Keyword: emittance
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MOXGB1 Report on SuperKEKB Phase 2 Commissioning luminosity, MMI, detector, optics 1
 
  • Y. Ohnishi
    KEK, Ibaraki, Japan
 
  The SuperKEKB electron-positron collider is being commissioned at KEK in three phases. The first phase was successfully completed in 2016, focusing on vacuum scrubbing and single beam studies without final focus optics. The second phase will start in March 2018 and until mid of July 2018. It will be dedicated to achieving the target specific luminosity larger than 4x1031 cm-2s-1/mA2, using the novel "nano-beam" collision scheme. Final focus optics will be installed, as well as the Belle-II detector, but without the vertex detector. The second phase of commissioning will also serve to assess and learn to control backgrounds induced by beam losses near the interaction region, expected to be larger than at KEKB in the past, as a result of the much smaller beams. This will be important before installing the vertex detector for the final phase of commissioning, due to start at the beginning of 2019, when high luminosity needed for data taking with the Belle-II detector should be achieved. The speaker will present the recent progress and performance of SuperKEKB that is enabled by these upgrades.  
slides icon Slides MOXGB1 [28.598 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOXGB1  
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MOZGBF5 Analysis of Polarization Decay at RHIC Store polarization, resonance, lattice, target 76
 
  • H. Huang, P. Adams, E.C. Aschenauer, A. Poblaguev, W.B. Schmidke
    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.
There are polarization losses in RHIC store due to various sources, such as emittance growth and higher order spin resonances. The beam polarization was measured several times over a store by the p-carbon polarimeters situated in both rings. These provide information on the polarization decay over time and also polarization profile development over time. A polarized jet was also used to monitor the polarization continuously through store, though with limited statistical accuracy. These polarization measurements and emittance measurements from the IPM are analyzed and the polarization loss from different sources are reviewed.
 
slides icon Slides MOZGBF5 [4.530 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF5  
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MOPMF002 Pre-Booster Ring Considerations for the FCC e+e Injector booster, damping, wiggler, extraction 83
 
  • O. Etisken
    Ankara University, Faculty of Sciences, Ankara, Turkey
  • F. Antoniou, Y. Papaphilippou
    CERN, Geneva, Switzerland
  • A.K. Çiftçi
    Izmir University of Economics, Balçova/Izmir, Turkey
 
  The FCC-e+e injector complex needs to produce and to transport a high-intensity e+/e beam at a fast repetition rate for topping up the collider at its collision energy. Two different options are under consideration as pre-accelerator before the bunches are transferred to the high-energy booster: using the existing SPS and a completely new ring. The purpose of this paper is to explore the needs and parameters of the existing SPS and the conceptual design of an alternative accelerator ring with injection and extraction energies of 6 and 20 GeV, respectively. In this study, the basic parameters of both choices are established, including the optics design and layout updates. Consideration for non-linear dynamics optimization and the impact of intra beam scattering are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF002  
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MOPMF006 Test of Stepwise Electron Bunch Replacement in eRHIC Using an Electron Lens in RHIC electron, proton, experiment, 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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MOPMF016 Progress on RCS eRHIC Injector Design resonance, polarization, lattice, detector 115
 
  • V.H. Ranjbar, M. Blaskiewicz, J.M. Brennan, S.J. Brooks, D.M. Gassner, H.-C. Hseuh, I. Marneris, F. Méot, M.G. Minty, C. Montag, V. Ptitsyn, K.S. Smith, S. Tepikian, F.J. Willeke, H. Witte, B. P. Xiao, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • I.V. Pogorelov
    Tech-X, Boulder, Colorado, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We have refined the design for the Rapid Cycling Synchrotron (RCS) polarized electron injector for eRHIC. The newer design includes bypasses for the eRHIC detectors and definition of the lattice layout in the existing RHIC tunnel. Additionally, we provide more details on the RF, alignment and orbit control, and magnet specifications.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF016  
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MOPMF021 Ground Motion Measurement and Analysis for HEPS ground-motion, site, ion-source, lattice 125
 
  • F. Yan, Z. Duan, D. Ji, Y. Jiao, Z.Z. Wang, Y. Wei, G. Xu
    IHEP, Beijing, People's Republic of China
 
  HEPS have very challenging beam stability require-ments. Special cares are mandatory in developing site vibration specifications, stable building design concepts, and passive and active ways to minimize effects on the stability of the photon beam and critical accelerator and beamline components caused by ambient ground motion sources. However, among all these work, reasonable as-sessment of the vibration induced beam instability has to be the first step. This paper will focuses on the measure-ment results of the ground motion on HEPS site, the es-tablishment of reasonable beam dynamic models, the influences of ground motion to the beam of main ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF021  
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MOPMF033 Probing the Forced Dynamic Aperture in the LHC at Top Energy Using AC Dipoles dipole, dynamic-aperture, insertion, resonance 165
 
  • F.S. Carlier, M. Giovannozzi, E.H. Maclean, T. Persson, R. Tomás
    CERN, Geneva, Switzerland
 
  Measurements of the dynamic aperture in colliders are a common method to ensure machine performance and offer an insight in the nonlinear content of the machine. Such direct measurements are very challenging for the LHC and High Luminosity LHC. Forced dynamic aperture has been demonstrated for the first time in the LHC at injection energy as a potential new observable to safely probe the nonlinear content of the machine. This paper presents the first measurements of forced dynamic aperture at top energy and discusses the proposed measurement schemes and challenges.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF033  
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MOPMF034 Layout and Performance of the FCC-ee Pre-Injector Chain linac, damping, injection, cavity 169
 
  • S. Ogur, T.K. Charles, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann
    CERN, Geneva, Switzerland
  • A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov
    BINP SB RAS, Novosibirsk, Russia
  • I. Chaikovska, R. Chehab
    LAL, Orsay, France
  • K. Furukawa, N. Iida, T. Kamitani, F. Miyahara
    KEK, Ibaraki, Japan
  • E.V. Ozcan
    Bogazici University, Bebek / Istanbul, Turkey
  • S.M. Polozov
    MEPhI, Moscow, Russia
 
  The Future Circular e+e Collider pre-injector chain consists of a 6 GeV S-Band linac, a damping ring at 1.54 GeV and pre-booster ring to reach 20 GeV for injection to the main booster. The electron and positron beams use the same accelerator chain alternatively. The e+ beam is generated from a novel low level RF-gun providing 6.5 nC charge at 11 MeV with 0.5 micron geometric emittance. The e+ beam is produced by the impact of a 4.46 GeV e- beam onto a hybrid target, accelerated in the linac up to 1.54 GeV, and injected to the damping ring for emittance cooling. Simulations on the performance of the DR are presented for reaching the required equilibrium emittances at the required damping time. As an alternative option, a 20 GeV linac is considered utilising C-Band cavities and simulations studies have been undertaken regarding the beam transport and transmission efficiency up to that energy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF034  
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MOPMF039 First Xenon-Xenon Collisions in the LHC luminosity, experiment, proton, injection 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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MOPMF048 Aperture Measurements with AC Dipole at the Large Hadron Collider dipole, optics, MMI, injection 212
 
  • N. Fuster-Martínez, R. Bruce, J. Dilly, E.H. Maclean, T. Persson, S. Redaelli, R. Tomás
    CERN, Geneva, Switzerland
  • L.J. Nevay
    Royal Holloway, University of London, Surrey, United Kingdom
 
  Global aperture measurements are crucial for a safe operation and to push the performance of the LHC, in particular, the knowledge of aperture at top energy allows pushing the optics to reduce the colliding beam sizes. The standard method used in the LHC commissioning requires using several bunches for one measurement and makes bunches un-usable for other activities. This paper presents first global aperture measurements performed at injection with a new method using the AC dipole. This method consists in exciting large coherent oscillations of the beam without spoiling its emittance. A gentle control of the oscillation amplitude enables re-using the beams for several measurements. These measurements are compared with aperture measurements performed using the standard method and possible benefits, for example for optics measurements, at top energy with squeezed optics, are elaborated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF048  
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MOPMF050 LHC Operational Experience of the 6.5 TeV Proton Run with ATS Optics operation, luminosity, optics, proton 216
 
  • M. Pojer, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, A. Calia, G.E. Crockford, S.D. Fartoukh, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, M. Hostettler, W. Höfle, Y. Le Borgne, D. Nisbet, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli, R. Suykerbuyk, D.J. Walsh, J. Wenninger, M. Zerlauth
    CERN, Geneva, Switzerland
 
  In May 2017, the CERN Large Hadron Collider (LHC) restarted operations at 6.5 TeV using the Achromatic Telescopic Squeeze (ATS) scheme with a target beta-star of 40 cm in ATLAS and CMS. The number of bunches was progressively increased to a maximum of 2556 with emittances of 2.5 um. In August, several machine parameters had to be re-tuned to mitigate beam loss induced instabilities and maintain a steady increase of the instantaneous luminosity. The use of a novel beam type and filling pattern produced in the injectors, allowed filling the machine with very low emittance beam (1.5 um) achieving an equivalent luminosity with 1868 bunches. In September, the beta-star was further lowered to 30 cm (using, for the first time, the telescopic technique of the ATS) and the bunch intensity pushed to 1.25·1011 protons. In the last 3 months of 2017, the LHC produced more than 500 pb-1 of integrated luminosity per day, delivering to each of the high luminosity experiments 50.6 fb-1, 10% above the 2017 target. A general overview of the operational aspects of the 2017 proton run will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF050  
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MOPMF052 Monitoring and Modeling of the LHC Luminosity Evolution in 2017 luminosity, experiment, 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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MOPMF054 Comparison of Different Transverse Emittance Measurement Techniques in the Proton Synchrotron Booster extraction, proton, optics, booster 232
 
  • G.P. Di Giovanni, S.C.P. Albright, V. Forte, M.A. Fraser, G. Guidoboni, B. Mikulec, F. Roncarolo, A. Santamaría García
    CERN, Geneva, Switzerland
 
  The measurement of the transverse emittance in an accelerator is a crucial parameter to evaluate the performance of the machine and to understand beam dynamics processes. In recent years, controlling and understanding the emittance became particularly relevant in the Proton Synchrotron Booster (PSB) at CERN as part of the LHC Injectors Upgrade (LIU). The LIU project is a necessary step to achieve the goals of the High-Luminosity LHC project. In this framework, an accurate and reliable emittance measurement of high brightness beams is mandatory to study the brightness reach of the LHC injectors. In the PSB there are two main instruments available for emittance measurements: wire scanners and secondary-emission (SEM) grids. In this paper emittance measurements performed during the 2017 physics run with these two systems are compared, taking into account various systematic error sources.  
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MOPMF057 FCC-ee Dynamic Aperture Studies and Frequency Map Analysis alignment, dynamic-aperture, resonance, sextupole 244
 
  • T. Tydecks, S. Aumon, T.K. Charles, B. Härer, B.J. Holzer, K. Oide, Y. Papaphilippou, J. Wenninger
    CERN, Geneva, Switzerland
 
  The FCC-ee Lepton Collider will provide e+e collisions in the beam energy range of 45.6 GeV to 182.5 GeV. FCC-ee will be a precision measurement tool for Z, W, H and t physics with expected luminosities of 2.07× 1036 cm-2 s-1 at the Z-pole and 1.3 × 1034 cm-2 s-1 at the tt- threshold. In order to achieve the foreseen luminosities, a vertical β* of 1 mm to 2 mm is mandatory. Dynamic aperture and frequency map analysis for the 97.75 km machine with such a squeezed accelerator optics are studied. Furthermore, effects of machine misalignments on dynamic and momentum aperture are presented and estimations for the required tolerances are given  
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MOPMF058 Status of the LHC Schottky Monitors injection, octupole, sextupole, damping 247
 
  • T. Tydecks, D. Alves, T.E. Levens, M. Wendt, J. Wenninger
    CERN, Geneva, Switzerland
 
  The Large Hadron Collider (LHC) features four transverse Schottky monitors detecting Schottky noise from the beam. From the Schottky noise signal, beam properties like tune, chromaticity, and bunch by bunch relative emittances, can be extracted. Being a non-destructive and purely parasitic method of measurement, the Schottky system is of great interest for real-time determination of beam chromaticities especially. Studies, including a dedicated machine development shift as well as parasitic measurements, concerning its capability to accurately measure the beam chromaticities are presented.  
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MOPMF059 Status of the FCC-ee Top-Up Booster Synchrotron booster, collider, optics, injection 250
 
  • B. Härer, B.J. Holzer, Y. Papaphilippou, T. Tydecks
    CERN, Geneva, Switzerland
 
  This contribution presents the status of the top-up booster synchrotron for the FCC electron-positron collider FCC-ee, which is a 100 km electron-positron collider being designed for precision studies and rare decay observations in the range of 90 to 365 GeV centre-of-mass energy. In order to keep the luminosity at a level of the order of 1035 cm-2s-1 continuous top-up injection is required, because of the short beam lifetime of less than one hour. The top-up booster synchrotron will be housed in the same tunnel as the collider rings and will ramp up the beam energy from 20 GeV at injection to the full energy between 45.5 GeV and 182.5 GeV depending on operation mode. The lattice design and two possible optics will be presented. The dynamic aperture was investigated for different sextupole schemes with and without misalignments of the lattice components. In addition, wigglers were installed to decrease the damping time and mitigate intra-beam-scattering.  
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MOPMF060 Safe Disposal of the LHC Beam without Beam Dump - Method and Experimental Verification experiment, collimation, 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.
 
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MOPMF061 Emittance Growth in Coast in the SPS at CERN cavity, scattering, experiment, 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.
 
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MOPMF065 LHC- and FCC-Based Muon Colliders positron, collider, target, factory 273
 
  • F. Zimmermann
    CERN, Geneva, Switzerland
 
  Funding: Work supported by the European Commission under the HORIZON 2020 project ARIES, grant agreement no. 730871.
In recent years, three schemes for producing low-emittance muon beams have been proposed: (1) e+e annihilation above threshold using a positron storage ring with a thin target [M. Boscolo, P. Raimondi et al.], (2) laser/FEL-Compton back-scattering off high-energy proton beams circulating in the LHC or FCC-hh [L. Serafini et al.], (3) the Gamma factory concept, where partially stripped heavy ions collide with a laser pulse to directly generating muons [W. Krasny]. The Gamma factory would also generate copious amounts of positrons which could in turn be used as source for option (1). On the other hand the top-up booster of the FCC-ee design would be an outstanding e+ storage ring, at the right beam energy, around 45 GeV. After rapid acceleration the muons, produced in one of the three ways, could be collided in machines like the SPS, LHC or FCC-hh. Possible collider layouts are suggested.
 
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MOPMF068 Quantum Excitation due to Classical Beamstrahlung in Circular Colliders collider, photon, simulation, radiation 281
 
  • M.A. Valdivia García, D. El Khechen, K. Oide, F. Zimmermann
    CERN, Geneva, Switzerland
 
  In the collisions of proposed future circular colliders, like FCC-ee and CEPC, the beamstrahlung regime is classical, i.e. with an "Upsilon parameter" much smaller than 1. In the classical regime, for a constant electromagnetic field a simple relation exists between the average photon energy u and the average squared photon energy u2, which is the same as for standard synchrotron radiation in storage rings. This relation breaks down, however, if the electromagnetic field is not constant in time and position, as is the case for a beam-beam collision. We derive an analytical expression for u2/u2, considering the case of Gaussian-bunch collisions with crossing angle (and possibly crab waist). We compare our result with the photon energies obtained in beam-beam simulation for FCC-ee at beam energies of 45.6 GeV and 175 GeV, using the two independent codes BBWS and Guineapig. Finally, we re-optimize the FCC-ee parameters of a possible mono-chromatization scheme for direct Higgs production at 125 GeV, derived previously, by applying the refined expression for the rms photon energy.  
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MOPMF073 Rejuvenation of 7-Gev SuperKEKB Injector Linac positron, linac, electron, injection 300
 
  • K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, H. Ego, A. Enomoto, Y. Enomoto, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kawamura, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, M. Nishida, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, M. Satoh, Y. Seimiya, A. Shirakawa, H. Sugimura, T. Suwada, T. Takenaka, M. Tanaka, N. Toge, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
    KEK, Ibaraki, Japan
 
  KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It was upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of flavor physics beyond the standard model of elementary particle physics. SuperKEKB energy-asymmetric electron-positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. The electron beam is generated by a new type of RF gun, that provides a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 μm to 10 μm in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The summary of the rejuvenation is reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF073  
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MOPMF074 Beam Phase Space Jitter and Effective Emittance for SuperKEKB Injector Linac target, linac, electron, positron 304
 
  • Y. Seimiya, N. Iida, T. Kamitani, M. Satoh
    KEK, Ibaraki, Japan
 
  In SuperKEKB linac, stable high charged low emittance beam is necessary. Transported beam to SuperKEKB Main Ring (MR) must be stable to the extent that the beam can be injected inside MR acceptance. SuperKEKB requirement must be satisfied for emittance including beam phase space jitter, called as effective emittance. Large amplitude beam position jitter has been measured at linac end. We evaluated that the effect of the beam position jitter on effective emittance and investigated the source of the beam phase space jitter.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF074  
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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, experiment, 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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MOPMF087 Muon Accumulator Ring Requirements for a Low Emittance Muon Collider from Positrons on Target target, positron, collider, interaction-region 330
 
  • M. Boscolo, M. Antonelli, O.R. Blanco-García, S. Guiducci
    INFN/LNF, Frascati (Roma), Italy
  • F. Collamati
    INFN-Roma1, Rome, Italy
  • L. Keller
    SLAC, Menlo Park, California, USA
  • S.M. Liuzzo, P. Raimondi
    ESRF, Grenoble, France
  • D. Schulte
    CERN, Geneva, Switzerland
 
  Very low emittance muon beams can be produced by direct annihilation of about 45~GeV positrons on atomic electrons in a thin target. With such a muon beam source, a mu+mu- collider can be designed in the multi-TeV range at very high luminosities. In this scheme two muon accumulator rings are foreseen to recollect the muon bunches that will be injected in the collider. We present in this paper the first consideration of the muon accumulator rings. Realistic muon beam emittance and energy spread coming from the muon target are described. Constraints on the accumulator ring requirements are derived.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF087  
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MOPML006 Multi-Stage Electron Cooling Scheme for JLEIC proton, electron, simulation, collider 397
 
  • H. Zhang, S.V. Benson, Y.S. Derbenev, Y. Roblin, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
JLEIC is the future electron ion collider under design at Jefferson Lab, which will provide a luminosity up to 1034 cm-2s-1. Electron cooling is essential for JLEIC to overcome the intrabeam scattering effect, reduce the ion beam emittance and thus achieve the high luminosity. The cooling time is approximately in proportion to the square of the energy and the 6D emittance. To avoid the difficulty of cooling the ion beam with large emittance at high energy, a multi-stage cooing scheme was designed for JLEIC. The ion beam was cooled at the low energy to reduce the emittance. Then it was ramped up to the collision energy. During the collision, electron cooling is implemented to maintain the emittance and the luminosity. Simulations for proton beam and lead ion beam at various stages are presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML006  
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MOPML008 JLEIC Electron Ring Dynamic Aperture with Non-linear Field Errors dynamic-aperture, electron, lattice, sextupole 404
 
  • Y.M. Nosochkov, Y. Cai
    SLAC, Menlo Park, California, USA
  • F. Lin, V.S. Morozov, G.H. Wei, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under US DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515.
We present results of dynamic aperture study for the updated electron ring lattice of the Jefferson Lab Electron-Ion Collider (JLEIC). The lattice design features low emittance arcs with local compensation of sextupole non-linear effects, and low emittance non-linear chromaticity correction sections. Dynamic aperture tracking simulations are performed to evaluate the effects of non-linear field errors, the sensitivity to betatron tune, and the impact of momentum error. Dynamic aperture is also evaluated with the measured PEP-II field errors. Preliminary tolerances to the non-linear field errors in the Final Focus quadrupoles are estimated.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML008  
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MOPML009 New High Luminosity LHC Baseline and Performance at Ultimate Energy operation, luminosity, optics, cavity 408
 
  • L.E. Medina Medrano
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
  • A. Apollonio, G. Arduini, O.S. Brüning, M. Giovannozzi, L.E. Medina Medrano, S. Papadopoulou, Y. Papaphilippou, S. Redaelli, R. Tomás
    CERN, Geneva, Switzerland
 
  Funding: Research supported by the HL-LHC project and the Beam project (CONACYT, Mexico).
The LHC machine is envisioned to operate eventually at an ultimate beam energy of 7.5 TeV at the end of LHC Run 4, i.e. after commissioning of the HL-LHC systems, a stage falling into the High Luminosity LHC (HL-LHC) era. In this paper we review the latest baseline parameters and performance, and study the potential reach of the HL-LHC with pushed optics at the ultimate beam energy. Results in terms of integrated luminosity and effective pile-up density of both the nominal (5.0×1034 cm-2 s−1) and ultimate (7.5×1034 cm-2 s−1) levelling operations are discussed
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML009  
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MOPML020 Numerical Simulations to Evaluate and Compare the Performances of Existing and Novel Degrader Materials for Proton Therapy scattering, simulation, proton, shielding 435
 
  • R. Tesse, A. Dubus, N. Pauly
    ULB - FSA - SMN, Bruxelles, Belgium
  • C. Hernalsteens, W.J.G.M. Kleeven, F. Stichelbaut
    IBA, Louvain-la-Neuve, Belgium
 
  The performance of the energy degrader in terms of beam properties directly impacts the design and cost of cyclotron-based proton therapy centers. The aim of this study is to evaluate the performances of different existing and novel degrader materials. The quantitative estimate is based on detailed Geant4 simulations that analyze the beam-matter interaction and provide a determination of the beam emittance increase and transmission. Comparisons between existing (aluminium, graphite, beryllium) and novel (boron carbide and diamond) degrader materials are provided and evaluated against semi-analytical models of multiple Coulomb scattering. The results showing a potential in emittance reduction for novel materials are presented and discussed in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML020  
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MOPML044 Start-to-End Beam Dynamic Simulations for PRAE gun, linac, laser, solenoid 495
 
  • A. Vnuchenko
    IFIC, Valencia, Spain
  • C. Bruni, M. El Khaldi, A. Faus-Golfe, P. Lepercq, C. Vallerand
    LAL, Orsay, France
  • A. Latina
    CERN, Geneva, Switzerland
 
  The PRAE project (Platform for Research and Applications with Electrons) aims at creating a multidisciplinary R&D facility in the Orsay campus gathering various scientific communities involved in radiobiology, subatomic physics, instrumentation and particle accelerators around an electron accelerator delivering a high-performance beam with energy up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and future challenging R&D. In this paper we report the first start-to-end simulations from the RF gun, going through the linac and finally to the different experimental platforms. The beam dynamics simulations have been performed using a concatenation of codes. In particular for the linac the RF-Track code recently developed at CERN will be used and benchmarked. The different working points have been analysed in order to minimise the transverse emittance and the beam energy spread including space charge effects at low electron energies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML044  
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TUXGBD1 Potential and Issues for Future Accelerators and Ultimate Colliders controls, photon, synchrotron, laser 578
 
