Keyword: scattering
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MOPAB021 Performance of OTR and Scintillator View Screens for the ARIEL Electron Linac target, linac, optics, radiation 117
 
  • D.W. Storey, J.M. Abernathy, D. Karlen, M.O. Pfleger, P.R. Poffenberger
    Victoria University, Victoria, B.C., Canada
  • P.S. Birney, P.E. Dirksen, S.R. Koscielniak, M. Lenckowski
    TRIUMF, Vancouver, Canada
  
  The ARIEL electron linac is a 0.3 MW CW accelerator, extensible to 0.5 MW, being installed at TRIUMF for radioactive beam production. To date, 17 view screen monitors have been installed along the beamline and have proven to be essential tools in the commissioning of e-linac systems. These are populated by two types of beam targets: P46 scintillator screens which provide diagnostics for low duty factor operation, while at locations with beam energies at and above 10 MeV, OTR foils using either Pyrolytic Graphite or Niobium foils are included to provide coverage up to 100's of μA average beam current. The design of the view screen is described including the image acquisition system and beam target selection. The performance thus far of the OTR foils under low duty factor commissioning is presented including quantification of the OTR emission distribution, thermal studies, and transmission of the beam through the linac after intercepting a foil.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB021  
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MOPAB029 Experimental Study of Halo Formation at ATF2 vacuum, simulation, electron, detector 142
 
  • R.J. Yang, P. Bambade, A. Faus-Golfe, V. Kubytskyi, S. Wallon
    LAL, Orsay, France
  • A. Aryshev, T. Naito
    KEK, Ibaraki, Japan
  • N. Fuster-Martínez
    IFIC, Valencia, Spain
  
  For Accelerator Test Facility 2 (ATF2), as well as other high-intensity accelerators, beam halo has been an important aspect reducing the machine performance and activating the components. It is imperative to clearly understand the mechanisms that lead to halo formation and to test the avail- able theoretical models with an adequate experiment setup. In this paper, the experimental measurement of the beam halo formation from beam gas scattering is presented. The upgrading of an OTR/YAG screen monitor for future halo study is also introduced.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB029  
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MOPAB065 Breit-Wheeler Scattering Events Produced by Two Interacting Compton Sources photon, electron, laser, background 261
 
  • I. Drebot, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • D. Micieli, E. Tassi
    UNICAL, Arcavacata di Rende, Italy
  • E. Milotti
    INFN-Trieste, Trieste, Italy
  • V. Petrillo
    Universita' degli Studi di Milano & INFN, Milano, Italy
  
  We present the dimensioning of a photon-photon collider based on conventional Compton gamma sources for the observation of Breit-Wheeler pair production and QED gamma-gamma generation. Two symmetric electron beams, generated by photocathodes and accelerated in linacs, produce two primary gamma rays through Compton back-scattering with two high-energy lasers. Tuning the system energy above the Breit-Wheeler cross section threshold, a flux of secondary electrons and positrons is generated. The process is analyzed by start-to-end simulations. The Monte Carlo code 'Rate Of Scattering Events' (ROSE) has been developed ad hoc for the counting of the QED events. Realistic numbers of the secondary particles yield, referring to existing or approved set-ups, a discussion of the feasibility of the experiment and the evaluation of the background are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB065  
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MOPAB077 Spatial Decoding Electro-Optic Bunch Measurement at Tsinghua Thomson Scattering X-ray Source laser, electron, experiment, diagnostics 302
 
  • W. Wang, Z.J. Chi, Y.-C. Du, W.-H. Huang, C.-X. Tang, L.X. Yan, Z. Zhang
    TUB, Beijing, People's Republic of China
  
  Electron bunches with duration of sub-picosecond are essential in ultraviolet and X-ray free electron laser (XFEL) to reach the desired peak current. Electro-optic (EO) technique is suitable for temporal profile measure-ment of these ultrashort bunches which is one of the key diagnostics in FELs. An electro-optic monitor based on spatial sampling has recently been designed and installed for bunch profile diagnostic at Tsinghua Thomson scat-tering X-ray source (TTX). An ultrashort laser pulse is used to detect the field induced birefringence of the bunch Coulomb field in an electro-optic crystal and the monitor allows direct time-resolved single-shot measure-ment of bunch profile with an accuracy of 135 femtosec-onds for a 40 MeV electron bunch in a non-destructive way, which can simultaneously record the relative time jitter between probe laser and electron bunch. This paper performs the layout of the setup and presents the current measurement results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB077  
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MOPAB098 Coronagraph Based Beam Halo Monitor Development for BERLinPro background, electron, dipole, linac 355
 
