance of electron-phonon scattering in photoemission from PbTe(111), and suggest that cooling could mitigate the phonon effects on the MTE for this material.
 
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TUPMF072 Microwave Instability and Energy Spread Measurement via Vertical Dispersion Bump in PETRA III emittance, undulator, quadrupole, wiggler 1427
 
  • Y.-C. Chae, D. Dzhingaev, M. Ebert, G. Falkenberg, J. Keil, G. Kube, G.K. Sahoo, M. Sprung, R. Wanzenberg, F. Westermeier
    DESY, Hamburg, Germany
  • A.I. Novokshonov
    TPU, Tomsk, Russia
 
  The recent measurement of bunch length versus current indicated that the longitudinal impedance (Z/n) is 0.15 Ω in close agreement with the impedance model*. Naive application of Keil-Schnell criteria predicts the threshold of microwave instability at 0.25 mA. Since the single bunch intensity is in the range of 0.2-2.5 mA depending on the fill-pattern of PETRA III, we expect to observe the fill-pattern dependent energy spread according to the theory. However, the 3rd generation light sources comparable to PETRA III often reported the observation which was much greater than the theoretical one. In order to induce the beam size variation we had used skew quadrupoles to generate the dispersion in vertical plane. In particular we made dispersion bump at the undulator sector so that we were able to use the X-ray optics for the precise determination of small vertical beam size. In this paper we report the experimental setup and measurement data with the estimate on the instability threshold. We also report the vertical emittance and energy spread based on the X-ray beam size measurement as well as the RF signal which was excited by the beam at the longitudinal feedback cavity.
* K. Balewski, R. Wanzenberg, "OBSERVATION OF INTENSITY DEPENDENT SINGLE BUNCH EFFECTS AT THE SYNCHROTRON LIGHT SOURCE PETRA III", Proc. of IPAC2011, p. 730.
 
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TUPMF078 Control of FEL Radiation Properties by Tailoring the Seed Pulses FEL, laser, electron, simulation 1444
 
  • V. Grattoni, R.W. Aßmann, J. Bödewadt, I. Hartl, C. Lechner, B. Manschwetus, M.M. Mohammad Kazemi
    DESY, Hamburg, Germany
  • A. Azima, W. Hillert, V. Miltchev, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Khan, T. Plath
    DELTA, Dortmund, Germany
 
  Seeded free-electron lasers (FELs) produce intense, ultrashort and fully coherent X-ray pulses. These seeded FEL pulses depend on the initial seed properties. Therefore, controlling the seed laser allows tailoring the FEL radiation for phase-sensitive experiments. In this contribution, we present detailed simulation studies to characterize the FEL process and to predict the operation performance of seeded pulses. In addition, we show experimental data on the temporal characterization of the seeded FEL pulses performed at the sFLASH experiment in Hamburg.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF078  
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TUPMF085 Status of the sFLASH Experiment FEL, electron, laser, photon 1471
 
  • C. Lechner, R.W. Aßmann, J. Bödewadt, V. Grattoni, I. Hartl, T. Laarmann, M.M. Mohammad Kazemi, A. Przystawik
    DESY, Hamburg, Germany
  • A. Azima, H.B. Biss, M. Drescher, W. Hillert, L.L. Lazzarino, V. Miltchev, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Khan, T. Plath
    DELTA, Dortmund, Germany
 
  Funding: This work is supported by the Federal Ministry of Education and Research of Germany within FSP-302 under FKZ 05K13GU4, 05K13PE3, and 05K16PEA.
The sFLASH experiment at the free-electron laser (FEL) FLASH1 is a setup for the investigation of external FEL seeding. Since 2015, the seeding scheme high-gain harmonic generation (HGHG) is being studied. At the end of the seeded FEL, an RF deflector enables time-resolved analysis of the seeded electron bunches while the photon pulses can be characterized using the technique of THz streaking. In this contribution, we present the current configuration of the experiment and give an overview of recent experimental results.
 
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TUPMK005 CSR Shielding Effect in Dogleg and EEX Beamlines shielding, dipole, simulation, emittance 1498
 
  • G. Ha, M.E. Conde, J.G. Power, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  Funding: Department of Energy, Office of HEP and BES under Contract No. DE-AC02-06CH11357.
CSR shielding is a well-known CSR suppression scheme which works by cutting off the low frequency CSR radiation. Although the shielding scheme is well known, its effects on the beam has been rarely studied. We investigate the CSR effect on the beam emittance when passing through a dogleg and a double dogleg type EEX beamline. An experimental study is planned at the Argonne Wakefield Accelerator facility where we can generate a 0.1-100 nC electron beam with an energy of 50 MeV and have a double dogleg EEX beamline. Tunable shielding plates are installed at the dipole magnet chambers of the EEX beamline to vary the shielding condition. Transverse and longitudinal phase space measurement systems are prepared to characterize the beam-CSR interaction, and bolometer and interferometry are prepared to characterize CSR. We present simulation results and preliminary experimental results.
 
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TUPMK015 Initial Studies into Longitudinal Ionization Cooling for the Muon g-2 Experiment emittance, simulation, storage-ring, target 1522
 
  • J. Bradley
    Edinburgh University, Edinburgh, United Kingdom
  • J.D. Crnkovic
    BNL, Upton, Long Island, New York, USA
  • D. Stratakis, M.J. Syphers
    Fermilab, Batavia, Illinois, USA
  • M.J. Syphers
    Northern Illinois University, DeKalb, Illinois, USA
 
  Fermilab's Muon g-2 experiment aims to measure the anomalous magnetic moment of the muon to an unprecedented precision of 140 ppb. It relies on large numbers of muons surviving many turns in the storage ring without colliding with the sides, at least long enough for the muons to decay. Longitudinal ionization cooling is introduced with respect to Fermilab's Muon g-2 experiment in an attempt to increase storage and through this the statistics and quality of results. The ionization cooling is introduced to the beam through a material wedge, an initial simulation study is made into the positioning, material, and geometrical parameters of this wedge using G4Beamline. Results suggest a significant increase of 20 - 30% in the number of stored muons when the optimal wedge is included in the simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK015  
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TUPMK016 Using Time Evolution of the Bunch Structure to Extract the Muon Momentum Distribution in the Fermilab Muon g-2 Experiment positron, storage-ring, bunching, injection 1526
 
  • W. Wu, B. Quinn
    UMiss, University, Mississippi, USA
  • J.D. Crnkovic
    BNL, Upton, Long Island, New York, USA
 
  Beam dynamics plays an important role in achieving the unprecedented precision on measurement of the muon anomalous magnetic moment in the Fermilab Muon g-2 Experiment. It needs to find the muon momentum distribution in the storage ring in order to evaluate the electric field correction to muon anomalous precession frequency. We will show how to use time evolution of the beam bunch structure to extract the muon momentum distribution by applying a fast rotation analysis on the decay electron signals.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK016  
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TUPMK018 Round Beam Studies at NSLS-II coupling, emittance, resonance, lattice 1529
 
  • Y. Hidaka, W.X. Cheng, Y. Li, T.V. Shaftan, G.M. Wang
    BNL, Upton, Long Island, New York, USA
 
  Funding: The study is supported by U.S. DOE under Contract No. DE-AC02-98CH10886.
Instead of typical flat beam, some synchrotron light us-ers prefer round beam, i.e., with equal horizontal and vertical emittance, for various reasons (e.g., simplified optics, smaller fraction of photons getting discarded, better phase space match between photon and e-beam). Several future upgrade storage rings such as APS-U, ALS-U, and SLS-2 currently plan to operate in round beam mode. We report our beam study results on round beam operating at NSLS-II by driving linear difference cou-pling resonance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK018  
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TUPML006 Updates of the Argonne Cathode Test-stand cathode, laser, electron, gun 1542
 
  • J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng
    ANL, Argonne, Illinois, USA
  • S.P. Antipov, G. Chen, E. Gomez, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S.V. Baryshev
    Michigan State University, East Lansing, Michigan, USA
 
  The Argonne Cathode Test-stand (ACT) is a unique testbed to develop cathodes and to conduct fundamental surface study under ultra-high rf field (up to 700 MV/m with pin-shaped cathodes). The test-stand consists of an L-band 1.3 GHz single-cell photocathode rf gun and a field emission (FE) imaging system to locate emitters with a resolution of ∼20 𝜇m. In the recent upgrade, UV laser has been introduced to improve the imaging system and to significantly expand the ACT towards photoemission and laser-assisted field emission research. In addition, a load-lock system has been added to the beam line to expedite the cathode switching period. The paper will present details of the upgrade as well as experiments planned in the near future.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML006  
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TUPML007 Short Pulse High Power RF Generation with an X-Band Dielectric Power Extractor simulation, acceleration, linear-collider, collider 1546
 
  • J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, N.R. Neveu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng
    ANL, Argonne, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  Short pulse high power rf generation is one of the key technologies for the Argonne Flexible Linear Collider (AFLC), a proposed 3 TeV electron-positron linear collider based on two-beam acceleration (TBA) scheme. Compared with metallic power extractors, dielectric structures have the potential to achieve lower fabrication cost and to withstand higher gradient. Recently, an X-band dielectric power extractor (a.k.a, DPETS) has been developed at the Argonne Wakefield Accelerator (AWA) facility and achieved 105 MW output power when driven by a high charge 8-bunch train separated by 770 ps. The design, the cold test measurement, the preliminary high power test results, and the structure inspection will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML007  
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TUPML009 Design and Test Plan for a Prototype Corrugated Waveguide GUI, wakefield, simulation, electron 1550
 
  • G.J. Waldschmidt, D.S. Doran, G. Ha, R. Kustom, A. Nassiri, J.G. Power, A. Zholents
    ANL, Argonne, Illinois, USA
  • A.E. Siy
    UW-Madison/PD, Madison, Wisconsin, USA
 
  A cylindrical, corrugated wakefield accelerating structure with a 1 mm radius bore is being designed to facilitate sub-terahertz Čerenkov radiation produced by an elec-tron bunch propagating along the waveguide. A 220 GHz axial mode for the wakefield is being considered. The waveguide is being optimized to maximize the trailing wakefield potential while maintaining a ratio of the trail-ing potential to the peak decelerating voltage in the bunch, or transformer ratio, of approximately 5 for the door step peak current distribution [1]. In order to evalu-ate the manufacturing tolerances and perform rf and electron beam testing of the waveguide, a 21 GHz proto-type waveguide structure will be built consisting of re-configurable parts allowing modelling of various fabrica-tion errors. Measurements with an electron beam will be performed at the Argonne Wakefield Accelerator (AWA) test facility. Analysis of the experimental layout has been performed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML009  
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TUPML011 Experiments Producing Nanopatterned Electron Beams electron, FEL, bunching, emittance 1553
 
  • L.E. Malin, W.S. Graves, J. Spence, K. Weiss, C. Zhang
    Arizona State University, Tempe, USA
  • R.K. Li, E.A. Nanni, X. Shen, S.P. Weathersby, J. Yang
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by NSF awards 1632780 and 1231306, DOE award DE-AC02-76SF00515, and the SLAC UED/UEM Initiative Program Development Fund.
RF photoinjectors are increasingly used to image at the nanoscale in much the same way as a Transmission Electron Microscope (TEM), which are generally sub-MeV energy. We have conducted electron diffraction experiments through a thin membrane of single crystal silicon using both the TEM and photoinjector, and have been able to model and predict the diffraction patterns using the multislice method. A nanopatterned single crystal silicon grating was also imaged in the TEM in the bright field, where all but the direct beam of the diffraction pattern is blocked, giving high contrast spatial modulations corresponding to the 400 nm pitch grating lithographically etched into the silicon. Drawing from our previous multislice calculations, we determined the crystallographic orientation that maximized the contrast in this spatial modulation at the energy of the TEM, giving a bunching factor comparable to a saturated FEL. We report on these key steps toward control of radiation phase and temporal coherence in an FEL.
 
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TUPML014 CO2 CPA Laser Development for User Experiments in Advanced Accelerators and Radiation Sources laser, plasma, optics, operation 1556
 
  • M.N. Polyanskiy, M. Babzien, M.A. Palmer, I. Pogorelsky
    BNL, Upton, Long Island, New York, USA
 
  The ATF* is a National User Facility for advanced research in accelerator physics and technology. The ATF's terawatt CO2 laser is a unique scientific instrument allowing researchers to explorer new particle acceleration mechanisms and to study light/matter interaction at an order-of-magnitude longer photon wavelengths compared to the majority of other laser research facilities (λ≈10μm). Continuous development over more than two decades brought the ATF's CO2 laser to the limit of peak power achievable in a conventional gas laser MOPA configuration (in ATF's amplifier geometry this is ~0.5 TW in routine operation, and up to 2 TW in some experiments). To overcome this limit, we employ, for the first time in a gas laser, a chirped-pulse amplification (CPA) scheme. The goal of our current research and development effort is to demonstrate 3-5 TW peak power at the system output and to reliably deliver a large fraction of this power as a high-quality beam to a range of user experiments. Achieving this goal will lay the ground work for implementation of a >10 TW mid-IR laser system "BESTIA" that is currently being constructed as a part of the ATF-II project.
*Accelerator Test Facility at Brookhaven National Laboratory
 
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TUPML015 Influence of Ionization and Beam Quality on Interaction of Tw-Peak Co2 Laser With Hydrogen Plasma laser, plasma, simulation, electron 1560
 
  • P. Kumar, V. Samulyak
    SBU, Stony Brook, USA
  • V. Samulyak, K. Yu
    BNL, Upton, Long Island, New York, USA
 
  3D numerical simulations of the interaction of a powerful CO2 laser with hydrogen jets demonstrating the role of ionization and laser beam quality are presented. Simulations are performed in support of the plasma wakefield accelerator experiments being conducted at the BNL Accelerator Test Facility (ATF). The CO2 laser at BNL ATF has several potential advantages for laser wakefield acceleration compared to widely used solid-state lasers. SPACE, a parallel relativistic Particle-in-Cell code, developed at SBU and BNL, has been used in these studies. A novelty of the code is its set of efficient atomic physics algorithms that compute ionization and recombination rates on the grid and transfer them to particles. The primary goal of the initial BNL experiments was to characterize the plasma density by measuring the sidebands in the spectrum of the probe laser. Simulations, that resolve hydrogen ionization and laser spectra, help explain several trends that were observed in the experiments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML015  
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TUPML017 Longitudinal Phase Space Reconstruction at FLASHForward Using a Novel Transverse Deflection Cavity, PolariX-TDS plasma, dipole, simulation, lattice 1567
 
  • R.T.P. D'Arcy, A. Aschikhin, P. González Caminal, V. Libov, J. Osterhoff
    DESY, Hamburg, Germany
 
  The FLASHForward project at DESY is an innovative beam-driven plasma-wakefield acceleration (PWFA) experiment, aiming to accelerate electron beams to GeV energies over a few centimeters of ionized gas. These accelerated beams are assessed for their capability to drive a free-electron laser. The ultra short, low emittance, and low energy spread properties of bunches produced from certain PWFA injection schemes naturally lend themselves to this task. However, these bunch lengths, typically in the few femtosecond range, are difficult to temporally resolve with traditional diagnostic methods. In order to longitudinally diagnose these bunches it is necessary to utilise the properties of a transverse RF deflecting cavity operating in a high-frequency regime. It is proposed that this type of X-band transverse deflection system, styled the PolariX-TDS due to its novel variable polarisation feature, will be introduced to the FLASHForward beam line in order to perform these single-shot longitudinal phase space measurements. This paper will concern itself with the efficacy of longitudinally reconstructing PWFA-bunches expected at FLASHForward with this TDS, with a focus on the variable bunch properties expected from early commissioning of the experiment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML017  
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TUPML020 Beamline Design of EMuS - the First Experimental Muon Source in China solenoid, proton, target, polarization 1574
 
  • Y. Bao, Y.K. Chen, Z.L. Hou, Y.P. Song, J.Y. Tang, N. Vassilopoulos, Y. Yuan, G. Zhao, L. Zhou
    IHEP, Beijing, People's Republic of China
  • H.T. Jing
    IHEP CSNS, Dongguan, People's Republic of China
 
  Funding: This work is supported by National Natural Science Foundation of China under Grants 11575217 and 11527811. Yu Bao thanks Hundred Talents Program of Chinese Academy of Science.
We report the beamline design of the Experimental Muon Source (EMuS) project in China. Based on the 1.6 GeV/100 kW proton accelerator at the Chinese Spallation Neutron Source (CSNS), EMuS will extract one bunch from every 10 double-bunch proton pulses to hit a stand-alone target sitting in a superconducting solenoid, and the secondary muons/pions are guided to the experimental area. The beamline is designed to provide both a surface muon beam and a decay muon beam, so that various experiments such as muSR applications and particle/nuclear physics experiments can be conducted. In this work we present the conceptual design and simulation of the beamlines, and discuss the future aspects of the project.
 
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TUPML031 Characterization of Polarization-Dependent Emittance From an Array of Au Nanorods using Velocity Map Imaging Spectrometer electron, laser, polarization, emittance 1612
 
  • H. Ye, F.X. Kärtner, S. T. Trippel
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • A. Fallahi, J. Küpper, O. Muecke
    CFEL, Hamburg, Germany
  • F.X. Kärtner
    MIT, Cambridge, Massachusetts, USA
  • F.X. Kärtner, J. Küpper, S. T. Trippel, H. Ye
    The Hamburg Center for Ultrafast Imaging, University of Hamburg, hamburg, Germany
  • J. Küpper, G.M. Rossi
    DESY, Hamburg, Germany
  • H. Ye
    University of Hamburg, Hamburg, Germany
 
  Electron beams of high quality, e.g., low emittance, are of crucial importance for cutting-edge scientific instruments, such as x-ray free electron lasers (XFELs) and ultrafast electron diffraction (UED) setups. A velocity-map-imaging (VMI) spectrometer was implemented to characterize the intrinsic root-mean-square (rms) normalized emittance from photocathodes. The spectrometer operated in both, spatial map imaging (SMI) and VMI modes. Therefore, spatial- and velocity-coordinates were recorded independently and quickly. The technique allows for fast complete emittance measurements, within minutes. A 75 μm pitch array of Au nanorods of dimension 100×30~nm, was studied under strong-field-emission regime by 100 fs 1 kHz 1.3 μm laser pulses with a 300×30 μm2 focus spot size on the sample. A patterned electron bunch was observed, each emitted from a single nanorod within the array. A polarization dependent photoemission study was performed showing a smaller rms-normalized divergence of 0.8 mrad with the laser polarization normal to the sample surface, compared to 1.15 mrad for the parallel case.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML031  
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TUPML039 First Order Sensitivity Analysis of Electron Acceleration in Dual Grating Type Dielectric Laser Accelerator Structures laser, electron, simulation, emittance 1626
 
  • F. Mayet, R.W. Aßmann, U. Dorda, W. Kuropka
    DESY, Hamburg, Germany
  • W. Kuropka, F. Mayet
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Funding: Gordon and Betty Moore Foundation. Grant GBMF4744
Symmetrically driven dual-grating type DLA (Dielectric Laser Accelerator) linac structures allow for in-channel electric field gradients on the order of GV/m at optical wavelengths. In this work we study the sensitivity of important final beam parameters like mean energy, energy spread and transverse emittance on DLA drive laser as well as input beam parameters. To this end a fast specialized particle tracking code (DLATracker) is used to compute the so called first order sensitivity indices based on a large number of Monte Carlo simulation runs of an exemplary external injection based DLA experiment. The results of this work point out important stability constraints on the drive laser setup and the externally injected electron beam.
 
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TUPML046 Characterization of Self-Modulated Electron Bunches in an Argon Plasma plasma, electron, solenoid, focusing 1645
 
  • M. Groß, P. Boonpornprasert, Y. Chen, J. Engel, J.D. Good, H. Huck, I.I. Isaev, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, R. Niemczyk, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan, Q.T. Zhao
    DESY Zeuthen, Zeuthen, Germany
  • R. Brinkmann, A. Martinez de la Ossa, J. Osterhoff
    DESY, Hamburg, Germany
  • F.J. Grüner
    CFEL, Hamburg, Germany
  • F.J. Grüner, A. Martinez de la Ossa
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • T.J. Mehrling, C.B. Schroeder
    LBNL, Berkeley, USA
  • I. Will
    MBI, Berlin, Germany
 
  The self-modulation instability is fundamental for the plasma wakefield acceleration experiment of the AWAKE (Advanced Wakefield Experiment) collaboration at CERN where this effect is used to generate proton bunches for the resonant excitation of high acceleration fields. Utilizing the availability of flexible electron beam shaping together with excellent diagnostics including an RF deflector, a supporting experiment was set up at the electron accelerator PITZ (Photo Injector Test facility at DESY, Zeuthen site), given that the underlying physics is the same. After demonstrating the effect* the next goal is to investigate in detail the self-modulation of long (with respect to the plasma wavelength) electron beams. In this contribution we describe parameter studies on self-modulation of a long electron bunch in an argon plasma. The plasma was generated with a discharge cell with densities in the 1013 cm-3 to 1015 cm-3 range. The plasma density was deduced from the plasma wavelength as indicated by the self-modulation period. Parameter scans were conducted with variable plasma density and electron bunch focusing.
* M. Gross et al., "Observation of the self-modulation instabil-ity via time-resolved measurements", accepted for publication at Phys. Rev. Lett.
 
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TUPML049 Comparison of Fourier Signal and Error Analysis Techniques for Identifying the Self-Modulation Frequency of a Proton Bunch plasma, proton, wakefield, electron 1651
 
  • S.J. Gessner
    CERN, Geneva, Switzerland
 
  The AWAKE experiment uses an ultra-high energy proton beam to create large amplitude wakefields for accelerating electrons in plasma. The proton beam is much longer than the plasma wavelength, and must be formed into small, sub- wavelength sized beamlets before it can effectively drive the wake. These beamlets are referred to as micro-bunches and are formed by the plasma self-modulation instability. An im- portant aspect of AWAKE is to measure the depth, frequency, and stability of the modulation, as this provides critical in- formation for establishing the presence of a high-amplitude wakefield driven by a self-modulation proton bunch. This paper discusses Fourier Analysis techniques for measuring the modulation frequency and compares error estimation techniques that work for both small and large datasets.
On behalf of the AWAKE Collaboration.
 
