Keyword: scattering
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MOZGBE3 Primary Study of High-Power Graphene Beam Window vacuum, Windows, proton, target 47
 
  • H. Wang, C. Meng, H. Qu, D.H. Zhu
    IHEP, Beijing, People's Republic of China
  • X. Sun, P.C. Wang
    DNSC, Dongguan, People's Republic of China
 
  Beam windows are usually used to isolate vacuum or other special environments, which is a key device for high-power accelerators. Graphene has extremely high thermal conductivity, high strength and high transparency to high energy ions. It is highly suitable for beam windows if the technology is allowable. This paper will discuss the primary tests of graphene films, including vacuum per-formance and thermal conductivity performance, as well as the simulated performance of an assumed graphene window.  
slides icon Slides MOZGBE3 [1.756 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE3  
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MOPMF061 Emittance Growth in Coast in the SPS at CERN emittance, cavity, 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF061  
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MOPMF085 Beam-gas Background Characterization in the FCC-ee IR simulation, background, vacuum, optics 322
 
  • M. Boscolo, O.R. Blanco-García
    INFN/LNF, Frascati (Roma), Italy
  • H. Burkhardt, R. Kersevan, M. Lueckhof
    CERN, Geneva, Switzerland
  • F. Collamati
    INFN-Roma1, Rome, Italy
 
  The MDISim toolkit is used to evaluate and characterize the beam-gas induced background in the FCC-ee Interaction Region. MDISim allows a full characterization of this beam background source with the locations where the beam-gas scattering occurs as well as the loss points, as a function of different vacuum conditions and composition, for the nominal optics and parameters. Detailed pressure distribution profiles have been obtained running coupled synchrotron radiation and molecular flow montecarlo codes, as an input to the GEANT4 calculations. The particles hitting the pipe in the IR can be tracked in the detectors with a full Geant-4 simulation. Semi-analytic estimates for the expected rates and lifetime are also performed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF085  
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MOPMF089 DAΦNE Luminosity Monitor luminosity, detector, experiment, injection 338
 
  • A. De Santis, C. Bisegni, O.R. Blanco-García, O. Coiro, A. Michelotti, C. Milardi, A. Stecchi
    INFN/LNF, Frascati (Roma), Italy
 
  This work presents a new method to measure the DAΦNE collider instantaneous luminosity. The method is based on the identification of Bhabha scattering events at low polar angle (∼10 degree) around the beam axis by using two small crystal calorimeters shared with the KLOE-2 experiment. A new experimental setup has been designed and realized in order to implement the fast luminosity monitor, also in view of the DAΦNE future physics runs. Besides total instantaneous luminosity the new diagnostic measures also Bunch-by-Bunch (BBB) luminosity. This peculiarity allows to investigate the beam-beam interaction for the Crab- Waist collisions at DAΦNE and luminosity dependence on the bunch train structure.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF089  
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MOPML020 Numerical Simulations to Evaluate and Compare the Performances of Existing and Novel Degrader Materials for Proton Therapy simulation, emittance, 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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MOPML023 Very-High Energy Electron (VHEE) Studies at CERN's CLEAR User Facility experiment, simulation, electron, proton 445
 
  • A. Lagzda, R.M. Jones
    UMAN, Manchester, United Kingdom
  • A. Aitkenhead, K. Kirkby, R. MacKay, M. Van Herk
    The Christie NHS Foundation Trust, Manchester, United Kingdom
  • R. Corsini, W. Farabolini
    CERN, Geneva, Switzerland
 
  Funding: Science and Technology Facilities Council (STFC) - United Kingdom
Here we investigate how inserts of various densities (0.001-2.2 g/cm3) affect the dose distribution properties of VHEE beams at ~150 MeV. A range variation comparison was also made with clinical proton beams using TOPAS/GEANT4 Monte Carlo simulations. In addition, we assess the viability of scattering foils for optimizing the size of VHEE beams for radiotherapy purposes. The experiments were conducted at CERN's CLEAR user facility.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML023  
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MOPML047 Diversified Application of ILC photon, neutron, FEL, electron 502
 
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • T. Hayakawa
    QST, Tokai, Japan
  • N. Kawamura, S. Makimura, K. Mishima, D. Nomura, K. Shimomura, S. Yamamoto, T. Yamazaki
    KEK, Ibaraki, Japan
 