  • S.J. Brooks
    BNL, Upton, Long Island, New York, USA
 
  Particle colliders have been remarkably successful tools in particle and nuclear physics. What are the future trends and limitations of accelerators as they currently exist, and are there possible alternative approaches? What would the ultimate collider look like? This talk examines some challenges and possible solutions. Accelerating a single particle rather than a thermal distribution may allow exploration of more controlled interactions without background. Also, cost drivers are possibly the most important limiting factor for large accelerators in the foreseeable future so emerging technologies to reduce cost are highlighted.  
slides icon Slides TUXGBD1 [2.590 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBD1  
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TUXGBE3 Status of Plasma-Based Experiments at the SPARC_LAB Test Facility plasma, electron, experiment, focusing 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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TUYGBF3 An EBIS-Based Low-Energy Accelerator for Fine-Focussed Ion Beams ion-source, electron, target, acceleration 647
 
  • M. Schmidt, P. Laux, G.H. Zschornack
    DREEBIT, Großröhrsdorf, Germany
 
  Technologies based on focused ion beams have become indispensable for research institutions as well as commercial laboratories and high-tech production facilities (micro- and nanotechnology, semiconductor technology). We report on a compact setup combining an Electron Beam Ion Source (EBIS), a Wien filter for ion species separation, and a fine focusing ion acceleration column capable of producing ion beams with beam diameters in the micrometer range at ion beam energies up to the MeV range. Almost all elements of the periodic system can be injected into the EBIS to produce a broad spectrum of ion charge states with only one ion source. The beam energy of a selected ion species can easily be varied by changing the electric potential of the EBIS drift tube in which the ions are generated, resulting in different implantation depths in various solids. We present studies on beam diameter and emittance, available charge states, and SEM imaging as application.  
slides icon Slides TUYGBF3 [3.977 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBF3  
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TUPAF002 Beam Commissioning of the 750 MHz Proton RFQ for the LIGHT Prototype rfq, MMI, linac, diagnostics 658
 
  • V.A. Dimov, M. Caldara, A. Degiovanni, L.S. Esposito, D.A. Fink, M. Giunta, A. Jeff, A. Valloni
    AVO-ADAM, Meyrin, Switzerland
  • A.M. Lombardi, S.J. Mathot, M. Vretenar
    CERN, Geneva, Switzerland
 
  ADAM (Application of Detectors and Accelerators to Medicine), a CERN spin-off company, is developing the Linac for Image Guided Hadron Therapy, LIGHT, which will accelerate proton beams up to 230 MeV. The design of the linac will allow fast intensity and energy modulation for pencil-beam scanning during cancer treatment. The linac consists of a 40 keV Proton Injector; a 750 MHz Radio Frequency Quadrupole (RFQ) accelerating the proton beam up to 5 MeV; a 3 GHz Side Coupled Drift Tube Linac (SCDTL) up to 37.5 MeV; and a 3 GHz Cell Coupled Linac (CCL) section up to 230 MeV. A prototype of LIGHT is being commissioned progressively with the installation of the accelerating structures at a CERN site. The beam commissioning of the RFQ, which was designed and built by CERN, was completed in 2017 using a movable beam diagnostic test bench with various instruments. This paper reports on the RFQ commissioning strategy and the results of the beam measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF002  
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TUPAF027 CERN PS Kicker for Proton Injection: from Beam-Based Waveform Measurements to Hardware Improvements kicker, simulation, injection, flattop 732
 
  • V. Forte, A. Ferrero Colomo, M.A. Fraser, T. Kramer
    CERN, Geneva, Switzerland
 
  For 2017 operation, the termination mode of the CERN Proton Synchrotron (PS) horizontal injection kicker was permanently changed to short-circuited, to be compliant with the future performances requested by the LHC Injectors Upgrade (LIU) project. An extensive campaign of measurements was performed through a dedicated beam-based technique. The measurements identified possibilities for optimisation of the kicker system and were fundamental to properly tune the PSpice simulation model of the kicker, as well as for validating the hardware changes. The model was finally used to estimate the horizontal emittance growth for the future injection schemes in the PS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF027  
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TUPAF033 Beam Optics Studies for BDF and for Tests of a Prototype Target target, optics, extraction, proton 754
 
  • C. Heßler, M. Calviani, Y. Dutheil, M.A. Fraser, B. Goddard, V. Kain, E. Lopez Sola, F.M. Velotti
    CERN, Geneva, Switzerland
 
  Within the frame of the Physics Beyond Collider project a new fixed target facility at the SPS North Area, the so-called Beam Dump Facility (BDF), is under study. BDF 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. This results in an exceptionally high average beam power of 355 kW on the target, which is a major challenge. To validate the target design, a test of a prototype target is planned for 2018 at an existing North Area beam line. A large part of this beam line is in common with the future BDF beam line with comparable beam characteristics and several measurement campaigns were performed in 2017 to study the optics of the line in preparation for the test. The intrinsic characteristics of the slow extraction process make the precise characterisation of the beam reaching the target particularly challenging. This paper presents beam and lattice characterisation methods and associated measurement results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF033  
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TUPAF047 Systematic Studies of Transverse Emittance Measurements Along the CERN PS Booster Cycle scattering, brightness, betatron, proton 806
 
  • A. Santamaría García, S.C.P. Albright, H. Bartosik, J.A. Briz Monago, G.P. Di Giovanni, V. Forte, B. Mikulec, F. Roncarolo, V. Vlachoudis
    CERN, Geneva, Switzerland
 
  The CERN Proton Synchrotron Booster (PSB) will need to deliver 2 times the current brightness to the Large Hadron Collider (LHC) after the LHC Injectors Upgrade (LIU) to meet the High-Luminosity-LHC beam requirements. Beam intensity and transverse emittance are the key parameters to increase brightness, the latter being more difficult to manipulate. It is, therefore, crucial to monitor not only the emittance evolution between the different injectors but also along each acceleration cycle. To this end, detailed emittance measurements were carried out for the four rings of the PSB at various times in the cycle with different beam types. A thorough analysis of systematic error sources was conducted including multiple Coulomb scattering happening during profile measurements with wire scanners, where experimental and analytical treatments of the emittance blow-up were compared to FLUKA simulations. In order to properly account for the dispersive contribution, the full momentum spread profile was considered using a deconvolution method. We conclude with an assessment of this first comprehensive emittance evolution measurement along the PSB cycle.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF047  
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TUPAF050 Beam Dynamics Simulations of the Effect of Power Converter Ripple on Slow Extraction at the CERN SPS extraction, quadrupole, sextupole, experiment 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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TUPAF063 Beam Dynamics Studies of the ESS LINAC Using a New Multicell Cavity Model cavity, linac, DTL, distributed 870
 
  • R. De Prisco, D.C. Plostinar
    ESS, Lund, Sweden
 
  The European Spallation Source is designed to deliver 5 MW proton beam power on the target while keeping the beam induced losses below 1 W/m throughout the LINAC. This implies the need of accurate models to correctly describe the longitudinal beam dynamics within the multi-cell cavities. In all the previous error studies the cells of a multi-cell cavity were modelled as a sequence of independent gaps and the errors were applied directly on the amplitude of each cell accelerating field, considered as random variable. In this paper, instead, we present a new detailed analysis of the effect of the error tolerances on the beam dynamics including a new model to calculate the amplitude errors of the accelerating field in the multi-cell cavities: errors are applied on the geometrical parameters of each cavity; then the accelerating field is calculated solving the Maxwell equations over all the cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF063  
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TUPAF067 Beam Physics Analysis of the ESS RFQ Non-Conformities rfq, alignment, ion-source, radio-frequency-quadrupole 886
 
  • A. Ponton
    ESS, Lund, Sweden
 
  During the fabrication of an RFQ, deviation from the perfect geometry will occur during assembling, brazing and machining the different parts. These geometrical defects will also impact the theoretical inter-vane voltage, given by the beam dynamics, even if tuners can correct partially the effect of the manufacturing. The combination of geometrical and voltage errors will alter the electro-magnetic field in the axis region leading to a degradation of the beam quality. The study proposes to expand the method to treat the voltage errors presented in * , in which the deviation from the theoretical parameters is represented by a sum of periodic functions of z, to the machining errors and to include positioning and alignment errors. The results of the error study will be presented. Then, using the results of the fabrication control by metrology, we will analyze the impact of the real RFQ geometry on the beam transport and compare the results will the prediction from the error study.
* A. Ponton et al., "Voltage errors studies in the ESS RFQ", presented at the 7th Int. Particle Accelerator Conf. (IPAC'16), Busan, Korea, May 2016, paper THPMB039.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF067  
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TUPAF077 Beam Optics Measurements in Medium Energy Beam Transport at PIP-II Injector Test Facility quadrupole, optics, rfq, beam-transport 909
 
  • A. Saini, J.-P. Carneiro, B.M. Hanna, L.R. Prost, A.V. Shemyakin
    Fermilab, Batavia, Illinois, USA
  • V.L. Sista
    BARC, Mumbai, India
 
  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-II Injector Test (PIP2IT) is an accelerator test facility under construction at Fermilab that will provide a platform to demonstrate critical technologies and concept of the front-end of the PIP-II linear accelerator (linac). The PIP2IT warm front-end comprises a H ion source capable of delivering 15 mA, 30 keV DC or pulsed beam, a Low Energy Beam Transport (LEBT), a 162.5 MHz, CW Radio Frequency Quadrupole (RFQ) that accelerates the beam to 2.1 MeV and, a 14 m medium energy beam transport (MEBT). Presently, beamline up to the MEBT has been commissioned and operates routinely at the PIP2IT facility. In this paper, we discuss beam measurements performed at the MEBT to analyze beam emittance and its RMS sizes along the MEBT. In addition, beam based calibration of the beamline elements using differential trajectory measurement is also presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF077  
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TUPAK002 Advanced Approach for Beam Matching along the Multi-Cavity SC CW Linac at GSI cavity, linac, heavy-ion, proton 955
 
  • S. Yaramyshev, W.A. Barth, M. Heilmann
    GSI, Darmstadt, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, V. Gettmann, T. Kürzeder, M. Miski-Oglu
    HIM, Mainz, Germany
  • M. Basten, M. Busch, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
 
  A multi-stage program for the development of a heavy ion superconducting (sc) continuous wave (cw) linac is in progress at HIM (Mainz, Germany) and GSI (Darmstadt, Germany) under support of IAP (Frankfurt, Germany). In 2017 the first section of the CW-Linac has been successfully commissioned at GSI. Beam acceleration at the CW-Linac is foreseen to be performed by up to twelve multi-gap CH cavities. The linac should provide the beam for physics experiments, smoothly varying the output particle energy from 3.5 to 7.3 MeV/u, simultaneously keeping high beam quality. Due to a wide variation of the input- and output -beam energy for each cavity, a longitudinal beam matching to every cavity is of high importance. An advanced algorithm for an optimization of matched beam parameters under variable rf-voltage and rf-phase of each cavity has been developed. The description of the method and the obtained results are presented in the paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK002  
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TUPAK004 Superconducting CH-Cavity Heavy Ion Beam Testing at GSI cavity, linac, heavy-ion, acceleration 962
 
  • W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • K. Aulenbacher, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu
    HIM, Mainz, Germany
  • M. Basten, M. Busch, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
 
  Recently the first section of a standalone superconducting (sc) continuous wave (cw) heavy ion Linac as a demonstration of the capability of 217 MHz multi gap Crossbar H-mode structures (CH) has been commissioned and extensively tested with beam from the GSI- High Charge State Injector. The demonstrator set up reached acceleration of heavy ions up to the design beam energy and beyond. The required acceleration gain was achieved with heavy ion beams even above the design mass to charge ratio at high beam intensity and full beam transmission. This contribution presents systematic beam measurements with varying RF-amplitudes and phases of the CH-cavity, as well as versatile phase space measurements for heavy ion beams with different mass to charge ratio. The worldwide first and successful beam test with a superconducting multi gap CH-cavity is a milestone of the R&D work of Helmholtz Institute Mainz (HIM) and GSI in collaboration with Goethe University Frankfurt (GUF) in preparation of the sc cw heavy ion Linac project and other cw-ion beam applications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK004  
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TUPAL018 Pulse-by-Pulse Switching of Operational Parameters in J-PARC 3-GeV RCS operation, injection, extraction, betatron 1041
 
  • H. Hotchi, H. Harada, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, Y. Watanabe, M. Yoshimoto
    JAEA/J-PARC, Tokai-mura, Japan
 
  J-PARC 3-GeV RCS (rapid cycling synchrotron) provides a high-power beam both to MLF (materials and life science experimental facility) and MR (main ring synchrotron) by switching the beam destination pulse by pulse. The beam properties required from MLF and MR are different; MLF needs a wide-emittance beam with less charge density, while MR requires a low-emittance beam with less beam halo. To meet the antithetic requirements while keeping beam loss at permissible levels, RCS has recently initiated pulse-by-pulse switching of operational parameters (betatron tune, chromaticity, painting emittance, etc.). This paper presents the recent efforts toward the performance upgrade of RCS while discussing the related beam dynamics issues.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL018  
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TUPAL020 Recent Status of J-PARC Rapid Cycling Synchrotron operation, injection, target, proton 1045
 
  • K. Yamamoto, P.K. Saha
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) provides more than 300 kW beam to the Material and Life Science Facility (MLF) and the Main Ring (MR). In such high intensity hadron accelerator, the lost protons that are a fraction of the beam less than 0.1 % cause many problems. Those particles bring about a serious radioactivation and a malfunction of the accelerator components. Therefore, we carried out the beam study to achieve high power beam operation. Moreover, we also maintain the accelerator components to keep a steady operation. We report present status of the J-PARC RCS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL020  
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TUPAL031 Errors Study of a Double-Pass Recirculating Superconducting Proton Linac linac, proton, cavity, quadrupole 1069
 
  • Y. Tao, K. Hwang, J. Qiang
    LBNL, Berkeley, California, USA
 
  The concept of recirculating superconducting proton linac was recently proposed. Beam dynamics simulations were carried out in a double-pass recirculating proton linac using a single bunch. Although all the beam line elements should be installed following the designed values, in reality, there exist machine imperfections that will cause beam off-centering and even particle losses. In this paper, we report on the study of the static and dynamic errors from RF cavities and magnetic focusing elements in the double-pass recirculating proton linac.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL031  
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TUPAL035 3D Beam Dynamics Modeling of MEBT for the New LANSCE RFQ Injector rfq, quadrupole, proton, simulation 1081
 
  • S.S. Kurennoy
    LANL, Los Alamos, New Mexico, USA
 
  The new RFQ-based proton injector at LANSCE requires a specialized medium-energy beam transfer (MEBT) after the RFQ at 750 keV due to a following long (~3 m) existing common transfer line that also serves for transporting negative-ion beams to the DTL entrance. The horizontal space for MEBT elements is limited because two beam lines merge at 18-degree angle. The MEBT design developed with envelope codes includes two compact quarter-wave RF bunchers and four short quadrupoles with steerers, all within the length of about 1 m. The beam size in the MEBT is large, comparable to the beam-pipe aperture, hence non-linear 3D field effects at large radii become important. Using CST Studio codes, we calculate buncher RF fields and quadrupole magnetic fields and use them to perform particle-in-cell beam dynamics modeling of MEBT with realistic beam distributions from the RFQ. Our results indicate a significant emittance growth not predicted by standard beam dynamics codes. Its origin was traced mainly to the quadrupole edge fields. Quadrupole design modifications are proposed to improve the MEBT performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL035  
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TUPAL051 Program for High-Intensity RFQ Design With Matched and Equipartitioned Design Strategy rfq, linac, ISOL, resonance 1126
 
  • H.P. Li, M.J. Easton, Q. Fu, P.P. Gan, Y.R. Lu, Q.Y. Tan, Z. Wang, K. Zhu
    PKU, Beijing, People's Republic of China
 
  The deuteron driver accelerator of the Beijing Iso-tope Separation On-Line (BISOL) facility will acceler-ate and deliver a 20 mA deuteron beam to the targets with an energy of 40 MeV. As the injector of the driver linac, an RFQ is required to bunch and accelerate the 20 mA deuteron beam to 3 MeV with very high beam quality. In order to fulfil these requirements and re-duce time spent on optimization, an RFQ design pro-gram named RFQEP has been developed to generate the input file for the PARMTEQM code. In this program, the ‘matched and equipartitioned' design strategy is adopted to prevent halo formation and to avoid struc-ture resonances in high intensity RFQs. The detailed design aspects are studied in this paper and simulation results are given for an RFQ designed by this code, which shows the accuracy and the merits of the new program.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL051  
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TUPAL058 Studies for Major ISIS Upgrades via Conventional RCS and Accumulator Ring Designs injection, simulation, lattice, space-charge 1148
 
  • C.M. Warsop, D.J. Adams, H.V. Cavanagh, P.T. Griffin-Hicks, B. Jones, B.G. Pine, R.E. Williamson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK, which provides 0.2 MW of beam power via a 50 Hz, 800 MeV proton RCS. Detailed studies are now under way to find the optimal configuration for a next generation, short pulsed neutron source that will define a major ISIS upgrade in ~2031. Accelerator configurations being considered for the MW beam powers required include designs exploiting FFAG rings as well as conventional accumulator and synchrotron rings. This paper describes work exploring the latter, conventional options, but includes the possibility of pushing further toward intensity limits to reduce facility costs. The scope of planned studies is summarised, looking at optimal exploitation of existing ISIS infrastructure, and incorporating results from recent target studies and user consultations. Results from initial baseline studies for an accumulator ring and RCS located in the existing ISIS synchrotron hall are presented. Injection scheme, foil limits, longitudinal and transverse beam dynamics optimization with related beam loss and activation are outlined, as are results from detailed 3D PIC simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL058  
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TUPAL068 The Development of a Nw Fast Harmonic Kicker for the JLEIC Circulator Cooling Ring kicker, cavity, simulation, electron 1171
 
  • G.-T. Park, F. Fors, J. Guo, R.A. Rimmer, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
After the first half-scale, 5 harmonic kicker cavity prototyping * for the JLEIC's CCR/ERL electron cooler and the beam dynamic simulation study of the 10-turn CCR **. The optimized circulation cooling turns has been changed to 11 and only 5 odd-harmonic modes from 86.6 MHz to 779.4 MHz plus a DC bias are needed for the harmonic RF kicker system. The new cavity design including the electromagnetic and thermal cooling optimization and its 11 turns beam bunch tracking simulation with the new numerology of RF deflecting voltages will be presented. Further design specifications for its RF harmonic drive and the broadband RF window, coupler and circulator component will be given for handling 5 kW of total RF power.
* Y, Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 122001 (2016).
** Y. Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 084201 (2016).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL068  
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TUPAL072 Dispersive Electron Cooling for JLEIC electron, proton, scattering, coupling 1178
 
  • H. Zhang, Y.S. Derbenev, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
JLEIC is the electron ion collider under design at Jefferson Lab, which will provide a luminosity up to 1034 cm-2s−1. To reach the high luminosity, short ion and electron bunches with high charge density colliding in high frequency are proposed in JLEIC design. The high charge density of the ion beam leads to strong intrabeam scattering effect, which enlarges the ion beam emittance and ruins the luminosity if not mitigated. Magnetized electron cooling is implemented to overcome the intrabeam scattering effect and to reduce or maintain the ion beam emittance. In this paper, we discuss the redistribution of the cooling effects in the longitudinal and the transverse directions by introducing the dispersion of the ion beam in the cooling section. When the charge density of the cooling electron beam varies, the dispersion of the ion beam leads to an increase of the transverse cooling rate and a reduction of the longitudinal cooling rate, while the total decrement of the Courant-Snyder invariant of the ion beam increases. Both theoretical analysis and numerical calculation are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL072  
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TUPAL073 Conceptual Design of a Drift Tube LINAC for Proton Therapy DTL, linac, proton, rfq 1182
 
  • P.F. Ma, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng
    TUB, Beijing, People's Republic of China
  • Y.H. Pu, J. Qiao, C.P. Wang, X.C. Xie, F. Yang
    Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People's Republic of China
 
  Funding: National Key Research and Development Program of China (grant number 2016YFC0105408)
The conceptual design of an Alvarez-type Drift Tube Linac for one proton therapy facility is described in this paper. The design optimization of the Drift Tube Linac is carried out in the principle of adopting domestic mature technologies and cost control. The error study of the Drift Tube Linac is also given in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL073  
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TUZGBD4 Impact of a Wideband Feedback Prototype System on TMCI in the SPS feedback, optics, injection, kicker 1208
 
  • W. Höfle, H. Bartosik, E.R. Bjørsvik, G. Kotzian, T.E. Levens, K.S.B. Li
    CERN, Geneva, Switzerland
  • J.E. Dusatko, J.D. Fox, C.H. Rivetta
    SLAC, Menlo Park, California, USA
  • O. Turgut
    Stanford University, Stanford, California, USA
 
  The transverse mode coupling instability (TMCI) in the SPS has been identified as one of the potential performance limitations for future high intensity LHC beams that will be required for the High Luminosity (HL)-LHC era and is being addressed by the LHC Injector Upgrade Project (LIU). A potential mitigation can be provided by wideband feedback systems with a frequency reach of about 1 GHz . For this reason, the development of a prototype system has been started in a CERN collaboration within the US-LARP framework in 2008. In this report we present latest experimental results in 2017 where this prototype system was used in single and multi-bunch studies. In particular, a successful mitigation against TMCI at injection could be demonstrated in single bunch studies.  
slides icon Slides TUZGBD4 [15.120 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBD4  
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TUPMF005 Simulation of Inverse Compton Scattering and Its Implications on the Scattered Linewidth electron, simulation, laser, scattering 1254
 
  • N. Ranjan, B. Terzić
    ODU, Norfolk, Virginia, USA
  • I. Drebot, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • G.A. Krafft
    JLab, Newport News, Virginia, USA
  • V. Petrillo
    Universita' degli Studi di Milano & INFN, Milano, Italy
 
  Funding: This paper is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Compton scattering, though first described some one hundred years ago, has recently experienced a surge of interest due to the search for energy sources that are capable of yielding low emission bandwidths. In particular, the desire for hard x-rays with energies greater than 10 keV has led to increased study of inverse Compton sources. The rise in interest concerning inverse Compton sources has increased the need for efficient models that properly quantify the behavior of scattered radiation given a set of interaction parameters. The current, state-of-the-art, simulations rely of Monte Carlo-based methods, which may fail to properly model collisions of bunches in low-probability regions of the spectrum. Furthermore, the random sampling of the simulations may lead to inordinately high runtimes. Our methods can properly model behaviors exhibited by the collisions by integrating over the emissions of the electrons in the bunch in a lessened amount of time. Analytical simulations of Gaussian laser beams closely verify the behavior predicted by an analytically derived scaling law describing bandwidth of scattered radiation.
Current affiliation of primary author (Nalin Ranjan) is Princess Anne High, Virginia Beach, VA 23452, USA.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF005  
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TUPMF017 Transport Line Design and Injection Configuration Optimization for the Advanced Photon Source Upgrade injection, septum, kicker, dipole 1287
 
  • A. Xiao, M. Borland
    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.
On-axis swap-out injection was chosen for the Advanced Photon Source Upgrade (APS-U) to allow pushing the beam emittance to an extremely low value. The injection section configuration was optimized within a multi-dimensional parameter space and made consistent with up-to-date technical developments. The booster-to-storage ring (BTS) transport line was designed to bring the electron beam from the existing Booster to the new storage ring (SR). Due to various limitations, this new BTS line is twisted both horizontally and vertically when approaching the injection point, which introduces challenges in both geometrical and optical matching. This paper presents our simple solution to these issues. The coupling effect caused by the twisted BTS line is also discussed.
 