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TUPML051 Studies of Collision and Compression of Pulsed Plasmas Generated by Coaxial Accelerators plasma, electron, ion-source, simulation 1653
 
  • T. Manegold, C. Benzing, M. Iberler, J. Jacoby, P. Mahmoodi Tavana, A. Müller-Münster, B. Podßus
    IAP, Frankfurt am Main, Germany
 
  This contribution is about our recent studies of collision and compression of plasma sheaths, generated by coaxial plasma accelerators. One application is the development of a pulsed ion source producing high ion currents, coming along with high electron densities. The experiment is built up of an energy storage with up to 1,35kJ with a 2% Hydrogen in Helium gas mixture as working gas. The small fraction of Hydrogen is necessary to use the linear Stark-broadening of the H-line to determine the electron density, which is in the range up to 1015cm-3. By the collision of two plasma sheaths in an angle of 180°, the electron density has been increased by a factor of 2.5 compared to the single plasma sheath. As an alternative, the compression of the plasma by funnel geometries has been studied. As has been found, the achieved electron densities are more than a magnitude higher, compared to the values of the plasma collision. Thus, the H-line is broadened too high to be used. Alternatively, the broadening of a copper line by the quadratic Stark-effect has been calibrated and used to determine those high electron densities of about 1018cm-3.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML051  
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TUPML052 Characterisation of the Second Stable Orbit Generated by Transverse Resonance Island Buckets (TRIBs) optics, resonance, emittance, simulation 1656
 
  • F. Kramer, P. Goslawski, A. Jankowiak, M. Ries, M. Ruprecht, A. Schälicke
    HZB, Berlin, Germany
 
  Funding: Federal Ministry of Education and Research
Operating the storage ring near a transverse tune resonance can generate TRIBs in the corresponding phase space, providing a second orbit twisting around the standard orbit. TRIBs as a bunch separation scheme in combination with the proposed variable bunch length storage ring BESSY VSR* represent a promising alternative to dedicated single or few bunch operation modes. The injection efficiency and stability of the two orbits at BESSY II and MLS are almost on par with and the lifetime at about 70 % of the standard user mode. Results from simulations and measurements of our present island optics will be presented. Beam parameters like the betatron motion, dispersion and emittance of both the core and island orbit will be discussed as well as the separation between the island and the core orbit. At BESSY II a dedicated test week together with the friendly users took place in the first week of February, 2018.
* A. Jankowiak et al., eds., BESSY VSR Technical Design Study, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany, June 2015. DOI: 10.5442/R0001
 
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TUPML060 Three-Dimentional Spiral Beam Injection for a Compact Storage Ring injection, solenoid, coupling, electron 1673
 
  • H. Iinuma
    Ibaraki University, Hitachi, Ibaraki, Japan
  • M.R. Abdul
    Sokendai, Ibaraki, Japan
  • Y. Fukao, K. Furukawa, H. Hisamatsu, T. Mibe, H. Nakayama, S. Ohsawa, K. Oide, K. Sasaki
    KEK, Tsukuba, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP26287055 and JP 23740216.
A newly developed three-dimensional spiral injection scheme for beam insertion into a compact (medical MRI size) solenoidal storage ring is introduced. This is a one of key R&D items for a new planned muon g-2/EDM experiment at J-PARC, which aims to measure g-2 to a factor 5 better statistical precision and a factor of 100 better sensitivity for the electric dipole moment measurement (EDM) compared to the previous experiments. The new scheme provides a smooth injection utilizing a radial solenoidal fringe field, without causing any error field in the storage volume. Magnetic pulsed kicker will guide and set the beam in the storage field volume. The strongest point of this new scheme is that any source of the electric field is removed in this scheme to perform ideal EDM measurement. We have performed a test bench experimental work to demonstrate a feasibility of this new injection scheme. Instead of the muon beam, we inject electron beam, from an electron-gun, into the solenoid magnet, and detect three-dimensional spiral beam trajectory inside of the storage chamber by CCD camera. We will discuss outline of a new injection scheme and the latest results from the test bench works.
*H. Iinuma et al.,Nuclear Instruments and Methods in Physics Research A, 832, 51-62 (2016)
 
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TUPML062 A Wedge Test in MICE emittance, beam-cooling, simulation, collider 1680
 
  • T.A. Mohayai
    IIT, Chicago, Illinois, USA
  • D.V. Neuffer
    Fermilab, Batavia, Illinois, USA
  • P. Snopok
    Illinois Institute of Technology, Chicago, Illlinois, USA
  • D.J. Summers
    UMiss, University, Mississippi, USA
 
  Emittance exchange mediated by wedge absorbers is required for longitudinal ionization cooling and for final transverse emittance minimization for a muon collider. A wedge absorber within the MICE cooling channel could serve as a demonstration of the type of emittance exchange needed for 6-D cooling, including the configurations needed for muon colliders. Parameters for this test have been explored in simulation and applied to experimental configurations using a wedge absorber in the MICE beam. A wedge absorber has been constructed and placed in MICE and data has been collected for both direct emittance exchange, where the longitudinal emittance decreases, and reverse emittance exchange, where the transverse emittance decreases. The simulation studies that led to the magnet configurations and beam configurations are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML062  
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TUPML063 A Non-parameteric Density Estimation Approach to Measuring Beam Cooling in MICE emittance, beam-cooling, simulation, solenoid 1684
 
  • T.A. Mohayai
    IIT, Chicago, Illinois, USA
  • D.V. Neuffer
    Fermilab, Batavia, Illinois, USA
  • P. Snopok
    Illinois Institute of Technology, Chicago, Illlinois, USA
 
  The goal of the international Muon Ionization Cooling Experiment (MICE) is to demonstrate muon beam ionization cooling for the first time. It constitutes a key part of the R&D towards a future neutrino factory or muon collider. The intended MICE precision requires development of analysis tools that can account for any effects (e.g., nonlinearities) which may lead to inaccurate cooling measurements. Non-parametric density estimation techniques, in particular, kernel density estimation (KDE), allow very precise calculations of the muon beam phase-space density and its increase as a result of cooling. In this study, these density estimation techniques and their application to measuring the reduction in muon beam phase-space volume and amplitude in MICE are investigated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML063  
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TUPML064 Staged Two Beam Acceleration Beam Line Design for the AWA Facility kicker, gun, laser, acceleration 1688
 
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  • W. Gai, C.-J. Jing, J.G. Power
    ANL, Argonne, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
Two beam acceleration is a candidate for future high energy physics machines and FEL user facilities. This scheme consists of two independent electron beam lines operating synchronously. High-charge, 70 MeV drive bunch trains are injected from the RF photo-injector into decelerating structures to generate a few hundred of MW of RF power. This RF power is transferred through an RF waveguide to accelerating structures that are used to accelerate the witness beam. Staging refers to the sequential acceleration (energy gain) in two or more structures on the witness beam line. A kicker was incorporated on the drive beam line to accomplish a modular design so that each accelerating structure can be independently powered by a separate drive beam. Simulations were performed in OPAL-T to model the two beam lines. Beam sizes at the center of the structures was minimized to ensure good charge transmission. The resulting design will be the basis for proof of principle experiments that will take place at the Argonne Wakefield Accelerator (AWA) facility.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML064  
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TUPML065 Phase Space Density Evolution in MICE emittance, simulation, factory, collider 1692
 
  • D. Rajaram
    Illinois Institute of Technology, Chicago, Illinois, USA
  • V. Blackmore
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
 
  Funding: STFC, DOE, NSF, INFN, and CHIPP
The Muon Ionization Cooling Experiment (MICE) collaboration will demonstrate the feasibility of ionization cooling, the technique proposed to cool the muon beam at a future neutrino factory or muon collider. The muon beam parameters are measured before and after the cooling cell using high precision scintillating-fibre trackers in a solenoidal magnetic field. Position and momentum reconstruction of each muon in MICE allows the development of several alternative figures of merit in addition to emittance. Contraction of the phase-space volume of the sample, or equivalently the increase in phases-pace density at its core, is an unequivocal cooling signature. Single-particle amplitude, defined as a weighted distance to the sample centroid, can be used to probe the change in density in the core of the beam. Alternatively, non-parametric statistics provide reliable methods to estimate the entire phase-space density distribution and reconstruct probability contours. The aforementioned techniques, robust to transmission losses and sample non linearities, are ideal candidates for a cooling measurement in MICE. Preliminary results are presented here*.
*Submitted by the MICE Speakers bureau, to be prepared and presented by a MICE member to be selected in due course
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML065  
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TUPML067 Recent Results from the Study of Emittance Evolution in MICE emittance, solenoid, detector, lattice 1699
 
  • V. Blackmore
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
 
  Funding: STFC, DOE, NSF, INFN, and CHIPP
The Muon Ionization Cooling Experiment (MICE) has measured the evolution of emittance due to ionization energy loss. Muons were focused onto an absorber using a large aperture solenoid. Lithium-hydride and liquid hydrogen-absorbers have been studied. Diagnostic devices were placed upstream and downstream of the focus, enabling the phase-space coordinates of individual muons to be reconstructed. By observing the properties of ensembles of muons, the change in beam emittance was measured. Data taken during 2016 and 2017 are currently under study to evaluate the change in emittance due to the absorber for muon beams with various initial emittance, momenta, and settings of the magnetic lattice. The current status and the most recent results of these analyses will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML067  
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TUPML071 Experimental Performance of the Chopper for the ESS Linac electron, high-voltage, linac, proton 1709
 
  • G. Torrisi, L. Allegra, A.C. Caruso, G. Castro, L. Celona, G. Gallo, S. Gammino, O. Leonardi, A. Longhitano, D. Mascali, L. Neri, S. Passarello, G. Sorbello
    INFN/LNS, Catania, Italy
 
  At the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS) the beam commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) was completed in November 2017. The ESS requires a high intensity proton beam (74 mA pulsed at 14 Hz of repetition rate), with fast Beam pulse rise/fall time (< 20 µs). In order to meet the project requirement, an electrostatic chopping system has been used in the Low Energy Beam Transport (LEBT). The design of the control system was done also to be the main element of the fast beam abort system and taking into account the radiation issue in the accelerator tunnel. This paper describes the performances of the chopper. The experimentally-achieved rise/fall times of the beam pulses measured by using an AC Current Transformer (ACCT) at the end of the LEBT collimator, are presented. An experimental investigation of the effects of different amounts and types of gas injected into the LEBT (for the sake of space charge compensation) has been carried out with respect to the beam and chopper parameters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML071  
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TUPML074 Resonant Excitation of Accelerating Field in Dielectric Corrugated Waveguide simulation, wakefield, electron, GUI 1715
 
  • A. Lyapin, S.T. Boogert, K. Lekomtsev
    JAI, Egham, Surrey, United Kingdom
  • A. Aryshev
    KEK, Ibaraki, Japan
  • A.A. Tishchenko
    MEPhI, Moscow, Russia
 
  Funding: This project has received funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655179.
Beam driven dielectric wakefield accelerators (DWAs) [*] typically operate in the terahertz frequency range, which pushes the plasma breakdown threshold for surface electric fields into the multi GV/m range. DWA technique allows one to accommodate a significant amount of charge per bunch, and opens access to conventional fabrication techniques for the accelerating structures. Resonant excitation of coherent Cherenkov radiation in DWA by a multi-bunch beam was used for selective resonant mode excitation [**] and enhancement of accelerating wakefield [***]. We investigate the resonant excitation of Cherenkov Smith-Purcell radiation [****] in a corrugated cylindrical waveguide by a multi-bunch electron beam. The accelerating field is calculated using Particle in Cell simulations and some basic post-processing is done in order to estimate the possible enhancement of the accelerating field. The aim of this work is to investigate regimes of the resonant excitation that can potentially produce accelerating gradients above 1 GV/m.
* C. Jing, Rev. Acc. Phys. and Tech. 9, 127 (2016).
** G. Andonian, APL 98, 202901 (2011).
*** J.G. Power, PRSTAB 3, 101302 (2000).
**** A.A. Ponomarenko, A.A. Tishchenko, NIMB 309, 223 (2013).
 
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WEYGBD1 12 GeV CEBAF Initial Operational Experience and Challenges operation, MMI, cryomodule, cavity 1771
 
  • M. F. Spata
    JLab, Newport News, Virginia, USA
 
  The 12 GeV Upgrade for the Continuous Electron Beam Accelerator Facility (CEBAF) achieved CD-4B, or Project Completion, on September 27, 2017. The 13-year $338M project doubled the beam energy of the CEBAF accelerator while also adding a fourth experimental hall. The scope of work for the accelerator complex was completed in 2014. Over the subsequent three years the upgrades for the experimental halls were completed, beamlines and spectrometers commissioned and transitions made to production running for the Nuclear Physics program. This paper will present an overview of the operational experience gained during initial accelerator commissioning through the recent achievements of simultaneous 4-Hall operations at full beam power.  
slides icon Slides WEYGBD1 [15.183 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBD1  
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WEPAF014 Commissioning the Superconducting Magnetic Inflector System for the Muon g-2 Experiment storage-ring, injection, MMI, simulation 1844
 
  • N.S. Froemming
    CENPA, Seattle, Washington, USA
  • K.E. Badgley, H. Nguyen, D. Stratakis
    Fermilab, Batavia, Illinois, USA
  • J.D. Crnkovic
    BNL, Upton, Long Island, New York, USA
  • L.E. Kelton
    UKY, Kentucky, USA
  • M.J. Syphers
    Northern Illinois University, DeKalb, Illinois, USA
 
  The Fermilab muon g-2 experiment aims to measure the muon anomalous magnetic moment with a precision of 140 ppb - a fourfold improvement over the 540 ppb precision obtained in the BNL muon g-2 experiment. Both of these high-precision experiments require an extremely uniform magnetic field in the muon storage ring. A superconducting magnetic inflector system is used to inject beam into the storage ring as close as possible to the design orbit while minimizing disturbances to the storage-region magnetic field. The Fermilab experiment is currently in its first data-taking run, where the Fermilab inflector system is the refurbished BNL inflector system. This discussion reviews the Fermilab inflector system refurbishment and commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF014  
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WEPAF015 Commissioning the Muon g-2 Experiment Electrostatic Quadrupole System quadrupole, storage-ring, positron, resonance 1848
 
  • J.D. Crnkovic, V. Tishchenko
    BNL, Upton, Long Island, New York, USA
  • K.E. Badgley, H. Nguyen, E. Ramberg
    Fermilab, Batavia, Illinois, USA
  • E. Barlas Yucel, M. Yucel
    Istanbul Technical University, Maslak, Istanbul, Turkey
  • J.M. Grange
    ANL, Argonne, Illinois, USA
  • A.T. Herrod
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • A.T. Herrod
    The University of Liverpool, Liverpool, United Kingdom
  • J.L. Holzbauer, W. Wu
    UMiss, University, Mississippi, USA
  • H.D. Sanders
    APP, Freeville, New York, USA
  • H.D. Sanders
    Sanders Pulsed Power LLC, Batavia, Illinois, USA
  • N.H. Tran
    BUphy, Boston, Massachusetts, USA
 
  The Fermilab Muon g-2 experiment aims to measure the muon anomaly with a precision of 140 parts-per-billion (ppb) - a fourfold improvement over the 540 ppb precision obtained by the BNL Muon g-2 experiment. These high precision experiments both require a very uniform muon storage ring magnetic field that precludes the use of vertical-focusing magnetic quadrupoles. The Fermilab Electrostatic Quadrupole System (EQS) is the refurbished and upgraded BNL EQS, where this overview describes the Fermilab EQS and its recent operations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF015  
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WEPAF016 Application of Quad-Scan Measurement Techniques to Muon Beams in the Muon g-2 Experiment emittance, storage-ring, quadrupole, scattering 1852
 
  • J. Bradley
    Edinburgh University, Edinburgh, United Kingdom
  • J.D. Crnkovic
    BNL, Upton, Long Island, New York, USA
  • B.E. Drendel, D. Stratakis
    Fermilab, Batavia, Illinois, USA
  • N.S. Froemming
    CENPA, Seattle, Washington, USA
 
  Determination of the properties of a beam during transport is a vital process for most accelerator-related experiments; for example Fermilab's Muon g-2 experiment requires large numbers of muons to be stored in a storage ring of 7 meter radius, and the transmission fraction has been shown to depend strongly on the properties of the beam, specifically the Twiss parameters. The current equipment in the muon campus beamlines allows only measurement of beam profiles which limits how well propagation can be predicted, however by using the well-studied quad-scan technique it is possible to obtain all of the Twiss parameters at a point using these profiles. Experimental quad-scans of muon beams have not yet been reported, this paper introduces the quad-scan technique and then goes on to discuss the analysis of one such experiment and the results obtained, showing that such a technique is applicable in the muon g-2 experiment to obtain the Twiss parameters without requiring installation of new equipment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF016  
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WEPAF035 Coherent Diffraction Radiation Imaging as an RMS Bunch Length Monitor radiation, FEL, target, detector 1895
 
  • J. Wolfenden, R.B. Fiorito, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • R.B. Fiorito, C.P. Welsch, J. Wolfenden
    The University of Liverpool, Liverpool, United Kingdom
  • T.H. Pacey, T.H. Pacey
    UMAN, Manchester, United Kingdom
  • A.G. Shkvarunets
    UMD, College Park, Maryland, USA
 
  Funding: This work was supported by the EU under Grant Agreement No. 624890 and the STFC Cockcroft Institute core Grant No. ST/G008248/1.
High-resolution bunch length measurement is of the utmost importance for current and future generations of light sources and linacs. It is also key to the optimisation of the final beam quality in plasma-based acceleration. We present progress in the development of a novel RMS bunch length monitor based on imaging the coherent diffraction radiation (CDR) produced by a non-invasive circular aperture. Due to the bunch lengths involved, the radiation produced is in the THz range. This has led to the development of a novel THz imaging system, which can be applied to low energy electron beams. For high energy beams the imaging system can be used as a single shot technique. Simulation results show that the profile of a CDR image of a beam is sensitive to bunch length and can thus be used as a diagnostic. The associated benefits of this imaging distribution methodology over the typical angular distribution measurement are discussed. Plans for experiments conducted at the SwissFEL (PSI, Switzerland), along with plans for future high energy single shot measurements are also presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF035  
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WEPAF058 Detection of X-Rays and Charged Particles via Detuning of the Microwave Resonator coupling, resonance, monitoring, network 1958
 
  • S.P. Antipov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S.V. Kuzikov
    Euclid Beamlabs LLC, Bolingbrook, USA
  • S. Stoupin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
 
  Funding: DOE SBIR
Critically coupled microwave resonator is a finely balanced system, reflection at the resonance is virtually zero. Small changes in dielectric properties of resonator parts destroy this balance, small reflection can be detected from the resonator. This measurement is used in electron paramagnetic resonance studies. In this paper we discuss two accelerator - related applications of this technology. First is related to beam halo measurement taking advantage of high sensitivity of the microwave measurement. High energy particles crossing the diamond inside of a tuned resonator induce a weak conductivity in the sensing material. This small change results in resonator decoupling providing a signal proportional to a number of particles crossing the diamond plate. Second application considered is the x-ray flux monitoring. In this case it is x-ray induced photoconductivity which alters resonator coupling and produces a signal. Interestingly, sensing dielectric material embedded in a resonator can be a diamond or kapton window, refractive lens or part of a silicon monochromator. Thus an inevitable x-ray absorption on optical elements of the beamline is used to monitor x-ray flux online.
 
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WEPAF064 Dependable Implementation of the Beam Interlock Mechanism in CERN Power Converter Controllers controls, operation, software, interface 1975
 
  • M. Di Cosmo, Q. King, R. Murillo-Garcia, D. Nisbet, B. Todd
    CERN, Geneva, Switzerland
 
  At CERN a Beam Interlock System (BIS) protects accelerators from accidental and uncontrolled release of beam energy, avoiding machine downtime. Throughout the accelerator complex numerous critical subsystems, including power converters, interact with the BIS indicating their readiness for operation with beam. Power converters play a vital role in establishing operational conditions, and an unmitigated power converter malfunction could lead to damage to the machine. For example a bending magnet converter set at an incorrect current would result in an incorrect field strength, and beam passing through this may impact and damage the machine. A fast and dependable Beam Interlock Mechanism is required between power converters and BIS, verifying that voltage and current levels are within tolerances. This paper describes the design and realisation of the Beam Interlock Mechanism, based on CERN's Function Generator Controller (FGC), the central processing unit power converter control. Particular emphasis is placed on the system architecture required to assure the integrity of the power converter parameters, and the protection of the CERN accelerator complex.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF064  
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WEPAF070 Commissioning of Beam Instrumentation at the CERN AWAKE Facility After Integration of the Electron Beam Line electron, proton, plasma, laser 1993
 
  • I. Gorgisyan, C. Bracco, S. Burger, S. Döbert, S.J. Gessner, E. Gschwendtner, L.K. Jensen, S. Jensen, S. Mazzoni, D. Medina, K. Pepitone, L. Søby, F.M. Velotti, M. Wendt
    CERN, Geneva, Switzerland
  • M. Cascella, S. Jolly, F. Keeble, M. Wing
    UCL, London, United Kingdom
  • V.A. Verzilov
    TRIUMF, Vancouver, Canada
 
  The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) is a project at CERN aiming to accelerate an electron bunch in a plasma wakefield driven by a proton bunch*. The plasma is induced in a 10 m long Rubidium vapour cell using a pulsed Ti:Sapphire laser, with the wakefield formed by a proton bunch from the CERN SPS. A 16 MeV electron bunch is simultaneously injected into the plasma cell to be accelerated by the wakefield to energies in GeV range over this short distance. After successful runs with the proton and laser beams, the electron beam line was installed and commissioned at the end of 2017 to produce and inject a suitable electron bunch into the plasma cell. To achieve the goals of the experiment, it is important to have reliable beam instrumentation measuring the various parameters of the proton, electron and laser beams such as transverse position, transverse profile as well as temporal synchronization. This contribution presents the status of the beam instrumentation in AWAKE, including the new instruments incorporated into the system for measurements with the electron beam line, and reports on the performance achieved during the AWAKE runs in 2017.
* Gschwendtner E., et al. "AWAKE, the Advanced Proton Driven Plasma Wakefield Experiment at CERN", NIM A 829 (2016)76-82
 
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WEPAF079 A Smart Framework for the Availability and Reliability Assessment and Management of Accelerators Technical Facilities operation, framework, GUI, controls 2024
 
  • L. Serio, A. Castellano, U. Gentile
    CERN, Geneva, Switzerland
  • F. Antonello, P. Baraldi, E. Zio
    Politecnico di Milano, Milan, Italy
 
  CERN operates and maintains a large and complex technical infrastructure serving the accelerator complex and experiments detectors. A performance assessment and enhancement framework based on data mining, artificial intelligence and machine-learning algorithms is under development with the objective of structuring, collecting and analyzing systems and equipment operation and failure data, to guide the identification and implementation of adequate corrective, preventive and consolidation interventions. The framework is designed to collect and structure the data, identify and analyze the associated driving events. It develops dynamically functional dependencies and logic trees, descriptive and predictive models to support operation and maintenance activities to improve the reliability and availability of the installations. To validate the performance of the framework and quality of the algorithms several case studies are being carried out. We report on the design, implementation and on the preliminary results inferred on historical and live stream data from CERN's technical infrastructure. Proposal for the full deployment and expected long-term capabilities will also be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF079  
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WEPAF082 A Systematic Analysis of the Prompt Dose Distribution at the Large Hadron Collider operation, radiation, luminosity, proton 2036
 
  • O. Stein, K. Bilko, M. Brugger, S. Danzeca, D. Di Francesca, R. Garcia Alia, Y. Kadi, G. Li Vecchi, C. Martinella
    CERN, Geneva, Switzerland
 
  During the operation of the Large Hadron Collider (LHC) the continuous particle losses create a mixed particle radiation field in the LHC tunnel and the adjacent caverns. Exposed electronics and accelerator components show dose dependent accelerated aging effects. In order to achieve an optimal lifetime associated to radiation damage, the position of the equipment is chosen in dependency of the amplitude of the radiation fields. Based on the continuous analysis of the data from more than 3900 ionisation chamber beam loss monitors the evolution of the radiation levels is monitored during the accelerator operation. Normalising the radiation fields with either the integrated luminosity or the integrated intensities allows extrapolating the radiation levels of future accelerator operation. In this paper, the general radiation levels in the arcs and the insertion regions at the LHC and their evolution will be presented. The changes in the prompt dose distribution along the LHC between the operation in 2016 and 2017 will be discussed. The impact of different accelerator settings on the local dose distribution will be addressed as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF082  
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WEPAK007 Slow Extraction Spill Characterization From Micro to Milli-Second Scale extraction, power-supply, resonance, betatron 2095
 
  • R. Singh, P. Boutachkov, P. Forck, S. Sorge, H. Welker
    GSI, Darmstadt, Germany
 
  This contribution deals with the topic of slow extraction spill quality characterization based on the measurements performed at GSI SIS-18. The sensitivity of the spill to power supply ripples are studied by introducing external ripples. An estimate of sources of inherent power supply ripples along with ripple magnitude are thus obtained. Spill characterization in time and frequency domain are discussed and exemplified by a typical spill and the differences from an ideal or Poisson spill. An appropriate spill characterization aims to provide a suitable abstraction for communication about the spill quality requirements between accelerator operations and users.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK007  
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WEPAL006 Experimental Study of a Differential Beam Intensity Monitoring for the CIADS LINAC pick-up, linac, monitoring, machine-protect 2155
 
  • Z.P. Xie, Y.K. Ding, J. Liang
    Hohai University, Nanjing, People's Republic of China
  • Y. He, Z.J. Wang, J.X. Wu, Y. Zhang
    IMP/CAS, Lanzhou, People's Republic of China
 