  ILC will be a very powerful accelerator complex. It has not only the high power energetic electron beam but also positron and photon beams. In addition to these beams, large cryogenic plants are equipped together with various utility facilities. Some suggestions on the assumption of availability of ILC are offered from various fields. These discussions will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML047  
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MOPML049 Generation of 1-MeV Quasi-Monochromatic Gamma-Rays for Precise Measurement of Delbrück Scattering by Laser Compton Scattering laser, electron, experiment, photon 508
 
  • H. Zen, T. Kii, H. Ohgaki
    Kyoto University, Kyoto, Japan
  • M. Fujimoto, M. Katoh, E. Salehi
    UVSOR, Okazaki, Japan
  • T. Hayakawa, T. Shizuma
    QST, Tokai, Japan
  • M. Katoh
    Sokendai - Okazaki, Okazaki, Aichi, Japan
  • J. Koga
    National Institutes for Quantum and Radiological Science and Technology, Kyoto, Japan
  • E. Salehi
    AUT, Tehran, Iran
 
  Delbrück scattering is the elastic scattering of photons by the electromagnetic field of an atomic nucleus, as a consequence of vacuum polarization. The isolated measurement of Delbrück scattering has not been performed because of interference with other elastic scattering processes. It was recently discovered that, using linearly polarized photons, Delbrück scattering can be measured nearly independently of the other scattering processes*. In order to perform a proof of principle experiment, a quasi-monochromatic gamma-ray beam with a maximum photon energy of 1 MeV has been generated at the UVSOR facility by colliding a CO2 laser with a 750-MeV electron beam. A preliminary experiment has been performed with 0.5-W laser power and 1-mA electron beam current. As a result, the measured gamma-ray flux was evaluated as 0.0006 photon/eV/mA/W/s around the peak energy of 1 MeV. If we accept 20 percent energy spread, in case of a 100-W CO2 laser colliding with a 300 mA electron beam, approximately 4 x 106-photons/s gamma-rays could be obtained. This flux is sufficiently high for the proof of principle experiment.
*J.K. Koga and T. Hayakawa, Phys. Rev. Lett. 118, 204801 (2017).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML049  
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TUYGBD4 Beam Loss Background and Collimator Design in CEPC Double Ring detector, background, radiation, simulation 632
 
  • S. Bai, J. Gao, H. Geng, D. Wang, Y. Wang, C.H. Yu, Y. Zhang
    IHEP, Beijing, People's Republic of China
 
  The Circular Electron Positron Collider (CEPC) is a proposed Higgs factory with center of mass energy of 240 GeV to measure the properties of Higgs boson and test the standard model accurately. Beam loss background in detectors is an important topic at CEPC. Radiative Bhabha scattering and Beamstrahlung effects are dominant mechanism of the beam induced backgrounds at CEPC due to the beam lifetime. In this paper, we evaluated the beam loss background in simulation and designed a series of collimators to suppress the radiation level on the machine and the detector.  
slides icon Slides TUYGBD4 [0.796 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBD4  
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TUPAF047 Systematic Studies of Transverse Emittance Measurements Along the CERN PS Booster Cycle emittance, 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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TUPAF053 Optimization of Diffuser (Pre-Scatterer) Configurations for Slow Extraction Loss Reduction at Electrostatic Septa septum, extraction, simulation, proton 830
 
  • B. Goddard, B. Balhan, J.C.C.M. Borburgh, M.A. Fraser, L.O. Jorat, V. Kain, C. Lolliot, L.S. Stoel, P. Van Trappen, F.M. Velotti
    CERN, Geneva, Switzerland
  • D. Barna
    Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
  • V.P. Nagaslaev
    Fermilab, Batavia, Illinois, USA
 
  Uncontrolled beam loss at the electrostatic septum is a performance limit for several existing or planned high power hadron accelerators delivering slow-extracted spills to fixed targets. A passive diffuser, or pre-scatterer, in a suitable configuration has been shown to reduce such beamloss significantly, with the actual gain factor depending on the parameters and details of the extraction process and hardware. In this paper, the optimization of diffuser configurations is investigated for a range of beam energies and extraction conditions, and the sensitivity to the available parameters explored via simulation results. The advantages and limitations of the diffuser are discussed and conclusions drawn concerning the specific case studies of the 8 GeV Fermilab debuncher ring and 400 GeV CERN SPS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF053  
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TUPAL030 Improvement of RF Capture with Multi-Turn H Injection in KURRI FFAG Synchrotron injection, acceleration, proton, closed-orbit 1066
 