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TUPMF030 Operation and Performance of NSLS-II operation, feedback, MMI, photon 1312
 
  • G.M. Wang
    BNL, Upton, Long Island, New York, USA
 
  NSLS-II facility hosts 23 operating beamlines with 2 more under commissioning. The radiation sources varies, including damping wiggler, IVU, EPU, 3PW, and bending magnets. Over the past year, the storage ring performance continuously improved, including frequency feedback and photon local feedback. Machine reliability reached 96.9% for 4500 hrs operation with beam current upto 350 mA. Beam orbit short and long term stability has been significantly improved. Operation beam emittance were optimized with beamlines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF030  
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TUPMF038 Design Considerations for an Ultralow Emittance Storage Ring for the Canadian Light Source sextupole, lattice, quadrupole, electron 1334
 
  • L.O. Dallin
    CLS, Saskatoon, Saskatchewan, Canada
 
  Demands from light source scientists for more brilliant xray beams have resulted in the emergence of 4th generation storage rings. These demands include photon beams that are highly focussed and beams with high transverse coherence. Both these requirements are achieved with ultralow electron beam emittance. The practical development of the multi-bend achromat (MBA) concept by MAX IV has spurred many synchrotron light sources around the world to develop similar machines. For existing facilities two options are available: upgrading existing machines or building a new structure. The Canadian Light Source (CLS) has explored both options and has determined a new storage ring is required. Several design options for a 3.0 GeV ring have been developed. Best results are achieved when tracking is used to optimize the phase advance through the MBA structure to reduce the impact of the sextupoles on the dynamic aperture. Structures where no geometric sextupoles are required have been achieved while producing ultralow emittances.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF038  
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TUPMF042 Design of a High Dose Rate Micro-Focused X-Ray Source electron, target, dipole, cavity 1346
 
  • X. He, S.Q. Liao, J. Long, J. Shi, W. Wang, L. Yang
    CAEP/IFP, Mainyang, Sichuan, People's Republic of China
 
  High energy X-ray computer tomography has wide application in industry, especially in quality control of complicated high-tech equipment. In many applications, higher spatial resolution is needed to discover smaller defects. Decreasing the spot size of the X-Ray source is a promising way to get higher spatial resolution. Rhodotron have been used to produce high power CW electron beam in hundreds of kilowatts level. In this paper, we propose to use an improved Rhodotron to generate high brightness electron beam with high average power. Beam dynamics study shows that when producing tens of kilowatts electron beam, the normalized RMS emittance can be lower than 10 μm, and the relative RMS energy spread can be lower than 0.2%. The beam can be focused to a spot size of about 100μm by using a series of quadruple, and converted to X-Ray by using a rotating target within several kilowatts beam power. Improved Rhodotron proposed in this paper is a good candidate of X-ray source for high resolution high energy industrial CT systems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF042  
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TUPMF049 Evolution of the Lattice Design for the High Energy Photon Source lattice, storage-ring, injection, photon 1363
 
  • G. Xu, S.Y. Chen, Y. Jiao, J.L. Li, Y.M. Peng, Q. Qin, J.Q. Wang, C.H. Yu
    IHEP, Beijing, People's Republic of China
 
  The High Energy Photon Source (HEPS) is a high-energy, ultralow-emittance, kilometer-scale storage ring light source to be built in China. The HEPS lattice design has been started since 2008. In this paper we will review the evolution of the HEPS lattice design over the past ten years, focusing mainly on the linear optics design and nonlinear optimization.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF049  
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TUPMF050 DA Optimization Experiences in the Heps Lattice Design lattice, sextupole, photon, storage-ring 1367
 
  • Y. Jiao, G. Xu
    IHEP, Beijing, People's Republic of China
 
  In the past decade, the so-called diffraction-limited storage ring (DLSR) light sources were proposed, promising much better radiation performance than available in the existing third generation light sources. Regarding the very strong focusing and chromatic sextupoles that required for reaching an ultralow emittance, to optimize the nonlinear dynamics and achieve an adequate dynamic aperture is an important topic in a DLSR design. In this paper we will present some tips distilled from the DA optimization experience of the High Energy Photon Source over the past ten years, hoping it could provide some aids to other ultralow-emittance designs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF050  
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TUPMF052 Progress of Lattice Design and Physics Studies on the High Energy Photon Source lattice, booster, storage-ring, injection 1375
 
  • G. Xu, X. Cui, Z. Duan, Z. Duan, Y.Y. Guo, D. Ji, Y. Jiao, J.L. Li, X.Y. Li, C. Meng, Y.M. Peng, Q. Qin, S.K. Tian, J.Q. Wang, N. Wang, Y. Wei, H.S. Xu, F. Yan, C.H. Yu, Y.L. Zhao
    IHEP, Beijing, People's Republic of China
 
  The High Energy Photon Source (HEPS) is an ultralow-emittance, kilometer-scale storage ring light source to be built in China. In this paper we will introduce the progress of the physical design and studies on HEPS over the past one year, covering issues of storage lattice design and optimization, booster design, injection design, collective effects, error study, insertion device effects, beam lifetime, etc.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF052  
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TUPMF054 Performance Comparison of Different Ultralow Emittance Unit Cells lattice, dipole, storage-ring, quadrupole 1382
 
  • Y. Jiao, X.Y. Li, G. Xu
    IHEP, Beijing, People's Republic of China
 
  The available minimum emittance of a storage ring and the ring performance is closely related to the unit cell of the lattice. Up to now, several ultralow-emittance unit cells have been proposed and applied in the lattice design of the diffraction-limited storage ring light sources. In this study we quantitatively compared the performance of three typical unit cells, based on mainly the parameters of the High Energy Photon Source. The results indicate that the modified-TME unit cell with antibend and longitudinal gradient dipole allows the lowest possible emittance, given a long enough cell length.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF054  
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TUPMF056 Brightness Dependence Investigation and Optimizaiton for the Heps brightness, lattice, photon, undulator 1390
 
  • Y. Jiao, M. Li, X.Y. Li
    IHEP, Beijing, People's Republic of China
 
  The High Energy Photon Source (HEPS) is an ultralow-emittance, kilometer-scale storage ring light source to be built in China. To maximize the photon spectral brightness, one of the most important performance parameters of the light source, we investigated the dependence of brightness on different parameters, such as the natural emittance, coupling, beta functions of the undulator section, and length of the undulator section. Based on this study, we optimized the HEPS lattice by using brightness as an optimizing objective.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF056  
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TUPMF061 Physical Design of the 500 MeV Electron Linac for the High Energy Photon Source linac, electron, gun, bunching 1404
 
  • S. Pei, D.Y. He, X. He, J.L. Li, J. Liu, X. Ma, C. Meng, X. Wang, O. Xiao, J.R. Zhang, Z.S. Zhou
    IHEP, Beijing, People's Republic of China
  • S. Shu
    Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
 
  Funding: Work supported by the HEPS project and the National Natural Science Foundation of China (11475201). peisl@ihep.ac.cn
The High Energy Photon Source (HEPS) is a 6 GeV light source with ultra-low emittance, it is proposed to be built at Huairou district, northeast suburb of Beijing, China. A 500 MeV electron linac will be used to generate the electron beam for injection into the booster. Here the preliminary physical design of the electron linac is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF061  
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TUPMF069 Low Gain FEL Oscillator Option for PETRA IV FEL, undulator, storage-ring, electron 1420
 
  • I.V. Agapov
    DESY, Hamburg, Germany
  • Y.-C. Chae
    ANL, Argonne, Illinois, USA
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Next generation synchrotron storage rings will have electron beam density approaching that necessary for driving an XFEL. It falls short of the quality required for the high-gain x-ray regime above 1 keV, mainly due to the large energy spread and small peak current, bit is sufficient to reach low-gain regime. Here we explore the parameter space of a low gain XFEL oscillator, to establish the feasibility range of such a device for the Petra upgrade project.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF069  
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TUPMF072 Microwave Instability and Energy Spread Measurement via Vertical Dispersion Bump in PETRA III experiment, 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF072  
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TUPMF074 Control of Collective Effects by Active Harmonic Cavity in an MBA-based Light Source with Application to the PETRA Upgrade cavity, impedance, lattice, synchrotron 1433
 
  • Y.-C. Chae, J. Keil
    DESY, Hamburg, Germany
 
  Based on the reference lattice for PETRA IV* we investigated collective effects with non-zero current. Out of many possibilities we firstly computed the intrabeam-scattering (IBS) effects on the emittance as well as lifetime as a function of current. The result indicated that PETRA IV would benefit from the reduced peak current when the harmonic cavity lengthens the bunch. The operating point of harmonic cavity was explored by tracking simulations as well as analytic formula. In order to compute the energy spread and bunch length we had used the known impedance function of the APS**. In this way more realistic estimation of IBS effects was expected. However, because of the complex nature of PETRA IV lattice, which includes achromatic cells for undulators, arc cells of octants and straight sectors for damping wigglers, we simplify the longitudinal dynamics by assuming the ring made of 92 multi-bend-achromat (MBA) cells. The optics is approximated as a linear-chromatic transfer map enabling fast tracking and the ring impedance is concatenated into the one location. The detailed collective effects with and without harmonic cavities are presented in the paper.
* J. Keil, "A PETRA IV Lattice Based on Hybrid Seven Bend Achromats", these proceedings.
** Y.-C. Chae and Y. Wang, "Impedance Database II for the Advanced Photon Source Storage Ring", Proc. PAC2007.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF074  
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TUPMF075 Lattice Studies of a Booster Synchrotron for PETRA IV lattice, booster, damping, optics 1436
 
  • H.C. Chao
    DESY, Hamburg, Germany
 
  Associated with an upgrade study of the PETRA III light source toward ultra low-emittance is an upgrade study of the booster synchrotron. One possible solution obtained from a scaling of the ALBA booster to a circumference of 300 m is considered. It is based on a modified FODO lattice with combined function magnets and achromat straights. In this paper a method utilizing piecewise matchings supervised and optimized with evolutionary algorithm (PMSOEA) was devised to search the lattice. Some preliminary results are shown and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF075  
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TUPMF083 Influence of Intrabeam Scattering on the Emittance of PETRA III scattering, damping, wiggler, synchrotron 1463
 
  • J. Keil, G. Kube, G.K. Sahoo, R. Wanzenberg
    DESY, Hamburg, Germany
 
  PETRA~III is a 6 GeV hard X-ray synchrotron radiation source at DESY in Hamburg (Germany) and is in user operation since~2010. The natural emittance of PETRA III is extremely low with 1.3 nm*rad and the coupling is typically less than 1%. PETRA III is operated with a beam current of 100 mA using two different filling modes: a continuous mode with 960 bunches and a timing mode with 40 bunches. It has been observed that the horizontal emittance depends on the filling pattern and is in timing mode slightly larger compared to the emittance in the continuous mode. Despite the high energy of 6 GeV intrabeam scattering contributes for a slight emittance growth due to the small natural emittance and coupling of the machine. The increase of the emittance as a function of the single bunch current has been measured by using different filling patterns at a fixed beam current of 100 mA. The measurements of the emittance and the lifetime as a function of the single bunch current will be compared with theoretical expectations of the emittance growth due to intrabeam scattering and the Touschek lifetime.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF083  
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TUPMK004 Using Decoherence to Prevent Damage to the Swap-Out Dump for the APS Upgrade simulation, kicker, electron, storage-ring 1494
 
  • M. Borland, J.C. Dooling, R.R. Lindberg, V. Sajaev, A. Xiao
    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.
The Advanced Photon Source (APS) is pursuing an upgrade of the storage ring to a hybrid seven-bend-achromat* design, which will operate in swap-out mode. The ultra-low emittance (about 30 pm in both planes) combined with the desire to provide high charge (15 nC) in individual bunches, entails very high energy density in the beam. Simple estimates, confirmed by simulation, indicate that interaction of such a bunch with the dump material will result in localized melting. Over time, it is possible that the beam would drill through the dump and vent the ring vacuum. This would seem to prevent extraction and dumping of bunches as part of swap out, and also suggests that transferring of bunches out of the ring carries significant risk. We devised an idea for using a pre-kicker to cause decoherence of the target bunch emittances, making it safe to extract. Simulations show that the concept works very well.
*L. Farvacque et al., IPAC13, 79 (2013).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK004  
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TUPMK005 CSR Shielding Effect in Dogleg and EEX Beamlines shielding, dipole, experiment, simulation 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK005  
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TUPMK006 Sub-fs Electron Bunch Generation Using Emittance Exchange Compressor simulation, sextupole, cavity, electron 1501
 
  • J.M. Seok, M. Chung
    UNIST, Ulsan, Republic of Korea
  • M.E. Conde, J.G. Power
    ANL, Argonne, Illinois, USA
  • G. Ha
    PAL, Pohang, Republic of Korea
 
  Sub-fs electron bunch has been pursued in the last decade using several different methods. These methods rely on one of the velocity difference or path length difference to compress a long bunch to sub-fs bunch. Here, we introduce a new method to generate the compression. Emittance Exchange (EEX) beamline makes transverse-to-longitudinal exchange of phase space. In this beamline, a transverse focusing at the upstream introduces a longitudinal compression at the downstream due to the exchange. Since this exchange scheme does not rely on the velocity or the path length differences, it does not require any longitudinal manipulation (e.g. chirp), and it could generate a short bunch with well-controlled nonlinear effects using nonlinear magnets. We present preliminary simulation results of EEX based bunch compression and sub-fs bunch generation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK006  
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TUPMK011 Single Ring Permanent Magnet Lens solenoid, permanent-magnet, optics, TRIUMF 1513
 
  • K. Jayamanna, R.A. Baartman, Y. Bylinskii, T. Planche
    TRIUMF, Vancouver, Canada
  • M. Corwin
    UW/Physics, Waterloo, Ontario, Canada
  • R.N. Simpson
    UBC, Vancouver, B.C., Canada
 
  Funding: TRIUMF receives its funding from the National Research Council of Canada.
A permanent magnet lens has been designed to be a non-powered alternative to solenoids for low energy beam transport. The lens consists of a single ring of 12 sectors, each sector with poles directed inward. This forms an axial field that reverses sign at the midpoint, somewhat like two opposing short solenoids. It is similar to the Iwashita lens* but consists of only one ring, not two. A prototype lens optimized to decrease the magnetic material required while also reducing aberration, has been built and tested for a 25 keV H-minus beam. Emittance figures measured downstream of the lens are compared with theory.
* Y. Iwashita, "Axial Magnetic Field Lens with Permanent Magnet", Proc. PAC 1993, p.3154.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK011  
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TUPMK015 Initial Studies into Longitudinal Ionization Cooling for the Muon g-2 Experiment simulation, experiment, 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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TUPMK018 Round Beam Studies at NSLS-II coupling, resonance, lattice, experiment 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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TUPML004 Correction of Emittance Growth Due to Quad Components in Solenoids With Quad Correctors at AWA solenoid, simulation, linac, electron 1536
 
  • L.M. Zheng, C.-X. Tang
    TUB, Beijing, People's Republic of China
  • M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  An asymmetrical electron beam is observed on the drive beamline at Argonne Wakefield Accelerator (AWA) due to the quad components in the solenoids. An ASTRA simulation shows that the emittance will increase when the electron beam passes through solenoids with quad errors. We use two quad correctors to correct this emittance growth. A preliminary emittance correction result is presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML004  
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TUPML011 Experiments Producing Nanopatterned Electron Beams electron, FEL, bunching, experiment 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML011  
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TUPML027 Barium Tin Oxide Ordered Photocathodes: First Measurements and Future Perspectives electron, photon, cathode, laser 1597
 
  • A. Galdi, E. B. Lochocki, H. Paik, C.T. Parzyck, D. G. Schlom, K.M. Shen
    Cornell University, Ithaca, New York, USA
  • G. Adhikari, W.A. Schroeder
    UIC, Chicago, Illinois, USA
  • I.V. Bazarov, L. Cultrera, W. H. Li, J.M. Maxson, C. M. Pierce
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
Single crystalline photocathodes with small electron effective mass are supposed to enable ultra-low emittance beams, by taking advantage of the conservation of transverse (crystal) momentum. We present a preliminary study on photoemission from epitaxial films of La-doped BaSnO3 with (100) orientation. We demonstrate here the possibility of generating and characterizing electron beams by exciting photoelectrons solely from the conduction band. We report quantum efficiency and mean transverse energy meaurements as a function of photon energy from the bare and Cs-activated La-doped BaSnO3 surface.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML027  
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TUPML028 Photocathodes R&D for High Brightness and Highly Polarized Electron Beams at Cornell University electron, cathode, gun, simulation 1601
 
  • L. Cultrera, J. Bae, A.C. Bartnik, I.V. Bazarov, R. Doane, A. Galdi, C.M. Gulliford, W. H. Li, J.M. Maxson, S.A. McBride, T.P. Moore, C. M. Pierce, C. Xu
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Cornell University is a leader in the development of photocathode materials for the production of high brightness electron beam sources for applications in large scale accelerators and small scale electron scattering experiments. During the last year we have also included Mott polarimetry to investigate long lifetime spin-polarized photocathodes materials. Another thrust of our laboratory is the exploration of ultra low emittance photocathodes at cryogenic temperatures, for which we are building a novel LHe cryogenic electron source. We will review updates from our lab across each of these areas.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML028  
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TUPML029 Novel Photocathode Geometry Optimization: Field Enhancing Photoemission Tips cathode, electron, solenoid, simulation 1605
 
  • W. H. Li, I.V. Bazarov, C.M. Gulliford, J.M. Maxson
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was supported by the U.S. National Science Foundation under award PHY-1549132, the Center for Bright Beams.
For photoemission sources, the extraction electric field defines the maximum achievable emission current, and hence the maximum achievable beam brightness. Recently, interest has been growing in studying photocathodes with non-flat geometries to produce local field enhancements in excess of what can be achieved with large area flat cathodes. However, such geometries cause image charge effects which require self-consistent field solvers to correctly simulate. We present a novel simulation framework which combines a full particle in cell field solver (WARP) with a fast adaptive mesh space charge particle tracker (GPT) and a parallel multi-objective genetic optimizer to explore photocathode geometries for ultra high brightnesses. A first application of this technique is also shown, namely the use of field enhanced photoemission tips to create bright beams for ultra-fast electron diffraction.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML029  
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TUPML031 Characterization of Polarization-Dependent Emittance From an Array of Au Nanorods using Velocity Map Imaging Spectrometer electron, laser, polarization, experiment 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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TUPML038 Simulation of Phase-Dependent Transverse Focusing in Dielectric Laser Accelerator Based Lattices lattice, focusing, laser, quadrupole 1622
 
  • 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
The Accelerator on a CHip International Program (ACHIP) funded by the Gordon and Betty Moore Foundation aims to demonstrate a prototype of a fully integrated accelerator on a microchip based on laser-driven dielectric structures until 2021. Such an accelerator on a chip needs all components known from classical accelerators. This includes an electron source, accelerating structures and transverse focusing arrangements. Since the period of the accelerating field is connected to the drive laser wavelength of typically a few microns, not only longitudinal but also transverse effects are strongly phase-dependent even for few femtosecond long bunches. If both the accelerating and focusing elements are DLA-based, this needs to be taken into account. In this work we study in detail the implications of a phase-dependent focusing lattice on the evolution of the transverse phase space of a transported bunch.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML038  
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TUPML039 First Order Sensitivity Analysis of Electron Acceleration in Dual Grating Type Dielectric Laser Accelerator Structures laser, electron, simulation, experiment 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML039  
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TUPML052 Characterisation of the Second Stable Orbit Generated by Transverse Resonance Island Buckets (TRIBs) optics, resonance, experiment, 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
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML052  
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TUPML062 A Wedge Test in MICE experiment, 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 beam-cooling, experiment, 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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TUPML065 Phase Space Density Evolution in MICE simulation, factory, experiment, 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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TUPML066 Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices plasma, simulation, scattering, cavity 1696
 
  • P. Snopok
    Illinois Institute of Technology, Chicago, Illinois, USA
  • J.S. Ellison
    IIT, Chicago, Illinois, USA
 
  Funding: Work supported by the Department of Energy.
New computational tools are essential for accurate modeling and simulation of the next generation of muon-based accelerators. One of the crucial physics processes specific to muon accelerators that has not yet been simulated in detail is beam-induced plasma effect in liquid, solid, and gaseous absorbers. We report here on the development of required simulation tools and their applications to studying the properties of plasma and its effects on the beam in muon ionization cooling channels.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML066  
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TUPML067 Recent Results from the Study of Emittance Evolution in MICE solenoid, detector, experiment, 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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WEXGBE2 Compensation of Insertion Device Induced Emittance Variations in Ultralow Emittance Storage Rings wiggler, lattice, electron, photon 1751
 
  • F. Sannibale, S.C. Leemann, H. Nishimura, D. Robin, C. Steier, C. Sun, M. Venturini
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
With the advent of multi-bend achromat lattices, extremely low emittances are to become the norm in storage ring-based X-ray photon sources. In these lattices, the ratio of beam energy lost to radiation in the Insertion Devices (IDs) to the overall beam energy loss is relatively larger than in 3rd generation light sources. As a result, these machines are more sensitive to the energy loss variations occurring as the users operate variable-gap IDs and to the concurrent variations in radiation damping time, equilibrium emittance, and ultimately transverse properties of the beam. With possibly tens of variable gap IDs continuously and independently varying their gaps to meet the experiment needs, the resulting variation in emittance and beam sizes can be significant and can jeopardize the experimental performance in some of the beamlines. In this paper we describe and discuss possible methods for compensating such emittance variations and maintaining constant transverse beam properties for the experiments.
 
slides icon Slides WEXGBE2 [4.548 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBE2  
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WEXGBE3 IBS Studies at BESSY II and MLS simulation, scattering, radiation, damping 1755
 
  • T. Mertens
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
  • T. Atkinson, J. Feikes, P. Goslawski, J.G. Hwang, A. Jankowiak, J. Li, D. Malyutin, Y. Petenev, M. Ries, I. Seiler
    HZB, Berlin, Germany
 
  Intrabeam Scattering (IBS) effects will become a limiting factor for the attainable emittances and single-bunch currents in future electron storage rings and light sources. IBS studies were performed for BESSY II at the Helmholtz-Zentrum Berlin (HZB) and for the Metrology Light Source (MLS) at the Physikalisch-Technische Bundesanstalt (PTB) to quantify the IBS contributions to equilibrium beam sizes in these machines and make predictions for the BESSY II upgrade project, BESSY VSR. The energy dependence of IBS effects (γ −4 ) makes especially the MLS machine susceptible to IBS effects due to the relatively low energy ranges at which it can be operated (50 MeV-630 MeV). We compare experimental data with simulations and present IBS simulation results for BESSY VSR.  
slides icon Slides WEXGBE3 [0.922 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBE3  
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WEYGBE1 Suppressing CSR Microbunching in Recirculation Arcs bunching, dipole, lattice, radiation 1784
 
  • C.-Y. Tsai
    SLAC, Menlo Park, California, USA
 
  We provide sufficient conditions for suppression of CSR-induced microbunching instability along transport or recirculation arcs. The example lattices include low-energy (∼100 MeV) and high-energy (∼1 GeV) recirculation arcs, and medium-energy compressor arcs. Our studies show that lattices satisfying the proposed conditions indeed have microbunching gain suppressed. Beam current dependencies of maximal CSR microbunching gains are also demonstrated, which should help outline a beam line design for different scales of nominal currents. We expect this analysis can improve future lattice design.  
slides icon Slides WEYGBE1 [10.979 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBE1  
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WEPAF001 A Diagnostic Test Bench for the LIGHT Accelerator MMI, rfq, proton, DTL 1808
 