  Funding: Work supported by the National Natural Science Foundation of China (Grant No. 91026001) and the Fundamental Research Funds for the Chinese Central Universities
A BPM based beam loss monitoring scheme for the China initiative accelerator driven subcritical (CIADS) facility has been proposed for the MEBT section of its high power Linac. In this scheme, a differential beam monitoring algorithm is utilized that relies on beam intensity measurements using BPM electrodes. Discussions of the experimental results for the scheme are presented. Further experiments have been performed with some promising results. This paper describes the experimental results with some analyses on measurement errors of the system. The proposed physical design of this system is described and further development is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL006  
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WEPAL011 iPipe: An Innovative Fiber Optic Monitoring System for Beam Induced Heating on Accelerator Pipes monitoring, radiation, operation, detector 2166
 
  • F. Fienga, S. Buontempo, M.R. Masullo
    INFN-Napoli, Napoli, Italy
  • A. Ball, N. Beni, B. Salvant, W. Zeuner
    CERN, Geneva, Switzerland
  • G. Breglio, A. Irace
    University of Napoli Federico II, Napoli, Italy
  • Z. Szillasi
    ATOMKI, Debrecen, Hungary
  • V.G. Vaccaro
    Naples University Federico II and INFN, Napoli, Italy
 
  The iPipe project consists in the instrumentation, with Fiber Bragg Grating sensors (FBGs), of the beam pipe of the CMS experiment, which is part of the LHC. Being spectrally encoded, the FBGs are not sensitive to electromagnetic interference and broadband-radiation-induced losses. These characteristics allow to realize long distance punctual sensing systems, capable to operate in harsh environments like the underground experimental and accelerator facilities at CERN. The iPipe secures the measurement of any deformation induced on the central beam pipe by any motion in the CMS detector due to element displacement or to magnetic field induced deformations. Moreover, the iPipe FBG temperature sensors represent a unique solution to monitor the beam pipe thermal behavior during the various operational and maintenance phases. This paper reports the use of the iPipe to measure the beam induced heating on the CMS vacuum chamber throughout 2016 and 2017. A first comparison between the measurements and the heat load predicted from beam induced RF heating due to the coupling impedance of the CMS pipe is also reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL011  
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WEPAL018 A Non-destructive 2D Profile Monitor Using a Gas Sheet electron, proton, linac, target 2190
 
  • N. Ogiwara, Y. Namekawa
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • M. Fukuda, K. Hatanaka, T. Shima, K. Takahisa
    RCNP, Osaka, Japan
  • Y. Hikichi, J. Kamiya, M. Kinsho
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Hori
    KEK, Tokai, Ibaraki, Japan
 
  We are developing a non-destructive and fast-response beam profile monitor using a dense gas sheet target. To make a gas sheet, we use the beaming effect, which is well known in vacuum science and technology. The emitted molecules through a long rectangular channel, which has a very small ratio of the gap to the width, are forced to concentrate on a plane. The gas sheet with a thickness of 1.5 mm and the density of 2×10-4 Pa was easily generated by the combination of the deep slit and the thin slit. Here, the gas sheet was produced by the deep slit, and the shape of the sheet was improved by the thin slit. The usefulness of this monitor was shown by the following experiments: 1) For the electron beam of 30 keV with a diameter greater than 0.35 mm, the position and the two-dimensional profiles were well measured using the gas sheet. 2) Then the profiles of the 10 and 400 MeV proton beam with a current of several microamperes were well measured, too. 3) Recently, the profiles of the 400 MeV H ion beams in J-PARC linac were measured.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL018  
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WEPAL023 Pulsed Operation at MAMI with High Beam Loading beam-losses, operation, klystron, beam-loading 2206
 
  • M. Dehn, K. Aulenbacher, F. Fichtner, P. Jennewein, W. Klag, H.-J. Kreidel, J.R. Röthgen
    IKP, Mainz, Germany
 
  Funding: Work supported by DFG (CRC 1044) and the German federal state of Rhineland-Palatinate
The Mainz Microtron Accelerator (MAMI) is a microtron cascade which is normally operated CW for particle physics experiments. For certain investigations it is necessary to use a pulsed beam (macro pulses, several milliseconds). Up to now this pulsed mode can only be applied if the beam loading for the accelerating RF structures is negligible. To achieve higher pulse intensities the accelerator RF infrastructure needs to be equipped with feed-forward techniques to compensate for the expected beam loading. To monitor beam losses the machine protection system at MAMI needs to be extended to be able to localize fast occurrences of beam losses. This paper will present the possibilities being investigated to allow pulsed operation of MAMI within the near future.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL023  
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WEPAL024 High Precision Beam Parameter Stabilization for P2 at MESA cavity, electron, controls, resonance 2209
 
  • R.F.K. Kempf, J. Diefenbach
    IKP, Mainz, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
 
  Funding: Cluster of Excellence PRISMA (EXC 1098/2014) German Research Foundation DFG (GRK 2128)
The experiment P2 will measure the weak mixing angle with an all-time high precision via electron-proton scattering. The measured physics asymmetry and its uncertainty has to be corrected by the apparatus' asymmetry, which is generated by helicity correlated fluctuations of the beam parameters position, angle, intensity and energy. This Poster will describe how the high precision of 0.1 ppb of the parity violating asymmetry can be provided by the high precision measurements of the parameters position, angle and intensity.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL024  
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WEPAL034 Bunch Length Measurements Using Coherent Smith-Purcell Radiation With Several Gratings at CLIO booster, radiation, detector, laser 2239
 
  • N. Delerue, S. Jenzer, V. Khodnevych, A. Migayron
    LAL, Orsay, France
  • J.P. Berthet, N. Jestin, J.-M. Ortega, R. Prazeres
    CLIO/ELISE/LCP, Orsay, France
 
  Funding: Financially supported by the Université Paris-Sud (programme "attractivité"), by the French ANR (contract ANR-12-JS05-0003-01) and by IN2P3.
Coherent Smith Purcell radiation allows the measurement of a beam longitudinal profile through the study of the emission spectrum of the radiation emitted when a grating is brought close from the beam. In order to increase the dynamic range of our measurements we have used several gratings and we report on the measured bunch form factor using this technique. We report on these measurements and on the background rejection used.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL034  
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WEPAL041 FPGA Based Optical Phase Control for Coherent Laser Pulse Stacking cavity, controls, FPGA, laser 2265
 
  • Y. Yang, L.R. Doolittle, Q. Du, G. Huang, W. Leemans, R.B. Wilcox, T. Zhou
    LBNL, Berkeley, California, USA
  • A. Galvanauskas
    University of Michigan, Ann Arbor, Michigan, USA
 
  Coherent temporal pulse stacking combines the energy from a train of pulses into one pulse through a series of optical cavities. To stabilize the output energy, the cavity roundtrip phases must be precisely locked to particular values. Leveraging the LLRF expertise we have for conventional accelerators, a FPGA-based control system has been developed for optical cavity phase control. A phase measurement method, ''Modulated Impulse Response'', has been developed and implemented on FPGA. An experiment demonstrated that it can measure and lock the optical phases of four stacking cavities, leading to combination of 25 pulses into one pulse with 1.5 % RMS stability over 30 hours.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL041  
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WEPAL066 Determination of RF Resonator Axis Inclination to Beam Axis in Electron-Positron Storage Ring resonance, kicker, electron, positron 2330
 
  • Leshenok D. Leshenok
    NSU, Novosibirsk, Russia
  • S.A. Nikitin
    BINP SB RAS, Novosibirsk, Russia
 
  We proposed and tested the method that allows obtaining of an upper limit for an angle of the RF resonator axis inclination relative to a beam axis. Such disturbance gives an additional contribution to separation of electron and positron orbits due to action of the transverse component of the electric field. In the horizontal plane, this effect can lead to increase of the difference between electrons and positrons spin precession frequencies in a storage mono-ring collider. This effect can play a great role in FCC. At the angular disturbance of axis in the certain VEPP-4M RF resonators ~10-3 rad, the difference between the spin frequencies is about 10-8. Our method is based on resonant excitation of betatron oscillations using phase modulation of the master oscillator of the RF system. The maximal amplitude of the enforced oscillations is measured by the counting rate of the VEPP-4M Touschek polarimeter scintillation counters. Comparison of the obtained results with the data of the special calibration experiment allows estimating the value of the inclination angle. In this calibrated experiment the betatron oscillations excite using the VEPP-4M kicker.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL066  
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WEPMF009 Influence of Argon-Ion Irradiation on Field Emission from Polycrystalline Cu and Large-Grain NB Surfaces radiation, niobium, cavity, vacuum 2384
 
  • S. Soykarci
    University of Wuppertal, Wuppertal, Germany
  • D. Lützenkirchen-Hecht, V. Porshyn, P. Serbun
    Bergische Universität Wuppertal, Wuppertal, Germany
 
  Funding: This work is funded by the BMBF project 05H15PXRB1.
In the present work, systematic investigations of the enhanced field emission (EFE) from polycrystalline copper and large grain niobium surfaces before and after argon-ion irradiation with an energy of 5 keV were performed with a variation of the irradiation time. Results show that the suppression of the EFE might be achievable.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF009  
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WEPMF010 Laser Treatment of Niobium Surface for SRF Aplications laser, cavity, niobium, electron 2387
 
  • V. Porshyn, D. Lützenkirchen-Hecht, P. Serbun
    Bergische Universität Wuppertal, Wuppertal, Germany
  • H. Bürger, S. Soykarci
    University of Wuppertal, Wuppertal, Germany
 
  Funding: The research was funded by the German Federal Ministry of Education and Research (BMBF) under project number 05H15PXRB1.
We report on a laser surface treatment of high purity niobium (110) single crystals. Typical surface defects like scratches, pits, sharp rims and holes were eliminated by a focused pulsed ns-laser beam. A laser fluence of about 0.68 J/cm2 and 40 - 80 pulses per spot were required to induce well detectable surface modifications. The remelted surface was sufficiently smooth, but exhibited also a number of wave structures. Thus, the surface roughness slightly increased with increasing number of pulses. Finally, boiling traces and µm-deep ablation were observed and studied as well. Local field electron emission measurements showed no emission up to 700 MV/m from a moderate remelted area below the boiling point.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF010  
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WEPMF032 Experimental Studies on Secondary Electron Emission Characteristics for Chamber Materials of Accelerators electron, detector, vacuum, neutron 2425
 
  • Y. Jiao, Z. Duan, W.B. Liu, Y.D. Liu
    IHEP, Beijing, People's Republic of China
  • Liu. S. Liu
    Institute of High Energy Physics (IHEP), People's Republic of China
  • P.C. Wang
    DNSC, Dongguan, People's Republic of China
 
  Funding: National Natural Science Foundation of China (11275221) and Key Laboratory Foundation of Particle Acceleration Physics &Technology (Y5294106TD)
Secondary electron emission (SEE) of surface is origin of multipacting effect which could seriously deteriorate beam quality and even perturb the normal operation of particle accelerators. Experimental measurements on secondary electron yield (SEY) on different materials and coating have been developed in many accelerator laboratory. In fact, the SEY is just one parameter of secondary electron emission characteristics which include spatial and energy distribution of emitted electrons. A novel experimental apparatus was set up in China Spallation Neutron Source (CSNS) and innovative measurement methods were applied to obtain the whole characteristics of SEE. With some traditional accelerator chamber materials such as Cu, Al, TiN, SEY dependence on primary electron energy and beam injection angle, spatial and energy distribution of emitted secondary electrons were achieved with this measurement apparatus. This contribution also tries to give all the experimental results a reasonable theoretical analysis.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF032  
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WEPMF039 Experimental Results on the Field and Frequency Dependence of the Surface Resistance of Niobium Cavities cavity, niobium, vacuum, electron 2451
 
  • P.N. Koufalis, M. Liepe, J.T. Maniscalco, T.E. Oseroff
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  We investigate the field and frequency dependence of the surface resistance of single-cell niobium cavities as a function of surface treatment at 1.3, 2.6, and 3.9 GHz. The surface resistance is broken down into two parts: the temperature-independent residual resistance and the temperature-dependent BCS resistance. While the low-field BCS resistance is known to vary quadratically with frequency, the exact dependence of the BCS and residual resistances on field at higher frequencies are important topics for further investigation. We offer results on a systematic experimental study of the residual and BCS resistance as a function of frequency and field for clean niobium and high-temperature nitrogen-doped niobium.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF039  
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WEPMF041 Insights into the Role of C, N, and O Introduced by Low Temperature Baking on Niobium Cavity Performance cavity, niobium, ECR, superconductivity 2455
 
  • P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Previous experiments have shown that introducing nitrogen gas during low temperature bakes (120-160 C) of niobium cavities introduces C, N, and O impurities to the first 10-100 nm of the surface. This new treatment results in higher quality factors and even 'anti-Q-slope' in some cases. However, it is not entirely clear the role that each of these impurities plays in the performance enhancement of the cavities. It has been suggested that interstitial N within the first few nm of the surface is solely responsible for the observed enhancement, but little work has been done on the role of C and O. Because both C and O are abundant in much higher quantities than N near the surface, it is important to understand whether they are beneficial or detrimental to cavity performance. We provide further insight into the effects of C and O on cavity performance by baking in an ambient atmosphere rich in CO2 as opposed to N2.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF041  
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WEPMF046 Modeling of the Frequency and Field Dependence of the Surface Resistance of Impurity-Doped Niobium cavity, niobium, ECR, SRF 2471
 
  • J.T. Maniscalco, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  The anti-Q-slope, a field-dependent decrease in surface resistance observed in impurity-doped niobium, has been investigated extensively in 1.3 GHz cavities. New early research into this effect has recently been performed at higher and lower frequencies, revealing an additional dependence on frequency: the anti-Q-slope is stronger at higher frequencies and weaker at lower frequencies. Several models have been proposed to explain the anti-Q-slope, with varying success in this new frequency-dependent regime. In this work, we analyze recent experimental data from a low-temperature-doped 1.3 GHz cavity and a high-temperature nitrogen-doped 2.6 GHz cavity and discuss the implications of these results on the proposed models.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF046  
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WEPMF057 PETRA III Vacuum System - Experiences from the First Decade of Operation vacuum, operation, radiation, photon 2499
 
  • L. Lilje, R. Bospflug, N. Plambeck
    DESY, Hamburg, Germany
 
  In 2008 the construction of the PETRA III vacuum system started. A year later the first photons were delivered to initial experiments and in 2010 the user operation started. In this paper the operation of the vacuum system will be reviewed. Some of the lessons learned in the initial phase will be presented as well as the main upgrades since then. By now the vacuum system has shown a very high reliability and shows no significant impact on the availability of the machine.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF057  
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WEPMF071 Dynamic Testing and Characterization of Advanced Materials in a New Experiment at CERN HiRadMat Facility target, damping, site, proton 2534
 
  • A. Bertarelli, C. Accettura, E. Berthomé, L. Bianchi, F. Carra, C. Fichera, M.I. Frankl, G. Gobbi, P. Grosclaude, M. Guinchard, A. Lechner, M. Pasquali, S. Redaelli, E. Rigutto, O. Sacristan De Frutos
    CERN, Geneva, Switzerland
  • Ph. Bolz, P. Simon
    GSI, Darmstadt, Germany
  • T.R. Furness
    University of Huddersfield, Huddersfield, United Kingdom
  • J. Guardia Valenzuela
    Universidad de Zaragoza, Zaragoza, Spain
  • P. Mollicone, M. Portelli
    UoM, Msida, Malta
 
  Funding: This work has received funding from the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871.
An innovative and comprehensive experiment (named "Multimat") was successfully carried out at CERN HiRadMat facility on 18 different materials relevant for Collimators and Beam Intercepting Devices. Material samples, tested under high intensity proton pulses of 440 GeV/c, exceeding the energy density expected in HL-LHC, ranged from very light carbon foams to tungsten heavy alloys, including novel composites as graphite/carbides and metal/diamond without and with thin-film coatings. Experimental data were acquired relying on extensive integrated instrumentation (strain gauges, temperature sensors, radiation-hard camera) and on laser Doppler vibrometer. This allows investigating relatively unexplored and fundamental phenomena as dynamic strength, internal energy dispersion, nonlinearities due to inelasticity and inhomogeneity, strength and delamination of coatings and surfaces. By benchmarking sophisticated numerical simulations against these results, it is possible to establish or update material constitutive models, which are of paramount importance for the design of devices exposed to interaction with particle beams in high energy accelerators such as the HL-LHC or FCC-hh.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF071  
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WEPMF079 Experimental Modal Analysis of Lightweight Structures used in Particle Detectors: Optical non-contact Method laser, detector, operation, GUI 2565
 
  • M. Guinchard, M. Angeletti, F.B. Boyer, A. Catinaccio, C.G. Gargiulo, L.L. Lacny, E.L. Laudi, L.S. Scislo
    CERN, Geneva, Switzerland
 
  CERN's specialized structures such as particle detectors are built to have high rigidity and low weight, which comes at a cost of their high fragility. Shock and vibration issues are a key element for their successful transport, handling operations around the CERN infra-structure, as well as for their operation underground. The experimental modal analysis measurement technique is performed to validate the Finite Element Analysis in the case of complex structures (with cables and substructure coupling). In the case of lightweight structures, standard contact measurements based on accelerometers are not possible due to the high mass ratio between the accelerometers and the structure itself. In such a case, the vibration of the structure can be calculated based on the Doppler shift of the laser beam reflected off the vibrating surface. This paper details the functioning and application of an advanced laser-scanning vibrometry system, which utilizes the fore-mentioned non-contact method. The results of the Experimental Modal Analysis of selected lightweight structure using this instrument is also presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF079  
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WEPMF080 Investigation and Estimation of the LHC Magnet Vibrations Induced by HL-LHC Civil Engineering Activities civil-engineering, network, operation, monitoring 2568
 
  • M. Guinchard, M. Cabon, C. Charrondière, K. Develle, P. Fessia, L.L. Lacny, J.A. Osborne, L.S. Scislo, J. Wenninger
    CERN, Geneva, Switzerland
 
  HL-LHC requires the excavation of large underground infrastructures in order to host new equipment. The tunnel shall be ready for installation for LS3 (2022) and therefore its construction shall take in place in parallel with the LHC exploitation. Effect of vibrations induced by civil engineering activities need to be evaluated in order to take required corrective actions. For this purpose, several diverse measurements and experiments have been performed in order to estimate the vibration sources and determine the vibration transfer path through the floor and the structure. The transfer functions from amplitude and phase point of view were determined through molasses rock, for both horizontal and vertical vibrations, with dedicated tools and Experimental Modal Analysis was carried out on mechanical structure. The campaign of measurements have been used to confirm the effect of the surface induced vibration on the circulating beam orbit at the resonance frequencies of the structure. This paper reviews the advanced technique of measurements, results and the conclusion about the impact of operating civil engineering machines (road header, hydraulic hammer) during beam exploitation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF080  
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WEPMF081 Mechanical Strain Measurements Based on Fiber Bragg Grating Down to Cryogenic Temperature - R&D Study and Applications radiation, cryogenics, superconducting-magnet, GUI 2572
 
  • M. Guinchard, A. Bertarelli, L. Bianchi, F.B. Boyer, M. Cabon, M. Calviani, O. Capatina, A. Catinaccio, P. Ferracin, P. Grosclaude
    CERN, Geneva, Switzerland
 
  In recent years, optical fiber sensors have been increasingly used due to their outstanding performances. Their application is preferable in case of special requirements that exclude the application of conventional electrical sensors. The scientific background of optical fiber sensors is well developed. However, the characteristic of sensors employed in rather harsh environments is often different from the one determined in laboratory conditions or prior to their installation. In order to achieve long-term stable functioning and reliable measurement under severe working environments, such as those occurring at CERN (radiation, cryogenics, high magnetic and electrical field), a statistical measurement campaign was carried out following the international standard ISO 5725. The paper describes the ongoing study to define the accuracy of optical fiber sensors based on Fiber Bragg Grating (FBG) for strain measurements, from room temperature down to 4.2 K. It also describes some of the demanding applications for which optical fiber sensors have been deployed to perform experimental strain measurements (e.g. detectors components, high-energy beam targets and dumps, superconducting magnets).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF081  
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WEPMF083 Comparison of Superconducting Septa Topologies and Parameter Space Exploration septum, dipole, shielding, target 2578
 
  • M.G. Atanasov, J.C.C.M. Borburgh, M. Hourican, A. Sanz Ull
    CERN, Geneva, Switzerland
 
  The unprecedented energy scale of the FCC poses challenging requirements for its magnetic elements including the septum magnets for injection and extraction. With an ambitious target field of 4 T and an apparent septum thickness of only 25 mm, different superconducting septa topologies have been investigated to explore their limitations. This article will cover the currently feasible topologies, amongst which the truncated cosine-theta, the double truncated cosine-theta, the superconducting shield (SuShi) and the so called stealth dipole. A performance figure of merit will be proposed, taking into account the maximum achievable magnetic field, the septum thickness and the leak field magnitude.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF083  
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WEPMF087 LHC Injectors Upgrade Project: Outlook of the Modifications to the Super Proton Synchrotron (SPS) Vacuum System and Impact on the Operation of the Carbon-Coated Vacuum Chambers vacuum, impedance, proton, extraction 2589
 
  • C. Pasquino, G. Bregliozzi, P. Chiggiato, P. Cruikshank, A. Farricker, A. Harrison, J. Perez Espinos, J.A.F. Somoza, M. Taborelli, C. Vollinger
    CERN, Geneva, Switzerland
 
  Aiming at doubling the beam intensity and reducing the beam emittance, significant modifications of the LHC and its injector chain will take place during Long Shutdown 2 (LS2), starting from 2019. The LIU project (LHC Injector Upgrade), in the specific, touches Linac4, the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) as well as the heavy ion chain. During LS2, important changes will take place mainly in the Long Straight Sections of the SPS to host a newly conceived dumping system, upgraded RF cavities and upgraded extraction channels. Additionally, the vacuum chambers of the main bending and focusing magnets as well as vacuum drifts will be coated with amorphous carbon in order to reduce the dynamic pressure effects induced by multipacting. The modifications to the different vacuum sectors will be described in details as well as the impact on operation of amorphous carbon coated sectors that have been already deposited.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF087  
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WEPMF090 Upgrade of the CMS Experimental Beam Vacuum During LS2 vacuum, detector, operation, luminosity 2596
 
  • J.S. Sestak, G. Bregliozzi, P. Chiggiato, C. Di Paolo
    CERN, Geneva, Switzerland
 
  Starting from December 2018, the Large Hadron Collider (LHC) is going to interrupt its physic operations for more than two years within the period called second long shutdown (LS2). The Compact Muon Solenoid (CMS) experiment will undergo the biggest upgrade of its experimental beam vacuum system since the first operations in 2008. The new experimental vacuum layout should comply with demanding structural, vacuum, integration and physics requirements. Moreover, the new layout should be compatible with foreseen engineering changes of the detector and the machine during the upgrade phase of High-Luminosity LHC in LS3. This paper gives an overview of the CMS LS2 experimental vacuum sectors upgrades. Both design and production phase of the new vacuum layout is discussed in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF090  
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WEPMG002 Beam Dump Facility Target: Design Status and Beam Tests in 2018 target, radiation, operation, simulation 2604
 
  • E. Lopez Sola, O. Aberle, P. Avigni, L. Bianchi, J. Busom, M. Calviani, M. Casolino, J.P.C. Espadanal, M.A. Fraser, S. Girod, B. Goddard, D. Grenier, M. Guinchard, C. Heßler, R. Illan Fiastre, R. Jacobsson, M. Lamont, A. Ortega Rolo, B. Riffaud, G. Romagnoli, L. Zuccalli
    CERN, Geneva, Switzerland
 