  • T. Uesugi, Y. Fuwa, Y. Ishi, Y. Kuriyama, Y. Mori, H. Okita
    Kyoto University, Research Reactor Institute, Osaka, Japan
 
  In the KURRI FFAG synchrotron, charge-exchanging multi-turn injection is adopted with a stripping foil located on the closed orbit of injection energy. No injection bump orbit system is used and the beam escapes from the foil according to the closed-orbit shift by acceleration. The particles hit the foil many times and the emittance grows up during the injection. In this paper, the capture efficiencies are studied with different rf process, including adiabatic capture.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL030  
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TUPAL049 SNS Proton Power Upgrade Status linac, proton, cavity, injection 1120
 
  • M.A. Plum, G. A. Bloom, M.S. Champion, J. Galambos, M.P. Howell, S.-H. Kim, J. Moss, B.W. Riemer, K.S. White
    ORNL, Oak Ridge, Tennessee, USA
  • R.B. Saethre, R. W. Steffey
    ORNL RAD, Oak Ridge, Tennessee, USA
 
  Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. This research was supported by the DOE Office of Science, Basic Energy Science, Scientific User Facilities.
The Spallation Neutron Source (SNS) Proton Power Upgrade (PPU) project aims to double the proton accelerator beam power from 1.4 to 2.8 MW. Over the past year PPU has completed the reviews necessary for Critical Decision-1 approval. The baseline design choices are being refined, and a cost-effective approach has been identified. The beam energy will be increased by 30% and the beam current capability improved by ~50%. The sub-system improvements and anticipated schedule will be discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL049  
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TUPAL072 Dispersive Electron Cooling for JLEIC electron, emittance, proton, 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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TUPMF005 Simulation of Inverse Compton Scattering and Its Implications on the Scattered Linewidth electron, simulation, emittance, laser 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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TUPMF065 The Role of Electron-Phonon Scattering in Transverse Momentum Conservation in PbTe(111) Photocathodes electron, experiment, photon, cathode 1414
 
  • J. K. Nangoi, T.A. Arias
    Cornell University, Ithaca, New York, USA
  • S.S. Karkare, H.A. Padmore
    LBNL, Berkeley, California, USA
  • W.A. Schroeder
    UIC, Chicago, Illinois, USA
 
  Funding: The U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
The state of the art in creating high quality electron beams for particle accelerator applications and next generation ultrafast electron diffraction and microscopy involves laser-generated photoemission. A high quality beam requires that electrons emerge from the surface with low mean transverse energy (MTE). Recent density-functional theory calculations by T. Li and W. A. S. [arXiv:1704.00194v1 [physics.acc-ph] (2017)] suggest that PbTe(111) will produce low-MTE photoelectrons due to the low effective electron mass associated with its electronic band structure. Based on this, we measured the distribution of photoelectrons from PbTe(111) and found the MTE to be about 20x larger than expected. To explain the apparent lack of transverse momentum conservation, we carried out many-body photoemission calculations including electron-phonon scattering. Our results are in far better agreement with the experiment, underscoring the importance of electron-phonon scattering in photoemission from PbTe(111), and suggest that cooling could mitigate the phonon effects on the MTE for this material.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF065  
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TUPMF083 Influence of Intrabeam Scattering on the Emittance of PETRA III emittance, 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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TUPML066 Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices plasma, simulation, emittance, 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.
 
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WEXGBE3 IBS Studies at BESSY II and MLS simulation, emittance, 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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WEPAF016 Application of Quad-Scan Measurement Techniques to Muon Beams in the Muon g-2 Experiment experiment, emittance, storage-ring, quadrupole 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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WEPAG003 Hadron Beam Monitor Design with Gas-Filled RF Resonators in Intense Neutrino Source cavity, hadron, target, radiation 2067
 
  • M.D. Balcazar, K. Yonehara
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
For the future Long Baseline Neutrino Facility at Fermilab, a new radiation-robust hadron beam profile monitor has been proposed consisting of an interface of gas-filled radiofrequency cavity detectors in the backward region of the LBNF decay pipe. A tailored monitor layout will be used along with the new RF instrumentation. Proposed designs for the detector configuration include a variety of radially symmetric arrangements of RF resonators located at the position of maximum gradient in the beam distribution across the monitor. Until the final detector cavities are available, a prototype tunable Q-factor RF cavity will provide functional emulation for studies of the monitor layout configurations presented here.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAG003  
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WEPAL058 Beam Loss Studies at the Taiwan Photon Source radiation, injection, vacuum, undulator 2309
 