  • A. Jeff, A. Benot-Morell, M. Caldara, P. Nadig
    A.D.A.M. SA, Meyrin, Switzerland
 
  The LIGHT accelerator is the first compact Linac that will deliver proton beams up to 230 MeV for cancer treatment. The accelerator is only 24m long and is being built to be modular and capable of changing proton beam energy and intensity pulse-to-pulse at up to 200Hz. The LIGHT prototype is currently being commissioned by AVO / ADAM at CERN, while the first full installation is foreseen in 2019. Here we present the design and implementation of a moveable diagnostic test bench which is used to measure a full set of beam properties at each commissioning step. Parameters measured include beam current, pulse length, energy, position, transverse profile and emittance. The compact instruments, the electronics and the controls that equip the test bench are the same as those who will be permanently installed along the accelerator after the commissioning. The first results obtained with the test bench for beams up to 16 MeV are shown here. We demonstrate that the chosen instrumentation achieves a very high sensitivity, dynamic range, reliability and immunity to EM noise. Procedures for on-line calibration of the instruments are also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF001  
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WEPAF011 Developments of Bunch by Bunch Feedback System at NSLS-II Storage Ring feedback, operation, vacuum, storage-ring 1833
 
  • W.X. Cheng, B. Bacha, Y. Li
    BNL, Upton, Long Island, New York, USA
  • D. Teytelman
    Dimtel, San Jose, USA
 
  Funding: Work supported by DOE contract No: DE-SC0012704
Transverse bunch-by-bunch (BxB) feedback system has been constructed and in operation since the very beginning of NSLS-II storage ring commissioning. As the total beam current continues increasing in the past years, the system has been operating stable and reliable. Advanced BxB diagnostic functions have been developed using the system. Continuous tune measurement is realized with a diagnostic single bunch. Coupled bunch instability growth rate is able to be measured with the transient excitation. The BxB feedback system is also capable to excite a small fraction of total bunches for lattice measurement during high current operations. We present the most recent developments and operation experience on the BxB feedback system at NSLS-II.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF011  
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WEPAF012 Improvements of NSLS-II X-ray Diagnostic Beamlines storage-ring, vacuum, photon, radiation 1837
 
  • W.X. Cheng, B. Bacha, B.N. Kosciuk, D. Padrazo Jr
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by DOE contract No: DE-SC0012704
There are two X-ray diagnostic beamlines (XDB) developed at NSLS-II storage ring to measure emittance, energy spread, and other machine parameters. The first beamline utilizes a soft bending magnet radiation has been in operation since 2014. The tungsten pinhole originally located in the air had corrosion issue. The beamline has been improved by extending the vacuum to the imaging system. The second X-ray pinhole beamline using three-pole wiggler (TPW) radiation has been constructed and commissioned recently. Energy spread is able to be precisely measured due to large dispersion at the source point. A gated camera is equipped with the new beamline to acquire profiles within one turn. Recent operation experience and beam measurements will be presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF012  
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WEPAF016 Application of Quad-Scan Measurement Techniques to Muon Beams in the Muon g-2 Experiment experiment, 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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WEPAF017 Correction of ID-Induced Transverse Linear Coupling at NSLS-II coupling, operation, quadrupole, resonance 1856
 
  • Y. Hidaka, Y. Li, T.V. Shaftan, T. Tanabe, Y. Tian, 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.
Sizeable lifetime jumps have been observed sporadically since March 2016 at NSLS-II. These jumps were found to coincide with insertion device (ID) gap motions. Particularly, one of the in-vacuum undulators (IVUs) at Cell 17 was discovered to have large localized skew quadrupole component variation with gap. To allow the machine to operate stably in the low-emittance mode, a global coupling feedforward system has been recently implemented and successfully deployed. After installation of a new additional skew quadrupole, coupling compensation of this ID is now performed by a local coupling feedforward system. Furthermore, the maximum gap limit of all the existing IVUs has been decreased from 40 mm to 25 mm to limit the skew component variation during user operation.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF017  
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WEPAF026 Beam Induced Fluorescence Measurements of 100 keV Deuterons in LIPAc Accelerator electron, injection, detector, plasma 1877
 
  • R. Varela, A. Guirao, L.M. Martínez, J. Mollá, I. Podadera
    CIEMAT, Madrid, Spain
  • T. Akagi, R. Ichimiya, Y. Ikeda, M. Sugimoto
    QST, Aomori, Japan
  • B. Bolzon, N. Chauvin
    CEA/IRFU, Gif-sur-Yvette, France
  • P. Cara
    Fusion for Energy, Garching, Germany
  • H. Dzitko
    F4E, Germany
  • J. Knaster
    IFMIF/EVEDA, Rokkasho, Japan
 
  Funding: Work partially supported by the Spanish Ministry of Science and Innovation under project FIS2013-40860-R
The LIPAc accelerator will be a linear CW deuteron accelerator capable of delivering a 9 MeV, 125 mA beam which aims to validate the technology that will be used in the future high power accelerator-driven neutron source, IFMIF. In summer 2017 a campaign of measurements was done during the injector commissioning, in which a Fluorescence Profile Monitor based on an Intensified CID camera (ICID) was used to measure the beam transverse profile at the extraction of the ion source. In this contribution we review the design of the ICID, its performance and discuss the measurements carried out. The performance of ICID monitors for its use in future accelerators will be assessed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF026  
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WEPAF032 An Alternative Fast Orbit Feedback Design of HEPS feedback, lattice, controls, closed-orbit 1888
 
  • X.Y. Huang, J.S. Cao, Y.Y. Du, F. Liu, Y.H. Lu, Y.F. Ma, Y.F. Sui, S.J. Wei, Q. Ye, X.E. Zhang, D.C. Zhu
    IHEP, Beijing, People's Republic of China
 
  The High Energy Photon Source (HEPS) is a fourth generation light source in China and will be built in this year. The emittance of HEPS storage ring is approaching diffraction limit and the circumstance of the ring is about 1.3 kilometres. To stabilize the electron beam, fast orbit feedback (FOFB) system is prerequisite. In this paper, the requirements on the HEPS beam stability are discussed and an alternative FOFB design based on DBPM are introduced with algorithm and architecture.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF032  
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WEPAF041 Use of Dimension-Reduction Techniques With Multi-Objective Genetic Algorithms to Improve the Vertical Emittance and Orbit at CESR storage-ring, simulation, lattice, electron 1901
 
  • W.F. Bergan, I.V. Bazarov, C.J. Duncan, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Liarte, J.P. Sethna
    Cornell University, Ithaca, New York, USA
 
  Funding: DOE DE-SC0013571 NSF DGE-1650441
In order to reduce the vertical emittance at the Cornell Electron Storage Ring (CESR), we first measure and correct the vertical orbit, dispersion, and coupling. However, due to the finite resolution of our optics measurements, we still retain a significant residual emittance. In order to correct this further, we made use of the theory of sloppy models, according to which certain high-dimensionality systems can be modeled with significantly fewer "eigenparameters" that still contain most of the effect on the desired objective, in this case, the emittance.* However, we noted that using these knobs for tuning often resulted in increased vertical orbit errors. In an attempt to constrain these, we have applied multi-objective genetic algorithms to this problem. We have found that it can be more efficient to run such algorithms using our eigenparameters as the genes to be varied, as opposed to the raw magnet values. When running with the first 8 such knobs as genes, we can get either orbits or beam sizes as good as we obtain with our regular emittance-tuning algorithm which uses all the corrector magnets.
*K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).
 
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WEPAF047 Status and Commissioning of the Wire Scanner System for the European XFEL detector, FEL, undulator, MMI 1919
 
  • T. Lensch, S. Liu
    DESY, Hamburg, Germany
 
  The European-XFEL (E-XFEL) is an X-ray Free Electron Laser facility located in Hamburg (Germany). The superconducting accelerator for up to 17.5 GeV electrons will provide photons simultaneously to several user stations. Currently 12 Wire Scanner stations are used to image transverse beam profiles in the high energy sections. These scanners provide a slow scan mode which is currently used to measure beam emittance and beam halo distributions. When operating with long bunch trains (>100 bunches) also fast scans are planned to measure beam sizes in an almost nondestructive manner. This paper describes the current installations and the latest developments of the system at European-XFEL. Furthermore, the commissioning status of the system and first results of beam halo studies will be shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF047  
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WEPAF063 RF Manipulations for Special LHC-Type Beams in the CERN PS extraction, brightness, flattop, cavity 1971
 
  • H. Damerau, S. Hancock, A. Lasheen, D. Perrelet
    CERN, Geneva, Switzerland
 
  Beams with special longitudinal characteristics for the Large Hadron Collider (LHC) have been produced in the Proton Synchrotron (PS) and CERN. The flexibility of its RF systems consisting of in total 25 RF cavities at frequencies from 400 kHz to 200 MHz allows a variety of longitudinal beam manipulations. In particular the main RF system is split into three independent groups tunable from 2.8 MHz to 10 MHz. It is used to merge, split and change the spacing between bunches by applying different voltage and phase programs to the three groups of cavities at different harmonic numbers simultaneously. The batch compression, merging and splitting (BCMS) process has been operationally used for LHC fillings since 2016. To mitigate issues with long bunch trains in the LHC in 2017, short gaps of four bunch positions have been introduced between mini-batches of eight bunches (8b4e). A higher brightness version resulting in four mini-batches per PS extraction has been delivered for luminosity production in the LHC. This paper summarizes the operational experience and indicates possible future RF manipulation schemes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF063  
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WEPAF072 Transverse Feedback System for the CERN FCC-hh Collider injection, feedback, damping, kicker 1997
 
  • W. Höfle, J. Komppula, G. Kotzian, K.S.B. Li, D. Valuch
    CERN, Geneva, Switzerland
 
  For the future hadron Collider (FCC-hh) being studied at CERN a strong transverse feedback system is required to damp coupled bunch instabilities. This system is also planned to be used for injection damping. Based on the LHC transverse feedback design we derive requirements for power and kick strength for this system for the different options of bunch spacing, 25 ns and 5 ns, and injection energy. Operation at high gain and close to a half integer tune is being considered and constrains the layout and signal processing. Requirements for the pick-up resolution are derived from the need to keep the emittance increase small. The performance is evaluated using numerical simulations based on the headtail code. Future areas of research and development and possible prototype developments are outlined.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF072  
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WEPAF080 Beam Size Measurements Based on Movable Quadrupolar Pick-ups pick-up, alignment, embedded, quadrupole 2028
 
  • A. Sounas, M. Gąsior, T. Lefèvre, A. Mereghetti, J. Olexa, S. Redaelli, G. Valentino
    CERN, Geneva, Switzerland
 
  Measurements with quadrupolar pick-ups (PU) have attracted particular interest as non-intercepting diagnostics for determining the transverse beam size. They are based on processing the signals of an electromagnetic PU for the extraction of the second-order moment, which contains information about the beam size. Despite the simplicity of the concept, quadrupololar measurements have always been highly challenging in reality. This comes from the fact that the quadrupolar moment constitutes only a very small part of the total PU signal dominated by the intensity and the position signals. Therefore, the beam size information can easily be lost due to small imperfections in the signal processing chain, such as asymmetries in the electronics and cables. In this paper, we present a new method for quadrupolar measurements using movable PUs. Through position and aperture scans, our technique minimizes the parasitic beam position signal and takes into account imperfections of the PU, cables and electronics, thus enabling an efficient auto-calibration of the measurement system. Preliminary studies, using collimators with embedded electrostatic PUs in the LHC at CERN, have shown very promising results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF080  
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WEPAF087 The First Experience and Results of Beam Diagnostics Deployment at the ESS Accelerator ion-source, MMI, electron, diagnostics 2054
 
  • V. Grishin, E.C. Bergman, B. Cheymol, C.S. Derrez, T.J. Grandsaert, H. Hassanzadegan, A. Jansson, H. Kocevar, O. Midttun, S. Molloy, J. Norin, T.J. Shea, C.A. Thomas
    ESS, Lund, Sweden
  • W. Ledda
    Vitrociset s.p.a, Roma, Italy
  • F. Senée, O. Tuske
    CEA/IRFU, Gif-sur-Yvette, France
 
  The European Spallation Source (ESS) will produce neutrons for science by subjecting a tungsten target to the high-intensity proton beam from a superconducting linear accelerator. A complete suite of beam diagnostics will enable tuning, monitoring and protection of the accelerator during commissioning, studies and operation. As an initial step toward neutron production, the Ion Source and the 75 keV Low Energy Transport Line is installed on the ESS site in Lund, Sweden. To support the commissioning and characterization of this first beam-producing system, a subset of the full diagnostics suite is deployed. This includes the following equipment: a faraday cup, current transformers, an emittance measurement unit, beam-induced fluorescence monitors, and a doppler-shift spectroscopy system. All aspects of the deployment experience, from acceptance testing through installation, verification, and commissioning will be presented.
*Beam Instrumentation
 
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WEPAK006 Bunch Shape Measurements at the GSI CW-Linac Prototype linac, cavity, heavy-ion, bunching 2091
 
  • T. Sieber, W.A. Barth, P. Forck, V. Gettmann, M. Heilmann, H. Reeg, A. Reiter, S. Yaramyshev
    GSI, Darmstadt, Germany
  • F.D. Dziuba, T. Kürzeder, M. Miski-Oglu
    HIM, Mainz, Germany
  • A. Feschenko, S.A. Gavrilov
    RAS/INR, Moscow, Russia
 
  The existing GSI accelerator will become the injector for FAIR. To preserve and enhance the current experimental program at UNILAC, a new Linac is under development, which shall run in parallel to the FAIR injector, providing cw-beams of ions at energies from 3.5 - 7.3 MeV/u. For this cw-Linac a superconducting prototype cavity has been developed and was first operated with beam in summer 2017. The resonator is a cross-bar H-structure (CH) of 0.7 m length, with a resonant frequency of 216.8 MHz. It has been installed behind the GSI High Charge State Injector (HLI), which provided 108 MHz bunches of 1.4 MeV/u Ar6+/9+/11+ ions at a duty cycle of 25 %. Due to the frequency jump and small longitudinal acceptance of the CH, proper matching of the HLI beam to the prototype was required. The bunch properties of the injected beam as well as the effect of different phase- and amplitude-settings of the cavity were measured in detail with a bunch shape monitor (BSM) fabricated at INR, Moscow, while the mean energy was analyzed by time of flight method. In this contribution, the bunch shape measurements are described and the capabilities of the used BSM measurement principle are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK006  
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WEPAL019 A Novel Field Cage Design for the CPS IPM and Systematic Errors in Beam Size and Emittance electron, detector, cathode, extraction 2193
 
  • K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • D. Bodart, S. Levasseur, G. Schneider, J.W. Storey
    CERN, Geneva, Switzerland
  • M. Sapinski
    GSI, Darmstadt, Germany
 
  An ionization profile monitor has been recently installed in the CERN proton synchrotron. We design a novel and simple structure field cage that suppresses the secondary electrons that are induced by the ionized ions. We discuss a field cage design, and the systematic error on the basis of beam size and emittance, considering the non-uniformity of the fields, the space-charge effect of the beam, and the lattice parameter errors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL019  
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WEPAL020 Measurement of Transverse Dipole and Quadrupole Moments with the BPMS in the J-PARC 3-50 BT quadrupole, dipole, beam-transport, optics 2197
 
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • H. Kuboki, K. Satou, M. Tejima
    KEK, Tokai, Ibaraki, Japan
 
  We measure dipole and quadrupole moments of the beam using the BPMs in the beam transport line 3-50BT of J-PARC and obtain differences of squared horizontal- and vertical-rms-sizes for those BPMs. Then we obtain rms emittances and rms momentum by fitting with given Twiss parameters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL020  
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WEPAL044 ENSOLVE : A Simulation Code for FXR LIA Downstream Section solenoid, target, space-charge, electron 2271
 
  • Y.H. Wu, Y.-J. Chen
    LLNL, Livermore, California, USA
 
  Funding: This work was performed under the auspi-ces of the U.S. Department of Energy by Law-rence Livermore National Laboratory under Contract DE-AC52-07NA27344.
In this paper, we describe an envelope code, ENSOLVE. It solves the rms beam envelope equation by including space change depression of the potential, spherical aberration of the so-lenoidal lens, emittance growth and focusing effects of backstreaming ions in the final focus region. In this paper, we focus on the physics included for beam transport simulations in the downstream section of flash x-ray radiography linear induction accelerators, such as FXR LIA. We have used ENSOLVE to design final focus tunes for FXR LIA downstream section
 
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WEPAL045 An Electrostatic Fixed-Slit Emittance Measurement System cathode, electron, focusing, FEL 2274
 
  • J.W. Lewellen, H.L. Andrews, R.L. Fleming, K.E. Nichols, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Los Alamos National Laboratory LDRD Program
The emittance of a field emission cathode can be difficult to measure close to the emitter, due to the high average current density of the beam and the potential for desorbed material from an imaging screen to contaminate the cathode. We present the design for a dual fixed-slit emittance measurement system for a field emitter cathode, implemented using electrostatic deflecting plates. Results from fabrication and initial testing will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL045  
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WEPAL062 Bunch Length Measurements with a Streak Camera in Low Alpha Lattice Operation at the TPS synchrotron, lattice, operation, photon 2316
 
  • C.H. Chen, J.Y. Chen, M.-S. Chiu, P.J. Chou, K.T. Hsu, K.H. Hu, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, G.-H. Luo, H.-J. Tsai, F.H. Tseng
    NSRRC, Hsinchu, Taiwan
 
  We developed and tested lattice with lower momentum compaction factor (low alpha) in TPS (Taiwan Photon Source) recently. Operating low alpha lattice can provide picosecond bunch length for time-resolved research and coherent IR/THz synchrotron light. The bunch length around 2.5 picosecond rms was measured by a streak camera* in low alpha mode while operating in the routine users mode** it was around 10 picosecond. This paper presents the related processes and measurements.
* L.Y. Liao et al., "Preliminary beam test of synchrotron radiation monitoring system at Taiwan Photon Source", IPAC'15.
** C.C. Kuo et al., "Commissioning of Taiwan Photon Source", IPAC'15.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL062  
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WEPAL072 A Novel Longitudinal Laserwire to Non-Invasively Measure 6-Dimensional Bunch Parameters at High Current Hydrogen Ion Accelerators laser, detector, linac, simulation 2349
 
  • S.M. Gibson, A. Bosco
    Royal Holloway, University of London, Surrey, United Kingdom
  • S.E. Alden, A. Bosco, S.M. Gibson
    JAI, Egham, Surrey, United Kingdom
  • A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • J.K. Pozimski
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • J.K. Pozimski
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
 
  Funding: We acknowledge funding by the STFC Grant ST/P003028/1 and the John Adams Institute at Royal Holloway, University of London.
Optical methods for non-invasive beam diagnostics of high current H ion accelerators have been developed in recent years*, **. Such laserwires typically measure a 1D beam profile and/or 2D transverse emittance from the products of photo-detached ions as a laser beam is scanned across the H beam. For laser pulse durations (~80ns) longer than the RF period (~3ns), the detector integrates many complete bunches, enabling only transverse beam monitoring. This paper presents a new technique to capture a series of time resolved transverse emittance measurements along the bunch train. A fast (~10ps) pulsed laser photo-detaches ions within each bunch and is synchronized to sample consecutive bunches at certain longitudinal positions along each bunch. A fast detector records the spatial distribution and time-of-flight of the neutralized H0, thus both the transverse and longitudinal emittance are reconstructed. We present simulations of a time varying pulsed laser field interacting within an H bunch, and estimate the yield, spatial and time distributions of H0 arriving at the detector. We summarise the design of a recently funded longitudinal laserwire being installed in FETS at RAL, UK.
* NIM-A, 830, p526-531, T. Hofmann et al
** T. Hofmann et al, 'Commissioning of the Operational Laser Emittance Monitors for LINAC4 at CERN' IPAC18.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL072  
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WEPAL074 Commissioning of the Operational Laser Emittance Monitors for LINAC4 at CERN laser, electron, detector, linac 2357
 
  • T. Hofmann, G.E. Boorman, A. Bosco, S.M. Gibson
    Royal Holloway, University of London, Surrey, United Kingdom
  • F. Roncarolo
    CERN, Geneva, Switzerland
 
  A laser-based emittance monitor has been developed to non-invasively measure the transverse emittance of the LINAC4 H beam at its top energy of 160MeV. After testing several sub-systems of the instrument during linac commissioning at intermediate energies, two instruments are now permanently installed. These instruments use a pulsed laser beam delivered to the accelerator tunnel by optical fibres before final focusing onto the H beam. The photons in the laser pulse detach electrons from the H ions, which can then be deflected into an electron multiplier. In addition, the resulting neutral H0 atoms can be separated from the main beam by a dipole magnet before being recorded by downstream diamond strip-detectors. By scanning the laser in the horizontal and vertical plane the beam profiles are obtained from the electron signals and the emittance can be reconstructed by the H0 profiles at the diamond detectors. This paper describes the final system layout that consists of two independent instruments, each measuring profile and emittance of the H beam in the horizontal and vertical plane and discusses the preliminary commissioning results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL074  
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WEPMF021 Magnet Design Considerations for an Ultralow Emittance Canadian Light Source quadrupole, lattice, storage-ring, FEL 2413
 
  • L.O. Dallin, D. Bertwistle
    CLS, Saskatoon, Saskatchewan, Canada
 
  The strong focusing requirements for ultralow emittance light sources result in high field magnets that are very close together. High fields are readily achieved by using small magnet gaps. This is possible due to the small beam sizes involved. Reduction in the physical aperture and the reduction in the good field region requirements results in magnets with compact transverse dimensions. The very strong focusing of the magnets results in very small drift spaces between the various magnetic elements. To keep these drift spaces clear magnets with recessed coils have been studied. In such magnets the coils do not stick out beyond the end of the magnet yoke in the longitudinal direction. By placing the coils on the outer yoke loss of efficiency can be avoided while maintaining good control of the higher order field harmonics. This is very well suited for quadrupole magnets where only two coils are required. Possible designs for gradient dipoles and sexutpoles are also considered.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF021  
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THXGBE2 Optical Diagnostics for Extreme Beam Conditions radiation, diagnostics, electron, experiment 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 experiment, 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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THYGBF1 High Power Beam Operation of the J-PARC RCS and MR operation, extraction, quadrupole, betatron 2938
 
  • Y. Sato
    KEK, Ibaraki, Japan
 
  This invited talk presents the most recent status of improving J-PARC main ring (MR) beam operation together with the rapid cycling synchrotron (RCS) effort. The RCS has optimized the beam performance for the MR injection as well as the muon and neutron targets, where each requires different emittance and beam halo size. The MR has two extraction modes; fast extraction (FX) for the long baseline neutrino oscillation experiment, T2K, and slow extraction (SX) for experiments in the hadron experimental facility. At present, achieved beam intensities are 2.4·1014 protons per pulse (ppp) with cycle time 2.48 s (470 kW) in the FX mode and 5.1013 ppp with cycle time 5.52 s (44 kW) in the SX mode. For the FX operation, recent improvements are settings of new betatron tune, corrections of resonances near the betatron tune, and adopting 2nd harmonic rf voltage to reduce space charge effect. Beam instabilities have been suppressed with controlling chromaticity correction and transverse feedback systems. For the SX mode, a dynamic bump scheme for reducing extracted beam loss is successfully adopted. A high extraction efficiency of 99.5 % is achieved at the 44 kW beam operation.  
slides icon Slides THYGBF1 [6.669 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBF1  
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THYGBF2 PIP-II Injector Test Warm Front End: Commissioning Update kicker, rfq, operation, focusing 2943
 