  The Beam Dump Facility (BDF) Project, currently in its design phase, is a proposed general-purpose fixed target facility at CERN, dedicated to the Search for Hidden Particles (SHiP) experiment in its initial phase. At the core of the installation resides the target/dump assembly, whose aim is to fully absorb the high intensity 400 GeV/c SPS beam and produce charmed mesons. In addition to high thermo-mechanical loads, the most challenging aspects of the proposed installation lie in very high energy and power density deposition that are reached during operation. In order to validate the design of the BDF target, a scaled prototype is going to be tested during 2018 in the North Area at CERN, upstream the existing beryllium primary targets. The prototype testing under representative beam scenarios will allow having an insight of the material response in an unprecedented regime. Online monitoring and an extensive Post Irradiation Experimental (PIE) campaign are foreseen. The current contribution will detail the design and handling aspects of the innovative Target Complex as well as the design of the BDF target/dump core and the design and construction of the prototype target assembly.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMG002  
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WEPMK008 In-Depth Analysis of the Vertical Test Results of the Third-Harmonic Cavities for the E-XFEL Injector cavity, FEL, feedback, SRF 2644
 
  • M. Bertucci, A. Bignami, A. Bosotti, J.F. Chen, C.G. Maiano, P. Michelato, L. Monaco, R. Paparella, P. Pierini, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • C.G. Maiano, P. Pierini
    ESS, Lund, Sweden
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
 
  The results of the vertical tests performed at LASA on the 3.9 GHz third-harmonic cavities for the E-XFEL injector are here discussed. Analysis of experimental data allows to confirm that such high frequency cavity, prepared with standard BCP treatment and 800°C annealing treatment, suffers an intrinsic performance limitation at around 22 MV/m (@ 2 K) due to a global thermal dissipation mechanism. A quantitative interpretation of the high field Q slope is also presented according to the latest theoretical models of field-dependent surface resistance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK008  
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WEPMK012 Update on Plasma Processing R&D for LCLS-II plasma, cavity, HOM, SRF 2656
 
  • P. Berrutti, A. Grassellino, T.N. Khabiboulline, M. Martinello
    Fermilab, Batavia, Illinois, USA
  • M. Doleans, S.-H. Kim, K.E. Tippey
    ORNL, Oak Ridge, Tennessee, USA
  • D. Gonnella, G. Lanza, M.C. Ross
    SLAC, Menlo Park, California, USA
 
  Funding: Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
SRF cavities performance preservation is crucial, from vertical test to accelerator operation. Field emission is still one of the main problems to overcome and plasma cleaning has been proven successful by SNS, in cleaning field emitters and increasing the work function of Nb. A collaboration has been established between FNAL, SLAC and ORNL with the purpose of applying plasma processing to LCLS-II cavities, in order to minimize and overcome field emission without affecting the high Q of N-doped cavities. The recipe will follow the neon-oxygen active plasma adopted at SNS, allowing in-situ processing of cavities and cryomodules from hydrocarbon contaminants. A novel method for plasma ignition has been developed at FNAL: a plasma glow discharge is ignited using high order modes to overcome limitations imposed by the fundamental power coupler. The results of experiments on 9-cell LCLS-II cavity are presented, along with plasma ignition studies. In addition the RF system is shown and N-doped Nb samples studies are discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK012  
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WEPML002 Design of 650 MHz Tuner for PIP-II Project cavity, interface, simulation, linac 2671
 
  • Y.M. Pischalnikov, S. Cheban, J.C. Yun
    Fermilab, Batavia, Illinois, USA
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The Proton Improvement Plan (PIP) II project at Fermilab is a proton driver linac which will use of five different cavity geometries including a 650 MHz 5-cell elliptical cavities that will operate in RF-pulse mode. Detuning of these cavities by Lorentz Forces will be large and strongly depend of the stiffness of the cavity's tuner. First prototype tuner built and tested warm [1,2]. Measured stiffness of the prototype tuner was below 30kN/mm instead of expected from simulation 70kN/mm [2]. Significant effort has been invested into understanding discrepancy between simulation and experimental data that led to newest tuner design. Updated 'dressed cavity-helium vessel-tuner' model provided consistent results between ANSYS simulations and experiment results. Modified tuner design and analysis in limitations for overall 'cavity/tuner system' stiffness will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML002  
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WEPML013 Anti-Q-slope enhancement in high-frequency niobium cavities cavity, ECR, niobium, SRF 2707
 
  • M. Martinello, S. Aderhold, S.K. Chandrasekaran, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A.S. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
 
  N-doped 1.3 GHz niobium cavities showed for the first time the so-called anti-Q-slope, i.e. the increasing of the Q-factor as a function of the accelerating field. It was verified that the anti-Q-slope is consequence of the decreasing of the temperature-dependent component of the surface resistance as a function of the field. This trend is opposite compared to the increasing of the surface resistance previously observed in 1.3 GHz standard (EP, BCP, 120 C baked) niobium cavities. The effect of the different state-of-the-art surface treatments on the field dependence of the surface resistance is studied for 650 MHz, 1.3 GHz, 2.6 GHz and 3.9 Ghz cavities. This proceeding shows that the field dependence of the temperature-dependent component of the surface resistance has a strong frequency dependence and that the anti-Q-slope may appear even in clean niobium cavities if the resonant frequency is high enough, suggesting new routes toward the understanding of the anti-Q-slope effect.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML013  
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WEPML025 Advantages and Challenges of Nb3Sn Superconducting Undulators undulator, site, operation, photon 2734
 
  • A.V. Zlobin, E.Z. Barzi, D. Turrioni
    Fermilab, Batavia, Illinois, USA
  • Y. Ivanyushenkov, I. Kesgin
    ANL, Argonne, Illinois, USA
 
  Funding: This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Superconducting undulators (SCUs) employ superconducting coils, and due to high critical current density in a superconductor, outperform undulators based on permanent magnets in terms of the level of magnetic field. So far, most of the SCUs, including devices built at Advanced Photon Source (APS), use Nb-Ti superconductor. Utilization of Nb3Sn conductor offers a possibility to increase the undulator field even further but requires to overcome certain challenges that are described in this paper. Based on experience of developing Nb3Sn accelerator magnets at Fermi National Accelerator Laboratory, possible solutions are discussed. The achievable field levels for Nb3Sn version of existing APS and the future APS-Upgrade superconducting undulators are also presented and discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML025  
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WEPML038 Plasma Window as a Pressure Valve for FAIR plasma, cathode, electron, vacuum 2776
 
  • B. F. Bohlender, M. Iberler, J. Jacoby
    IAP, Frankfurt am Main, Germany
  • A. Michel
    Goethe Universität Frankfurt, Frankfurt am Main, Germany
 
  Funding: Funded by BMBF, Ref. No: 05P15 RFRBA and HIC for FAIR
This contribution shows the progress in the development of a plasma window at the institute for applied physics at Goethe University Frankfurt. A plasma window* is a membrane free transition between two regions of different pressure, enabling beam transmission from a rough vacuum area (~1 mbar) to a higher pressure (up to 1 bar) region on short length scales. In comparison to differential pumping stages a length reduction by a factor of up to 100 is achievable, while the absence of a solid membrane yields prolonged operation time. The sealing effect is based on the high temperature arc discharge sustained in a cooled copper channel between the pressure regimes. Due to a bulk temperature around 10,000K** the viscosity of the gas is dramatically increased, leading to a slower gas flow, enabling a higher pressure gradient. This contribution will present first results regarding the pressure gradient in dependence of the discharge current and the aperture. Until now, a pressure factor around 100 has been established for well over 50 min. This contribution goes along with the one from Mr. A. Michel, he focuses on the spectroscopic analysis of the arc plasma.
*A. Hershcovitch, J. Appl. Phys., AIP Publishing (1995) 78, 5283
**Y.E. Krasik et al., "Plasma Window Characterization", J. Appl. Phys., AIP Publishing (2007) 101, 053305.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML038  
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WEPML072 Gas Permeability Measurement of Graphene Films vacuum, background, neutron, detector 2856
 
  • P.C. Wang, X. Sun
    DNSC, Dongguan, People's Republic of China
  • Liu. S. Liu
    Institute of High Energy Physics (IHEP), People's Republic of China
  • C. Meng, H. Wang, D.H. Zhu
    IHEP, Beijing, People's Republic of China
 
  Graphene has extremely high strength and thermal conductivity, which can possibly be used for high-power beam window in accelerator. In this paper, gas permeabilities of different graphene films have been measured by the permeation measurement facility. According to the results, the possibility of the graphene-made beam windows will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML072  
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THXGBE1 6D Beam Measurement, Challenges and Possibilities simulation, rfq, quadrupole, linac 2890
 
  • A.V. Aleksandrov, S.M. Cousineau, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
  • B.L. Cathey
    ORNL RAD, Oak Ridge, Tennessee, USA
 
  A system to measure the full 6D beam parameters (not 3x2D) has been built at the SNS RFQ test stand. Such a measurement will allow detailed analysis of the beam physics from a properly measured input term. This invited provides an overview of the principles and design of this system, and reports on status and results.  
slides icon Slides THXGBE1 [4.476 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBE1  
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THXGBE2 Optical Diagnostics for Extreme Beam Conditions radiation, emittance, diagnostics, electron 2896
 
  • R.B. Fiorito
    The University of Liverpool, Liverpool, United Kingdom
 
  The development of simple, fast, precise and robust beam diagnostics is absolutely necessary to optimize the performance of present accelerators and to satisfy the needs of future accelerators, in particular those with ex-treme properties such as high brightness FELs and plasma wake-field accelerators. This invited talk will present the underlying physics and results from simulation and experiments for a number of advanced optical beam diagnostics currently under development at various accelerator re-search laboratories including efforts at the Cockcroft Institute.  
slides icon Slides THXGBE2 [13.922 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBE2  
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THYGBD2 Results of UFO Dynamics Studies with Beam in the LHC emittance, proton, beam-losses, simulation 2914
 
  • B. Lindstrom, A. Apollonio, P. Bélanger, M. Dziadosz, A.A. Gorzawski, L. K. Grob, E.B. Holzer, A. Lechner, R. Schmidt, M. Valette, D. Valuch, D. Wollmann
    CERN, Geneva, Switzerland
 
  Micrometer sized particles entering the LHC beam (the so-called Unidentified Falling Objects or UFOs) are a known cause of localized beam losses since the beginning of high intensity beam operation, however the origin of these particles is not fully known. Their effect limits LHC availability by causing premature dumps due to excessive beam losses and occasionally even magnet quenches. This could become an important limitation for future accelerators such as the High Luminosity upgrade of the LHC (HL-LHC) and the Future Circular Collider (FCC). The dynamics of these UFOs was investigated in two dedicated experiments. In the first experiment, it was shown that the transverse movements of these particles can be studied by observing bunch-by-bunch losses from bunches with different horizontal and vertical emittances. In the second experiment, UFO-like events around the 16L2 interconnect in the LHC, which has seen intense UFO activity in 2017, were studied with the above method. This paper summarizes the results of both experiments.  
slides icon Slides THYGBD2 [1.361 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD2  
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THYGBF3 Challenges of FAIR Phase 0 operation, controls, MMI, storage-ring 2947
 
  • M. Bai, A. Adonin, S. Appel, R. Bär, M.C. Bellachioma, U. Blell, C. Dimopoulou, G. Franchetti, O. Geithner, P. Gerhard, L. Groening, F. Herfurth, R. Hess, R. Hollinger, H.C. Hüther, H. Klingbeil, A. Krämer, S.A. Litvinov, F. Maimone, D. Ondreka, N. Pyka, S. Reimann, A. Reiter, M. Sapinski, B. Schlitt, G. Schreiber, M. Schwickert, D. Severin, R. Singh, P.J. Spiller, J. Stadlmann, M. Steck, R.J. Steinhagen, K. Tinschert, M. Vossberg, G. Walter, U. Weinrich
    GSI, Darmstadt, Germany
 
  After two-year's shutdown, the GSI accelerators plus the latest addition of storage ring CRYRING, will be back into operation in 2018 as the FAIR phase 0 with the goal to fulfill the needs of scientific community and the FAIR accelerators and detector development. Even though GSI has been well known for its operation of a variety of ion beams ranging from proton up to uranium for multi research areas such as nuclear physics, astrophysics, biophysics, material science, the upcoming beam time faces a number of challenges in re-commissioning its existing circular accelerators with brand new control system and upgrade of beam instrumentations, as well as in rising failures of dated components and systems. The cycling synchrotron SIS18 has been undergoing a set of upgrade measures for fulfilling future FAIR operation, among which many measures will also be commissioned during the upcoming beam time. This paper presents the highlights of the challenges such as re-establishing the high intensity heavy ion operation as well as parallel operation mode for serving multi users. The status of preparation including commissioning results will also be reported.  
slides icon Slides THYGBF3 [2.952 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBF3  
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THPAF010 Reduction of Coherent Betatron Oscillations Using RF Electric Fields in the Fermilab Muon g-2 Experiment dipole, quadrupole, simulation, betatron 2961
 
  • O. Kim, S. Hacıömeroğlu, Y.I. Kim, Y.K. Semertzidis
    CAPP/IBS, Daejeon, Republic of Korea
  • Y.F. Orlov
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  The Fermilab Muon g-2 experiment aims to measure the muon anomalous magnetic moment with a 140 parts-per-billion precision to investigate the greater than 3 standard deviation difference between the Standard Model prediction and the previous measurement by the BNL Muon g-2 experiment. The coherent betatron oscillation (CBO) beam effects must be corrected for in the decay-positron time spectra fits used in high precision muon storage ring based anomalous magnetic moment measurements. This MC simulation study indicates that the application of radio frequency (RF) electric fields to the muon storage ring beam can reduce the CBO amplitude by up to a factor of 10, as well to increase the symmetry of the beam phase space. This is achieved by correcting the mismatched oscillation phases between the high and low momentum muon populations by modulating the muon beam betatron oscillation frequencies with off-resonance RF fields.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF010  
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THPAF016 3D Tracking Methods in a GEANT4 Environment Through Electrostatic Beamlines simulation, quadrupole, proton, antiproton 2979
 
  • J.R. Hunt, J. Resta-López, V. Rodin, B. Veglia, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • J.R. Hunt, J. Resta-López, V. Rodin, B. Veglia, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: Work supported by the EU under Grant Agreement 721559 and the STFC Cockcroft Institute core Grant No. ST/G008248/1.
Due to the relatively infrequent use of electrostatic beamline elements compared with their magnetic counterparts, there are few particle tracking codes which allow for the straightforward implementation of such beamlines. In this contribution, we present 3D tracking methods for beamlines containing electrostatic elements utilising a modified version of the Geant4 based tracking code 'G4beamline'. In 2020 transfer lines will begin transporting extremely low energy (100 keV) antiproton beams from the Extra Low Energy Antiproton (ELENA) ring to the antimatter experiments at CERN. Electrostatic bending and focusing elements have been chosen for the beamlines due to their mass independence and focusing efficiency in the low energy regime. These beamlines form the basis of our model which is benchmarked against simplified tracking simulations. Realistic beam distributions obtained via tracking around ELENA in the presence of collective effects and electron cooling will be propagated along the optimised 3D transfer model to achieve the best beam quality possible for the experiments.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF016  
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THPAF020 Measurement of Transverse Impedance of Specific Components in CESR Using BPM Measurements of Pinged Bunches impedance, undulator, cavity, betatron 2990
 
  • M.P. Ehrlichman, J.P. Shanks, S. Wang
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  A beam-based technique is applied to determine the quadrupole impedance of large-impedance components of the CESR storage ring. Two bunches separated by ~1/3 of the ring circumference are charged to 0.85 and 0.3 mA. Each bunch is given a single kick, either horizontal or vertical. Turn-by-turn, bunch-by-bunch position information is recorded for ~16 k turns. BPM-by-BPM phase is calculated using the All-phase FFT method of spectral analysis. The difference in the BPM-to-BPM phase advance between the two bunches is a measurement of the local transverse impedance. The impedances of the small-aperture in-vacuum undulators, collimators, scrapers, RF cavities, electrostatic separators, and bulk impedance of the remaining ring are determined in this manner.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF020  
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THPAF062 Impact of Superconducting Magnet Protection Equipment on the Circulating Beam in HL-LHC dipole, quadrupole, simulation, shielding 3115
 
  • M. Valette, L. Bortot, A.M. Fernandez Navarro, B. Lindstrom, M. Mentink, R. Schmidt, E. Stubberud, A.P. Verweij, D. Wollmann
    CERN, Geneva, Switzerland
  • E. Ravaioli
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the HL-LHC project.
The new superconducting quadrupole and dipole magnets for the High Luminosity LHC (HL-LHC) will rely on quench heaters or Coupling-Loss Induced Quench (CLIQ) units or a combination of both to protect the magnet coils in case of a quench. After the detection of a quench, the quench heater power supplies will discharge currents of several hundreds of amperes into the quench heater strips glued to the coils, and the CLIQ units will discharge an oscillating current in the order of 1~kA directly into the coils. These currents can have a significant effect on the circulating beam if the discharge occurs before the beam is dumped. In the HL-LHC inner triplet quadrupole magnets and 11 T dipole magnets, which will be installed in the collimation region dispersion suppressor, this effect will even be stronger due to the larger number of quench heaters and use of CLIQ units (triplet magnets only) as well as due to the greater value of beta function in comparison with the present LHC. In this paper, the expected effects of quench heater and CLIQ discharges on the circulating beam are summarized, and several mitigation methods are proposed and evaluated.
Matthieu. Valette@cern.ch
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF062  
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THPAF068 Suppression of Instabilities Generated by an Anti-Damper With a Nonlinear Magnetic Element in IOTA simulation, lattice, optics, damping 3134
 
  • E.G. Stern, J.F. Amundson, A. Macridin
    Fermilab, Batavia, Illinois, USA
 
  Funding: US Department of Energy
The Integrable Optics Test Accelerator (IOTA) storage ring is being constructed at Fermilab as a testbed for new accelerator concepts. One important series of experiments tests the use of a novel nonlinear magnetic insert to damp coherent instabilities. To test the damping power of the ele- ment, an instability of desired strength may be intentionally excited with an anti-damper. We report on simulations of beam stabilization using the Synergia modeling framework over ranges of driving and damping strengths.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF068  
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THPAF073 Beam Phase Space Tomography at Fast Electron Linac at Fermilab lattice, coupling, MMI, linac 3146
 
  • A.L. Romanov
    Fermilab, Batavia, Illinois, USA
 
  FAST linear accelerator has been commissioned in 2017. Experimental program of the facility requires high quality beams with well-defined properties. Solenoidal fields at photoinjector, laser spot shape, space charge forces and other effects can distort beam distribution and introduce coupling. This work presents results of a beam phase space tomography for a coupled 4D case. Beam was rotated in two planes with seven quads by 180 degrees and images from YaG screen were used to perform SVD based reconstruction of the beam distribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF073  
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THPAK022 Beam Dynamic Simulation for the Beam Line from Charge Breeder to ALPI for SPES Project rfq, simulation, linac, quadrupole 3255
 
  • M. Comunian, L. Bellan, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • A.V. Ziiatdinova
    ITEP, Moscow, Russia
  • A.V. Ziiatdinova
    MEPhI, Moscow, Russia
 
  The SPES project (Selective Production of Exotic Species) is under development at INFN-LNL. This facility is intended for production of neutron-rich Radioactive Ion Beams (RIBs) by ISOL method. The +1 charged beam will be transformed to n+ charge by Charge Breeder (Electron Cyclotron resonance ion source) and reaccelerated by the ALPI (Acceleratore Lineare Per Ioni) superconducting Linac . This paper includes results of beam dynamic simulation at the beam line from Charge Breeder to ALPI.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK022  
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THPAK024 A new method to measure the Beta function in a Paul trap dipole, lattice, emittance, resonance 3262
 
  • L. Martin, S.L. Sheehy
    JAI, Oxford, United Kingdom
  • K. Ito, H. Okamoto
    HU/AdSM, Higashi-Hiroshima, Japan
  • D.J. Kelliher
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • S. Machida
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  The Simulator of Particle Orbit Dynamics (S-POD) is a linear Paul trap at Hiroshima University, Japan, used to study beam physics. S-POD has so far been used to study resonances in high intensity beams, predominantly using a simple alternating gradient lattice configuration. Recently a similar apparatus, the Intense Beam Experiment (IBEX), has been constructed at the Rutherford Appleton Lab in the UK. To use either of these experiments to study beam dynamics in more complex lattice configurations in the future further diagnostic techniques must be developed for Paul traps. Here we describe a new method to measure the beta function and emittance at a given time in a Paul trap.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK024  
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THPAK045 Summary of Beam Operation Capability at FXR LIA operation, cathode, electron, induction 3316
 
  • Y.H. Wu, J. Ellsworth
    LLNL, Livermore, California, USA
 
  Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344.
In this paper we summarize the current beam operation capability of FXR linear induc-tion accelerator (LIA) at LLNL. Experi-mental measurements for electron beam pa-rameters at different beam operations are pre-sented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK045  
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THPAK046 The Ion-Hose Instability in High-Current Multi-Pulse Induction Linacs electron, simulation, induction, vacuum 3320
 
  • C. Ekdahl
    LANL, Los Alamos, New Mexico, USA
 
  The ion-hose instability has long been considered a danger for long-pulse, high-current electron linear induction accelerators (LIAs)*. This instability is enabled by beam-electron ionization of residual background gas in the accelerator. The space-charge of the high-energy beam ejects low-energy electrons from the ionized channel, leaving a positively-charged ion channel that attracts the electron beam. The beam can oscillate in the potential well around the channel position. Likewise, the electron beam attracts the ions, which can oscillate about the beam position. Because of the vast differences in particle mass, the oscillations are out of phase, and the amplitudes grow unstably. The number of instability e-foldings is proportional to the channel ion density*, which in turn is proportional to the background pressure and pulse length. This scaling of the instability growth was demonstrated on the long-pulse DARHT-II linear induction accelerator (LIA) at Los Alamos**. The ion-hose instability is also problematic for high-current multi-pulse LIAs, because ion recombination times are so very long at typical background pressures. Moreover, because of low ion channel ion densities, and massive ions, channel expansion is too slow to reduce the instability growth by very much. In particular, the ion channel is expected to persist and its density to increase during the 3-microsecond duration of a four-pulse burst from the 2-kA, 20-MeV Scorpius LIA now being developed. Recent simulations with an experimentally validated code that was used to predict DARHT-II growth rates have shown that the magnetic focusing field designed for Scorpius will be strong enough to inhibit ion-hose instability if the background pressure is kept below a value that is readily attainable with the present designs of induction cells and other accelerator components. Details and results of these calculations are the subject of this presentation.
*H. L. Buchanan, Phys. Fluids, vol. 30, pp. 221 - 231, 1987
**C. A. Ekdahl, et al., IEEE Trans. Plasma Sci., vol. 34, pp. 460-466, 2006
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK046  
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THPAK056 Resonance Identification Studies at the CERN PS resonance, space-charge, sextupole, synchrotron 3350
 
  • F. Asvesta
    NTUA, Athens, Greece
  • H. Bartosik, A. Huschauer, Y. Papaphilippou, G. Sterbini
    CERN, Geneva, Switzerland
 
  In view of the LHC Injectors Upgrade (LIU) and the challenging high brightness target beam parameters, a broad range of possible working points for the Proton Synchrotron (PS) is being investigated. High order resonances have been identified, both structural resonances driven by space charge due to the lattice harmonics of the PS, and resonances excited by multipolar components in the machine. This paper provides a summary of the performed tune scan studies, covering both experimental and simulation results. Furthermore, non-linear analysis techniques have been used to characterize the resonances and their effect on the beam in presence of space charge.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK056  
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THPAK058 Planned Detection and Amplification of Infared Synchrotron Radiation for Electron-Beam Diagnostics and Manipulations radiation, laser, synchrotron, synchrotron-radiation 3358
 
  • M.B. Andorf, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
 
  Amplification of beam-induced radiation (e.g. synchrotron or undulator radiation) is a necessary component of optical stochastic cooling of hadrons or heavy ions. We discuss a proposal to measure and amplify synchrotron radiation from a bending magnet of the Advanced Photon Source. The measurements will be in the short-wavelength infrared region (SWIR) and amplification will be accomplished using a pumped Chromium:Zinc Selenide (Cr:ZnSe) crystal with maximum gain at λ≅ 2.2~μm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK058  
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THPAK060 Transverse-to-Longitudinal Photocathode Distribution Imaging laser, quadrupole, electron, cathode 3361
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • W. Gai, G. Ha, J.G. Power, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • G. Ha
    PAL, Pohang, Republic of Korea
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  • G. Qiang
    TUB, Beijing, People's Republic of China
 