  • J.G. Hwang
    Kyungpook National University, Daegu, Republic of Korea
  • J. Kuszynski
    HZB, Berlin, Germany
  
  For linac based high power electron machines, beam halo induced by nonlinear space charge force and scattering of trapped ions is one of the critical issues on a machine protection system. It causes additional radiation which can be a heat source on a cryogenic system as a result of uncontrolled beam losses. During the last decades, several instruments have been newly developed for measuring the beam halo distribution. The conceptual design and optimization of the coronagraph based halo monitor were performed to measure the beam halo which has ~ 10-3 contrast to the beam core.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB098  
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MOPAB146 Electron Beam Diagnosis Using K-edge Absorption of Laser-Compton Photons electron, laser, photon, emittance 473
 
  • Y. Hwang, T. Tajima
    UCI, Irvine, California, USA
  • C.P.J. Barty, D.J. Gibson, R.A. Marsh
    LLNL, Livermore, California, USA
  
  Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The mean energy, energy spread and divergence of the electron beam can be deduced from laser-Compton scattered X-rays filtered by a material whose K-edge is near the energy of the X-rays. This technique, combined with a spot size measurement of the beam, can be used to measure the emittance of electron bunches, and can be especially useful in LWFA experiments where conventional methods are unavailable. The effects of the electron beam parameters on X-ray absorption images are discussed, along with experimental demonstrations of the technique using the Compact Laser-Compton X-ray Source at LLNL. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB146  
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MOPAB150 Imaging the Spatial Modulation of a Relativistic Electron Beam electron, experiment, quadrupole, emittance 480
 
  • C. Zhang, W.S. Graves, L.E. Malin, J. Spence
    Arizona State University, Tempe, USA
  • D.B. Cesar, J.M. Maxson, P. Musumeci, A. Urbanowicz
    UCLA, Los Angeles, USA
  • C. Limborg, E.A. Nanni
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by NSF awards 1632780, 1415583, 1231306 and DOE award de-sc0009914
We describe Bragg diffraction of relativistic electron beams through a patterned Si crystal consisting of alternating thick and thin strips to produce nanometer scale electron density modulations. Multi-slice simulations show that a two-beam situation can be set up where, for a particular thickness of Si, nearly 100% of the electron beam is diffracted. Plans are underway to carry out experiments showing this effect in UCLA's ultrafast electron microscopy lab with 3.5 MeV electrons. We will select either the diffracted beam or the primary beam with a small aperture in the diffraction plane of a magnetic lens, and so record either the dark or bright field magnified image of the strips. Our first goal is to observe the nanopatterned beam at the image plane. We will then investigate various crystal thickness and sample orientations to maximize the contrast in the pattern and explore tuning the period of the modulation through varying magnification. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB150  
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MOPIK028 Simulation Study of Halo Collimation in the TRIUMF Ariel Proton Beam Line proton, collimation, cyclotron, simulation 557
 
  • F.W. Jones, R.A. Baartman, I.V. Bylinskii, Y.-N. Rao
    TRIUMF, Vancouver, Canada
  
  Funding: Funded under a contribution agreement with NRC (National Research Council of Canada). Capital funding from CFI (Canada Foundation for Innovation).
The TRIUMF 500 MeV H− cyclotron uses stripping foil extraction to drive several proton beam lines serving different experimental programs. As part of TRIUMF's Ariel facility now under construction, a new proton beam line 4-North will be installed to transport up to 100 microamps of 480 MeV protons to an ISOL target station for rare isotope beam production. This beam line has been designed for low-loss (< 1nA/m) operation and provides space for a collimator to remove the beam halo produced by large-angle scattering in the cyclotron extraction foil. We have studied proton loss patterns and collimation efficiency using simulation codes: the older REVMOC program and a fully 3D simulation based on Geant4, with all particle interactions in matter included. Scattering in the foil is treated by a separate iterated single-scatter model. Using these tools we arrive at a prototype design for an effective collimator. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK028  
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MOPIK044 The Use of a Passive Scatterer for SPS Slow Extraction Beam Loss Reduction extraction, septum, proton, simulation 607
 