  • L.R. Prost, R. Andrews, C.M. Baffes, J.-P. Carneiro, B.E. Chase, A.Z. Chen, E. Cullerton, P. Derwent, J.P. Edelen, J. Einstein-Curtis, D. Frolov, B.M. Hanna, D.W. Peterson, G.W. Saewert, A. Saini, V.E. Scarpine, A.V. Shemyakin, V.L. Sista, J. Steimel, D. Sun, A. Warner
    Fermilab, Batavia, Illinois, USA
  • C.J. Richard
    NSCL, East Lansing, Michigan, USA
  • V.L. Sista
    BARC, Mumbai, India
 
  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 Warm Front End (WFE) of the Proton Improvement Plan II Injector Test [1] at Fermilab has been constructed to its full length. It includes a 15-mA DC, 30-keV H ion source, a 2 m-long Low Energy Beam Transport (LEBT) with a switching dipole magnet, a 2.1 MeV CW RFQ, followed by a Medium Energy Beam Transport (MEBT) with various diagnostics and a dump. This report presents the commissioning status, focusing on beam measurements in the MEBT. In particular, a beam with the parameters required for injection into the Booster (5 mA, 0.55 ms macro-pulse at 20 Hz) was transported through the WFE.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBF2  
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THPAF015 Beam Tracking Studies of Electron Cooling in ELENA electron, proton, antiproton, simulation 2975
 
  • B. Veglia, J.R. Hunt, J. Resta-López, V. Rodin, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • J.R. Hunt, J. Resta-López, V. Rodin, C.P. Welsch
    The University of Liverpool, Liverpool, 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 storage ring (ELENA), which is currently being commissioned at CERN, will further decelerate antiprotons extracted from the Antiproton Decelerator (AD) from 5.3 MeV to energies as low as 100 keV. It will provide high quality beams for the antimatter experiments located within the AD hall. At such low energies, it is important to correctly evaluate the long term beam stability. To provide a consistent explanation of the different physical phenomena affecting the beam, tracking simulations have been performed and the results will be presented in this contribution. These include electron cooling and various scattering effects under realistic conditions. The effects of several imperfections in the electron cooling process will also be discussed. In addition, analytical approximations of the temporal variation of emittance under these conditions will be presented, and compared with numerical simulation results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF015  
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THPAF024 Understanding and Compensating Emittance Diluting Effects in Highly Optimized Ultrafast Electron Diffraction Beamlines electron, space-charge, cathode, gun 3004
 
  • C. M. Pierce, I.V. Bazarov, C.M. Gulliford, J.M. Maxson
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • S. Baturin
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  • M.A. Gordon, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
 
  Funding: This work was supported by the Center for Bright Beams, NSF PHY-1549132 and Department of Energy grant DE-SC0014338.
The application of Multiobjective Genetic Algorithm optimization (MOGA) to photoemission based ultrafast electron diffraction (UED) beamlines featuring extremely low cathode mean transverse energies has lead to designs with emittances as low as 1 nm for sub-picosecond bunches with 105 electrons*. Analysis of these results shows significant emittance growth during transport: with emittance dilution as high as a factor of 200-4000% for various designs and optics settings. In this study we quantify and model the individual sources of emittance growth (slice mismatches and space charge), and explore the use of the core emittance as a strong invariant.
C. Gulliford, A. Bartnik, and I. Bazarov. Multi-
objective optimizations of a novel cryocooled dc gun based
UED beam line. Phys. Rev. Ac-
celerators and Beams, 19(9):093402, 2016.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF024  
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THPAF025 Progress in Measurement and Modeling of Electron Cloud Effects at CesrTA electron, dipole, simulation, positron 3007
 
  • S. Poprocki, S.W. Buechele, J.A. Crittenden, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
The synchrotron-radiation-induced buildup of low-energy electron densities in positron and proton storage rings limits performance by causing betatron tune shifts and incoherent emittance growth. The Cornell Electron Storage Ring (CESR) Test Accelerator project includes extensive measurement and modeling programs to quantify such effects and apply the knowledge gained to the design of future accelerator projects. We report on improved measurements of betatron tune shifts along a train of positron bunches, now accurate in both horizontal and vertical planes. Improved electron cloud buildup modeling uses detailed information on photoelectron production properties obtained from recently developed simulations and successfully describes the measurements after determining ring-wide secondary-yield properties of the vacuum chamber by fitting the model to data with a multi-objective optimizer. Cloud splitting in dipole magnetic fields is seen to be the source of horizontal tune shifts decreasing at higher bunch populations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF025  
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THPAF031 A PETRA IV Lattice based on Hybrid Seven Bend Achromats lattice, damping, wiggler, sextupole 3021
 
  • J. Keil, I.V. Agapov, R. Brinkmann, X.N. Gavaldà, R. Wanzenberg
    DESY, Hamburg, Germany
 
  For the PETRA IV project at DESY it is planned to convert the 6 GeV synchrotron light source PETRA III into a diffraction limited storage ring with ultra-low emittances. PETRA IV should provide a natural emittance two orders of magnitude smaller as now. The energy and the current of 100 mA should be unchanged. Currently different lattice options are investigated to achieve an emittance in the range of 10-30 pm*rad. As one candidate for a lattice of PETRA IV a ring based on the concept of hybrid multi-bend achromats (HMBA) has been studied in detail. Due to the unique layout of PETRA III with long straight sections it is possible to use damping wigglers to reduce the emittance further. While this helps to mitigate intrabeam scattering it has the disadvantage of an increased energy spread. The linear and nonlinear parameters of this HMBA-based lattice and the influence of damping wigglers on beam parameters are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF031  
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THPAF032 Simulation Study of an RF Injector for the LWFA Configuration at EuPRAXIA linac, injection, plasma, simulation 3025
 
  • J. Zhu, R.W. Aßmann, A. Ferran Pousa, B. Marchetti, P.A. Walker
    DESY, Hamburg, Germany
 
  The Horizon 2020 Project EuPRAXIA (EuropeanPlasma Research Accelerator with eXcellence In Applications) aims at producing a design report of a highly compact and cost-effective European facility with multi-GeV electron beams using a plasma accelerator. LWFA with external injection from an RF accelerator is one of the most promising configurations. In order to achieve the goal parameters for the 5 GeV, 30 pC electron beam at the entrance of the undulator, a high-quality electron beam with bunch length of less than 10 fs (FWHM) and matched beta functions (~1 mm) at the plasma entrance is required. In addition, from the compactness point of view, the injection energy is desired to be as low as possible. A hybrid compression scheme is considered in this paper and a detailed start-to-end simulation is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF032  
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THPAF033 Degradation of Electron Beam Quality for a Compact Laser-Based FEL electron, FEL, laser, space-charge 3029
 
  • A.Y. Molodozhentsev, L. Pribyl
    Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic
  • K.O. Kruchinin
    ELI-BEAMS, Prague, Czech Republic
 
  Laser wake field acceleration (LWFA) mechanism allows to produce extremely short electron bunches of a few fs length with the energy up to a few GeV in extremely compact geometries providing unique electron beam parameters, in particular, transverse beam emittance (order of 1pi mm mrad), extremely short bunch length and high beam charge (up to 100pC) . This novel acceleration method therefore opens a new way to develop compact 'laser-based' FELs. In the frame of this report we analyze effects, which lead to degradation of an electron beam quality. The chromatic and collective effects are analyzed for a compact dedicated electron beam line to transport the electron beam to an undulator. In addition, the SASE FEL performance has been discussed taking into consideration the degradation of the electron beam quality.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF033  
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THPAF037 Bunch Compression and Turnaround Loops Design in the FCC-ee Injector Complex dipole, sextupole, linac, damping 3044
 
  • T.K. Charles, F. Zimmermann
    CERN, Geneva, Switzerland
  • M.J. Boland
    CLS, Saskatoon, Saskatchewan, Canada
  • K. Oide
    KEK, Ibaraki, Japan
 
  The Future Circular e+e Collider (FCC-ee) requires two 180-degree turnaround loops to transport the positron beam from the damping ring to the lower energy section of the linac. In addition bunch compression is required to reduce the RMS bunch length from 5 mm to 0.5 mm, prior to injection into the linac. A dogleg bunch compressor comprised of two triple bend achromat (TBAs) can achieve this compression. Sextupole magnets are incorporated into the bunch compressor design for chromaticity correction as well as optimisation of the second-order longitudinal dispersion, T566, and to linearize the longitudinal phase space distribution. In this paper we present the design of the transport line and the bunch compressor. Measures to limit emittance growth due to coherent synchrotron radiation (CSR) are also discussed, because despite the relatively long bunch length, the large degree of bending required introduces cause for consideration of CSR.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF037  
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THPAF040 Estimated Impact of Ground Motion on HL-LHC Beam Orbit ground-motion, quadrupole, luminosity, closed-orbit 3052
 
  • D. Gamba, R. Corsini, M. Guinchard, M. Schaumann, J. Wenninger
    CERN, Geneva, Switzerland
 
  Funding: Research supported by the HL-LHC project.
The High Luminosity LHC (HL-LHC) will require unprecedented orbit stability at the low beta collision points (IP1 and IP5), and the effect of seismic noise might become a relevant source of luminosity loss. Many studies have been conducted in the past to characterise the actual ground motion in the LHC tunnel, and recently a few geo-phones have been installed to permanently monitor the ground stability at IP1 and IP5. An estimate of the impact of the main machine element vibration on orbit at the IPs and collimators is presented, together with a first look at the data collected by the installed geo-phones.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF040  
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THPAF041 Uncontrolled Longitudinal Emittance Blow-Up during RF Manipulations in the CERN PS impedance, cavity, simulation, controls 3056
 
  • A. Lasheen, H. Damerau, G. Favia
    CERN, Geneva, Switzerland
 
  The CERN Proton Synchrotron (PS) determines the basic bunch spacing for the Large Hadron Collider (LHC) by means of rf manipulations. Several rf systems in a frequency range from 2.8 MHz to 200 MHz are available for beam acceleration and manipulations. Each of the six bunches injected from the PS Booster is split in several steps into 12 bunches spaced by 25 ns, yielding a batch of 72 bunches at transfer to the Super Proton Synchrotron (SPS). In the framework of the LHC Injector Upgrade (LIU) project the bunch intensity must be doubled. However, with most of the planned upgrades already in place this intensity has not yet been achieved due to collective effects. One of them is uncontrolled longitudinal emittance blow-up during the bunch splittings. In this contribution, measurements of the blow-up during the splitting process are presented and compared with particle simulations using the present PS impedance model. Beam-based measurements of the impedances of the rf cavities have been performed. They revealed that to reproduce the instability an additional impedance source is required in the PS impedance model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF041  
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THPAF042 Improvement of the Longitudinal Beam Transfer from PS to SPS at CERN cavity, acceleration, controls, proton 3060
 
  • A. Lasheen, H. Damerau, J. Repond, M. Schwarz, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
 
  The beam transfer from the Proton Synchrotron (PS) to the Super Proton Synchrotron (SPS) at CERN is a critical process for the production of beams for the Large Hadron Collider (LHC). A bunch-to-bucket transfer is performed with the main drawback that the rf frequency in the SPS (200 MHz) is five times higher than the one in the PS (40 MHz). The PS bunches are therefore shortened non-adiabatically before extraction by applying a fast rf voltage increase (bunch rotation) to fit them into the short rf buckets in the SPS. However, particles with large amplitude of synchrotron oscillations in the PS longitudinal phase space are not properly captured in the SPS. They contribute to losses at the injection plateau and at the start of acceleration in the SPS. In this contribution, we present measurements and simulations performed to identify the source of the uncaptured particles. The tails of the particle distribution were characterized by applying longitudinal shaving during acceleration. Furthermore, the rotated bunch distribution was improved by linearizing the rf voltage using a higher-harmonic rf cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF042  
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THPAF047 Measurements and Impact of Stray Fields on the 380 GeV Design of CLIC site, dipole, collider, background 3072
 
  • C.G. Gohil, M.C.L. Buzio, E. Marín, D. Schulte
    CERN, Geneva, Switzerland
  • P. Burrows
    JAI, Oxford, United Kingdom
 
  Previous studies of the 3 TeV Compact Linear Collider (CLIC) design have shown a sensitivity to external dynamic magnetic fields (stray fields) on the nanoTesla level. In this paper the obtained tolerances for stray fields in the 380 GeV CLIC design are presented. In order to determine potential stray field sources, a measurement sensor has been acquired and used to investigate the magnetic contamination from technical equipment. The collected measurements, as well as details of the sensor, are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF047  
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THPAF053 Lower-Harmonic RF System in the CERN SPS impedance, simulation, cavity, proton 3087
 
  • J. Repond, H. Damerau, A. Lasheen, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
 
  Significant beam losses increasing with intensity are observed at capture and along the SPS flat bottom for the LHC-type proton beam. The intensity should be doubled for HL-LHC and high losses may be a major performance limitation. Bunches extracted from the PS, the SPS injector, are produced in a 40 MHz RF system applying a bunch rotation at the end of the cycle and therefore cannot be perfectly matched to the 200 MHz SPS RF bucket. The possibility of using a lower harmonic additional RF capture system in the SPS was already proposed after the LEP era in preparation for transfer of the LHC beam but the bunch rotation was the preferred solution, since the induced voltage in the SPS 200 MHz RF system would be too large to ensure stability in a low harmonic system without mitigation measures. However, the use of the upgraded one-turn feedback and the 200 MHz RF system as a Landau cavity could help to improve stability. The feasibility of this scenario to reduce capture losses in the SPS is analysed and presented in this paper. The choice of an optimum RF frequency and voltage is also discussed. The transfer to the main 200 MHz is simulated using a realistic bunch distribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF053  
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THPAF054 Characterization of Losses and Emittance Growth for Ion Beams on the SPS Injection Plateau resonance, space-charge, injection, scattering 3091
 
  • Á. Saá Hernández, F. Antoniou, H. Bartosik, A. Huschauer
    CERN, Geneva, Switzerland
 
  Losses and transverse emittance growth in the Super Protron Synchrotron (SPS) impose presently the main performance limitation on the Large Hadron Collider (LHC) ion injector chain. In this paper we present the measurements performed in 2016 with Pb82+ ions and the analysis to characterize the observations of beam degradation during the long injection plateau. Residual gas scattering, intrabeam scattering (IBS) and resonance excitation have been studied.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF054  
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THPAF055 Space Charge Studies on LEIR resonance, space-charge, simulation, lattice 3095
 
  • Á. Saá Hernández, H. Bartosik, N. Biancacci, S. Hirlaender, A. Huschauer, D. Moreno Garcia
    CERN, Geneva, Switzerland
 
  The performance of the CERN Low Energy Ion Ring with electron cooled ion beams is presently limited by losses occurring once the beam has been captured in the RF buckets. An intense machine study program was started by the end of 2015 to mitigate the losses and improve the performance of the accelerator. The measurements pointed to the interplay of direct space charge forces and excited betatron resonances as the most plausible driving mechanism of these losses. In this paper, we present the systematic space-charge measurements performed in 2017 and compare them to space-charge tracking simulations based on an adaptive frozen potential.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF055  
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THPAF071 McMillan Lens in a System with Space Charge simulation, resonance, quadrupole, lattice 3143
 
  • I. Lobach
    University of Chicago, Chicago, Illinois, USA
  • S. Nagaitsev, E.G. Stern, T. Zolkin
    Fermilab, Batavia, Illinois, USA
 
  Space charge (SC) in a circulating beam in a ring produces both betatron tune shift and betatron tune spread. These effects make some particles move on to a machine resonance and become unstable. Linear elements of beam optics cannot reduce the tune spread induced by SC because of its intrinsic nonlinear nature. We investigate the possibility to mitigate it by a thin McMillan lens providing a nonlinear axially symmetric kick, which is qualitatively opposite to the accumulated kick by SC. Experimentally, the proposed concept can be tested in Fermilab's IOTA ring. A thin McMillan lens can be implemented by a short (70 cm) insertion of an electron beam with specifically chosen density distribution in transverse directions. In this article, to see if McMillan lenses reduce the tune spread induced by SC, we make several simulations with particle tracking code Synergia. We choose such beam and lattice parameters that tune spread is roughly 0.5 and a beam instability due to the half-integer resonance 0.5 is observed. Then, we try to reduce emittance growth by shifting betatron tunes by adjusting quadrupoles and reducing the tune spread by McMillan lenses.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF071  
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THPAF075 Numerical Simulations of Space Charge Compensation with an Electron Lens space-charge, electron, lattice, simulation 3154
 
  • E.G. Stern, Y.I. Alexahin, J.F. Amundson, A.V. Burov, A. Macridin, V.D. Shiltsev
    Fermilab, Batavia, Illinois, USA
 
  The future high energy physics program at Fermilab requires that the proton complex operate with beam bunch intensities four times larger than is currently handled. At these intensities space charge nonlinear defocussing effects cause unacceptable particle losses especially in the low energy rapid-cycling-synchrotron (RCS) Booster. Focusing electron lens elements may offer a solution by providing partial space charge compensation but there is a need for detailed simulations as this technique has not been demonstrated. We report on high fidelity numerical 6D space charge simulations in a model accelerator lattice with a record high space charge tune shift approaching unity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF075  
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THPAF078 Expected Performance of the Stochastic Cooling and RF System in the Collector Ring bunching, proton, antiproton, simulation 3165
 
  • O.E. Gorda, C. Dimopoulou, A. Dolinskyy
    GSI, Darmstadt, Germany
  • T. Katayama
    Nihon University, Narashino, Chiba, Japan
 
  The Collector Ring is designed for stochastic cooling of antiprotons or radioactive ions at FAIR. Simulations of the cooling process in combination with the required RF beam manipulations have been done taking into account the improved and recently fixed ion-optics. The measured RF properties of the first of series debuncher system have been considered to evaluate the performance of the bunch rotation, de-bunching and re-bunching process within the planned CR operation cycle. The expected beam parameters and matching at extraction to the HESR storage ring are discussed in this paper. The latest hardware developments of the stochastic cooling system components are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF078  
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THPAF082 Frequency Jump at Low Energies rfq, linac, bunching, simulation 3176
 
  • C. Zhang
    GSI, Darmstadt, Germany
  • H. Podlech
    IAP, Frankfurt am Main, Germany
 
  One or more radio-frequency jumps are usually necessary for realizing a ≥100 AMeV/u proton or ion driver linac. Typically, such jumps happen in the range of β = 0.2-0.6 between the resonator structures fitting to this β-range, e.g. DTL, HWR, CCL or elliptical cavities. We propose to perform the first frequency jump already at low energies (β ≤ 0.1) between two RFQ accelerators, which can bring some unique advantages. First studies have been performed and the results proved that this idea is feasible and promising. Many efforts have been and are being made to address the most critical issue for the jumps i.e. the beam matching at the transition.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF082  
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THPAF087 Multi-Objective Optimization of an SRF Photoinjector with Booster Section for High Brightness Beam Performance booster, cavity, brightness, gun 3193
 
  • E. Panofski, A. Jankowiak, T. Kamps, A. Neumann
    HZB, Berlin, Germany
 
  Several future accelerator projects, light sources and user experiments require high brightness electron beams. SRF photoinjectors operating in continuous-wave (cw) mode hold the potential to serve as an electron source generating beams of high average brightness and short bunch lengths. Different operation and design parameters of the SRF photoinjector impact the beam dynamics and thus the beam brightness. A universal multi-objective optimization program based on a genetic algorithm was developed to extract optimum gun parameter settings from Pareto-optimum solutions. After getting the first optimum results, the photoinjector is supplemented with a booster section downstream. The new optimization results are presented. Further, the optimization program is applied to evaluate the impact of the field flatness of the gun cavity on the high brightness performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF087  
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THPAK006 Design Status of the Beam Switchyard for ESSnuSB proton, target, linac, quadrupole 3215
 
  • E. Bouquerel
    IPHC, Strasbourg Cedex 2, France
 
  Funding: This project is now supported by the COST Action CA15139/EuroNuNet and EU/H2020 innovation programme ESSnuSB under grant agreement No 777419.
The ESSnuSB project, recently granted by the EU H2020 framework programme for a 4-year design study, proposes to use the proton linac (2 GeV, 5 MW) of the European Spallation Source (ESS) currently in construction in Lund (Sweden) to deliver a neutrino super beam. One of the work packages of this design study is dedicated to the primary proton beam-line completing the linac. It will mainly consist of an accumulator ring to compress the 2.86 ms long beam pulse to 1.32 µs and of a switchyard to distribute the protons onto a 4-target station. Dipoles, steerers, quadrupoles, collimators and several diagnostics will compose the switchyard to ensure the protons to hit the target with desired characteristics. This paper presents the objectives of this work package and the design status of this switchyard system.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK006  
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THPAK007 Beam Extraction from TR24 Cyclotron at IPHC extraction, cyclotron, betatron, closed-orbit 3218
 
  • N.Yu. Kazarinov, I.A. Ivanenko
    JINR, Dubna, Moscow Region, Russia
  • F.R. Osswald
    IPHC, Strasbourg Cedex 2, France
 
  The CYRCé cyclotron is used at IPHC (Institut Pluridisciplinaire Hubert Curien) for the production of radio-isotopes for diagnostics, medical treatments and fundamental research in radiobiology. The TR24 cyclotron manufactured and commercialized by ACSI delivers a 16-25 MeV proton beam with intensity from few nA up to 500 microA. The TR24 is a separated-sector isochronous cyclotron with normal-conducting magnet and stripper foil. It is a challenge to fit the high intensity proton beam used for target irradiation to radiobiology and analytical applications due to requirements on beam quality and energy resolution. Field distribution in the region of the extraction performed with OPERA 3D as well as beam dynamics related with stripping are analysed. 3D calculation model and hypothesis about geometry and beam are described. Our goal is to evaluate the extraction efficiency and the beam characteristics in the focusing plane outside the cyclotron which will serve as inputs for the design of future beam lines and enable beam matching conditions. Therefore, different issues are discussed: energy dispersion, transverse dynamics and orbit separation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK007  
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THPAK009 Benchmark Analyses of Electrostatic Devices for SPIRAL2-DESIR Beam Lines quadrupole, simulation, optics, electrostatic-devices 3225
 
  • L. Perrot, M. Kemel, S. Rousselot
    IPN, Orsay, France
 
  Funding: French ANR, Investissements d'Avenir, EQUIPEX. Contract number ANR-11-EQPX-0012.
The new ISOL facility SPIRAL2 is currently being built at GANIL, Caen France. The commissioning of the accelerator is in progress since 2015. SPIRAL2 will produce a large number of new radioactive ion beams (RIB) at high intensities. In 2023, the DESIR facility will receive beams from the upgraded SPIRAL1 facility of GANIL (stable beam and target fragmentation), from the S3 Low Energy Branch (fusion-evaporation and deep-inelastic reactions). In order to deliver the RIB to the experimental set-ups installed in the DESIR hall, 140 meters of beam line are studied since 2014. The transfert lines are today fully design and building will start in 2018. Electrostatic devices (quadrupoles, steerers and deflectors) have been intensively study using various tools. This paper will focus on the detail results of a benchmark using OPERA3D and Comsol Multiphysics apply to the DESIR quadrupole conception.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK009  
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THPAK019 Beam Dynamics of the First Beams for IFMIF-EVEDA RFQ Commissioning rfq, proton, extraction, solenoid 3246
 