  In this paper, we present a tunable picosecond-scale bunch train generation technique combining a microlens array (MLA) transverse laser shaper and a transverse-to-longitudinal emittance exchange (EEX) beamline. The modulated beamlet array is formed at the photocathode with the MLA setup. The resulting patterned electron beam is accelerated to 50 MeV and transported to the entrance of the EEX setup. A quadrupole channel is used to adjust the transverse spacing of the beamlet array upstream of the EEX, thereby enabling the generation of a bunch train with tunable separation downstream of the EEX beamline. Additionally, the MLA is mounted on a rotation stage which provides additional flexibility to produce high-frequency beam density modulation downstream of the EEX. Experimental results obtained at the Argonne Wakefield Accelerator (AWA) facility are presented and compared with numerical simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK060  
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THPAK062 Bunch Compression of Flat Beams emittance, simulation, cavity, booster 3368
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev
    Fermilab, Batavia, Illinois, USA
 
  Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University.
Flat beams can be produced via a linear manipulation of canonical angular momentum (CAM) dominated beams using a set of skew-quadrupole magnets. Recently such beams were produced at Fermilab Accelerator Science and Technology (FAST) facility. In this paper, we report the results of flat beam compression study in a magnetic chicane at an energy of E~32 MeV. Additionally, we investigate the effect of energy chirp in the round-to-flat beam transform. The experimental results are compared with numerical simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK062  
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THPAK063 Electron Beam Pattern Rotation as a Method of Tunable Bunch Train Generation lattice, electron, laser, HOM 3372
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
 
  Transversely modulated electron beams can be formed in photo injectors via microlens array (MLA) UV laser shaping technique. Micro lenses can be arranged in polygonal lattices, with resulting transverse electron beam modulation mimicking the lenses pattern. Conventionally, square MLAs are used for UV laser beam shaping, and generated electron beam patterns form square beamlet arrays. The MLA setup can be placed on a rotational mount, thereby rotating electron beam distribution. In combination with transverse-to-longitudinal emittance exchange beam line, it allows to vary beamlets horizontal projection and tune electron bunch train. In this paper, we extend the technique to the case of different MLA lattice arrangements and explore the benefits of its rotational symmetries.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK063  
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THPAK074 Beam Manipulation Using Self-Induced Fields in the SwissFEL Injector wakefield, FEL, electron, laser 3401
 
  • S. Bettoni, P. Craievich, R. Ganter, P. Heimgartner, H. Jöhri, F. Marcellini, S. Reiche
    PSI, Villigen PSI, Switzerland
 
  Several possibilities of manipulating the electron beam using sources of wakefield are being explored. Wakefield have been successfully used to remove or enhance the energy chirp residual from the magnetic compression to control the free electron laser bandwidth (dechirper), to linearize the compressed beam (linearizer), to generate more bunches to produce two color mode, and to perform experiments of wakefield acceleration. At the SwissFEL injector we plan to install 2 m long system to accommodate sources of wakefield with different periodicities, each of them associated with one of the discussed beam manipulation. In this paper we summarize the design and the characterization of the system and the planned activities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK074  
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THPAK087 Software-Computing System for Numerical Modelling of Beam Dynamics in Accelerators software, controls, interface, simulation 3435
 
  • E. Krushinevskii, E. Sboeva
    Saint Petersburg State University, Saint Petersburg, Russia
  • S.N. Andrianov, A.N. Ivanov, N.V. Kulabukhova
    St. Petersburg State University, St. Petersburg, Russia
 
  The spectrum of software packages for the physics of charged particles beams is extremely wide. From most popular and effective systems can be allocated such programs as COSY Infinity, MAD X, MARYLIE, TRANSPORT. Heterogeneous individual formats of input and output data, the lack of a common and user-friendly interface and the narrow specialization of these programs poses a number of challenges for the modern researchers. It significantly reduces the effectiveness and quality of corresponding computational experiments. In this article we present a universal tool for automation and acceleration of computing experiments. The authors consider a method for developing the concept and prototype of a corresponding software package that would combine the advantages of existing (non-commercial) systems. This software will be able to unify the input and output data format for certain programs, visualize the information in various ways, provide reference and training information for "beginners". The results obtained within the developed framework will be a significant contribution both to the development of numerical and symbolical methods for solving evolution nonlinear equations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK087  
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THPAK116 Modeling Surface Roughness Effects and Emission Properties of Bulk and Layered Metallic Photocathode simulation, electron, emittance, cathode 3515
 
  • D.A. Dimitrov, G.I. Bell
    Tech-X, Boulder, Colorado, USA
  • I. Ben-Zvi, J. Smedley
    BNL, Upton, Long Island, New York, USA
  • J. Feng, S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under Contract Nos. DE-SC0013190, DE-AC02-05CH11231, and KC0407-ALSJNT-I0013.
The thermal limit of the intrinsic emittance of photocathodes represents an important property to measure experimentally and to understand theoretically. Detailed measurements of intrinsic emittance have become possible in momentatron experiments. Moreover, recent developments in material design have allowed growing photoemissive layers with controlled surface roughness. Although analytical formulations of the effects of roughness have been developed, a full theoretical model and experimental verification are lacking. We aim to bridge this gap by developing realistic models for different materials in the three-dimensional VSim particle-in-cell code. We have recently implemented modeling of electron photo-excitation, transport, and emission from photoemissive layers grown on a substrate. We report results from simulations with these models on electron emission from antimony and gold. We consider effects due to density of states, photoemissive layer thickness, surface roughness and how they affect the spectral response of quantum yield and intrinsic emittance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK116  
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THPAK121 Accelerator Optimization through LIV. DAT plasma, proton, radiation, wakefield 3526
 
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: LIV. DAT is supported by the STFC under contract ST/P006752/1.
The Liverpool Big Data Science (LIV. DAT) Center for Doctoral Training (CDT) is a hub for training students in managing, analysing and interpreting large, complex datasets and high rates of data flow. LIV. DAT offers a unique training approach addressing some of the biggest challenges in data intensive science to tackle a growing skills gap. It currently provides training to a cohort of almost 20 PhD students. Their research projects address R&D challenges in astronomy, nuclear, particle and accelerator physics. This contributions presents initial research results from modeling studies of the physics and biology of proton beam therapy using a Monte Carlo approach, as well as plasma-beam interaction in the cases of AWAKE and EuPRAXIA.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK121  
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THPAK131 Investigation of Two-Bunch Train Compression by Velocity Bunching bunching, electron, cavity, emittance 3548
 
  • D. Wang, Y. C. Du, W.-H. Huang, X. Liu, X.L. Su, C.-X. Tang, Q.L. Tian, L.X. Yan
    TUB, Beijing, People's Republic of China
  • H. Zhang
    Tsinghua University, Beijing, People's Republic of China
 
  Two electron beamlets, also referred as two-bunch train with adjustable time and energy spacing are popular in many applications such as two color FEL and pump-probe experiments. We investigate compression of two-bunch train via velocity bunching scheme in a traveling wave accelerator (TWA) tube by varying the phase of TWA tube in a very large range. Beam dynamics simulations show that when the phase injected into the accelerator tube for the beam is set to ≪-100 degree, velocity bunching occurs in a deep over-compression mode, where two-bunch train is continuously tunable in time and in energy space, and the emittance of each sub-bunch is also preserved. In the experiment, we use energy spectrum and defecting cavity to diagnose the train's energy space and time space respectively, the measurements demonstrated that two-bunch train through deep over-compression scheme is separated both in time and in energy space, which also agree well with the predictions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK131  
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THPAK137 Beam-Based Sextupolar Nonlinearity Mapping in CESR sextupole, simulation, resonance, lattice 3565
 
  • L. Gupta, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • S. Baturin
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  • M.P. Ehrlichman, J.M. Maxson, R.E. Meller, D. L. Rubin, D. Sagan, J.P. Shanks
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: Work supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams
In order to maintain beam quality during transport through a storage ring, sextupole magnets are used to make chromatic corrections, but necessarily introduce deleterious effects such as nonlinear resonances and reduced dynamic aperture. Implementing intricate sextupole distributions to mitigate these effects will rely on precision beam-based measurement of the applied sextupole distribution. In this work, we generalize previous sextupole mapping techniques by using resonant phase-locked excitation of the beam at the Cornell Electron Storage Ring (CESR), which accounts for variations in the normal mode tunes on a turn by turn basis. The methods presented here are applied to simulation and actual turn by turn data in CESR for both simplified and realistic sextupole distributions.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK137  
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THPAK139 Lost Muon Studies for the Muon g-2 Experiment at Fermilab positron, storage-ring, background, resonance 3573
 
  • S. Ganguly, K. T. Pitts
    University of Illinois at Urbana-Champaign, Urbana, USA
  • J.D. Crnkovic
    BNL, Upton, Long Island, New York, USA
  • C. C. Polly
    Fermilab, Batavia, Illinois, USA
 
  The Fermilab Muon g-2 experiment aims to measure the muon anomalous magnetic moment aµ with an unprecedented precision of 140 parts per billion (ppb), a four-fold improvement over the 540~ppb precision obtained by the BNL Muon g-2 Experiment. This study presents preliminary work on estimating the muon losses by using double coincidences in the calorimeters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK139  
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THPAK141 Initial Tests of Nonlinear Quasi-Integrable Optics at the University of Maryland Electron Ring octupole, electron, optics, simulation 3581
 
  • H. Baumgartner, B.L. Beaudoin, I. Haber, T.W. Koeth, D.B. Matthew, K.J. Ruisard
    UMD, College Park, Maryland, USA
 
  Funding: Funding for this project and travel is provided by DOE-HEP, NSF GRFP and NSF Accelerator Science Program.
An octupole channel has been inserted into the University of Maryland Electron Ring (UMER), in order to investigate the mitigation of destructive resonances as a novel approach in high-intensity beam transport. The individual octupole magnets have been characterized using our in-house 3-dimensional magnet mapping stage, with a measured gradient of 51.6 ± 1.5 T/m3/A. A single section (20°) of an 18-cell FODO lattice has been replaced by a longitudinally-varying octupole channel constructed from seven flexible printed circuits (PCBs). We present the design of the channel and preliminary beam based measurements on the ring.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK141  
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THPAK143 Tuning Low-Current Beam for Nonlinear Quasi-Integrable Optics Experiments at the University of Maryland Electron Ring lattice, octupole, optics, quadrupole 3585
 
  • K.J. Ruisard, H. Baumgartner, B.L. Beaudoin, S. Bernal, B. M. Cannon, L. Dovlatyan, I. Haber, T.W. Koeth
    UMD, College Park, Maryland, USA
 
  Funding: Travel was supported by the NSF, the APS DPB, and TRIUMF. Funding for the work was provided through DOE-HEP Award DESC0010301, NSF Award PHY1414681 and the NSF GRFP program.
Design of accelerator lattices with nonlinear integrable optics is a novel approach to suppress transverse resonances and may be crucial for enabling low-loss high-intensity beam transport. Lattices with large amplitude-dependent tune spreads, driven by strong nonlinear magnet inserts, have reduced response to resonant driving perturbations [*]. This paper describes preparations for tests of a quasi-integrable octupole lattice at the University of Maryland Electron Ring (UMER). The planned tests employ a low-current highemittance beam with low space charge tune shift (∼ 0.005) to probe the dynamics of a lattice with large external tune spread (∼ 0.26).
* V. Danilov and S. Nagaitsev, Nonlinear accelerator lattices
with one and two analytic invariants, PRSTAB, 13, 084002, 2010.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK143  
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THPAL010 Sector DC Dipoles Design for the Beam Test Facility Upgrade dipole, linac, quadrupole, electron 3634
 
  • A. Vannozzi, S. Lauciani, L. Pellegrino, L. Sabbatini, C. Sanelli, G. Sensolini
    INFN/LNF, Frascati (Roma), Italy
  • P. Valente
    INFN-Roma, Roma, Italy
 
  The Beam Test Facility is part of the DAΦNE accelerators system of INFN Frascati National Laboratory. It is a transfer-line optimized for electrons and positrons extracted from the DAΦNE LINAC. An upgrade of the line is scheduled for two purposes: reach a beam energy of 920 MeV (with respect to the actual 750 MeV) and add a new branch to the present transfer line. This new layout foresees six new quadrupoles one fast ramped dipole, two H-shape and one C-shape sector dipoles. The design of the magnets has been completely performed at INFN involving Electromechanical Enterprise partner in the design phase in order to optimise the manufacturing process. This effort lead to a complete set of detailed CAD drawings that can be directly used by manufacturer to build the magnets. The goal is to boost the manufacturing of prototypes and small series from Small and Medium Enterprises. Magnetic measurements will be performed at INFN. This poster is focused on the realization of the two full iron yoke H-shape and C-shape dipoles, respectively with 45 and 15 bending angle. They are characterized by a high flux density of 1.7 T in a gap of 35 mm. They have a bending radius of 1.8 m  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL010  
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THPAL029 Comparison of Horizontal and Vertical Electropolishing Methods using Niobium Single-Cell Coupon Cavity cavity, cathode, niobium, accumulation 3692
 
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
 
  Horizontal electropolishing (HEP) is an established tech-nique for surface treatment of niobium accelerating cavi-ties. Vertical electropolishing (VEP), in which the cavity is electropolished in the vertical posture, is in R&D phase for parameter optimization. We performed HEP and VEP of a niobium single-cell coupon cavity to compare the effect of both the methods on surface state and removal at different positions of the cavity. HEP was performed at STF, KEK with the standard EP parameters. VEP was performed at Marui Galvanizing Company with a cathode called 'Ninja cathode' that can be rotated during the VEP process. The optimized cathode design and VEP parame-ters resulted in symmetric removal as obtained with the HEP technique and yielded a smooth inner surface of the entire cavity  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL029  
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THPAL032 1.3GHz Nb Single-Cell Cavity Vertical Electropolishing with Ninja Cathode and Results of Vertical Test cavity, cathode, accelerating-gradient, factory 3702
 
  • K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
  • H. Ito
    Sokendai, Ibaraki, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
 
  Marui Galvanizing Co., Ltd. has been developing Nb cavity vertical electropolishing (VEP) technologies in collaboration with KEK. Until now, we reported that inner surface state and removal thickness distribution were improved in VEP with Ninja cathode and coupon cavity. This time, a 1.3GHz Nb single-cell cavity VEP with Ninja cathode was performed in Marui and vertical test was performed in KEK. The inner surface state and removal thickness distribution were satisfactory. And as a result of vertical test, the accelerating gradient of 32MV/m (Q0=8.0E9) was achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL032  
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THPAL033 Measurement of the Internal Dark Current in a High Gradient Accelerator Structure at 17 GHz multipactoring, acceleration, electron, simulation 3705
 
  • H. Xu, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of High Energy Physics, under Grant No. DE-SC0015566
We report a study of internal dark current generation by multipactor inside a 17 GHz single cell standing wave disk-loaded waveguide accelerator structure. The multipactor takes place on the side wall of the central cell, driven by the local rf electric and magnetic fields. Theory indicates that a resonant multipactor mode with two rf cycles can be excited near 45 MV/m gradient and a single rf cycle multipactor mode near 60 MV/m. The accelerator structure had two thin slits opened on the side wall of the central cell to directly extract and measure the internal dark current. The dark current was measured as a function of the gradient up to a gradient of 70 MV/m. The experimental results agreed well with theory, showing the two predicted multipactor modes. To further study the effect of the central cell side wall surface properties on the structure performance, we prepared and tested a second structure with the central cell side wall coated with a layer of diamond-like carbon. The comparison of the results showed that the coating reduced the internal dark current and thus enhanced the structure performance considerably.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL033  
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THPAL039 Improved Magnetron Stability and Reduced Noise in Efficient Transmitters for Superconducting Accelerators controls, SRF, cavity, feedback 3726
 
  • G.M. Kazakevich, R.P. Johnson
    Muons, Inc, Illinois, USA
  • V.A. Lebedev, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  State of the art high-current superconducting accelerators require efficient RF sources with a fast dynamic phase and power control. This allows for compensation of the phase and amplitude deviations of the accelerating volt-age in the Superconducting RF (SRF) cavities caused by microphonics, etc. Efficient magnetron transmitters with fast phase and power control are attractive RF sources for this application. They are more cost effective than traditional RF sources such as klystrons, IOTs and solid-state amplifiers used with large scale accelerator projects. However, unlike traditional RF sources, controlled magnetrons operate as forced oscillators. Study of the impact of the controlling signal on magnetron stability, noise and efficiency is therefore important. This paper discusses experiments with 2.45 GHz, 1 kW tubes and verifies our analytical model which is based on the charge drift approximation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL039  
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THPAL040 Lossy Beam Pipe HOM Load Ceramics with DC Conductivity vacuum, HOM, site, controls 3729
 
  • M.L. Neubauer, A. Dudas
    Muons, Inc, Illinois, USA
  • F. Marhauser
    JLab, Newport News, Virginia, USA
 
  The ceramic materials used in the beam pipe for super-conducting RF accelerators have the problem of charging due to the electron cloud and secondary electron emission. A novel solution is in the application of conductive nanoparticles to the lossy ceramic. The lossy ceramic is pre-processed to provide for pores that will accept the conductive nanoparticles and then coated with a thin film to prevent the nanoparticles from entering the environment. The same process was also done with sub-micron carbon particles. Measurements of surface conductivity with and without a vacuum compatible sealant are reported on along with microwave measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL040  
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THPAL044 The Permanent Magnets Magnetic Characteristics Change Under Effect of 10 MeV Beam radiation, electron, permanent-magnet, ECR 3742
 
  • I.S. Guk, O.M. Bovda, V.O. Bovda, A.N. Dovbnya, A.I. Kalinichenko, S.S. Kandybey, V.N. Ljashchenko, A. Mytsykov, L.V. Onishchenko, O.A. Repikhov, A.Y. Zelinsky
    NSC/KIPT, Kharkov, Ukraine
 
  Magnets of applied electron accelerators are under direct effect of electrons and bremsstrahlung radiation stipulated by the electron beam. The choice of the materials for the rare elements alloy accelerator magnets has the decisive importance for the long term magnet parameters keeping. The experimental studies of the magnetic fields around the Nd-Fe-B and Sm2Co17 alloy magnets under effect of the electron beam have been done. The samples of 30х24х12 mm geometrical sizes were bombarded by electron beam of applied NSC KIPT accelerator KUT-1 with electron energy of 10 MeV and were irradiated by correspondent bremsstrahlung. The magnetic field value around Nd-Fe-B alloy samples was decreased nonlineary under electron beam bombarding with change of irradiation doze from 16 to 160 GRad. Under effect of bremsstrahlung the magnetic field value around samples was not changed. The repeated sample magnetizations allowed to restore the initial magnetic field distribution around magnets. The magnetic field distribution around Sm2Co17 alloy samples was not changed under effect of the electron beam and bremsstrahlung within irradiation dozes mentioned above. The induced activity in the Nd-Fe-B and Sm2Co17 alloy samples was changed slightly during the experiments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL044  
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THPAL057 Development of the Aluminum Beam Duct for the Ultra-Low Emittance Light Source vacuum, storage-ring, impedance, emittance 3775
 
  • G.-Y. Hsiung, J.-R. Chen, C.M. Cheng, S-N. Hsu, H.P. Hsueh, Y.C. Yang
    NSRRC, Hsinchu, Taiwan
  • J.-R. Chen
    National Tsing Hua University, Hsinchu, Taiwan
 
  The future light source with ultra-low emittance, typically < 500 pm rad, requests the beam duct with inner aperture < 20 mm for the electron storage ring. Besides, the cross section of the beam duct must be kept smooth for lowering the impedance. The aluminum extruded beam duct of 10 mm inside and 1 ~ 2 m in length was developed for this purpose. The beam duct was machined in ethanol to obtain a clean surface for a lower thermal outgassing rate. To mitigate the impedance of the flange connection, a special designed diamond-edge gasket and the aluminum flange without knife edge were developed. The inner diameters of both flange and gasket, 10 mm, are the same as that of beam duct. The sealing of the gasket has been proved leak-tight. The ultimate pressure and the thermal outgassing rate of the beam duct has achieved < 2.0·10-10 Torr and < 1.4·10-13 Torr l/(s cm2), respectively after baking. Those results fulfill both the ultrahigh vacuum and lowest impedance are applicable for the next generation ultra-low emittance light source.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL057  
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THPAL058 Effect of Ozonated Water Cleaning on Photon Stimulated Desorption in a Stainless Steel Chamber photon, vacuum, ECR, radiation 3778
 
  • C.M. Cheng, C.K. Chan, C.-C. Chang, Y.T. Cheng, J. -Y. Chuang, G.-Y. Hsiung, L.H. Wu, Y.C. Yang
    NSRRC, Hsinchu, Taiwan
 
  Aluminium vacuum chambers cleaned with ozonated water show a reduction of residual carbon and lower surface outgassing rate after baking. We would like to investigate if stainless steel chambers show similar ef-fects. A stainless steel test chamber was cleaned by stand-ard chemical cleaning only and then compared with an-other one after immersion in 30ppm ozonated water for thirty minutes. Both samples were baked, then photon exposed and the photon desorption yields were deter-mined by vacuum gauges and residual gas analysers at the TLS 19B beamline. The test results on photon stimulated desorption yields and partial pressure variations with and without ozonated water cleaning of the stainless steel tubes will be discussed in some detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL058  
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THPAL060 Advanced Modeling of Klystrons by the Tesla-Family of Large-Signal Codes klystron, cavity, impedance, simulation 3785
 
  • I.A. Chernyavskiy, D.K. Abe, B. Levush, A.N. Vlasov
    NRL, Washington, DC, USA
  • T.M. Antonsen
    UMD, College Park, Maryland, USA
  • T.M. Antonsen
    Leidos Corp, Billerica, MA, USA
  • J. Rodgers
    Naval Research Laboratory (NRL), Washington, USA
 
  Funding: US Office of the Naval Research
Klystrons and IOTs are widely used or proposed to be used in accelerators as high-power RF sources. Development and optimization of klystron and IOT designs is aided by the use of different simulation tools, including highly efficient large-signal codes. We present an overview of the advances in the code development and modeling using Naval Research Laboratory (NRL) set of TESLA-family of large-signal codes, suitable for the modeling of single-beam and multiple beam klystrons and IOTs. Original 2D large-signal algorithm of the code TESLA* was developed for the modeling of klystrons based on (relatively) high Q resonators and is applicable to the multiple-beam devices in an approximation of identical beams/beam-tunnels. Parallel extension of TESLA algorithm (code TESLA-MB**) enabled an accurate, quasi-3D modeling of multiple-beam devices with non-identical beams/beam-tunnels. Recently developed more general TESLA-Z algorithm*** is based on the impedance matrix approach and enabled geometry-driven large-signal modeling. Examples of applications of TESLA-family of codes to the modeling of advanced single-beam and multiple-beam klystrons (and IOTs) will be presented.
*A.N. Vlasov, et al,IEEE TPS, v.30(3), 1277-1291, June 2002
**I.A. Chernyavskiy, et al.,IEEE TPS, v.36(3), 670-681, June 2008
***I.A. Chernyavskiy, et al.,IEEE TED, v.64(2), 536-542, Feb 2017
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL060  
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THPAL064 Burst-Mode UV Enhancement Cavity for Laser-Assisted Hydrogen Ion Beam Stripping at SNS cavity, laser, resonance, controls 3799
 