  • C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu
    NSRRC, Hsinchu, Taiwan
 
  PIN-photodiodes and RadFETs are installed in the storage ring of the Taiwan Photon Source (TPS) to study beam loss distributions and mechanisms. In the highest dose area, the radiation comes mainly from hard X-rays produced by synchrotron bending magnets. During beam cleaning and after replacing a vacuum chamber, losses due to inelastic Coulomb scattering occur mostly downstream from bending magnets while elastic scattering causes electrons to get lost mainly after an elliptically polarizing undulator which has a limited vertical aperture. During the injection period, the beam loss pattern can be changed by modifying injection conditions or lattice settings. The beam loss usually happens in the injection section and small-aperture section. The injection efficiency can be improved by minimizing the detected injection loss.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL058  
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WEPAL069 Reentrant Cavity Resonator for Low Intensities Proton Beam Measurements simulation, pick-up, cavity, resonance 2341
 
  • S. Srinivasan, P.-A. Duperrex
    PSI, Villigen PSI, Switzerland
 
  A non-interceptive beam current monitor has been developed to investigate the measurement possibilities of low-intensity beams down to 1 nA for proton therapy machines without the drawback of interceptive monitors. This works on the principle of a reentrant cavity resonator such that its fundamental mode resonance frequency of 145.7 MHz matches the second harmonic of the pulse repetition rate of the cyclotron beam i.e. 72.85 MHz. The Driven Modal analysis from the simulation tool ANSYS HFSS was used for parametric model development and to optimize design parameters such as e.g. the position of the inductively coupled pick-ups. A ceramic plate has been inserted in the resonator gap to relax the precision required during manufacturing. A test bench has been designed and constructed for the characterization tests of the prototype. Comparison of the simulated and the experimental scattering parameter from the test bench shows a good agreement.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL069  
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THPAF054 Characterization of Losses and Emittance Growth for Ion Beams on the SPS Injection Plateau emittance, resonance, space-charge, injection 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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THPAF076 Using Graphic-Turtle with the Particle Beam Optics Laboratory (PBO Lab) optics, simulation, software, quadrupole 3158
 
  • G.H. Gillespie
    G.H. Gillespie Associates, Inc., Del Mar, California, USA
 
  A Particle Beam Optics Laboratory (PBO Lab) module has been developed for the Paul Scherrer Institute (PSI) version of the TURTLE program commonly known as Graphic-Turtle. The PSI-TURTLE version extends the original TURTLE program by including several unique beam optics capabilities, as well as by providing a self-contained graphics package. The unique optics modeling, together with the data visualization enhancements, make the PSI-TURTLE program ideal for certain types of beam simulations. The PBO Lab environment provides a single graphic user interface (GUI) that features an easy-to-learn and easy-to-use drag-and-drop beamline construction kit. Underlying the GUI is a sophisticated object model developed specifically for the accelerator community. PBO Lab provides a common interface for multiple charged particle optics codes. Modules have been developed for a number of popular beam optics programs that cover a range of accelerator types and applications. The PSI-TURTLE Module extends those capabilities. The module is described and its main capabilities and limitations are summarized.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF076  
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THPMF060 Touschek Beam Loss Simulation for Light Source Storage Rings electron, storage-ring, coupling, simulation 4206
 
  • M. Takao, K. Soutome
    JASRI/SPring-8, Hyogo-ken, Japan
  • Y. Shimosaki
    JASRI, Hyogo, Japan
  • K. Soutome, H. Tanaka
    RIKEN SPring-8 Center, Hyogo, Japan
 
  In light source storage rings, it is important to know the distribution of lost electrons due to the Touschek scattering for protecting insertion devices (IDs) from radiation damage. This will become crucial especially in future light sources where narrow gap in-vacuum IDs are normally used. While the Touschek scattered electron begins to oscillate in the horizontal direction with the amplitude proportional to the dispersion at the scattering point and to the momentum deviation after scattering, the motion is converted into the vertical direction due to the betatron coupling and some of the scattered electrons are lost at the narrow gaps of in-vacuum IDs. The momentum deviation by the Touschek scattering reaches 5% more, and according to which the vertical oscillation is more excited. Hence electrons even scattered at small horizontal dispersion are also lost at narrow gap IDs. We carried out computer simulations by taking the present SPring-8 storage ring and a planned 3GeV low-emittance ring as examples. The results and possible measures for ID protection will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF060  
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THPMF072 Implementation of Ultra-Low Frequency Non-Linear Raman Spectroscopy with the Gun Laser at FLUTE experiment, laser, gun, optics 4242
 