  • L. Bellan, C. Baltador, M. Comunian, E. Fagotti, F. Grespan, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • T. Akagi
    KEK, Ibaraki, Japan
  • B. Bolzon, N. Chauvin
    CEA/DSM/IRFU, France
  • H. Dzitko
    F4E, Germany
  • K. Kondo, M. Sugimoto
    QST, Aomori, Japan
  • I. Podadera
    CIEMAT, Madrid, Spain
  • F. Scantamburlo
    IFMIF/EVEDA, Rokkasho, Japan
 
  The installation of the IFMIF-EVEDA RFQ, MEBT, LEBT, source and beam dump was completed in September 2017. The beam dynamics of the first beams for the IFMIF-EVEDA RFQ commissioning is presented. Moreover, a proposal for the CW RFQ steady state commissioning is shown, with a focus on the beam dynamics challenges of the beam transport after the RFQ.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK019  
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THPAK021 Design of High Resolution Mass Spectrometer for SPES dipole, HOM, simulation, high-voltage 3252
 
  • M. Comunian, C. Baltador, L. Bellan, M. Cavenago, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • E. Khabibullina
    ITEP, Moscow, Russia
  • E. Khabibullina
    MEPhI, Moscow, Russia
 
  Within the framework of the SPES (Selective Production of Exotic Species) project at National Institute of Nuclear Physics (INFN laboratory, Legnaro, Italy) the High Resolution Mass Spectrometer (HRMS) will be build. HRMS needs to provide full separation of the ions with mass resolution 1/20000 for the following breeding and acceleration on ALPI Linac. In this article the main design choice of the HRMS and of the transport channel will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK021  
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THPAK024 A new method to measure the Beta function in a Paul trap dipole, experiment, lattice, 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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THPAK040 Bunched Beam Envelope Instability in a Periodic Focusing Channel focusing, simulation, lattice, solenoid 3301
 
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  The space-charge driven envelope instability presents a great danger in high intensity accelerator design. In this paper, we report on the study of bunched beam envelope instability in a periodic focusing channel using three-dimensional envelope model for a 3D uniform Waterbag distribution and a 3D Gaussian distribution. Our results show that the envelope instability stopband becomes broader with the increase of longitudinal focusing and are not sensitive to the type of distribution. Self-consistent macroparticle simulations using both distributions show similar structure in emittance growth but also extra instability stopbands. The emittance growth from the Waterbag distribution has larger stopband than that from the Gaussian distribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK040  
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THPAK042 On Long-Term Space-Charge Tracking Simulation space-charge, simulation, lattice, optics 3305
 
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  The nonlinear space-charge effects in high intensity accelerator can degrade beam quality and cause particle losses. Self-consistent macroparticle tracking simulations have been widely used to study these space-charge effects. However, it is computationally challenging for long-term tracking simulation of these effects. In this paper, we study a fully symplectic self-consistent particle-in-cell model and numerical methods to mitigate numerical emittance growth. We also discuss about a fast alternative frozen space-charge model that has a potential to improve computational speed significantly.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK042  
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THPAK044 Self-Consistent Modeling using a Lienard-Wiechert Particle-Mesh Method space-charge, simulation, radiation, synchrotron 3313
 
  • R.D. Ryne, C.E. Mitchell, J. Qiang
    LBNL, Berkeley, California, USA
  • B.E. Carlsten
    LANL, Los Alamos, New Mexico, USA
 
  In this paper we describe a parallel, large-scale simulation capability using a Lienard-Wiechert Particle-Mesh (LWPM) method. The approach is a natural extension of the convolution-based technique to solve the Poisson equation in space-charge codes. It provides a unified method to compute both Coulomb-like self-fields and radiative phenomena like coherent synchrotron radiation (CSR). The approach brings together several mathematical and computational capabilities including the use of integrated Green function (IGF) methods and adaptive quadrature methods. We will describe the theoretical model and our progress to date.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK044  
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THPAK047 Comparison of Profile Measurements and TRANSPORT Beam Envelope Predictions Along the 80-m LANSCE pRad Beamline linac, proton, diagnostics, simulation 3323
 
  • P.K. Roy, C. Pillai, C.E. Taylor
    LANL, Los Alamos, New Mexico, USA
 
  Funding: *Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
The Proton Radiography (pRad) experimental facility beam transport line is over 80 meters in length starting from the end of the LANSCE linear accelerator. The 800-MeV beam is transported through a beam line containing many bending and focusing elements before it reaches the pRad beam optics system where the beam spot size requirement is nominally 2 mm (RMS). Here we discuss the efforts to reconcile the beam transport inconsistencies (sizes) seen between comparisons of the beam sizes obtained using the LANL version of the beam envelope code TRANSPORT with those measured along the beam line. The transverse input beam parameters for the code were extracted from a fit to several wire-scanner measurements located in the downstream portion of the LINAC. The longitudinal input beam parameters were extrapolated from lower-energy information. Recently, new measurements were made of the beam line element locations and compared with legacy drawings. Beam envelope measurements made at various locations throughout the beam line using wire scanners and gated imaging systems were compared to the calculated results. The predicted beam envelopes and measured data agree within expected errors.
*Los Alamos National Laboratory (LA-UR-17-30876)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK047  
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THPAK054 Optics Calibration and Measurement for Low Alpha Lattices in TPS Storage Ring lattice, optics, coupling, operation 3343
 
  • F.H. Tseng, C.H. Chen, J.Y. Chen, P.C. Chiu, C.H. Huang, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, H.-J. Tsai
    NSRRC, Hsinchu, Taiwan
 
  In order to provide short-pulse radiation for pump-probe experiments and coherent radiation for THz/IR measurements, we develop low alpha lattices to reduce the momentum compaction factor from nominal operation values 2.4*10-4 to 2.6*10-5 or lower. The corresponding bunch length at 2.8 MV RF voltage and zero current are from 10.78 ps to 3.55 ps or less. In the low alpha operations, the bunch lengthening as a function of bunch current, the orbit drift and noise enhancements as well as rf stability effect are observed. In this report we will present our studies on the lattice design, optics correction, beam parameters measurements and alpha measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK054  
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THPAK061 Magnetized and Flat Beam Generation at the Fermilab's FAST Facility quadrupole, cathode, simulation, solenoid 3364
 
  • 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.
Canonical angular momentum (CAM) dominated beams can be formed in photoinjectors by applying an axial magnetic field on the photocathode surface. Such a beam possess asymmetric eigenemittances and is characterized by the measure of its magnetization. CAM removal using a set skew-quadrupole magnets maps the beam eigenemittances to the conventional emittance along each transverse degree of freedom thereby yielding flat beam with asymmetric transverse emittance. In this paper we report on the experimental generation of CAM dominated beam and their subsequent transformation into flat beams at the Fermilab Accelerator Science and Technology (FAST) facility. Our results are compared with numerical simulations and possible applications of the produced beams are discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK061  
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THPAK062 Bunch Compression of Flat Beams simulation, experiment, 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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THPAK072 Generation of Flat Ultra-Low Emittance Beams quadrupole, cathode, simulation, permanent-magnet 3398
 
  • N.R. Bell
    UCLA, Los Angeles, USA
  • L. Phillips
    PBPL, Los Angeles, USA
 
  By placing a cathode in a longitudinal magnetic field generated by a solenoid or permanent magnet, angular-momentum dominated electron beams can be produced. Such beams can be uncoupled using a skew-quadrupole channel to remove the angular momentum and yield flat beams with an ultralow emittance in one of the transverse dimensions. Flat beams have immediate relevance in our pursuit of ultrahigh brightness in two dimensions for dielectric laser accelerator (DLA) or slab beam applications. We are currently investigating the possibility of implementing flat beam generation at the UCLA Pegasus beamline. We utilize particle tracking simulations to optimize the transverse emittance ratio and normalized transverse emittance. Our simulations show emittance ratios of more than 100 and normalized emittances in the <5 nm range in the vertical dimension, matching analytic estimates. In addition to simulation results, experimental plans to implement and test the flat beam transform (FBT) are also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK072  
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THPAK078 GPT-CSR: a New Simulation Code for CSR Effects radiation, simulation, electromagnetic-fields, linac 3414
 
  • S.B. van der Geer, M.J. de Loos
    Pulsar Physics, Eindhoven, The Netherlands
  • A.D. Brynes, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • I.D. Setija, P.W. Smorenburg
    ASML Netherlands B.V., Veldhoven, The Netherlands
 
  For future applications of high-brightness electron beams, including the design of next generation FEL's, correct simulation of Coherent Synchrotron Radiation (CSR) is essential as it potentially degrades beam quality to unacceptable levels. However, the long interaction lengths compared to the bunch length, numerical cancellation, and difficult 3D retardation conditions make accurate simulation of CSR effects notoriously difficult. To ease the computational burden, CSR codes often make severe simplifications such as an ultra-relativistic bunch travelling on a prescribed reference trajectory. Here we report on a new CSR model implemented in the General Particle Tracer (GPT) code that avoids most of the usual assumptions: It directly evaluates the Liénard'Wiechert potentials based on the stored history of the beam. It makes no assumptions about reference trajectories, and also takes into account the transverse size of the beam. Example results demonstrating normalised emittance growth in the first bunch compressor of FERMI@Elettra are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK078  
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THPAK082 Simulation of Perturbative Effects in IOTA simulation, lattice, optics, octupole 3422
 
  • C.C. Hall, D.L. Bruhwiler, N.M. Cook, J.P. Edelen, S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
 
  The Integrable Optics Test Accelerator (IOTA) is being commissioned at Fermi National Laboratory for study of the concept of nonlinear integrable optics. The use of a special nonlinear magnetic element introduces large tune spread with amplitude while constraining the idealized dynamics by two integrals of motion. The nonlinear element should provide suppression of instabilities through nonlinear decoherence. We examine the case of a bunch injected off-axis and the resulting damping of centroid oscillations from decoherence. A simple model of the damping is described and compared to simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK082  
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THPAK108 Fourier Coefficients of Long-Range Beam-Beam Hamiltonian via Two-Dimensional Bessel functions resonance, lattice, optics, TRIUMF 3486
 
  • D. Kaltchev
    TRIUMF, Vancouver, Canada
 
  The two-dimensional coefficients (resonance basis) in the Fourier expansion of the long-range beam-beam Hamiltonian have been expressed through the (less familiar) generalized modified Bessel functions of two arguments. We describe an efficient method to compute these coefficients based on the above representation. The method has been applied to HL-LHC lattices and benchmarked against MadX simulations of detuning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK108  
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THPAK116 Modeling Surface Roughness Effects and Emission Properties of Bulk and Layered Metallic Photocathode simulation, electron, experiment, 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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THPAK117 Space Charge Limitations for Bunch Compression in Synchrotrons space-charge, resonance, simulation, synchrotron 3518
 
  • Y.S. Yuan, O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  • G. Franchetti, I. Hofmann
    GSI, Darmstadt, Germany
 
  Bunch compression achieved via a fast bunch rotation in longitudinal phase space is a well-accepted scheme to generate short, intense ion bunches for various applications. During bunch compression, coherent beam instabilities and incoherent single particle resonances can occur because of increasing space charge, resulting in an important limitation for the bunch intensity. We present an analysis of the relevant space charge driven beam instability and resonance phenomena during bunch compression. A coupled longitudinal-transverse envelope approach is compared with Particle-In-Cell (PIC) simulations. Two distinct cases of crossing are discussed and applied to the GSI SIS18 heavy-ion synchrotron. It is shown that during bunch compression, the 90° condition of phase advance is associated with a fourth order single particle resonance and the 120° condition with the recently discovered dispersion-induced instability. The agreement between the envelope and PIC results indicates that the stop band is defined by the 120° dispersion instability, which should be avoided during bunch compression.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK117  
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THPAK127 Toroidal Merger Simulations for the JLEIC Bunched Beam Electron Cooler Ring electron, solenoid, space-charge, simulation 3540
 
  • A.V. Sy
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The bunched beam electron cooler ring for the Jefferson Lab Electron-Ion Collider (JLEIC) requires a merger system to transport magnetized electron beams of two different energies to the same energy recovery linac (ERL) beamline. The system is especially challenging compared to existing mergers for ERL or hadron cooling applications (as at COSY) due to the small separation in energy between the two beams; for the JLEIC bunched beam cooler, the two beam energies may only differ by a factor of 4. An additional complication is the use of a magnetized beam. A toroidal merger system is studied using G4Beamline/GEANT4. Preservation of the quality of the low energy beam from the injector is especially vital for efficient cooling performance and compatibility with the ERL. Effects of the toroidal system on transverse and longitudinal emittances of the magnetized beams, as well as space charge effects, are presented and discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK127  
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THPAK131 Investigation of Two-Bunch Train Compression by Velocity Bunching bunching, electron, cavity, experiment 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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THPAK136 Wide-Ranging Genetic Research of Matching Line Design for Plasma Accelerated Beams with GIOTTO plasma, electron, target, FEL 3561
 
  • M. Rossetti Conti
    Universita' degli Studi di Milano & INFN, Milano, Italy
  • A. Bacci, A.R. Rossi
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • A. Giribono, C. Vaccarezza
    INFN/LNF, Frascati (Roma), Italy
 
  GIOTTO is a code based on a Genetic Algorithm, being used in the field of particles accelerators for some years*-***. Its main use concerns beam-dynamics optimizations for low energy linacs, or injectors, where the beam space-charge plays an important role on its dynamics. Typical optimizations regard the Velocity Bunching technique or, more generally, the emittance and energy spread minimization. Recent improvements in GIOTTO, here discussed, have added the important capability to solve problems with a wide research domain, making GIOTTO able to design a beam Transfer Line (TL) from scratch****. The code, taking as input the TL length and the optics elements, can define the correct lattice of the line that transports and matches the beam from the linac to the undulators of an FEL, finding the right gradients, positions and dimensions for the optics elements by exploring the parameters values in selected ranges. Further, the introduction of Twiss parameters into the fitness function makes GIOTTO a powerful tool in the design of highly different beam lines. Lastly, a new routine for the statistical analysis of parameters jitters effects on the beam is under development.
*Bacci et al, NIM-B, 263, 488 (2007)
**Bacci et al, presented at PAC'07, THPAN031
***Bacci et al, presented at IPAC'16, WEPOY039
****Rossetti Conti et al, NIM-A (2018, in press)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK136  
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THPAK147 Super-Period Multi-Bend Achromat Lattice with Interleaved Dispersion Bumps for the HALS Storage Ring lattice, storage-ring, sextupole, controls 3597
 
  • Z.H. Bai, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  We have proposed a multi-bend achromat (MBA) lattice concept, called the MBA with interleaved dispersion bumps, in which two pairs of interleaved dispersion bumps are created in each lattice cell. Due to that many nonlinear effects can be effectively cancelled out within one cell and also many knobs can be used for nonlinear optimization, this MBA concept has given both large dynamic aperture (DA) and large dynamic momentum aperture in the lattice design of the Hefei Advanced Light Source (HALS). In this paper, to further enlarge DA, we extend the concept to the case of a super-period lattice consisting of two cells. In the super-period lattice, there are 1.5 pairs of bumps in each cell. A super-period 7BA lattice is preliminarily designed for the HALS, and a larger DA is obtained.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK147  
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THPAK148 Preliminary Study of a Nine-Bend Achromat Lattice for a Diffraction-Limited Storage Ring lattice, storage-ring, sextupole, synchrotron 3600
 
  • P.H. Yang, Z.H. Bai, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  In recent years, multi-bend achromat (MBA) lattices have been widely used for the design of diffraction-limited storage rings (DLSRs) being developed around the world as the next-generation storage ring synchrotron sources. To better solve the problem of very serious non-linear dynamics in the DLSR lattice design, recently we proposed a new MBA lattice concept called the MBA lattice with interleaved dispersion bumps *, which was then applied to designing 7BA lattices for the Hefei Ad-vanced Light Source (HALS), with the result showing rather good nonlinear dynamics performance. In this paper, a 9BA lattice also following our MBA concept is preliminarily designed as a possible option for the HALS with a natural emittance of less than 30 pm·rad. Since generally the 9BA lattice can have a much lower emit-tance than the usually used 7BA lattice, the work in the paper will provide an inspiration for the existing third-generation synchrotron sources to upgrade to DLSRs with much lower emittances.
* Zhenghe Bai et al., MOPH13, Proc. SAP2017, Jishou, China, 2017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK148  
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THPAK154 Beam Parameter Optimization for UEM Facility with Photo-Emission S-band RF Gun electron, gun, space-charge, laser 3610
 
  • H.R. Lee, P. Buaphad, Y. Joo
    University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
  • S.C. Cha, Y. Kim
    KAERI, Daejon, Republic of Korea
  • B.L. Cho
    KRISS, Daejeon, Republic of Korea
  • H. Suk
    GIST, Gwangju, Republic of Korea
 
  Ultrafast Electron Microscopy (UEM) can provide snapshot images of a dynamic process in samples with an ultrafast time resolution, which is shorter than picosecond. The Future Accelerator R&D Team at KAERI has been preparing a UEM facility with a photo-emission S-band (= 2856 MHz) RF gun by collaborating with GIST and KRISS. To achieve a higher spatial resolution as well as a higher time resolution, the transverse beam emittance, beam divergence, and energy spread should be smaller, and the bunch length should be shorter. Beam dynamics simulations with ASTRA code is used to optimize those beam parameters in the RF gun. In this paper, we describe ASTRA optimizations of the S-band RF gun to achieve high spatial-temporal resolutions for the UEM facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK154  
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THPAL008 A RFQ Cooler Development rfq, ion-source, quadrupole, injection 3627
 
  • M. Cavenago, L. Bellan, M. Comunian, M. Maggiore, L. Pranovi
    INFN/LNL, Legnaro (PD), Italy
  • G. Maero, N. Panzeri, M. Romé
    Universita' degli Studi di Milano e INFN, Milano, Italy
 
  Funding: INFN group 5 (exp. PLASMA4BEAM)
The cooling of beams of exotic nuclei (both in energy spread and in transverse oscillations) is critical to downstream mass spectrometry devices and can be provided by collisions with light gases as in the Radio Frequency Quadrupole Cooler (RFQC). As in other traps, several electromagnetic systems can be used for beam deceleration confinement and deceleration, as a radiofrequency (rf) quadrupole, a magnetic solenoid and electrostatic acceleration. Since rf contributes both to beam cooling and heating, operational parameters should be carefully optimized. The LNL RFQC prototype is going to be placed inside the existing Eltrap solenoid, capable of providing a magnetic flux density component Bz up to 0.2 T, where z is the solenoid axis. Setup progress and related rf component development are reported; in particular simple matching boxes are discussed; the differential gas pumping system is also described.
 
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THPAL024 A Simple Variable Focus Lens for Field Emitter Cathodes cathode, focusing, laser, simulation 3677
 
  • R.L. Fleming, H.L. Andrews, K. Bishofberger, D. Kim, J.W. Lewellen, K.E. Nichols, D.Y. Shchegolkov, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Los Alamos National Laboratory LDRD Program
We present the design for a simple, variable-focus solenoidal lens with integrated emittance filtering. The design was developed as a first-iteration injection optics solution for transport of a beam from a field-emitter cathode into a dielectric laser accelerator structure. The design is easy to fabricate and, while based on permanent magnets, can readily be modified to allow for remote control of the focal length. The emittance is controlled via selection of collimating irises. The focal length can be changed by altering the spacing between two permanent ring magnets. Results from fabrication and initial testing will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL024  
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THPAL027 Transverse RF Deflecting Structures for the MAX IV LINAC GUI, linac, polarization, klystron 3684
 
  • D. Olsson, F. Curbis, E. Mansten, S. Thorin, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  The MAX IV LINAC operates both as a full-energy injector for two electron storage rings, and as a driver for a Short Pulse Facility (SPF). A soft X-ray Laser (SXL) beamline will also be installed in the end of the existing LINAC. For SPF and SXL operation, it is important to characterize beam parameters such as bunch profile, slice energy spread and slice emittance. For these measurements, two 3 m long transverse deflecting RF structures with a matching section are being developed. The structures are operating at S-band and have variable polarizations. When fed via a SLED pulse compressor, the two structures can generate a total integrated deflecting voltage higher than 100 MV which is sufficient for measurements with temporal resolutions down to 1 fs. This paper describes the initial RF design of the deflecting structures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL027  
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THPAL057 Development of the Aluminum Beam Duct for the Ultra-Low Emittance Light Source vacuum, experiment, storage-ring, impedance 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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THPAL071 Preliminary Emittance Measurement of Laser Driven Proton Beam Employing a Quadruple Triplet Magnet proton, laser, experiment, 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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THPAL116 Development and Installation of the CANREB RFQ Buncher at TRIUMF rfq, bunching, TRIUMF, operation 3914
 
  • B. Barquest, F. Ames, T. Au, L. Graham, M.R. Pearson, V. Zvyagintsev
    TRIUMF, Vancouver, Canada
  • J. Bale, J. Dilling, R. Kruecken, Y. Lan
    UBC & TRIUMF, Vancouver, British Columbia, Canada
  • G. Gwinner
    University of Manitoba, Manitoba, Canada
  • N. Janzen, R.A. Simpson
    UW/Physics, Waterloo, Ontario, Canada
  • R. Kanungo
    Saint Mary's University, Halifax, Canada
 
  Funding: TRIUMF receives federal funding via the National Research Council of Canada. CANREB is funded by the Canada Foundation for Innovation (CFI), the Provinces NS, MB and TRIUMF.
Pure, intense rare isotope beams at a wide range of energies are crucial to the nuclear science programs at TRIUMF. The CANREB project will deliver a high resolution spectrometer (HRS) for beam purification, and a charge breeding system consisting of a radiofrequency quadrupole (RFQ) beam cooler and buncher, an electron beam ion source (EBIS), and a Nier-type spectrometer to prepare the beam for post-acceleration. Bunching the beam prior to charge breeding will significantly enhance the efficiency of the EBIS. The RFQ buncher will accept continuous §I{60}{keV} rare isotope beams from the ARIEL or ISAC production targets and efficiently deliver low emittance bunched beams. A pulsed drift tube (PDT) will adjust the energy of the bunched beam for injection into the EBIS to match the acceptance of the post-accelerating RFQ. Ion optical simulations were carried out to inform the design of the RFQ buncher and PDT. Simulations indicate that delivery of up to 107~ions per bunch with high efficiency is possible. Experience with previous beam bunchers was also brought to bear in the design effort. Installation of the RFQ is under way, and tests with offline beam are expected to be performed in late 2018.
 