  • A. Rakhman, Y. Liu
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: This work has been supported in part by U.S. DOE grant DE-FG02-13ER41967. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Recent success of laser-assisted charge exchange for 10 µs duration Hydrogen ion beams at SNS motivates laser development necessary for efficient stripping of 1.0 ms duration beam at full duty cycle. To overcome the laser power challenge, the interaction point was chosen inside an optical cavity. A doubly-resonant enhancement cavity and a novel locking technique have been developed, and a coherent enhancement of 402.5 MHz, 50 ps, 1.05 MW peak power ultraviolet (355 nm) laser pulses operating at 10-μs/10-Hz burst mode has been demonstrated. This will enable 1.0 ms duration laser macropulses at 60 Hz to be stored inside such a cavity to achieve efficient stripping at SNS.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL064  
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THPAL069 Simulation of a 10 mm Diameter Cascaded Plasma Window plasma, cathode, simulation, vacuum 3812
 
  • P.P. Gan, S. Huang, Y.R. Lu, S.Z. Wang, K. Zhu
    PKU, Beijing, People's Republic of China
 
  As a windowless vacuum device, the 10 mm diameter 60 mm long plasma window designed by Peking University only achieved to separate 28.8 kPa from 360 Pa experimentally with 50 A direct current and 2.5 kW power. Based on our 10 mm diameter plasma window, we have proposed a cascaded plasma window to achieve the isolation of atmosphere and high vacuum. In this paper, a numerical 2D FLUENT-based magneto-hydrodynamic simulation on 10 mm diameter cascaded plasma window was developed. The gas inlet, arc creation and plasma expansion segments are all contained in this model. A set of parameters including pressure, temperature, velocity and current distribution were obtained and analysed. In our first simulation, the isolation of 100 kPa and 50 Pa pressure has been realised, and some interesting phenomena occurred.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL069  
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THPAL071 Preliminary Emittance Measurement of Laser Driven Proton Beam Employing a Quadruple Triplet Magnet proton, emittance, laser, quadrupole 3818
 
  • Wu,M.J. Wu, Y.X. Geng, Q. Liao, C. Lin, H.Y. Lu, Y.R. Lu, W.J. Ma, Y.R. Shou, X. Xu, X.Q. Yan, Y.Y. Zhao, J.G. Zhu, K. Zhu
    PKU, Beijing, People's Republic of China
 
  The Compact Laser Plasma Accelerator (CLAPA) has been built recently at Peking University, which composed of a 200TW laser acceleration platform and a beam line system. Proton with energy spread of <1%, up to 10 pC charge and different energies below 10 MeV have been produced and transported to the irradiation platform. Emittance is a critical parameter for beam transportation. The preliminary emittance measurement has been per-formed for CLAPA's proton beams using the quadrupole scan technique (QST). In the experiment, the focal spot size of the proton beam was changed by scanning the current of a quadrupole triplet magnet. The result shows that the normalized emittance is smaller than 0.01 mm·mrad for 5 MeV laser driven protons, which is on the same level of the previously reported work.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL071  
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THPAL074 Numerical Studies of Normal Conducting Deflecting Cavity Designs for the ELBE Accelerator cavity, HOM, electron, impedance 3824
 
  • T.G. Hallilingaiah, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Arnold, U. Lehnert, P. Michel
    HZDR, Dresden, Germany
 
  Currently, in the electron linac ELBE there is a single beam line. Therefore, at any given time only single user can use the beam. Moreover, as different user experiments require distinct beam intensity settings, not all the experiments fully utilize the 13 MHz CW beam capability of the facility. To utilize the full beam capacity, multiple beam lines can be established by using an array of transverse deflecting structures. For that, an RF cavity was the design choice due to its inherent advantages with respect to repeatability of the kick voltage amplitude and phase, and the possibility of CW operation in the MHz range. Potential design candidates are the CEBAF RF separator, the three proposed crab cavities for the HL-LHC upgrade project, and a novel NC deflecting cavity design. In this comparative study, the figures of merit of the cavities are computed from electromagnetic field simulations for a transverse voltage of 300 kV. This comparative study supported our selection of the deflecting cavity design for ELBE.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL074  
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THPAL076 Experimental Methods for the Assessment of NEG Pumps Working in Dust-Sensitive Environments vacuum, cavity, SRF, background 3828
 
  • T. Porcelli, E. Maccallini, P. Manini, M. Mura, M.F. Urbano
    SAES Getters S.p.A., Lainate, Italy
 
  NEG pumps have been widely adopted by many accelerator facilities since decades. However, their use in dust-sensitive areas - such as superconductive radio frequency (SRF) cavities - has always been limited by concerns about accidental dust emission, which could induce detrimental field emission. As future machines will necessarily rely on highly-efficient SRF cavities, able to supply very high accelerating gradients, requirements in terms of particle release from vacuum components (e.g., pumps and valves) are becoming more and more stringent. At the same time, achieving stable ultra-high vacuum conditions is crucial, as condensed residual gas might also be a potential source of field emission. At present, a unified standard procedure to assess dust generation and propagation along a machine is still missing and discussions are ongoing in the vacuum community. Recent experimental measurements demonstrated the compatibility of sintered NEG pumps with ultra-clean environments, due to their intrinsic very low dust release. In parallel, in-situ tests performed at different accelerator facilities showed absence of dust contamination from NEGs and no impact on cavities efficiency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL076  
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THPAL089 Design, Assembly and Commissioning of a New Cryogenic Facility for Complex Superconducting Thin Film Testing SRF, site, cavity, operation 3859
 
  • O.B. Malyshev, L. Bizel-Bizellot, K.D. Dumbell, P. Goudket, N. Pattalwar, S.M. Pattalwar, P. Pizzol, P.A. Smith, R. Valizadeh, S. Wilde
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • P. Pizzol
    The University of Liverpool, Liverpool, United Kingdom
 
  An ongoing study on the superconducting thin films for future superconducting RF cavities requires an intense testing of various superconducting properties. We have designed, built and tested a new facility for complex superconducting thin film testing that includes: (1) RRR measurement with and without magnetic field, (2) planar and (3) tubular magnetic field penetration experiments, (4) a superconducting coaxial resonator for bulk niobium and superconducting thin film characterisation. The system is based on a closed cycle refrigerator, eliminating the need for liquid helium, thus making it simple and safe to operate. The details of the design and commissioning will be presented at the conference.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL089  
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THPAL092 Test Particle Monte Carlo Simulation of NEG Coated Narrow Tubular Samples vacuum, ECR, simulation, SRF 3862
 
  • O. Seify, A.N. Hannah, O.B. Malyshev, Sirvinskaite, R. Sirvinskaite, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • Sirvinskaite, R. Sirvinskaite
    Loughborough University, Loughborough, Leicestershire, United Kingdom
 
  The pumping properties of the NEG coated vacuum chambers play an important role in the efficiency of vac-uum system of accelerators. The sticking probability of the NEG films is one the most important parameters to characterise the pumping properties of the NEG coated vacuum chambers. In order to investigate the NEG film sticking probability, Test Particle Monte-Carlo (TPMC) models were used. The models were based on the design of the installed experimental setup in ASTeC Vacuum Science group laboratory at Daresbury Laboratory (DL). The results of the simulations have been used for inter-preting the results of the measurements in the experi-mental setup.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL092  
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THPAL098 Pumping Properties of Single Metal Zirconium Non-Evaporable Getter Coating vacuum, target, site, injection 3869
 
  • Sirvinskaite, R. Sirvinskaite, M.D. Cropper, M.D. Cropper
    Loughborough University, Loughborough, Leicestershire, United Kingdom
  • A.N. Hannah, O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • O.B. Malyshev, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Non-evaporable getter (NEG) coating has been used for years in many particle accelerator facilities due to its evenly distributed pumping speed, low thermal outgassing, and low photon and electron stimulated desorption yields. We have previously demonstrated that quaternary Ti-Zr-Hf-V coating deposited from an alloy wire has the lowest desorption yields, the highest sticking probability and sorption capacity. In this work, we explore the single element targets which are widely available and can be produced in a form of a wire that is easy to apply for a uniform coating of various shapes of vacuum chamber. Single metal Zr coatings have been tested to find a more efficient and cheaper way of producing the NEG-coated vacuum chambers. Two samples coated with Zr of dense and columnar structure were analysed and results of the pumping properties are reported. The results show that pure Zr coating could be an economic solution, despite not being as effective as can be achieved with quaternary NEG film. It shows that columnar Zr coating can be activated and reaches full pumping capacity at 160°C. This is close to the activation temperature of Ti-Zr-Hf-V and lower than that for the widely used ternary Ti-Zr-V alloy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL098  
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THPAL105 Lower Critical Field Measurement System of Thin Film Superconductor controls, simulation, SRF, embedded 3882
 
  • H. Ito
    Sokendai, Ibaraki, Japan
  • C.Z. Antoine
    CEA/IRFU, Gif-sur-Yvette, France
  • A. Four
    CEA/DRF/IRFU, Gif-sur-Yvette, France
  • H. Hayano, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • R. Ito, T. Nagata
    ULVAC, Inc, Chiba, Japan
  • Y. Iwashita, R. Katayama, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
 
  Funding: The work is supported by Japan Society for the Promotion of Science Grant-in-Aid for Young Scientist (A) No.17H04839.
Superconducting thin film is the promising technology to increase the performance of SRF cavities. The lower critical field Hc1, which is one of the important physical parameters characterizing a superconducting material, will be enhanced by coating Nb with thin film superconductor such as NbN. To investigate the performance of thin film, we developed the Hc1 measurement system using the third harmonic response of applied AC magnetic field. The measurement system consists of helium cryostat with two of GM refrigerators, sample Cu stage, solenoid coil Cu mount, solenoid coil, temperature sensors, and liquid helium level meter. AC magnetic field is produced by a coil which is driven by function generator and power amplifier at around 1 kHz. In order to control the temperature of the sample stage and coil mount, the depth of thermal anchors attached to the stage and the mount can be moved by the motor. By this temperature control the sample state can be easily transferred from Meissner state to mixed state. So that the measurement is repeated for various applied magnetic field, and the transition curve can be made. In this report, performance of the measurement system is described.
 
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THPAL114 The Analytical Model of the Helical Accelerating Structure of Linac with Helix Outside of the Vacuum Chamber vacuum, simulation, resonance, TRIUMF 3908
 
  • N.V. Avreline
    TRIUMF, Vancouver, Canada
 
  An analytical model of the helical RF resonator for the single charged 250 keV nitrogen ion implanter operating in CW was developed. The analytical model allowed to determine the geometry of the accelerating structure and to construct CST Microwave Studio and ANSYS HFSS models based on this analytical model. Results obtained from the analytical model and simulations were within 5% of each other. The experimental investigation of the accelerating section confirmed that the models are correct. The accelerating section was tuned and verified for the right accelerating field distribution and operating frequency. Finally, the section was successfully tested in 2 kW CW RF power.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL114  
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THPAL127 Structural Investigations of Nitrogen-Doped Niobium for Superconducting RF Cavities niobium, cavity, vacuum, ECR 3940
 
  • M. Major, L. Alff, M. Arnold, J. Conrad, S. Flege, R. Grewe, M. Mahr, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    KPH, Mainz, Germany
 
  Funding: Work supported by the German Federal Ministry for Education and Research (BMBF) through grant 05H15RDRBA.
Niobium is the standard material for superconducting RF (SRF) cavities. Superconducting materials with higher critical temperature or higher critical magnetic field allow cavities to work at higher operating temperatures or higher accelerating fields, respectively. Enhancing the surface properties of the superconducting material in the range of the penetration depth is also beneficial. One direction of search for new materials with better properties is the modification of bulk niobium by nitrogen doping. In the Nb-N phase diagram the cubic delta-phase of NbN has the highest critical temperature (16 K). Already slight nitrogen doping of the alpha-Nb phase results in higher quality factors.* Nb samples were N-doped at the refurbished UHV furnace at IKP Darmstadt. Reference samples were annealed in 1 bar nitrogen atmosphere at different temperatures. In this contribution the results on the structural investigations (x-ray diffraction and pole figure, secondary ion mass spectroscopy, scanning electron microscopy) at the Materials Research Department of TU Darmstadt will be presented.
*Grassellino et al., Proc. SRF2015, MOBA06, 48.
 
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THPAL128 Autonomous Topography Detection and Traversal for an Inspection Robot Within the Beamline of Particle Accelerators vacuum, FEL, kicker, heavy-ion 3943
 
  • N. Schweizer
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • I. Pongrac
    GSI, Darmstadt, Germany
 
  Particle accelerators feature ultra-high vacuum pipe systems with unique topography, i.e. with a multitude of different vacuum chambers of varying dimensions and varying pipe apertures. In order to be able to examine the interior of the entire vacuum system, even those parts which are not accessible without disassembling large parts of the accelerator, a semi-autonomous robot is being developed which shall traverse and visually inspect the vacuum system of particle accelerators. We present a generic concept based on distance sensors for the inspection robot to detect steps between vacuum chambers and gaps in the beamline. Movement strategies to autonomously overcome these basic obstacles are introduced. For evaluation we use simulations of ideal environments with flat surfaces as well as realistic beam pipe environments of the SIS100 particle accelerator. Additionally, a prototype of our robot concept confirms the implementation of all maneuvers. Results show that obstacles of previously unknown dimensions can be detected and reliably traversed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL128  
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THPAL130 Effect of Deposition Temperature and Duration on Nb3Sn Diffusion Coating SRF, cavity, niobium, superconductivity 3950
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley, J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
 
  Funding: Partially authored by Jefferson Science Associates under contract no. DE¬AC05¬06OR23177. Work at College of William & Mary supported by Office of High Energy Physics under grant SC0014475.
Nb3Sn is a potential candidate to replace Nb in SRF accelerator cavities to reduce cost and advance perfor-mance. Tin vapor diffusion is the preferred technique to realize such cavities by growing a few microns thick Nb3Sn coating on the interior surface of the niobium cavity. The coating process typically uses temperatures of 1100-1200 °C for 3-6 hours. It is important to better understand the coating process, and optimize the coating parameters to overcome the current limitation on the performance of Nb3Sn coated SRF cavities. We investi-gate Nb3Sn coatings prepared in the temperature range of 900-1200 °C and duration of 3 - 12 hours using various material characterization tools. Variation of these pa-rameters appears to have notable effect on microstructure and topography of the obtained surface.
 
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THPAL131 Studies of Electropolishing and Oxypolishing Treated Diffusion Coated Nb3Sn Surfaces cavity, niobium, SRF, superconductivity 3954
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley, J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
 
  The Nb3Sn-coated cavities aim to enhance perfor-mance and significantly reduce cost. Their fabrication involves tin vapor diffusion coating of Nb3Sn on the interior surface of a Nb cavity. Controlled removal of first few layers to obtain a smoother and cleaner surface could be desirable to improve the high field RF perfor-mance. Our first results from the application of elec-tropolishing and oxypolishing techniques on Nb3Sn-coated surfaces indicated reduced surface roughness, and the surface composition appeared nominally unchanged. Systematic studies explore the effect of different polish-ing parameters into the roughness and composition. We present the latest results from SEM/EDS and AFM studies of Nb3Sn-coated samples treated with electropolishing and oxypolishing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL131  
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THPAL133 LASE Surfaces for Mitigation of Electron Cloud in Accelerators electron, laser, vacuum, cavity 3958
 
  • B.S. Sian
    UMAN, Manchester, United Kingdom
  • O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Vacuum chamber surface characteristics such as the photon and secondary electron yields (PEY and SEY) are critical parameters in the formation of an electron cloud, a serious problem that limits the performance of proton and positron accelerators. A few years ago it was discovered by the Vacuum Solutions Group at Daresbury laboratory that Laser Ablation Surface Engineering (LASE) could provide surfaces with SEY<1 [1,2]. The LASE surfaces are considered as a baseline solution for electron cloud miti-gation in the Future Circular Collider (FCC). However, these surfaces are undergoing further optimisation for the FCC application. While keeping SEY<1 the surfaces should meet the following criteria: Low outgassing, Low particulate generation and low surface resistance. In this paper we will report a number of new surfaces created using the LASE technique with different laser parameters (wavelength, scan speed, pitch, repetition rate, power, and pulse length) and their effect on the SEY, surface re-sistance and vacuum properties, etc  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL133  
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THPAL149 RF System Based on Two Klystrons and Phase Modulation for Photo-Cathode Injector gun, klystron, linac, cathode 3996
 
  • P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha
    TUB, Beijing, People's Republic of China
 
  We proposed an RF system with two klystrons, of which the powers are combined by a 3dB-hybrid. By managing the phases of the two klystrons respectively, the two pulses from the two output ports of the 3dB-hybrid can be of different powers, phases, and shapes. One of the two pulses can be set to an RF gun, while the other one can feed traveling accelerating structures. Two methods of phase modulation were proposed based on this scheme. Comparing with the state-of-art RF system, the new one can be of high efficiency or can generate electron beams with higher energy. The detailed analysis of the two methods and some experiments are described in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL149  
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THPAL151 Progress in Understanding Breakdown Characteristics of X-Band Choke-Mode Structures timing, cavity, HOM, operation 4002
 
  • X.W. Wu, D.Z. Cao, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People's Republic of China
  • T. Abe, T. Higo, S. Matsumoto
    KEK, Ibaraki, Japan
 
  Funding: National Natural Science Foundation of China (Grant No. 11135004).
As one of the higher-order-mode (HOM) damping structures, X-band choke-mode accelerating structures had been studied for several years. However, the breakdown characteristics of the X-band choke are still unknown. Five different single-cell choke-mode accelerating structures and one reference structure were designed, fabricated and high-gradient tested to study the related RF breakdown characteristics. The absence of field emission current flash was proposed to be the sign of breakdowns occurring inside the choke, this was verified by the post-mortem observation. Evaluation of the breakdown rate revealed that there is memory effect with pulse width and electric field. The breakdown rate in a single RF pulse did not have the 5th order pulse width and 30th order electric field dependency predicted by the empirical formula.
 
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THPAL154 High-Gradient Performance of X-Band Choke-Mode Structures ECR, GUI, HOM, damping 4011
 
  • X.W. Wu, D.Z. Cao, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People's Republic of China
  • T. Abe, T. Higo, S. Matsumoto
    KEK, Ibaraki, Japan
 
  Funding: National Natural Science Foundation of China (Grant No. 11135004)
The choke-mode accelerating structure is one of the higher-order-mode (HOM) damping structures. It has the advantage of relatively simple fabrication and low surface magnetic field. C-band choke-mode accelerating structures have been successfully applied in multibunch XFEL. However, the X-band choke-mode study remains in the theoretical design stage. The high-gradient performance of the choke is still unknown. Five different single-cell choke-mode accelerating structures were designed, fabricated and high-gradient tested to study the related RF breakdown characteristics. It was observed that high electric field and small choke dimension caused serious breakdowns in the choke which was the main limitation of the high-gradient performance. The Choke-mode accelerating structures reached 130 MV/m by decreasing the electric field and increasing the choke gap. A new quantity was proposed to give the high-gradient performance limit of choke-mode accelerating structures due to RF breakdown. The new quantity was obtained from the summary of the high-gradient experiments and could be used to guide high-gradient choke-mode accelerating structure design.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL154  
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THPAL157 Investigation of Transverse Wakefield and Beam Break Up Effect in Irradiation Linacs cavity, wakefield, linac, simulation 4020
 
  • X.C. Meng, H.B. Chen, J. Shi, Z.H. Wang, H. Zha, S.X. Zheng
    TUB, Beijing, People's Republic of China
  • G.H. Li, J.S. Liu, Y.H. Liu
    NUCTECH, Beijing, People's Republic of China
 
  Study of beam break up effect in linacs has been done in recent years. The beam-induced high order dipolar modes, especially the TM11-like mode were investigated for the linacs both in travelling wave and backward trav-elling wave. Measurements of beam-break up in a travel-ling wave linac were carried out and results are discussed. Moreover, a theoretical model was developed for the irradiation linacs to study the detailed interaction be-tween the transverse wakefield and the electron beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL157  
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THPMF011 Femtosecond Laser Ablation for Manufacturing of X-ray Lenses and Phase Corrector Plates optics, laser, photon, storage-ring 4057
 
  • S.P. Antipov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • L. Assoufid, W.C. Grizolli, J. Qian, X. Shi
    ANL, Argonne, Illinois, USA
 
  Funding: DOE SBIR
The next generation light sources such as diffraction limited storage rings and high repetition rate free electron lasers (FELs) will generate X-ray beams with significantly increased peak and average brilliance. These future facilities will require X-ray optical components capable of handling large instantaneous and average power densities while tailoring the properties of the X-ray beams for a variety of scientific experiments. In this paper we report on research and development of a single crystal diamond compound refractive lens. Diamond lenses presented here are fabricated by fs-laser cutting and subsequent polishing. Grating interferometry measurement data of these lenses had been performed at the Advanced Photon Source (Argonne). Besides the lenses, we fabricated and tested several phase correction plates, a refractive elements designed to correct for cumulative X-ray beam aberrations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF011  
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THPMF014 First Experiments at the CLEAR User Facility electron, radiation, operation, plasma 4066
 
  • R. Corsini, A. Curcio, S. Curt, S. Döbert, W. Farabolini, D. Gamba, R. Garcia Alia, T. Lefèvre, G. McMonagle, P.K. Skowroński, M. Tali, F. Tecker
    CERN, Geneva, Switzerland
  • E. Adli, C.A. Lindstrøm, K.N. Sjobak
    University of Oslo, Oslo, Norway
  • R.M. Jones, A. Lagzda
    UMAN, Manchester, United Kingdom
 
  The new "CERN Linear Electron Accelerator for Research" (CLEAR) facility at CERN started its operation in fall 2017. CLEAR results from the conversion of the CALIFES beam line of the former CLIC Test Facility (CTF3) into a new testbed for general accelerator R&D and component studies for existing and possible future accelerator applications. CLEAR can provide a stable and reliable electron beam from 60 to 220 MeV in single or multi bunch configuration at 1.5 GHz. The experimental program includes studies for high gradient acceleration methods, e.g. for CLIC X-band and plasma technology, prototyping and validation of accelerator components, e.g. for the HL-LHC upgrade, and irradiation test capabilities for characterization of electronic components and for medical applications. An overview of the facility capabilities and a summary of the latest results will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF014  
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THPMF024 Commissioning and Operation of FAST Electron Linac at Fermilab cavity, electron, cryomodule, MMI 4096
 
  • A.L. Romanov, C.M. Baffes, D.R. Broemmelsiek, K. Carlson, D.J. Crawford, N. Eddy, D.R. Edstrom, E.R. Harms, J. Hurd, M.J. Kucera, J.R. Leibfritz, I.L. Rakhno, J. Reid, J. Ruan, J.K. Santucci, V.D. Shiltsev, G. Stancari, R.M. Thurman-Keup, A. Valishev, A. Warner
    Fermilab, Batavia, Illinois, USA
 
  We report results of the beam commissioning and first operation of the 1.3 GHz superconducting RF electron linear accelerator at Fermilab Accelerator Science and Technology (FAST) facility. Construction of the linac was completed and the machine was commissioned with beam in 2017. The maximum total beam energy of about 300 MeV was achieved with the record energy gain of 250 MeV in the ILC-type SRF cryomodule. The pho-toinjector was tuned to produce trains of 200 pC bunches with a frequency of 3 MHz at a repetition rate of 1 Hz. This report describes the aspects of machine commission-ing such as tuning of the SRF cryomodule and beam optics optimization. We also present highlights of an experimental program carried out parasitically during the two-month run, including studies of wake-fields, and advanced beam phase space manipulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF024  
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THPMF048 Bunch Length Measurements Using CTR at the AWA with Comparison to Simulation simulation, laser, gun, electron 4166
 
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  • S.P. Antipov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  • J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
In this paper we present electron bunch length measurements at the Argonne Wakefield Accelerator (AWA) photoinjector facility. The AWA accelerator has a large dynamic charge density range, with electron beam charge varying between 0.1 nC - 100 nC, and laser spot size diameter at the cathode between 0.1 mm - 18 mm. The bunch length measurements were taken at different charge densities using a metallic screen and a Martin-Puplett interferometer to perform autocorrelation scans of the corresponding coherent transition radiation (CTR). A liquid helium-cooled 4K bolometer was used to register the interferometer signal. The experimental results are compared with Impact-T and OPAL-T numerical simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF048  
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THPMF049 Photoinjector Optimization Studies at the AWA simulation, emittance, laser, gun 4169
 