  • S. Funkner, E. Bründermann, A.-S. Müller, M.J. Nasse, G. Niehues, T. Schmelzer, J.L. Steinmann, M. Yan
    KIT, Eggenstein-Leopoldshafen, Germany
  • M. Tani
    University of Fukui, Fukui, Japan
 
  At the Karlsruhe Institute of Technology (KIT) the new compact versatile linear accelerator FLUTE is currently under commissioning. This accelerator will provide intense broadband THz pulses for spectroscopic experiments. Here, we demonstrate the implementation of a coherent Raman spectrometer using the RF gun laser of FLUTE. With our experiment, we can measure the Raman spectrum at ultra-low frequencies. The measurement principle, which was recently published, is based on coherent nonlinear excitation of the observed sample. The spectrometer consists of a stretcher and an interferometer, which can be simply built from standard optics. We will show that the accessible spectral range overlaps well with that from the THz pulses of the planned FLUTE experiment. Thus, the coherent Raman experiment can provide spectral information complementary to absorption spectral measurements using the THz radiation of FLUTE.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF072  
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THPMF083 Dynamic Simulation for Low Energy Compton Scattering Gamma-Ray Storage Ring laser, electron, emittance, 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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THPMK146 Enhancement of Laser-Compton X-ray by Crab Crossing laser, electron, luminosity, photon 4645
 
  • Y. Koshiba, R. Morita, S. Ota, M. Washio
    Waseda University, Tokyo, Japan
  • T. Higashiguchi
    Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
 
  Funding: This work is supported by JSPS Research Fellowships for Young Scientists (17J04371).
We are going to apply crab crossing of electrons and laser photons for the enhancement of laser-Compton X-ray flux. Crab crossing will enable quasi-head-on collision and increase the luminosity. Therefore, it could be combined with an optical enhancement cavity without the interference of beams and cavity mirrors, leading to the generation of intense X-ray pulses. Calculation show more than fourfold luminosity will be achievable in our system, and could be larger depending on beam parameters. Although crab crossing in laser-Compton scattering has been already proposed*, it has not been demonstrated yet anywhere. This will be the proof-of-principle study of the crab crossing laser-Compton scattering. In this conference, we will report our laser system based on thin-disk technology, and results of crab crossing laser-Compton scattering.
*Variola Alessandro, et al. "Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators." Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK146  
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THPML058 Recent Results from MICE on Multiple Coulomb Scattering and Energy Loss emittance, 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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THPML092 Electromagnetic and Mechanical Design of High Gradient S-Band Accelerator in TTX HOM, cavity, laser, linac 4876
 
  • D.Z. Cao, H.B. Chen, Y. C. Du, W. Gai, W.-H. Huang, J. Shi, C.-X. Tang, P. Wang, H. Zha
    TUB, Beijing, People's Republic of China
 
  Thomson scattering x-ray source is an essential scien-tific research tool in x-ray imaging technology for vari-ous fields. Upgrading plan of replacing the 3-meter S-band linac with a shorter structure operating at higher gradient in Tsinghua Thomson scattering X-ray source (TTX) is undergoing so far, aiming to enhance the accel-erating gradient from 15 MV/m to 30 MV/m. Detailed parameters of couplers and mechanical design of acceler-ation structure are presented in this work.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML092  
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THPML136 Study of Secondary Electron Generation and Transport in Diamond electron, simulation, cathode, database 5004
 
  • T.L. He, K. Huang, Z.L. Ren, L. Wang, D.R. Xu, H. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Energetic primary electrons (~ keV) impinging on the diamond film with its both surface under bias field in ~ MV/m, will excite secondary electron (SE) response including SE generation & transport. Although there have been 3D Monte Carlo (MC) simulation to study the two processes, this paper will introduce another method. Based on optical dielectric model, 3D MC simulation was implemented to study the generation process, and SE generation function was obtained by fitting the calculations. Using this function, the diffusion-drift equation of charge carriers (electron and hole) can be solved in 1D for the transport process, and the variation of SE depth distribution with time can be obtained.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML136  
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