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THPMF001 Beam Dynamics Studies for Beam Focusing and Solenoid Alignment at SINBAD solenoid, alignment, linac, gun 4026
 
  • S. Yamin, R.W. Aßmann, B. Marchetti, J. Zhu
    DESY, Hamburg, Germany
 
  SINBAD (Short INnovative Bunches and Accelerators at DESY) facility under construction at DESY plans to host several experiments for the production of ultra-short bunches and will be a test facility for high-gradient compact novel acceleration techniques. The ARES (Accelerator Research Experiment at SINBAD) linac is foreseen to produce ultra-short bunches to be injected e.g. into Novel Dielectric Laser Acceleration structures or Laser Wake-Field Acceleration experiments. The work presented in this paper is based on optimization of the focusing system consisting of solenoids for the ARES, which have been studied earlier in detail but is revisited for updated beamline. Moreover tolerances for the possible misalignment of solenoids are presented investigating the effect on the beam properties during the gun commissioning.
* J. Zhu, R. Assmann, U. Dorda, B. Marchetti, "Matching sub-fs electron bunches for laser-driven plasma acceleration at SINBAD", Nucl. Instrum. Methods Phys. Res., Sect. A 829, 229 (2016)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF001  
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THPMF005 Evaluating the Impact of Diamond-II Possible Lattices on Beamlines lattice, photon, radiation, synchrotron 4033
 
  • M. Apollonio, L. Alianelli, F. Bakkali Taheri, R. Bartolini, A.J. Dent
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini, J. Li
    JAI, Oxford, United Kingdom
 
  At Diamond Light Source we are considering an upgrade of the machine aimed at significantly reduced emittance (la factor 20), that follows a worldwide trend in similar synchrotron radiation sources. An important aspect in the design of the upgrade is the optimization of the photon beam properties, such as flux, brilliance, spot size, divergence or coherence of the new sources and how these are translated into requirements on the electron beam and on the machine design. We present a study based on a combination of accelerator physics tracking codes (AT, elegant) and of radiation codes (SPECTRA, SRW, SHADOW), with the aim at bridging the gap between machine and beamlines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF005  
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THPMF008 Conceptual Design of an Accumulator Ring for the Diamond II Upgrade injection, storage-ring, lattice, dynamic-aperture 4046
 
  • I.P.S. Martin, R. Bartolini
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
 
  Diamond Light Source is in the process of reviewing several lattice options for a potential storage ring upgrade. As part of these studies, it has become clear that a substantial reduction in emittance can be achieved by adopting an on-axis injection scheme, thereby relaxing the constraints on the dynamic aperture. In order to achieve the necessary injected bunch properties for this to be viable, a new accumulator ring would be needed. In this paper we review the requirements placed on the accumulator ring design, describe the lattice development process and analyse the performance of the initial, conceptual design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF008  
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THPMF009 Lattice Options for DIAMOND-II lattice, injection, sextupole, linear-dynamics 4050
 
  • B. Singh, R. Bartolini, J. Bengtsson, H. Ghasem
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
  • A. Streun
    PSI, Villigen PSI, Switzerland
 
  Funding: Diamond Light Source Ltd
Generalized MBA (Multi-Bend-Achromat) Chasman-Green type lattices, with a low-dispersion mid-straight, have been studied and refined by pursuing a generalized Higher Order Achromat to control the non-linear dynamics to obtain a robust design. New candidate lattice have been produced aiming for a horizontal emittance of 150 pm×rad for off-axis injection and 75 pm×rad for on-axis, the latter making use of reverse bends. The results of these studies and evaluations have been summarized in this paper.
 
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THPMF010 Status of Elettra and Future Upgrades operation, dipole, lattice, status 4054
 
  • E. Karantzoulis, A. Carniel, R. De Monte, S. Krecic, C. P. Pasotti
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the possible future upgrades especially concerning the next ultra low emittance light source Elettra 2.0  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF010  
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THPMF017 Operation Improvements and Emittance Reduction of the ESRF Booster booster, operation, quadrupole, SRF 4077
 
  • N. Carmignani, N. Benoist, J-F. B. Bouteille, M.G. Di Vito, F. Ewald, L. Farvacque, A. Franchi, O. Goudard, J.M. Koch, S. Lagarde, S.M. Liuzzo, B. Ogier, T.P. Perron, P. Raimondi, D. Robinson, F. Taoutaou, E.T. Taurel, P.V. Verdier, R. Versteegen, P. Vidal, S.M. White
    ESRF, Grenoble, France
 
  The ESRF storage ring will be replaced by the Extremely Brilliant Source (EBS) in 2020 and the equilibrium emittance will decrease from the present 4 nmrad to 134 pmrad. The current injector system, composed by a linac and a synchrotron booster, will be used to inject into the new storage ring. To increase the injection efficiency in the new storage ring, three methods to reduce the horizontal emittance of the booster have been considered and tested. This paper presents the studies and achievements in terms of operation improvements and emittance reduction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF017  
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THPMF020 A 4th Generation Light Source for South-East Europe lattice, SRF, storage-ring, synchrotron 4084
 
  • H. Ghasem, R. Bartolini
    DLS, Oxfordshire, United Kingdom
  • D. Einfeld
    ESRF, Grenoble, France
 
  In Europe, most of the Synchrotron Light Sources are located in the middle, west and northern regions while the south-east is still lacking any major project. Hence a new initiative has been set up to propose the construction of a 4th Generation Light Source in that region. Design requirements limit the beam energy between 2.5 GeV to 3 GeV, the circumference is limited to 350 m, the emittance should be smaller than 250 pm rad and at least 14 to 16 straights have to be available for the users. Several mag-net configurations have been investigated and the results revealed that the HMBA lattice can fully meets the requirements and is therefore proposed for the Light Source in the SEE-region of Europe. These studies show that for a 4th Generation Light Source with energies up to 3 GeV a circumferences of 350 m will be adequate.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF020  
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THPMF025 Emittance Measurements at FAST Facility MMI, linac, electron, controls 4100
 
  • J. Ruan, D.R. Broemmelsiek, D.J. Crawford, A.L. Edelen, J.P. Edelen, D.R. Edstrom, A.H. Lumpkin, P. Piot, A.L. Romanov, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The FAST facility at Fermilab recently been commissioned has demonstrated the generation of electron beam within a wide range of parameter (energy, charge) suitable for accelerator-science and beam-physics experiments. This accelerator consists of a photo-electron gun, injector, ILC-type cryomodules, and multiple downstream beam-lines. It will mainly serve as injector for the upcoming Integrable Optical Test Accelerator (IOTA). At the same time we will also carry out a LINAC based intense gamma ray experiment based on the Inverse Compton scattering. It is essential to understand the beam emittance for both experiments. A number of techniques are used to characaterizing the beam emittance including slit based method and quad scan method. An on-line emittance measurement based on multi-slit method is developed so the emittance measured will be immediately available to support further beam optimization. In this report we will present the results from the emittance studies using this tool. We will also present the emittance measurement based on quads scan technique for the high energy beam line.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF025  
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THPMF035 Numerical Analysis of Excitation Property of Pulse Picking by Resonant Excitation at BESSY II betatron, synchrotron, kicker, radiation 4131
 
  • J.G. Hwang, M. Koopmans, R. Müller, M. Ries, A. Schälicke
    HZB, Berlin, Germany
 
  The pulse picking by resonant excitation (PPRE) method is applied at BESSY II to provide pseudo single bunch operation by separating the radiation from one horizontally enlarged bunch from the light of the multi-bunch filling. The bunch is enlarged by an excitation with an external signal close to the tune resonance. The variation of the beam size depends strongly on the frequency and amplitude of the excitation signal. In this paper we show the properties of the PPRE bunch studied by analytical modeling and numerical calculations using Elegant. The simulation results are compared with beam size measurements using a new interferometry beam size monitor at BESSY II.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF035  
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THPMF036 Status of the Conceptual Design of ALS-U lattice, vacuum, kicker, cavity 4134
 
  • C. Steier, A.P. Allézy, A. Anders, K.M. Baptiste, E.S. Buice, K. Chow, G.D. Cutler, S. De Santis, R.J. Donahue, D. Filippetto, J.P. Harkins, T. Hellert, M.J. Johnson, J.-Y. Jung, S.C. Leemann, D. Leitner, M. Leitner, T.H. Luo, H. Nishimura, T. Oliver, O. Omolayo, J.R. Osborn, G.C. Pappas, S. Persichelli, M. Placidi, G.J. Portmann, S. Reyes, D. Robin, F. Sannibale, C. Sun, C.A. Swenson, M. Venturini, S.P. Virostek, W.L. Waldron, E.J. Wallén
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The ALS-U conceptual design promises to deliver diffraction limited performance in the soft x-ray range by lowering the horizontal emittance to about 70 pm rad resulting in two orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a nine bend achromat lattice, with reverse bending magnets and on-axis swap-out injection utilizing an accumulator ring. This paper shows some aspects of the completed conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last years.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF036  
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THPMF041 Low Emittance Lattice for PF-AR optics, injection, cavity, operation 4148
 
  • N. Higashi, K. Harada, S. Nagahashi, N. Nakamura, T. Obina, R. Takai, H. Takaki
    KEK, Ibaraki, Japan
  • K. Hirano
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
 
  PF-AR is a synchrotron-type 6.5 GeV light source in KEK. The user-run was started in 1987, and the lattice is almost the same as the original one. Now we consider the emittance improvement to enlarge the horizontal tune advance in the normal cell. Thanks to this manipulation, the emittance will be improved to about a half of the current value.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF041  
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THPMF049 Photoinjector Optimization Studies at the AWA simulation, laser, experiment, 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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THPMF051 Research of a Locally-round Beam in HEPS Storage Ring Using Solenoids solenoid, storage-ring, dynamic-aperture, undulator 4175
 
  • C.C. Du, J.Q. Wang
    IHEP, Beijing, People's Republic of China
 
  "Round beam", that is, a beam with equivalent transverse emittance, is expected for a significant fraction of the beamline users in light sources. We investigate the possibility of reaching round beam in a storage ring, by means of a local exchange of the apparent horizontal and vertical emittance, performed with solenoids in a dedicated insertion line in the storage ring. In this paper, we show that a locally-round beam can be achieved by using solenoid in High Energy Photon Source (HEPS) storage ring, particularly to one of the design having natural emittance of 34.2 pm·rad.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF051  
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THPMF054 Beam Performance Simulation with Error Effects and Correction on HEPS Design multipole, optics, sextupole, alignment 4186
 
  • D. Ji, X. Cui, Z. Duan, Y. Jiao, Y. Wei, Y.L. Zhao
    IHEP, Beijing, People's Republic of China
 
  The High Energy Photon Source (HEPS) is a 6-GeV, ul-tralow-emittance kilometre-scale storage ring light source to be built in China. In this paper, the progress of the error and correction effect study on HEPS over the past one year will be presented, including error requirement and correction progress update. And beam performance eval-uation with static error and correction on orbit, optics, emittance and dynamic aperture will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF054  
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THPMF055 Ion Instability Simulation in the HEPS Storage Ring electron, simulation, storage-ring, lattice 4189
 
  • S.K. Tian, Y. Jiao, N. Wang
    IHEP, Beijing, People's Republic of China
  • K. Ohmi
    KEK, Ibaraki, Japan
 
  The High Energy Photon Source (HEPS), a kilometre scale storage ring light source, with a beam energy of 6 GeV and transverse emittances of a few tens of pm.rad, is to be built in Beijing and now is under design. We investigate the ion instability in the storage ring with high beam intensity and low-emittance. We performe a weak-strong simulation to show characteristic phenomena of the instability in the storage ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF055  
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THPMF059 Simulation Studies of Beam Commissioning and Expected Performance of the SPring-8-II Storage Ring quadrupole, lattice, simulation, sextupole 4203
 
  • Y. Shimosaki
    JASRI, Hyogo, Japan
  • K. Soutome, M. Takao
    JASRI/SPring-8, Hyogo-ken, Japan
  • H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
 
  In the SPring-8 upgrade project, the 5-bend achromat lattice is adopted for achieving a very low emittance of 157 pm.rad at 6 GeV. Since the dynamic aperture (DA) and the beam performance become sensitive against errors due to the strong quadrupoles and sextupoles, we carried out tracking simulations to evaluate the tolerance of machine imperfections such as the misalignment, magnetic field errors, the BPM offset, etc. It is found that the first-turn-steering (FTS) with the use of single-pass BPM's is indispensable because even under strict (but attainable) tolerances the beam cannot be stored without steering kicks. We then confirmed that after the FTS a sufficiently large DA can be obtained for accumulating the beam by the off-axis injection. By performing the orbit and optics corrections for the stored beam, we can finally achieve an emittance value of 160 ~ 180 pm.rad, being close to the design value. We also found that a naive application of the SVD algorithm to orbit corrections yields unwanted local bumps between BPM's and this deteriorates the vertical emittance. A possible scheme to avoid such local bumps by effectively interpolating the measured orbit will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF059  
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THPMF064 Beam Based Alignment of SRF Cavities in an Electron Injector Linac cavity, linac, alignment, electron 4219
 
  • F. Hug
    KPH, Mainz, Germany
  • M. Arnold, T. Bahlo, J. Pforr, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
 
  Funding: Funded by DFG through Cluster of Excellence EXC 1098/2014 "PRISMA" and RTG 2128 "AccelencE" and by the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871
Proper alignment of accelerating cavities is an important issue concerning beam quality of accelerators. In particular SRF cavities of injector linacs using high accelerating gradients on low beta electron beams can affect the beam quality significantly when not aligned perfectly. On the other hand knowing the exact position of every cavity after several cool-down cycles of a cryomodule can be difficult depending on the cryomodule design. We will report on operational experience on the SC injector of the Darmstadt superconducting linac and ERL (S-DALINAC) showing unexpected effects on beam dynamics and beam quality. Operators could observe transverse beam deflections by changing accelerating phases of the injector SRF-cavities while a growth of tranverse emittance occurred at the same time. As beam currents in the S-DALINAC injector do never exceed 100 µA and the effects could even be observed at nA beam currents space-charge effects could be eliminated to be the reason for these observations. In this work we will report on the possibility to align SRF cavities after cooldown by measuring the transverse deflection of the beam and compare results with beam dynamics simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF064  
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THPMF077 A Novel 7BA Lattice for a 196-m Circumference Diffraction-Limited Soft X-Ray Storage Ring lattice, focusing, optics, sextupole 4252
 
  • S.C. Leemann, W.E. Byrne, M. Venturini
    LBNL, Berkeley, California, USA
  • J. Bengtsson
    DLS, Oxfordshire, United Kingdom
  • A. Streun
    PSI, Villigen PSI, Switzerland
 
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231
The current baseline for the ALS Upgrade to a diffraction-limited soft x-ray storage ring is a 9BA lattice with two dispersion bumps for localized chromatic corrections. Although this lattice meets the very aggressive emittance goal, it offers limited margins in terms of dynamic aperture and momentum acceptance. In this paper we explore a different approach based on a 7BA lattice with distributed chromatic correction. This lattice relies heavily on longitudinal gradient bends and reverse bending in order to suppress the emittance so that despite fewer bends an emittance comparable to the baseline lattice can be reached albeit with larger dynamic aperture and momentum acceptance. We present linear optics design, trade-offs between achievable emittance and longitudinal stability, as well as the employed nonlinear tuning approach and the resulting performance of this alternate lattice.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF077  
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THPMF080 Physical and Chemical Roughness of Alkali-Animonide Cathodes cathode, electron, laser, vacuum 4259
 
  • S.S. Karkare, S. Emamian, G. Gevorkyan, H.A. Padmore, A.K. Schmid
    LBNL, Berkeley, California, USA
  • I.V. Bazarov
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • A. Galdi
    Cornell University, Ithaca, New York, USA
 
  Over the last decade, alkali-antimonides have been investigated as high QE cathodes in green light and more recently as ultra-low intrinsic emittance cathodes in near-threshold red wavelengths at cryogenic temperatures*. Nano-meter scale surface non-uniformities (physical roughness and chemical roughness or work function variations) are thought to limit the smallest possible emittance from these materials at the photoemission threshold under cryogenic conditions**. Despite this, the surfaces of alkali-antimonides have not been well characterized in terms of the surface non-uniformities. Here, we present measurements of both the physical and chemical roughness of alkali-antimonide surfaces using several surface characterization techniques like atomic force microscopy, kelvin probe force microscopy, low energy electron microscopy and near-threshold photoemission electron microscopy and show how such non-uniformities limit the intrinsic emittance.
*L. Cultrera et al Phys. Rev. ST Accel. Beams 18, 113401 (2015)
**J. Feng et al, J. of Appl. Phys. 121, 044904 (2017)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF080  
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THPMF081 Intrinsic Emittance of Single Crystal Cathodes photon, electron, cathode, acceleration 4263
 
  • S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
  • G. Adhikari, W.A. Schroeder
    UIC, Chicago, Illinois, USA
 
  The transverse momentum of electrons is conserved during photoemission from atomically ordered surfaces of single crystal materials. Photocathodes used in all photoinjectors today have disordered surfaces and do not exploit this phenomenon. Recently, using this conservation of transverse momentum, significant reduction in intrinsic emittance was demonstrated from the (111) surface of silver*. Here, we present measurements of transverse momentum distributions of electrons photoemitted from the ordered surfaces of Ag and Cu single crystals at several photon energies. These measurements will help in understanding the photoemission process and show how band-structure and the conservation of transverse momentum can be used to obtain further reduction in intrinsic emittance from photocathodes.
*Karkare et al., Phys. Rev. Lett. 118, 164802 (2017)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF081  
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THPMF083 Dynamic Simulation for Low Energy Compton Scattering Gamma-Ray Storage Ring laser, electron, scattering, storage-ring 4271
 
  • Z. Pan, J.M. Byrd, C. Sun
    LBNL, Berkeley, USA
  • H. Hao, Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
  • W.-H. Huang, C.-X. Tang
    TUB, Beijing, People's Republic of China
 
  We have designed a dedicated low-energy electron storage ring to generate gamma-rays based on Compton scattering technique. The natural emittance of the ring is 3.4 nm at 500 MeV beam energy and the ring circumference is about 59 m. The resulting maximum gamma-ray photon energy is about 4 MeV by interacting with ~1 um laser. Due to the large energy loss associated with the gamma-ray photon emission, the electron beam dynamics are greatly affected. We have simulated the whole physics process including Compton scattering, radiation damping and quantum excitation and find that the equilibrium energy spread may be increased by one orders of magnitude depending on the laser parameters. We have studied the dependence of the equilibrium state on the laser intensity and wavelength, and the electron parameters based on our candidate ring lattice.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF083  
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THPMF085 Beam Dynamics Simulation of the Solenoid Sextupole Error in the LCLS-II Injector sextupole, solenoid, simulation, electron 4277
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  • S.D. Anderson, D. Dowell, P. Emma, J.F. Schmerge, M.D. Woodley, F. Zhou
    SLAC, Menlo Park, California, USA
 
  The LCLS-II injector is a high brightness, high-repetition rate RF injector that consists of a 186 MHz VHF photo-electron gun, a focusing solenoid, a buncher cavity, another focusing solenoid, and a superconducting accelerating cryomodule to boost the electron beam energy to about final 100MeV. The solenoids provide transverse focusing and emittance compensation for the electron beam. However, in reality, the solenoid is not perfect due to manufacturing errors. Especially, the sextupole error in the solenoid field, which can cause significant beam emittance growth. In this paper, we report on the beam dynamics study of the effects of sextupole errors in the current LCLS-II injector.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF085  
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THPMK001 Creating Two-Pulse Beams from a Photoinjector for Two Color FEL or Beam Driven PWFA Experiments linac, gun, simulation, cathode 4294
 
  • J. Andersson, J. Björklund Svensson, M. Kotur, F. Lindau, S. Thorin
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  The MAX IV linac is investigated as a FEL driver in the SXL project, but there is also an ongoing investigation in using the linac as a driver for beam driven plasma wakefield acceleration experiments. From both these applications, double pulses from the photoinjector within the same RF period is desired. In this paper we discuss the possibilities of using the current photoinjector at MAX IV as driver and show simulations results from the pre-injector, both for FEL applications and for PWFA applications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK001  
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THPMK002 The Pre-Injector Design for the MAX IV SXL gun, cathode, linac, laser 4297
 
  • J. Andersson, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, D. Olsson, L.K. Roslund, S. Thorin
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  In this paper we present the current status of the design for the pre-injector (photo-cathode gun, solenoid and first linac) for the SXL project at MAX IV. The SXL project requires a higher repetition rate and since improved beam quality compared to what the current photo-cathode gun can operate at is needed, a new photo-cathode gun will be manufactured. We briefly describe the components of the pre-injector, followed by the design of the new photo-cathode gun. The design is similar to the old gun but with a new RF cavity using elliptical irises and racetrack profile main cell. The current parameters for the next gun to be manufactured are discussed, and some simulations and expected beam quality from the injector are shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK002  
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THPMK004 Pulse-Picking by Resonant Excitation (PPRE) for Timing Users at the MAX IV 3 GeV Storage Ring photon, simulation, storage-ring, cavity 4300
 
  • T. Olsson, Å. Andersson, D.K. Olsson
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  At synchrotron light storage rings there is demand for serving both high-brilliance and timing users simultaneously. At many rings this is commonly achieved by operating fill patterns with gaps of sufficient length, but this is not favorable for rings that operate with passive harmonic cavities to damp instabilities and increase Touschek lifetime by lengthening the bunches. For such rings, gaps in the fill pattern could severely reduce the achievable bunch lengths. For the MAX IV 3 GeV storage ring, sufficient bunch lengthening is also essential for conserving the ultralow emittance and reducing heat load on vacuum components at high current. It is therefore of interest to study methods to serve timing users while operating without gap in the fill pattern. Once such method is PPRE, where the transverse emittance of one bunch in the bunch train is increased by an incoherent betatron excitation. This paper presents simulations for the MAX IV 3 GeV storage ring and discusses the machine requirements as well as the achievable performance for timing users.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK004  
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THPMK013 A Wiggler Magnet Design for the TPS wiggler, photon, electron, undulator 4317
 
  • J.C. Jan, Y.L. Chu, C.-S. Hwang, F.H. Tseng
    NSRRC, Hsinchu, Taiwan
 
  The Taiwan Photon Source (TPS) at the National Synchrotron Radiation Research Center (NSRRC) is an advanced photon source facility operating at an electron energy of 3 GeV. Ten insertion devices (IDs) have been installed in phase-I during 2015. Recently, plans and designs for several phase-II IDs including In-vacuum Undulators (IU), Cryogenic Undulators (CU), Elliptical Polarization Undulators (EPU) and Wiggler magnets are pursued at NSRRC. These IDs are expected to be installed before 2020. In particular, a room temperature wiggler magnet with 100 mm period length (W100), will be designed and installed for phase-II. The field strength of the W100 is 1.8 T and the number of main periods is four. It is designed to generate 5-50 keV photons for the microscopy beam line. The magnetic design and photon characteristics of the W100 together with its effects on the stored beam will be discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK013  
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THPMK015 Low Momentum Compaction Lattice Operation of the Taiwan Photon Source lattice, storage-ring, operation, quadrupole 4325
 
  • C.-C. Kuo, C.H. Chen, J.Y. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.C. Liang, C.Y. Liao, Y.-C. Liu, Z.K. Liu, H.-J. Tsai, F.H. Tseng
    NSRRC, Hsinchu, Taiwan
 
  In order to provide short bunch length for picosecond time-resolved experiments and for coherent IR/THz radiation, low momentum compaction factor (alpha) lattices have been commissioned recently at the Taiwan Photon Source (TPS). The momentum compaction can be positive or negative and its value can be reduced by more than two orders of magnitude. In this paper, we discuss variable low alpha lattice optics, its beam dynamics issues, the measured momentum compaction and bunch lengths as well as beam orbit stability issues, etc.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK015  
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THPMK018 Design of a rotationally symmetric S-band photocathode RF gun gun, cathode, impedance, coupling 4336
 
  • Zh. X. Tang
    USTC, Hefei, Anhui, People's Republic of China
  • Z.G. He, W.W. Li, Y.J. Pei, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  The photocathode RF gun is one of the most critical components for high quality electron beam sources. The asymmetric multi-pole field contributes to the transverse emittance growth and degrades the beam quality. In order to overcome the problem, we propose a novel rotationally symmetric 1.6 cell RF gun to construct the symmetric field in this paper. The concrete proposal is that a coaxial cell with a symmetrical distribution of four grooves is concatenated to the first 0.6 cell at the photocathode end to form a new resonant cell (NRC) to mantain the symmetric multi-pole field in 1.6 cell. Our simulations indicate that 3D multi-pole fields of NRC are with the perfect symmetry. After that, the profile of the RF gun is optimized to improve the shunt impedance and mode separation and make the surface peak electric field at the photocathode end. Our simulations demonstrate promising outlook of using coaxial cell for photocathode RF guns with various applications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK018  
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THPMK029 Towards an Upgrade of the Swiss Light Source lattice, storage-ring, sextupole, injection 4358
 