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  • J. Larson, J.G. Power
    ANL, Argonne, Illinois, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
With a variable charge range of 0.1 nC - 100 nC, the Argonne Wakefield Accelerator facility (AWA) has a unique and dynamic set of operating parameters. Adjustment of the optics and occasionally the rf phases is required each time the bunch charge is changed. Presently, these adjustments are done by the operator during each experiment. This is time consuming and inefficient, more so at high charge and for complex experimental set ups. In an attempt to reduce the amount of time spent adjusting parameters by hand, several optimization methods in simulation are being explored. This includes using the well-known Genetic Algorithm (NSGA-II), incorporated into OPAL-T. We have also investigated a model-based method and novel structure based algorithms developed at ANL. Ongoing efforts include using these optimization methods to improve operations at the AWA. Simulation results will be compared to measured beam parameters at the AWA, and one optimization method will be selected for use in guiding operations going forward.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF049  
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THPMF063 The MESA 15 kW cw 1.3 GHz Solid State Power Amplifier Prototype operation, SRF, linac, cavity 4216
 
  • R.G. Heine, F. Fichtner
    IKP, Mainz, Germany
 
  The Mainz Energy recovering Superconducting Accelerator MESA is a multi-turn energy recovery linac with beam energies in the 100 MeV regime currently designed and build at Institut für Kernphysik (KPH) of Johannes Gutenberg-Universität Mainz. The main accelerator consists of two superconducting Rossendorf type modules, while the injector MAMBO (MilliAMpere BOoster) relies on normal conducting technolgy. The high power RF system is planned completely in solid state technology. With the high power demands of the normal conducting RF cavities up-to-date transistor technology with increased power density has to be used. A 15 kW CW power ampifier prototype with the new technology has been developed by Sigma Phi Electronics and deliverd to KPH. In this paper we will present the results of the performance measurements of the amplifier.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF063  
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THPMF068 Commissioning Status of FLUTE gun, electron, laser, MMI 4229
 
  • A. Malygin, A. Bernhard, E. Bründermann, A. Böhm, S. Funkner, S. Marsching, W. Mexner, A. Mochihashi, A.-S. Müller, M.J. Nasse, G. Niehues, R. Ruprecht, T. Schmelzer, M. Schuh, N.J. Smale, P. Wesolowski, M. Yan
    KIT, Karlsruhe, Germany
  • I. Križnar
    Cosylab, Ljubljana, Slovenia
  • M. Schwarz
    CERN, Geneva, Switzerland
 
  FLUTE (Ferninfrarot Linac- Und Test-Experiment) will be a new compact versatile linear accelerator at the KIT. Its primary goal is to serve as a platform for a variety of accelerator studies as well as to generate strong ultra-short THz pulses for photon science. The phase I of the project, which includes the RF photo injector providing electrons at beam energy of 7 MeV and a corresponding diagnostics section, is currently being commissioned. In this contribution, we report on the latest progress of the commissioning phase. The status of the gun conditioning will be given, followed by an overview of the RF system and the laser system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF068  
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THPMF072 Implementation of Ultra-Low Frequency Non-Linear Raman Spectroscopy with the Gun Laser at FLUTE scattering, laser, gun, optics 4242
 
  • S. Funkner, E. Bründermann, A.-S. Müller, M.J. Nasse, G. Niehues, T. Schmelzer, J.L. Steinmann, M. Yan
    KIT, Eggenstein-Leopoldshafen, Germany
  • M. Tani
    University of Fukui, Fukui, Japan
 
  At the Karlsruhe Institute of Technology (KIT) the new compact versatile linear accelerator FLUTE is currently under commissioning. This accelerator will provide intense broadband THz pulses for spectroscopic experiments. Here, we demonstrate the implementation of a coherent Raman spectrometer using the RF gun laser of FLUTE. With our experiment, we can measure the Raman spectrum at ultra-low frequencies. The measurement principle, which was recently published, is based on coherent nonlinear excitation of the observed sample. The spectrometer consists of a stretcher and an interferometer, which can be simply built from standard optics. We will show that the accessible spectral range overlaps well with that from the THz pulses of the planned FLUTE experiment. Thus, the coherent Raman experiment can provide spectral information complementary to absorption spectral measurements using the THz radiation of FLUTE.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF072  
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THPMK023 Coherent Transition Radiation Generated from Transverse Electron Density Modulation radiation, electron, detector, simulation 4348
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • A.I. Benediktovitch
    BSU, Minsk, Belarus, Belarus
  • S.N. Galyamin, A.V. Tyukhtin
    Saint Petersburg State University, Saint Petersburg, Russia
  • P. Piot
    Fermilab, Batavia, Illinois, USA
 
  Coherent Transition radiation (CTR) of a given frequency is commonly generated with longitudinal electron bunch trains. In this paper we present a study of CTR production from electron transverse density modulation. We demonstrate via numerical simulations a simple technique to generate THz-scale frequencies from mm-scale transversely separated electron beamlets. The results and a potential experimental setup are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK023  
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THPMK062 Transverse Energy Distribution Measurements for Polycrystalline and (100) Copper Photocathodes with Known Levels of Surface Roughness cathode, electron, emittance, detector 4438
 
  • L.B. Jones, B.L. Militsyn, T.C.Q. Noakes
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • L.B. Jones, D.P. Juarez-Lopez, B.L. Militsyn, T.C.Q. Noakes, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • D.P. Juarez-Lopez, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: This work is part of EuCARD-2, partly-funded by the European Commission, GA 312453.
The minimum achievable emittance in an electron accelerator depends strongly on the intrinsic emittance of the photocathode electron source. This is measureable as the mean longitudinal and transverse energy spreads in the photoemitted electrons. ASTeC's Transverse Energy Spread Spectrometer (TESS)* experimental facility can be used with III-V semiconductor, multi-alkali and metal photocathodes to measure transverse and longitudinal energy distributions. Our R&D facilities also include in-vacuum quantum efficiency measurement, XPS, STM, plus ex-vacuum optical and STM microscopy for surface metrology. Intrinsic emittance is strongly affected by the photocathode surface roughness**, and the development of techniques to manufacture the smoothest photocathode is a priority for the electron source community. We present energy distribution measurements for electrons emitted from copper photocathodes with both defined single-crystal (100) and polycrystalline surfaces with measured levels of surface roughness.
* Proc. FEL'13, TUPPS033, pp. 290-293.
** Proc. FEL'06, THPPH013, pp. 583-586.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK062  
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THPMK077 The Preliminary Experiment Studies for Soft X-Ray Self-Seeding System Design of SCLF Facility photon, FEL, simulation, electron 4481
 
  • K.Q. Zhang, C. Feng, D. Wang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
 
  The preliminary experiment studies for soft x-ray self-seeding system design of SCLF facility have been pre-sented in this paper. Some practical problems and pre-engineering design have been studied for the experimental prepare of soft x-ray self-seeding for the future SCLF facility. The monochromator system designs in this paper include optical structure, optical parameters and mechanical design. The designed optical system has an optical resolution of 1/10000 at the photon energy of 700-1300eV based on the optical simulation. To make the system satisfy the experimental requirements, mechanical install requirements and install precisions are also analysed. Considering the actual varies errors, the errors analyses such as the surface errors of the optical mirror and the machining errors of the VLS grating are also carried out. In conclusion, preliminary experimental studies including system design and varies engineering requirements are introduced to make sure that the presented design is reliable for final soft x-ray self-seeding experiment of SCLF facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK077  
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THPMK094 Thermal Design of a 100 kW Electron to Gamma Converter at TRIUMF electron, target, TRIUMF, ISOL 4520
 
  • B.G. Cade, L. Egoriti, A. Gottberg
    TRIUMF, Vancouver, Canada
  • D.R. Priessl
    UVIC, Victoria, Canada
 
  The electron target station (AETE) of the TRIUMF-ARIEL Facility will employ an electron "driver" beam to irradiate Isotope Separator On-Line (ISOL) targets for the production of radioactive isotopes via photofission. 30 MeV electrons will be converted to gamma spectrum Bremsstrahlung photons via an electron to gamma (e-y) converter located upstream of the ISOL target. The e-y concept uses a composite metal with two layers: One high-Z material to convert electrons to photons, and one low-Z material to provide structural support, thermal dissipation, and maximal transparency to the produced gamma photons. Several material combinations and bonding processes are currently being evaluated and tested using TRIUMF's E-LINAC. Water-cooling and thermal design are being optimized for 100 kW operation and have thus far been validated up to 10 kW driver beam power. The latest test results and future prospects are summarized.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK094  
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THPMK099 Measurement of the Laser-Induced Energy Modulation Amplitude at the Short-Pulse Facility at DELTA laser, electron, radiation, synchrotron 4538
 
  • A. Meyer auf der Heide, B. Büsing, S. Khan, N.M. Lockmann, C. Mai, B. Riemann, B. Sawadski
    DELTA, Dortmund, Germany
 
  The short-pulse facility at the synchrotron light source DELTA operated by the TU Dortmund University employs coherent harmonic generation (CHG) to provide ultrashort pulses in the vacuum ultraviolet and terahertz regime. Here, a laser-electron interaction results in a modulation of the electron energy which is transformed into a density modulation by a magnetic chicane. Measurements of the energy modulation amplitude with different techniques including an RF phase modulation are presented. A combination of the results allow to estimate the energy spread of the electron beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK099  
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THPMK111 Negative Electron Affinity Gallium Arsenide Photocathodes Based on Optically Resonant Nanostructure cathode, resonance, electron, simulation 4575
 
  • S. Zhang, M. Poelker, M.L. Stutzman
    JLab, Newport News, Virginia, USA
  • X. Peng, J. Zou
    East China University of Science and Technology, Shanghai, People's Republic of China
 
  Funding: DOE
We report the design and fabrication of a new type of negative electron affinity (NEA) gallium arsenide (GaAs) photocathode with optically resonant nanostructures. We observed a significant enhancement of the quantum effi-ciency (QE) from the GaAs photocathode with nanowire arrays (NWA) due to the Mie resonance effect within the intended wavelength range. Theoretical calculations of the expected reflectance behaviour together with experi-mental results of optical and photoemission characteris-tics are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK111  
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THPMK113 From Coherent Harmonic Generation to Steady State Microbunching storage-ring, bunching, radiation, electron 4583
 
  • X.J. Deng, W.-H. Huang, T. Rui, C.-X. Tang
    TUB, Beijing, People's Republic of China
  • A. Chao, D.F. Ratner
    SLAC, Menlo Park, California, USA
  • J. Feikes, M. Ries
    HZB, Berlin, Germany
  • R. Klein
    PTB, Berlin, Germany
 
  Steady state microbunching (SSMB) is an electron storage ring based scheme proposed by Ratner and Chao to generate high average power narrow band coherent radiation with wavelength ranging from THz to EUV. One key step towards opening up the potential of SSMB is the experimental proof of the SSMB principle. In this paper, the SSMB experiment planned and prepared by a recently established collaboration is presented starting from a modified coherent harmonic generation (CHG). Single particle dynamics of microbunching in an electron storage ring are analyzed. Though oriented for CHG and SSMB, some of the effects analyzed are also important in cases like bunch slicing, bunch compression, FEL beam transport lines etc, in which precise longitudinal phase space manipulations are involved. These dynamics together with some SSMB related collective effects are to be investigated on the storage ring MLS in Berlin.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK113  
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THPMK115 Optical Cavity R&D for Laser-Electron Interaction Applications cavity, laser, HOM, electron 4587
 
  • X. Liu, W.-H. Huang, C.-X. Tang, L.X. Yan
    TUB, Beijing, People's Republic of China
  • R. Chiche, K. Dupraz, P. Favier, A. Martens, H. Monard, Z.F. Zomer
    LAL, Orsay, France
  • D. Nutarelli
    LAC, Orsay, France
 
  Laser-electron Inverse Compton Scattering X-ray source based on optical enhancement cavity is expected to produce higher-flux and better-quality X-rays than conventional sources, in addition, to become more compact, much cheaper than Free Electron Laser and Synchrotron Radiation. One X-ray source named ThomX is under construction at LAL, France. An electron storage ring with 50 MeV, 16.7 MHz electron beam will collide with a few picosecond pulsed laser to produce 1013 photons per second. A prototype cavity with a high finesse (F=25,100) in the picosecond regime is used to perform R & D for ThomX. We obtained 380 kW power stored in the optical cavity and mode instabilities were observed. The EOM-based frequency modulation to measure the finesse, the influence of dust on finesse, high-power experiments and other related issues are mentioned briefly. We will also describe the TTX2 (Tsinghua Thomson Scattering X-ray source) at Tsinghua University which is in design process. TTX2 prefers using an electron storage ring and an optical cavity in order to get high X-ray flux.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK115  
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THPMK116 NEA Surface Activation of GaAs Photocathode with CO2 cathode, electron, ECR, emittance 4590
 
  • L.Guo. Guo
    UVSOR, Okazaki, Japan
  • H. Iijima
    Tokyo University of Science, Tokyo, Japan
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
  • K. Uchida
    Cosylab Japan, Ibaraki, Japan
 
  NEA (negative electron affinity)-GaAs cathode is able to generate highly spin polarized electron beam more than 90%. The NEA activation is performed usually with Cs and O2 or NF3, but the exact structure of the NEA surface is not known. In this paper, we performed the NEA activation on a cleaned GaAs surface with CO2, CO, N2, and O2 gases and compared the results to improve our understanding on the NEA surface. We found that CO2 activated the cathode, but N2 and CO did not. By analyzing CO2 activation, we found that atomic oxygen activates the NEA surface and CO degrades the NEA surface simultaneously. We found that the NEA activation ability of atomic oxygen is almost a half of that of O2 molecule.*
*L. Guo, M. Kuriki, H. Iijima, K. Uchida. "NEA surface activation of GaAs photocathode with different gases", Surface Science 664C (2017) pp. 65-69.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK116  
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THPMK118 GaN Thin Film Photocathodes for High Brightness Electron Beams cathode, electron, target, brightness 4594
 
  • M. Vogel, X. Jiang, M. Schumacher
    University Siegen, Siegen, Germany
 
  Funding: This work was supported by the German Federal Ministry of Education and Research under grant 05K16PS1 "HOPE II: Hochbrillante photoinduzierte Hochfrequenz-Elektronenquellen".
Gallium nitride (GaN) is one promising candidate as photocathode material showing high quantum efficiencies which is one of the requirements for high brightness electron beams. In addition to reported quantum efficiencies of up to 70%, GaN needs to satisfy the demands for long lifetime, low dark current and low thermal emittance. In this contribution, the ongoing activities of the synthesis by means of reactive rf magnetron sputtering and characterization of GaN is presented. The latter is done by standard materials science methods and in-situ measurements of the quantum efficiency in combination with lifetime and dark current measurements to asses and optimize the photocathode's performance. Along with the project's details, first experimental results of GaN thin films synthesized utilizing a GaAs source are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK118  
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THPMK147 Measurement of Slice-Emittance of Electron Bunch Using RF Transverse Deflector emittance, injection, acceleration, electron 4648
 
  • T. Sasaki, Y. Nakazato, M. Washio
    Waseda University, Tokyo, Japan
  • Y. Koshiba
    RISE, Tokyo, Japan
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
 
  We have been studying a compact electron accelerator based on an S-band Cs-Te photocathode rf electron gun at Waseda University. We are applying this high quality electron beam to soft X-ray generation, coherent THz wave generation and pulse radiolysis experiment. In these applications, longitudinal parameters of the electron beam are important. Thus, we developed the RF deflecting cavity which can directly convert longitudinal distribution of the beam to transverse with high temporal resolution, and succeeded in measuring longitudinal profile of an electron beam from the RF gun. Encouraged by these successful results, we started to measure slice emittance. Slice emittance would be very useful for improving the RF electron gun cavity. Therefore, we tried to measure the slice emittance of the electron beam by applying the Q-scan method to deflected beam by RF deflecting cavity. In this conference, we will report the principle, experimental results of the slice emittance measurement, and future prospects.
C. Vaccarezza et al., "Slice emittance measurements at SPARC photoinjector with a RF deflector", Proc. of EPAC08, Genoa, Italy
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK147  
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THPML007 An Investigation of Electron Beam Divergence from a Single DFEA Emitter Tip cathode, electron, laser, emittance 4662
 
  • H.L. Andrews, B.K. Choi, R.L. Fleming, D. Kim, J.W. Lewellen, K.E. Nichols, D.Y. Shchegolkov, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  Funding: We gratefully acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program for this work.
Diamond Field-Emitter Array (DFEA) cathodes are arrays of micron-scale diamond pyramids with nanometer-scale tips. DFEAs can produce high emission currents with small emittance and energy spread. At LANL, we have an ongoing program to test DFEA cathodes for the purpose of using them to generate high-current, low-emittance electron beams for dielectric laser accelerators. We have recently upgraded our cathode test chamber to use a mesh anode in place of a solid luminescent anode. In addition to allowing for downstream beam transport, this arrangement may eliminate earlier problems with reduced cathode performance due to ion back-bombardment. We are measuring divergence of the electron beam past the mesh in an effort to characterize the inherent beam divergence off the diamond tip and divergence contribution from the mesh. We will compare these observations with theoretical and modeled values.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML007  
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THPML010 Modeling of Diamond Field Emitter Arrays for Shaped Electron Beam Production electron, simulation, gun, emittance 4668
 
  • K.E. Nichols, H.L. Andrews, D.Y. Shchegolkov, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  We present simulations of shaped electron beam production from diamond field emitter array (DFEA) cathodes. DFEAs are arrays of diamond pyramids with bases of the order of 10 microns that produce high current densities. These arrays can be fabricated in arbitrary shapes such as a triangle or a double triangle, so that they produce an inherently shaped beam. These transversely shaped beams can be put through an emittance exchanger to produce a longitudinally shaped electron beam distribution for use with high-transformer ratio wakefield accelerators. Simulations are conducted with MICHELLE. We design cathodes and focusing systems that preserve the beam's shape while transporting it to the emittance exchanger.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML010  
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THPML012 Simulations and Measurements of the Wakefield Loading Effect in Argonne Wakefield Accelerator Beamline wakefield, linac, acceleration, higher-order-mode 4675
 
  • J. Upadhyay, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • M.E. Conde, Q. Gao, N.R. Neveu, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
 
  A beam driven acceleration experiment in a photonic band gap (PBG) structure is planned at Argonne wakefied accelerator (AWA) facility at Argonne National Laboratory. We plan to pass a high charge (drive) beam through a travelling wave 11.7 GHz PBG structure and generate a wakefield. This wakefield will be probed by a low charge (witness) beam to demonstrate wakefield acceleration and deceleration. The drive and witness bunches will be accelerated to above 60 MeV in the main accelerator at AWA which has frequency of 1.3 GHz. The charges used in this experiment could be as high as 20 nC. To measure the exclusive effect of PBG the structure on acceleration and deceleration of the witness bunch we have to exclude the effect of beam loading of the main AWA accelerator structure. To understand the wakefield effect in AWA, we conducted an experiment where we passed the high charge (10 nC) beam through the accelerator structure which was followed by a 2 nC witness beam separated by 4 wavelength. The energy of witness beam was measured in the presence and absence of the drive beam. The beam loading was observed and quantified. The results of this work will be presented in the conference.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML012  
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THPML013 Demonstration of the Wakefield Acceleration in an 11.7 GHz Photonic Band Gap Accelerator Structure wakefield, acceleration, electron, higher-order-mode 4678
 
  • J. Upadhyay, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • M.E. Conde, Q. Gao, N.R. Neveu, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  We plan to conduct a beam driven acceleration experiment in a photonic band gap (PBG) accelerator structure operating at 11.7 GHz at Argonne Wakefield Accelerator (AWA) facility. For the experiment, the PBG structure will be excited by a high charge (up to 10 nC) electron bunch, and a second smaller charge witness bunch will be accelerated. Because the PBG structure was fabricated with electroforming, the AWA beamline includes a Be window placed before the PBG structure that protects the cathode from contamination due to possible outgassing from the electroformed copper. The diameter of the Be window is 9 mm and the beam tube diameter of the PBG structure is 6.4 mm. The size of the high charge electron beam on Be window has to be minimized to minimize scattering. The parameters of the beamline had to be adjusted to achieve good propagation of the beam. An OPAL simulation for the AWA beamline was performed for 1, 5, and 10 nC beams. The beam size was experimentally measured at different positions in the beamline for different charges to verify simulations. Finally, the high charge electron beam was passed through the PBG structure and acceleration of the witness bunch was measured  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML013  
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THPML014 A Metamaterial Wagon Wheel Structure for Wakefield Acceleration by Reversed Cherenkov Radiation wakefield, simulation, acceleration, electron 4681
 
  • X.Y. Lu, I. Mastovsky, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
  • M.E. Conde, C.-J. Jing, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  Funding: U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0015566 and the U.S. Department of Energy Office of Science under Contract No. DE-AC02-06CH11357
We present the design and experimental operation on an X-band metamaterial (MTM) wagon wheel structure for wakefield acceleration. The structure was designed and fabricated at MIT, and tested at the Argonne Wakefield Accelerator (AWA) laboratory at Argonne National Lab. The MTM wagon wheel structure is an all-metal periodic structure at 11.4 GHz. The fundamental TM mode has a negative group velocity, so when an electron beam travels through, energy is extracted from the beam by reversed Cherenkov radiation, which was verified in the experiment. Single bunches up to 45 nC were sent through the structure with a beam aperture of 6 mm and generated microwave power up to 25 MW in a 2 ns pulse, in agreement with both the analytical wakefield theory and the numerical CST simulations. Two bunches with a total charge of 85 nC generated 80 MW of microwave power. The structure is scalable to a power extractor of over 1 GW by increasing the structure length from 8 cm to 22 cm.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML014  
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THPML015 Dielectric Multipactor Discharges at 110 GHz multipactoring, cavity, GUI, vacuum 4684
 
  • S. C. Schaub
    MIT, Cambridge, Massachusetts, USA
  • M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
 
  A 1.5 MW, 110 GHz gyrotron has been used to experimentally measure the maximum sustainable fields on dielectric materials in vacuum. The purpose of this work is to evaluate the suitability of these materials for future applications in high frequency linear accelerators and high power terahertz components. To our knowledge, these are the first measurements of multipactor phenomena in the millimeter wave or terahertz frequency range. Materials tested include alumina, sapphire, fused quartz, crystal quartz, and high resistivity silicon. Dielectric samples were tested both as windows, with electric fields parallel to the surface, and sub-wavelength dielectric rod waveguides, with electric fields perpendicular to the surface. Surface electric fields in excess of 52 MV/m were achieved in 3 microsecond pulses. Visible light emission, absorbed/scattered microwave power, and emitted electrons were measured to characterize the discharges on the dielectric surfaces. The results of these experiments have been compared to theoretical calculations of multipactor discharges, testing these theories at significantly higher frequencies than has been done before.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML015  
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THPML024 Monoenergetic Beam Generated by Laser Accelerator at Peking University laser, proton, quadrupole, acceleration 4702
 
  • K. Zhu, J.E. Chen, Y.X. Geng, C. Li, D.Y. Li, Q. Liao, C. Lin, H.Y. Lu, W.J. Ma, Y.R. Shou, Wu,M.J. Wu, X.H. Xu, X.Q. Yan, J.Q. Yu, Y.Y. Zhao, J.G. Zhu
    PKU, Beijing, People's Republic of China
 
  An ultrahigh-intensity laser incident on a target sets up a very strong electrostatic field exceeding 100 GV/m, it will few orders magnitude shrink down the traditional radio frequency accelerators. Whereas, to build a real accelerator for routine operation, many scientific and technical challenges for laser acceleration need to overcome before they could be applied to these applications. Recently A laser accelerator− Compact Laser Plasma Accelerator (CLAPA) is being built with a beam line to deliver proton beam with the energy of 1~15MeV, energy spread of ¡À1% and 107-8 protons per pulse. The very high current proton beam is accelerated in laser ultrathin-foil interaction and transported by a beam line consisting of the electric quadruple and analyzing magnets. It makes sure the good beam qualities such as energy spread, charge, repeatability and availability of different energy, which means that for the first laser acceleration becomes a real laser accelerator. With the development of high-rep rate PW laser technology, we can now envision a compact beam therapeutic machine of cancer treatment in the near future soon.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML024  
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THPML031 Collective Acceleration of Laser Plasma in Non-stationary and Non-uniform Magnetic Field plasma, laser, acceleration, target 4716
 
  • A.A. Isaev, C.I. Kozlovskij, E.D. Vovchenko
    MEPhI, Moscow, Russia
 
  This paper presents the new experimental results concerning acceleration of deuterium ions extracted from laser plasma in the rapid-growing nonuniform magnetic field in order to initiate the nuclear reactions D(d, n)3He and Т (d,n)4He. In order to obtain plasma a laser that generates in Q-switched mode the pulses of infrared radiation (λ = 1.06 μm) with the energy W ≤ 0.85 J and duration of ≈10 ns. In the present study, the velocity of a bunch of a laser plasma at a magnetic field induction rate of 3-108 T/s was experimentally measured, and angular distributions of accelerated particle fluxes were measured in the range from 0 to 30 degrees. The maximum and mean ion velocities were determined by the time-of-flight technique. The proposed system allows the generation of neutrons, including possibly thermonuclear ones, on counterflows using two similar magnetic accelerators located coaxially, facing each other. In this case the problem related to degradation of solid neutron-generating targets is resolved. There also occurs a possibility of fast accumulated running time of packed solid targets at using of deuteron-tritium laser targets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML031  
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THPML055 Scaled Studies on Radio Frequency Sources for Megawatt-Class Ionospheric Heaters electron, gun, impedance, cathode 4763
 
  • B.L. Beaudoin, T.M. Antonsen, J.A. Karakkad, A.H. Narayan, G.S. Nusinovich, K.J. Ruisard
    UMD, College Park, Maryland, USA
  • R. Fischer
    Naval Research Laboratory (NRL), Washington, USA
  • S.H. Gold, A. Ting
    NRL, Washington,, USA
 
  Funding: Funding for this project and travel is provided by the Air Force Office of Scientific Research under grant FA95501410019.
The ionosphere plays a prominent role in the performance of critical civilian and military communication systems. The key instrument in Ionospheric Modification (IM) research is a powerful, ground-based, High Frequency (HF) source of electromagnetic waves known as a heater. With a mobile heater, investigators would be able to conduct IM research at different latitudes without building a costly permanent installation. A new highly efficient Megawatt class of Radio Frequency sources is required to reduce the overall power demands on a fully deployable system. Such a source has been described previously*. Results of a scaled experiment, using the electron beam produced by a gridded gun to drive an external lumped element circuit for high efficiency radio frequency generation is presented. The IOT gun produces an electron beam bunched at the driving frequency that is then collected by an external circuit for impedance matching to the load. Results showed that effects such as the internal resistance of the inductor and deflection of beam electrons by the induced RF voltages on the beam collector are important considerations to be included in the design of a practical device.
* B.L. Beaudoin, G.S. Nusinovich, G. Milikh, A. Ting, S. Gold, J.A. Karakkad, A.H. Narayan, D.B. Matthew, D.K. Papadopoulos, T.M. Antonsen Jr., Journal of Elec. Waves and Appl.,31,17,pp.1786, 2017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML055  
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THPML062 A Beam Based Method to Optimize the SBPM System FEL, electron, quadrupole, site 4780
 
  • J. Chen
    SINAP, Shanghai, People's Republic of China
  • L.W. Lai, Y.B. Leng, T. Wu, R.X. Yuan
    SSRF, Shanghai, People's Republic of China
 
  For the electron accelerator, it is hoped that the trajec-tory of the beam can pass through the magnetic center of the quadrupole to minimize the orbital motion caused by the instability of the power supply. The relative deviation between the magnetic center of quadrupole and the elec-tric center of adjacent BPM is measured by electron beam usually in various accelerator facilities. But for the stripline BPM (SBPM) system, in order to achieve the best performance, the beam trajectory should also need to pass through the electrical center of the SBPM system. In this paper, a beam based method to optimize the SBPM system was proposed, the intensity of the magnet power was scanned to change the beam position in two-dimension and combine the change trend of the sum signal of adjacent SBPM to find out the relative deviation of BPM electric center and mechanical center. Relevant beam experiment work on the Shanghai Soft X-ray free electron laser (SXFEL) and the benefit of this method will be addressed as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML062  
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THPML067 SXFEL Linac BPM System Development and Performance Evaluation FEL, linac, status, electron 4794
 
  • F.Z. Chen, T. Wu
    SSRF, Shanghai, People's Republic of China
  • J. Chen, L.W. Lai, Y.B. Leng, L.Y. Yu, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
 
  Shanghai Soft X-ray Free Electron Laser (SXFEL) is a test facility to study key technologies and new FEL physics. In order to deliver high quality electron beams to the undulator section, a high resolution (better than 10 microns with 200pC beam) Linac beam position monitor system has been developed. The system consists of stripline pickup and custom designed DBPM processor. The hardware and software architecture will be introduced in this paper. The online performance evaluation results will be presented as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML067  
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THPML068 Upgrade of Bunch Phase Monitor at SSRF Storage Ring injection, SRF, storage-ring, pick-up 4797
 
  • Y.M. Zhou, Y.B. Leng, T. Wu, N. Zhang
    SSRF, Shanghai, People's Republic of China
 
  Beam instability is a serious problem for physics in beam diagnosis technology. With regard to the evaluation of longitudinal phase oscillations during the transient injection process, bunch-by-bunch phase measurement is a useful tool for studying the behavior of the refilled bunches. A new upgraded beam phase monitor system with 1.2GHz bandwidth PXI waveform digitizer has been developed at Shanghai synchrotron radiation source (SSRF). Bunch-by-bunch phase information, retrieved from button pickup signals, is calculated by the zero-crossing detection method with the best phase resolution of 0.4ps. The refilled bunches can be separated from the stored ones, and the longitudinal offset of each refilled bunch has been measured. Several groups of experiments have been performed to verify the repeatability of bunch-by-bunch phase measurement, and some results regarding refilled bunches will be discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML068  
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THPML070 Point Spread Function Study of Quasi-Monochromatic X-Ray Pinhole Camera at SSRF simulation, photon, SRF, synchrotron 4803
 
  • B. Gao, H.J. Chen
    SINAP, Shanghai, People's Republic of China
  • J. Chen, Y.B. Leng
    SSRF, Shanghai, People's Republic of China
 
  Since 2009 an X-ray pinhole camera that has been used to present the transverse beam size and emittance on diagnostic beam line of the storage ring at SSRF. The real beam size is a function of the image size of the CCD camera and point spread function (PSF) of the system. The performance of the measurement of the transverse electron beam size is given by the width of the PSF of X-ray pinhole camera. The contributions to the PSF width are the PSF of pinhole itself due to diffraction, and the PSF of the screen and camera. An X-ray monochromatic system has been established to measure the PSF accurately, and decrease the variation in the beam size between the theoretical values and the measured ones at SSRF. In this article, both calculated and measured PSF of quasi-monochromatic X-ray pinhole camera will be presented in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML070  
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THPML091 Design of a High Gradient 60 GHz Dielectric Accelerating Structure acceleration, electromagnetic-fields, electron, simulation 4873
 
  • D.Z. Cao, D. Dan, W. Gai, C.-X. Tang, H. Zha
    TUB, Beijing, People's Republic of China
 
  RF breakdown are the main limitation for the application of high gradient structures. Higher frequencies and shorter pulse length benefit the design of accelerating structure for the breakdown threshold of surface field is Es=f1/2 τ-1/4. Power source which generates very short V-band pulse with nearly hundred megawatt is now available. The paper presents the analysis of a V-band dielectric acceleration structure and power source. Future plan about RF transmission and power coupling of the whole structure will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML091  
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THPML093 New Fast Kicker Results from the Muon g-2 E-989 Experiment at Fermilab kicker, monitoring, simulation, MMI 4879
 
  • A.P. Schreckenberger
    The University of Texas at Austin, Austin, Texas, USA
  • D. Barak, C.C. Jensen, G.E. Krafczyk, R.L. Madrak, H. Nguyen, H. Pfeffer, M. Popovic, J.C. Stapleton, C. Stoughton
    Fermilab, Batavia, Illinois, USA
  • A.T. Chapelain, A.A. Mikhailichenko, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • N.S. Froemming
    CENPA, Seattle, Washington, USA
  • J.L. Holzbauer
    UMiss, University, Mississippi, USA
  • A.I. Keshavarzi
    The University of Liverpool, Liverpool, United Kingdom
 
  We describe the installation, commissioning, and characterization of the injection kicker system for the E-989 experiment at Fermilab for a precision measurement of the muon anomalous magnetic moment. Control and monitoring systems have been implemented to acquire and record the waveforms of each kicker pulse, and measurements of various kicker system observables were recorded in the presence of the 1.45 T g-2 storage ring magnetic field. These monitoring systems are necessary to understand the systematic contribution to the measurement of the precession frequency. We examine the dependence of muon capture to kicker field predictions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML093  
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THPML098 Design of Beam Profile Monitor Used at the Xi'an Proton Application Facility (XiPAF) detector, proton, radiation, synchrotron 4892
 
  • D. Wang, Z.M. Wang
    State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Shannxi, People's Republic of China
  • W. Chen
    NINT, Xi'an, People's Republic of China
  • P.F. Ma, Y.G. Yang
    TUB, Beijing, People's Republic of China
  • W. Wang
    Tsinghua University, Beijing, People's Republic of China
 
  A pixel ionization chamber for beam profile monitor (BPrM) is designed and manufactured by a new technology .The detector will be installed on the beam line just upstream of the target device of XiPAF. It has many advantages such as high resolution, high radiation hardness and it can work as a real-time monitor to show the distribution of the delivered relative dose. The physics design and construction of the detector are described in this paper, and its performances are tested offline.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML098  
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THPML100 A High Voltage Feedforward Subsystem of Low Level RF System for the High Power RF System high-voltage, LLRF, low-level-rf, controls 4898
 
  • Z.Y. Lin, Y. C. Du, H.Q. Feng, W.-H. Huang, CY. Song, C.-X. Tang, Y.L. Xu, J. Yang
    TUB, Beijing, People's Republic of China
  • G. Huang
    LBNL, Berkeley, California, USA
 
  The Low Level Radio Frequency control (LLRF) system measures the RF signals from the accelerator tube, compares it with the phase reference received from the timing distribution system, and provides the drive signal to the high power RF system to provide synchronized RF voltage to the electron beam. Usually, the LLRF system can achieve a ~50 fs RMS phase jitter which is limited by the microwave devices. The phase noise arise from the high voltage variation of the high power system will significantly increase phase noise from low level RF signal to high power RF. A high voltage feed forward subsystem is proposed to deal with the phase noise caused by the high voltage jitter of the modulator. The demo system is depolyed in Thomson scattering X-ray source (TTX).and the primary experiment result anaylse is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML100  
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THPML101 A Novel Double Sideband-Based Phase Averaging Line for Phase Reference Distribution System LLRF, laser, FPGA, pick-up 4901
 
  • Z.Y. Lin, Y.-C. Du, W.-H. Huang, Z. Pan, C.-X. Tang, C.-X. Tang, Y.L. Xu, J. Yang
    TUB, Beijing, People's Republic of China
  • G. Huang
    LBNL, Berkeley, California, USA
 
  Coaxial cable based solution is one of the most important scheme in Phase Reference Distribution System. A novel double sideband-based phase averaging line has been developed in Tsinghua accelerator lab. The sender chassis generates the 2856 MHz signal as the forward signal and receives the 2856 MHz signal and the reflected double sideband signal from the receiver. The forward signal is phase-locked with the reference signal, and the forward signal and the sideband signal are adjusted by the FPGA virtual delay line. The preliminary experiments result shows the phase stability can achieve about 1% by signal distorted by the phase shifter.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML101  
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THPML106 Electron Microscopy Inspired Setup for Single-Shot 4-D Trace Space Reconstruction of Bright Electron Beams emittance, electron, detector, focusing 4909
 
  • J. Giner Navarro, D.B. Cesar, P. Musumeci
    UCLA, Los Angeles, California, USA
  • R.W. Aßmann, B. Marchetti, D. Marx
    DESY, Hamburg, Germany
 
  Funding: This work has been partially supported by the National Science Foundation under Grant No. 1549132 and Department of Energy under award No. DE-SC0009914.
In the development of low charge, single-shot diagnostics for high brightness electron beams, Transmission Electron Microscopy (TEM) grids present certain advantages compared to pepper pot masks due to higher beam transmission. In this paper, we developed a set of criteria to optimize the resolution of a point projection image. However, this configuration of the beam with respect to the grid and detector positions implies the measurement of a strongly correlated phase space which entails a large sensitivity to small measurement errors in retrieving the projected emittance. We discuss the possibility of an alternative scheme by inserting a magnetic focusing system in between the grid and the detector, similar to an electron microscope design, to reconstruct the phase space when the beam is focused on the grid.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML106  
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THPML107 Steering Optimizations for the University of Maryland Electron Ring closed-orbit, dipole, lattice, injection 4913
 
  • L. Dovlatyan, B.L. Beaudoin, R.A. Kishek, K.J. Ruisard
    UMD, College Park, Maryland, USA
 
  Funding: This work is supported by the US Dept. of Energy, Office of High Energy Physics award # DE-SC0010301
The University of Maryland Electron Ring (UMER) has the flexibility to set up alternative lattices for different research experiments, including nonlinear optics studies using octupoles. Each alternative lattice requires an acceptable steering solution for use in experiments. Existing beam-based alignment tools can take a significant amount of time to run and become difficult to process with a low number of BPMs. The Robust Conjugate Directional Search (RCDS) optimizer* is used to quickly obtain steering solutions for different lattice configurations and has been adopted for beam steering at UMER. Steering magnets are optimized online to reduce scraping, correct equilibrium orbits, and increase beam lifetimes. This study presents the application of the optimizer at UMER.
* X. Huang, J. Corbett, J. Safranek, J. Wu, Nucl. Instr. Meth. A vol. 726, pp. 77-83, 2013.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML107  
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THPML111 Test of the Tune Measurement System Based on BBQ at HLS-II Storage Ring betatron, storage-ring, ion-source, controls 4926
 
  • L.T. Huang, F.L. Gao, P. Lu, B.G. Sun, H.Q. Wang, J.G. Wang, Q. Wang, F.F. Wu, Y.L. Yang, T.Y. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Supported by the National Science Foundation of China (Grant No. 11705203, 11575181)
The HLS-II storage ring is a crucial part of Hefei Light Source. Tune is one of the most important parameters of the electron storage ring, of which the tune measurement system is an integral component. In this paper, the design of a new tune measurement system based on BBQ (base band tune), is presented. Some experiments are performed to test this system. The new system is compared with the original system and the TBT (turn-by-turn) method respectively. The obtained results illustrate higher accuracy and higher stability for the new system. A new approach of calculating the betatron oscillation amplitude is proposed, and the betatron oscillation amplitudes in the normal running stage for the HLS-II storage ring are estimated at 95 nm (horizontal) and 60 nm (vertical).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML111  
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THPML120 Development of Coating Technique for Superconducting Multilayered Structure site, cavity, target, acceleration 4954
 
  • R. Ito, T. Nagata
    ULVAC, Inc, Chiba, Japan
  • H. Hayano, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • H. Ito
    Sokendai, Ibaraki, Japan
  • Y. Iwashita, R. Katayama
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
 
  In order to increase the maximum acceleration gradient of SRF cavities, S-I-S (superconductor-insulator-superconductor) multilayered structure theory has been proposed. We focused on NbN which has a higher superconducting transition temperature than Nb. Firstly, we researched the optimal deposition condition for N2 gas reactive sputtering of NbN by using in-house inter-back type DC magnetron sputtering equipment. The critical condition for a thin film with strong crystalline orientation of NbN was identified. The superconducting transition temperature of the NbN thin film, which were coated under the best condition, was over 14 K. Secondly, we tried making S-I-S multilayered samples that was composed of NbN/SiO2/Nb substrate. The coating condition for the NbN layer was determined based on the research results in a single layer. The SiO2 layer was deposited with a film thickness of 30 nm that was theoretically expected to be effective as barrier layer. We applied O2 gas reactive AC magnetron sputtering for coating. In this article, the detailed results of the NbN single layer and multilayer film depositions are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML120  
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THPML123 The ESR Barrier-Bucket LLRF System - Design and First Results LLRF, cavity, controls, synchrotron 4964
 
  • J. Harzheim, D. Domont-Yankulova, K. Groß, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Frey, H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  At GSI, Darmstadt, Germany, a Barrier-Bucket (BB) RF System is currently under development for the Experimental Storage Ring (ESR). The system consists of two broadband RF cavities, each driven by a solid state amplifier, with the purpose to produce two voltage pulses per beam revolution. This will enable highly sophisticated longitudinal beam manipulations like longitudinal capture, compression and decompression or stacking of the beam. For the LLRF System, several requirements have to be fulfilled. Besides high standards concerning the pulsed gap signal quality (e.g. ringing <2.5%), the system has to provide the flexibility for adiabatic voltage ramp-up and adiabatic pulse shifting with high timing accuracy. A connection to the FAIR Central Control System (CCS) is necessary, as amplitude and phase ramp data will be provided by the CCS. In this contribution, the structure of the ESR BB LLRF system is presented together with experimental results from the first version of the system, which will be installed in the ESR in March 2018.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML123  
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FRXGBD2 Fast Kicker for High Current Beam Manipulation: Experimental Facility kicker, simulation, septum, electron 5019
 
  • V.V. Gambaryan, A.A. Starostenko
    BINP SB RAS, Novosibirsk, Russia
  • A.A. Starostenko
    NSU, Novosibirsk, Russia
 
  The pulsed deflecting magnet (kicker) project was worked out in Budker Institute of Nuclear Physics. The kicker design parameters are: impulsive force, 1 mT*m; pulse edge, 5 ns; impulse duration, 200 ns. The unconventional approach is that the plates must be replaced by a set of cylinders. The obtained magnet construction enables the field homogeneity to be controlled by changing current magnitudes in cylinders. Furthermore, we demonstrated the method of field optimization. In addition, measurement technique for the harmonic components was considered and the possibility of control harmonic components value was demonstrated. The results with electron beam on actual facility was considered.  
slides icon Slides FRXGBD2 [4.869 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBD2  
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FRXGBD4 Observation of Saw-Tooth Effect Orbit in the VEPP-4 M Collider electron, positron, collider, storage-ring 5026
 
  • Leshenok D. Leshenok, E.A. Bekhtenev
    NSU, Novosibirsk, Russia
  • E.A. Bekhtenev, G.V. Karpov, S.A. Nikitin, O.A. Plotnikova
    BINP SB RAS, Novosibirsk, Russia
 
  We study the relative position of the electron and posi-tron closed orbits in the VEPP-4M single storage ring collider in experiments on orbit precision monitoring. A difference in the orbits can affect the accuracy of several fundamental experiments, e.g. precise comparison of the electron and positron spin frequencies (the CPT invari-ance test) [1]. In this case, the spin precession frequencies of particles should be compared within at least 5·10-9. The distinction of frequencies depends on the features of the radial orbits. Ideally, the difference in the electron and positron orbits is set only by distributed radiation losses of particle energy. The corresponding contribution to the total orbit distortions is called the Saw-Tooth effect orbit. Another example of possible precision experiment at VEPP-4M is search for the light speed anisotropy (LSA). In this case, it is necessary to ensure a stability of the difference in the radial orbits of electrons and positrons at a level of 1μm.  
slides icon Slides FRXGBD4 [1.607 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBD4  
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FRXGBE2 Muon Beam Dynamics and Spin Dynamics in the g-2 Storage Ring quadrupole, storage-ring, injection, positron 5029
 
  • D. L. Rubin, A.T. Chapelain
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • S. Charity, J. Price
    The University of Liverpool, Liverpool, United Kingdom
  • J.D. Crnkovic, W. Morse, V. Tishchenko
    BNL, Upton, Long Island, New York, USA
  • F.E. Gray
    Regis University, Denver, USA
  • J. E. Mott
    BUphy, Boston, Massachusetts, USA
  • W. Wu
    UMiss, University, Mississippi, USA
 
  Funding: This work was supported in part by the U.S. Department of Energy DOE HEP DE-SC0008037
The goal of the new g-2 experiment at fermilab is a measurement of the anomalous magnetic moment of the muon, with uncertainty of less than 140 ppb. The experimental method is to store a beam of polarized muons in a storage ring with pure vertical dipole field and electrostatic focusing, and to measure the precession frequency. Control of the systematics depends on unprecedented knowledge of the details of the phase space of the muon distribution. That knowledge is derived from direct measurements with scintillating fiber detectors that are inserted into the muon beam for diagnostic measurements, traceback straw tube tracking chambers, as well as the calorimeters that measure energy, time and position of the decay positrons. The interpretation of the measurements depends on a detailed model of the storage ring guide field. This invited talk presents results of studies of the distribution from the commissioning run of the experiment.
 
slides icon Slides FRXGBE2 [12.815 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBE2  
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FRXGBE3 First Demonstration of Ionization Cooling in MICE emittance, detector, electron, solenoid 5035
 
  • T.A. Mohayai
    IIT, Chicago, Illinois, USA
 
  The Muon Ionization Cooling Experiment (MICE) at Rutherford Appleton Laboratory has studied ionization cooling of muons. Several million individual muon tracks have been recorded passing through a series of focusing magnets and a liquid hydrogen or lithium hydride absorber in a variety of magnetic configurations. Identification and measurement of muon tracks upstream and downstream of the absorber are used to study the evolution of the 4D (transverse) emittance. This paper presents and discusses these results.  
slides icon Slides FRXGBE3 [77.083 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBE3  
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FRXGBF1 Re-Acceleration of Ultra Cold Muon in J-PARC Muon Facility linac, rfq, acceleration, emittance 5041
 
  • Y. Kondo, K. Hasegawa, T. Morishita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • S. Bae, H. Choi, S. Choi, B. Kim, H.S. Ko
    SNU, Seoul, Republic of Korea
  • Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, K. Shimomura, T. Yamazaki, M. Yoshida
    KEK, Tsukuba, Japan
  • N. Hayashizaki
    RLNR, Tokyo, Japan
  • T. Iijima, Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • H. Iinuma, Y. Nakazawa
    Ibaraki University, Ibaraki, Japan
  • K. Ishida
    RIKEN Nishina Center, Wako, Japan
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • Y. Iwata
    NIRS, Chiba-shi, Japan
  • R. Kitamura
    University of Tokyo, Tokyo, Japan
  • S. Li
    The University of Tokyo, Graduate School of Science, Tokyo, Japan
  • G.P. Razuvaev
    Budker INP & NSU, Novosibirsk, Russia
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP16H03987, and JP16J07784.
J-PARC is developing the reacceleration system of the ultra slow (30 meV) muon (USM) obtained by two-photon laser resonant ionization of muonium atoms. The muon beam thus obtained has low emittance, meeting the requirement for the g-2/EDM experiment. J-PARC E34 experiment aims to measure the muon anomalous magnetic moment (g-2) with a precision of 0.1 ppm and search for EDM with a sensitivity to 10-21 e cm. The USM's are accelerated to 212 MeV by using a muon dedicated linac to be a ultra cold muon beam. The muon LINAC consists of an RFQ, a inter-digital H-mode DTL, disk and washer coupled cell structures, and disk loaded structures. The ultra-cold muons will have an extremely small transverse momentum spread of 0.1% with a normalized transverse emittance of around 1.5 pi mm-mrad. Proof of the slow muon acceleration scheme is an essential step to realize the world first muon linac. In October 2017, we have succeeded to accelerate slow negative muoniums generated using a simpler muonium source to 89 keV. In this talk, present design of the muon linac and the result of the world first muon acceleration experiment are reported.
 
slides icon Slides FRXGBF1 [8.378 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBF1  
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