  • A. Streun, M. Aiba, M. Böge, T. Garvey, V. Schlott
    PSI, Villigen PSI, Switzerland
 
  An upgrade of the Swiss Light Source (SLS) is planned for the period 2021-24. The existing 12-TBA (triple bend achromat) lattice will be exchanged by a 12-7BA (7-bend achromat) lattice in order to reduce the emittance from present 5.5 nm down to about 125 pm at 2.4 GeV / 400 mA (IBS included). The new lattice is based on longitudinal gradient bends and reverse bends to realize low emittance despite the small circumference of 290 m. A conceptual design has been established. We present project status, lattice design and work in progress with emphasis on beam dynamics issues.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK029  
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THPMK045 Generation of High Power, High Intensity, Ultra Short X-Ray FEL Pulses electron, laser, free-electron-laser, photon 4384
 
  • M.W. Guetg, Y. Ding, Z. Huang, A.A. Lutman
    SLAC, Menlo Park, California, USA
 
  X-ray Free Electron Lasers combine high pulse power, short pulse length, narrow bandwidth and a high degree of transverse coherence. Any increase in the photon pulse power, while shortening the pulse length, will further push the frontier on several key XFEL applications including single molecule imaging and novel nonlinear X-ray methods. We will present experimental results at the Linac Coherent Light Source raising its maximum power to more than 300% of the current limit, while reducing the photon pulse length to 10 fs. This was achieved by minimizing residual transverse-longitudinal centroid beam offsets and beam yaw, and by correcting the dispersion when operating over 6 kA peak current with a longitudinally shaped beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK045  
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THPMK055 Self Seeding Scheme for LCLS-II-HE electron, FEL, undulator, simulation 4414
 
  • C. Yang, Y. Feng, J. Krzywinski, T.O. Raubenheimer, C.-Y. Tsai, J. Wu, M. Yoon, G. Zhou
    SLAC, Menlo Park, California, USA
  • H.X. Deng, X.F. Wang
    SINAP, Shanghai, People's Republic of China
  • D.H. He
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • Y. Hong, B. Yang
    University of Texas at Arlington, Arlington, USA
  • M. Yoon
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • G. Zhou
    IHEP, Beijing, People's Republic of China
 
  Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
Self-seeding is a reliable approach to generate fully coherent FEL pulses. Hard X-ray self-seeding can be realized by using a single crystal in Bragg transmission geometry. However, for a high repetition rate machine, the heat load on the crystal may become an issue. In this paper, we will study the facility performance of LCLS-II-HE by numerical simulations, and discuss the heat load and optimal undulator baseline configuration of LCLS-II-HE self-seeding scheme, and study the emittance tolerance of the LCLS-II-HE.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK055  
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THPMK062 Transverse Energy Distribution Measurements for Polycrystalline and (100) Copper Photocathodes with Known Levels of Surface Roughness cathode, electron, experiment, 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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THPMK071 Lattice Design for a 1.2 GeV Storage Ring dipole, lattice, storage-ring, optics 4464
 
  • S.Q. Shen, S.Q. Tian, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
 
  It is a very effective way to bring down the emittance of storage ring by using the MBA lattice design. Based on this concept, some other solutions have been developed to reduce the emittance furthermore for recent years. In this paper, the lattice design for a 1.2 GeV storage ring will be presented. The solution of horizontal and longitudinal gradient bending magnets tried in this lattice is going to be discussed in detailed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK071  
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THPMK085 Development of a Pre-Injector Test Bench for Future SLRI Light Source electron, gun, cavity, cathode 4499
 
  • K. Kittimanapun, Ch. Dhammatong, N. Juntong, W. Phacheerak, M. Phanak
    SLRI, Nakhon Ratchasima, Thailand
 
  A pre-injector test bench at the Synchrotron Light Research Institute (SLRI) is under development as one of the preparations for the future SLRI light source and of choices for the possible upgrade of the current injector. The pre-injector test bench includes a pulsed thermionic gun, a fast pulse deflector, a buncher and a pre-buncher. The thermionic electron gun with a cathode made of a single crystal CeB6 is employed as an electron emitter providing small emittance and uniform electron density. The fast pulse deflector shorten the extracted electrons of a few microseconds to that of a few nanoseconds. The electron pulses are further bunched by both the 238 MHz pre-buncher and the 476 MHz buncher to allow the 1-MeV electron beam. The experimental setups for emittance and beam profile measurements are installed on a movable diagnostic stand which is, later on, replaced by the beam bunching devices. The designs of the test bench will be discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK085  
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THPMK088 Low Emittance Thermionic Electron Gun at SLRI electron, gun, cathode, high-voltage 4509
 
  • K. Kittimanapun, Ch. Dhammatong, N. Juntong, W. Phacheerak, M. Phanak
    SLRI, Nakhon Ratchasima, Thailand
 
  The Synchrotron Light Research Institute (SLRI) has developed a new thermionic electron gun producing low emittance electron beam for the future upgrade of the existing one. The thermionic cathode made of a CeB6 single crystal is selected due to its properties providing high electron beam current, uniform current density, and high resistance to contamination. In addition, the CeB6 cathode of 3 mm in diameter can produce up to a few Amperes of electron beam current. The electron gun is pulsed at 500 kV with a few microseconds wide to avoid high voltage breakdown as well as to reduce space charge effect resulting in the emittance growth of the extracted electron beam. The preliminary simulation and design of the electron gun together with the high voltage system are described in the paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK088  
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THPMK107 Design of a High Charge, Low Energy, Magnetized Electron Injector electron, solenoid, cavity, cathode 4564
 
  • F.E. Hannon
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Simulations of a magnetized injector for the bunched-beam electron cooler ring, as part of the Jefferson Lab Electron Ion Collider (JLEIC) are presented. A challenge of such an injector is in generating a magnetized, 3.2nC electron bunch at low energy and preserving the angular momentum so it can subsequently be merged into the cooler ring and transported to the cooling solenoid without degradation. The design of the proposed injector and the effect it has on the beam are discussed in detail.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK107  
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THPMK110 300 kV DC High Voltage Photogun with Inverted Insulator Geometry and CsK2sb Photocathode cathode, gun, high-voltage, laser 4571
 
  • Y.W. Wang, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.M. Grames, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, G.A. Krafft, M.A. Mamun, G.G. Palacios Serrano, M. Poelker, R. Suleiman, M.G. Tiefenback, S. Zhang
    JLab, Newport News, Virginia, USA
  • G.A. Krafft, S.A.K. Wijethunga
    ODU, Norfolk, Virginia, USA
 
  Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177
A compact DC high voltage photogun with inverted-insulator geometry was designed, built and operated reliably at 300 kV bias voltage using alkali-antimonide photocathodes. This presentation describes key electrostatic design features of the photogun with accompanying emittance measurements obtained across the entire photocathode surface that speak to field non-uniformity within the cathode/anode gap. A summary of initial photocathode lifetime measurements at beam currents up to 4.5 mA is also presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK110  
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THPMK116 NEA Surface Activation of GaAs Photocathode with CO2 cathode, experiment, electron, ECR 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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THPMK120 Hefei Advanced Light Source: A Future Soft X-Ray Diffraction-Limited Storage Ring at NSRL storage-ring, lattice, radiation, injection 4598
 
  • L. Wang, Z.H. Bai, N. Hu, H.T. Li, W. Li, G. Liu, Y. Lu, Q. Luo, D.R. Xu, W. Xu, P.H. Yang, Z.H. Yang, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  To meet the fast-growing demands for high-quality low-energy photon beams, a new synchrotron radiation light source conception was brought forward several years ago by National Synchrotron Radiation Laboratory, which was named Hefei Advanced Light Source (HALS). The dominant radiation of HALS will be located in the VUV and soft X-ray region, which will be complementary with that of SSRF and HEPS. Except for high brilliance, high transverse coherence will be another signature feature of HALS. To achieve these goals, a multi-bend achromat based diffraction-limited storage ring was adopted as the main body of HALS. The general description and preliminary design of HALS will be briefly presented in this paper. Under the support of the Chinese Academy of Sciences and local government, the preliminary research and development (R&D) for HALS is undergoing. Several key technologies will be developed in the R&D project, which will lay good foundation for the construction of HALS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK120  
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THPMK121 Design of the Second Version of the HALS Storage Ring Lattice lattice, storage-ring, dipole, linear-dynamics 4601
 
  • Z.H. Bai, W. Li, L. Wang, P.H. Yang, Z.H. Yang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  In this paper, a new multi-bend achromat (MBA) lat-tice concept that we recently proposed for diffraction-limited storage rings is described, where two pairs of interleaved dispersion bumps are created in each cell and also most of the nonlinear effects produced by the sextupoles located in these bumps can be cancelled out within one cell. Following this concept, two 7BA lattices have been designed for the Hefei Advanced Light Source storage ring as the second version lattic-es, one with uniform dipoles and the other with nonu-niform dipoles. The latter has a lower natural emit-tance of 23 pm·rad, in which longitudinal gradient bends and anti-bends are employed. The optimized nonlinear dynamics for these two lattices are rather good, and especially the dynamic momentum aperture can be larger than 8% without off-momentum tunes crossing non-structure half-integer resonance lines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK121  
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THPMK123 Initial Design on the High Quality Electron Beam for the Hefei Advanced Light Source electron, bunching, laser, solenoid 4605
 
  • R. Huang, Z.G. He, Q.K. Jia, Y. Lu, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Work is supported by China Postdoctoral Science Foundation (Grant No. 51627901) and Chinese Universities Scientific Fund (Contract WK2310000063)
The Hefei Advanced Light Source (HALS) was proposed as a future soft X-ray diffraction-limited storage ring with a Free Electron Laser (FEL) at National Synchrotron Radiation Laboratory (NSRL). We present a design for a high brightness electron source as an injector of a 2.4 GeV linac-based diffraction limited storage ring and a free electron laser. The electron beams with low emittance and high peak current will be generated from a photoinjector and designed to fulfill the requirement of the HALS. To compress the bunch length and enhance the pulse current, velocity bunching scenario by a deceleration injection phase is designed. Owing to a linear compression, the electron beam is expected to be extremely short with a further magnetic compression.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK123  
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THPMK144 Lattices for a 4th-Generation Synchrotron Light Source lattice, synchrotron, SRF, radiation 4639
 
  • G. K. Shamuilov
    Uppsala University, Uppsala, Sweden
 
  Inspired by the ESRF upgrade (Extremely Brilliant Source, EBS), I present some modern lattices for a medium-sized 4th-generation synchrotron radiation source. They incorporate new elements, such as anti-bend magnets. The composed lattices are optimized using a simple double-objective algorithm. Its goal is to minimize the natural emittance and absolute chromaticities simultaneously. Then, the lattices are analyzed and compared to a version of the ESRF-EBS lattice scaled down in size. The design is performed to meet the needs of the user community of the Siberian Synchrotron and Terahertz Radiation Centre under the umbrella of the Budker Institute of Nuclear Physics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK144  
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THPMK147 Measurement of Slice-Emittance of Electron Bunch Using RF Transverse Deflector injection, experiment, 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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THPML002 Emittance Preservation in Plasma-Based Accelerators with Ion Motion plasma, wakefield, background, ECR 4654
 
  • C. Benedetti, E. Esarey, W. Leemans, T.J. Mehrling, C.B. Schroeder
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. DOE under Contract No. DE-AC02-05CH11231.
In a plasma-accelerator-based linear collider, the density of matched, low-emittance, high-energy particle bunches required for collider applications can be orders of magnitude above the background ion density, leading to ion motion, perturbation of the focusing fields, and, hence, to beam emittance growth. By analyzing the response of the background ions to an ultrahigh density beam, analytical expressions, valid for non-relativistic ion motion, are obtained for the perturbed focusing wakefield. Initial beam distributions are derived that are equilibrium solutions, which require head-to-tail bunch shaping, enabling emittance preservation with ion motion.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML002  
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THPML007 An Investigation of Electron Beam Divergence from a Single DFEA Emitter Tip cathode, experiment, electron, laser 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, experiment 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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THPML025 Operation of an RF Modulated Thermionic Electron Source at TRIUMF electron, cathode, TRIUMF, operation 4705
 
  • F. Ames, K. Fong, B. Humphries, S.R. Koscielniak, A. Laxdal, Y. Ma, T. Planche, S. Saminathan, E. Thoeng
    TRIUMF, Vancouver, Canada
 
  ARIEL (Advanced Rare IsotopE Laboratory) at TRIUMF will use a high-power electron beam to produce radioactive ion beams via photo-fission. The system has been designed to provide up to 10 mA of electrons at 30 MeV. The electron source delivers electron bunches with charge up to 16 pC at a repetition frequency of 650 MHz at 300 keV. The main components of the source are a gridded dispenser cathode (CPI - Y845) in an SF6 filled vessel and an in-air HV power supply. The beam is bunched by applying DC and RF fields to the grid. A macro pulse structure can be applied by additional low frequency modulation of the RF signal. This allows adjusting the average beam current by changing the duty factor of the macro pulsing. Unique features of the gun are its cathode/anode geometry to reduce field emission, and transmission of RF modulation via a dielectric (ceramic) waveguide through the SF6. The source has been installed and fully commissioned to a beam power up to 1 KW and tests with accelerated beams have been performed. Measurements of the beam properties and results from the commissioning and operational experiences of the source will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML025  
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THPML034 Baseline Lattice for the Upgrade of SOLEIL lattice, photon, injection, storage-ring 4726
 
  • A. Loulergue, P. Alexandre, P. Brunelle, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka, K.T. Tavakoli, M.-A. Tordeux, A. Vivoli
    SOLEIL, Gif-sur-Yvette, France
  • L. Hoummi
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Previous MBA studies converged to a lattice composed of 7BA-6BA with a natural emittance value of 200- 250 pm.rad range. Due to the difficulties of non-linear optimization in targeting lower emittance values, a decision was made to symmetrize totally the ring with 20 identical cells having long free straight sections longer than 4 m. A 7BA solution elaborated by adopting the sextupole paring scheme with dispersion bumps originally developed at the ESRF-EBS, including reverse-bends, enabling an emittance of 72 pm.rad has been defined as the baseline lattice. The sufficient on-momentum dynamic aperture obtained allows to consider off-axis injection. The linear and nonlinear dynamic properties of the lattice along with the expected performance in terms of brilliance and transverse coherence are presented. In particular, the beta functions tuned down to 1 m in both transverse planes at the center of straight sections allow matching diffraction limited photons up to 3 keV.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML034  
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THPML041 FEBIAD Ion Source Development at TRIUMF-ISAC target, ISAC, ion-source, TRIUMF 4730
 
  • B.E. Schultz, F. Ames, O.K. Kester, P. Kunz, A. Mjøs, J.F. Sandor
    TRIUMF, Vancouver, Canada
 
  The ISOL facility TRIUMF-ISAC utilizes a number of different ion sources to produce radioactive ion beams. Most isotopes are ionized using surface or resonant laser ionization, but these techniques are prohibitively inefficient for species with high ionization energies, such as noble gases and molecules. For these cases, the Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source can be used. The FEBIAD uses a hot cathode to produce electrons, which are accelerated through a potential (< 200 V) into the anode volume. Isotopes entering the resulting plasma undergo impact ionization and are extracted. Efforts are under way to better understand the physics and operation of the FEBIAD, using both theory and experiment. Recent measurements and simulations on the ISAC FEBIAD will be reported here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML041  
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THPML053 Computational Screening for Low Emittance Photocathodes electron, cathode, database, vacuum 4755
 
  • J.T. Paul, R.G. Hennig
    University of Florida, Gainesville, Florida, USA
  • I.V. Bazarov, A. Galdi
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
 
  The majority of photocathode materials in use in accelerator applications have been discovered empirically through trial and error with little guidance from material science calculations. Alternatively, one can envision a process which is heavily guided by computational search using latest advances in density functional theory (DFT). In this work, the MaterialsProject database is searched for potential single crystal photocathodes that would be suitable for ultralow emittance beam production. The materials in the database are initially screened on the basis of experimental practicality. Following this, the expected emittance is calculated from the DFT computed band structures for the pre-screened materials using the conservation of energy and transverse momentum during photoemission. Based on such computational screening, we provide a list of potential low emittance photocathode materials which can be investigated experimentally as high brightness electron sources.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML053  
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THPML058 Recent Results from MICE on Multiple Coulomb Scattering and Energy Loss scattering, detector, acceleration, lepton 4766
 
  • P. Franchini
    University of Warwick, Coventry, United Kingdom
 
  Funding: STFC, DOE, NSF, INFN, and CHIPP
Multiple Coulomb scattering and energy loss are well known phenomena experienced by charged particles as they traverse a material. However, from recent measurements made by the MuScat collaboration, it is known that the available simulation codes (GEANT4, for example) overestimate the scattering of muons in low Z materials. This is of particular interest to the Muon Ionization Cooling Experiment* (MICE) collaboration which has the goal of measuring the reduction of the emittance of a muon beam induced by energy loss in low Z absorbers. MICE took data without magnetic field suitable for multiple scattering measurements in the autumn of 2015 with the absorber vessel filled with xenon and in the spring of 2016 using a lithium-hydride absorber. In the autumn of 2016 MICE took data with magnetic fields on and studied the energy loss of muons in a lithium-hydride absorber. These data are all compared with the Bethe-Bloch formula and with the predictions of various models, including the default GEANT4 model.
*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-THPML058  
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THPML079 Multipole Tuning Algorithm for the CANREB HRS at TRIUMF multipole, TRIUMF, dipole, quadrupole 4836
 
  • D. Sehayek, R.A. Baartman, C.B. Barquest, J.A. Maloney, M. Marchetto, T. Planche
    TRIUMF, Vancouver, Canada
 
  The TRIUMF CANadian Rare isotope facility with Electron Beam ion source (CANREB) High Resolution Separator (HRS) has been designed to separate rare isotopes with mass/charge differences of only one part in 20,000 for beams with transverse emittances of 3 μm. To reach this resolution, high-order aberrations must be corrected using a multipole corrector. From experience, tuning such a multipole is very challenging. The unique geometry of our multipole motivated a novel tuning method based on determining the desired pole voltages directly from measured emmitance. This novel tuning algorithm is presented alongside a web application which has been developed in anticipation of the commissioning of the HRS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML079  
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THPML080 Preliminary Results of a New High Brightness H Ion Source Developed at TRIUMF ion-source, extraction, TRIUMF, high-voltage 4839
 
  • K. Jayamanna, F. Ames, Y. Bylinskii, J.Y. Cheng, M. Lovera, M. Minato
    TRIUMF, Vancouver, Canada
 
  This paper describes the preliminary results of a high brightness ion source developed at TRIUMF, which is capable of producing a negative hydrogen ion beam (H) of up to 5 mA of direct current. A 1.7 mm.mrad and 5 mm.mrad emittance(rms) is achieved for 500 uA and for 1 mA H-, respectively. Characteristics as well as a brief description regarding extraction issues of the source to date are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML080  
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THPML088 Cavity Impedance Reduction Strategies During Multi Cavity Operation in the SIS100 High Intensity Hadron Synchrotron cavity, controls, resonance, acceleration 4863
 
  • D. Mihailescu Stoica, D. Domont-Yankulova
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  Funding: Supported by GSI Helmholtzzentrum für Schwerionenforschung GmbH
The planned SIS100 heavy ion synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung will possess twenty ferrite accelerating cavities in its final stage of extension. As at injection and at flat top during slow extraction of the planned acceleration cycles the RF voltage will be relatively low, not all cavities will be active in this part of operation. It is important to analyse the impact of the inactive cavities on the overall RF voltage and subsequently their implication on the longitudinal particle dynamics. Classical approaches for reducing the beam impedance consist of active detuning of the cavities to pre-described parking frequencies. The fact that two out of ten buckets have to stay empty in all SIS100 scenarios is of particular interest as additional frequency components appear in the excitatory beam current, which have to be considered when the cavity is detuned. Therefore multi-cavity particle tracking simulations, consisting of twenty cavities and their attached LLRF control systems, are carried out in order to analyse different possibilities to minimize the impact on the beam dynamics and emittance growth.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML088  
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THPML089 Tuning of 3-tap Bandpass Filter During Acceleration for Longitudinal Beam Stabilization at FAIR feedback, controls, operation, synchrotron 4866
 
  • B.R. Reichardt, D. Domont-Yankulova
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  During acceleration in the heavy-ion synchrotrons SIS18/SIS100 at GSI/FAIR longitudinal beam oscillations are expected to occur. To reduce longitudinal emittance blow-up, dedi- cated LLRF beam feedback systems are planned. To date, damping of longitudinal beam oscillations has been demon- strated in SIS18 machine experiments with a 3-tap filter controller (e.g. *), which is robust in regard to control pa- rameters and also to noise. On acceleration ramps the control parameters have to be adjusted to the varying synchrotron frequency. Previous results from beam experiments at GSI indicate that a proportional tuning rule for one parameter and an inversely proportional tuning rule for a second parameter is feasible, but the obtained damping rate may not be opti- mal for all synchrotron frequencies during the ramp. In this work, macro-particle simulations are performed to evaluate, whether it is sufficient to adjust the control parameters pro- portionally (inversely proportionally) to the change in the linear synchrotron frequency, or if it is necessary to take more pa- rameters, such as bunch-length and synchronous phase, into account to achieve stability and a considerable high damping rate for excited longitudinal dipole beam oscillations. This is done for single- and dual-harmonic acceleration ramps.
* H. Klingbeil et al., "A Digital Beam-Phase Control System for Heavy-Ion Synchrotrons", in IEEE Transactions on Nuclear Science, vol. 54, no. 6, pp. 2604-2610, Dec. 2007.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML089  
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THPML106 Electron Microscopy Inspired Setup for Single-Shot 4-D Trace Space Reconstruction of Bright Electron Beams electron, detector, focusing, experiment 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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THPML134 Design of the Magnets of the HALS Project quadrupole, sextupole, dipole, lattice 4998
 
  • Z.L. Ren, C. Chen, T.L. He, L. Wang, X.Q. Wang, H. Xu, B. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Work supported by the National Nature Science Foundation of China under Grant Nos.11375176 * hlxu@ustc.edu.cn ** zhbo@ustc.edu.cn
The Hefei Advanced Light Source (HALS) is a future soft X-ray diffraction-limited storage ring at NSRL, this project aims to improve the brilliance and coherence of the X-ray beams and to decrease the horizontal emittance. The lattice of the HALS ring relies on magnets with demanding specifications, including combined function dipole-quadrupoles (DQs) with high gradients, dipoles with longitudinal gradients (DLs), high gradient quadrupoles and strong sextupoles. The combined dipole-quadrupole design developed is between the offset quadrupole and septum quadrupole types. The longitudinal-gradient dipoles are permanent magnets. The quadrupoles and sextupoles rely on a more conventional design. All the magnets have been designed using POSSION, Radia, and OPERA-3D.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML134  
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FRXGBE3 First Demonstration of Ionization Cooling in MICE detector, electron, experiment, 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, experiment, acceleration 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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