  • B. Goddard, B. Balhan, J.C.C.M. Borburgh, M.A. Fraser, L.S. Stoel, F.M. Velotti
    CERN, Geneva, Switzerland
  
  A significant reduction in the fraction of protons lost on the SPS electrostatic septum ES during resonant slow extraction is highly desirable for present Fixed-Target beam operation, and will become mandatory for the proposed SHiP experiment, which is now being studied in the framework of CERN's Physics Beyond Colliders program. In this paper the possible use of a passive scattering device (diffuser) is investigated. The physics processes underlying the use of a diffuser are described, and the dependence on the diffuser geometry, material and location of the potential loss reduction on the electrostatic septum (ES) wires is investigated with a semi-analytical approach. Numerical simulations to quantify the expected performance gain for the optimum configuration are presented, and the results discussed in view of the feasibility of a potential realisation in the SPS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK044  
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MOPVA023 Luminosity Increase in Laser-Compton Scattering by Crab Crossing Method laser, electron, luminosity, photon 902
 
  • Y. Koshiba, D. Igarashi, S. Ota, T. Takahashi, M. Washio
    RISE, Tokyo, Japan
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
  
  In collider experiments such as KEKB, crab crossing method is a promising way to increase the luminosity. We are planning to apply crab crossing to laser-Compton scattering, which is a collision of electron beam and laser, to gain a higher luminosity leading to a higher flux X-ray source. It is well known that the collision angle between electron beam and laser affects the luminosity. It is the best when the collision angle is zero, head-on collision, to get a higher luminosity but difficult to construct such system especially when using an optical cavity for laser. Concerning this difficulty, we are planning crab crossing by tilting the electron beam using an rf-deflector. Although crab crossing in laser-Compton scattering has been already proposed*, nowhere has demonstrated yet. We are going to demonstrate and conduct experimental study at our compact accelerator system in Waseda University. In this conference, we will report about our compact accelerator system, laser system for laser-Compton scattering, and expected 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-IPAC2017-MOPVA023  
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MOPVA031 Low Energy Compact Storage Ring Design for Compton Gamma-Ray Light Source electron, emittance, laser, storage-ring 921
 
  • 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
  
  Gamma-ray sources with high flux and spectral densities are highly demanded by many nuclear experiments. We design a low energy compact storage ring to produce gamma-ray with energy in the range of 4-20 MeV based on Compton backscattering technique. The storage ring energy is 500-800 MeV with the circumference of about 59 m and natural emittance of about 3 nmrad at 500 MeV. In this paper, we present the storage ring lattice design and propose two collision configurations for Compton gamma-ray generation. Intrabeam scattering has been investigated which can increase emittance from 3 nmrad to 6 nmrad horizontally for 500 MeV ring. We also discuss how Compton scattering affects longitudinal and transverse beam dynamics by tracking macro particles using our parallel simulation code. Based on this study, we can further optimize our storage ring lattice design for the higher gamma-ray flux production.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA031  
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TUPAB060 Development of the Laser System for the Proof-of-Principle Experiment of Crab Crossing Laser-Compton Scattering laser, electron, experiment, luminosity 1460
 
  • T. Takahashi, D. Igarashi, Y. Koshiba, S. Ota, M. Washio
    RISE, Tokyo, Japan
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
  
  An X-ray source via laser-Compton scattering has the advantage of small source, energy tunability and quasi-monochromaticity and is expected to be applied in a wide range of fields such as the industry and medical care. In laser-Compton scattering, the luminosity, which represents the collision frequency between the electrons and the photons, is very important. Increasing the luminosity is strongly required for increasing the scattered photon flux. One way to increase the luminosity is tilting electron bunches at the collision point, which is called crab crossing. It is the way to create the head-on collision artificially. The purpose of this study is the proof-of-principle of the crab crossing laser-Compton scattering. In this conference, we will report the design optimization and construction of the laser system for the collision and future prospects.
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-IPAC2017-TUPAB060  
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TUPAB067 Studies of Beam Lifetime at HEPS lattice, electron, storage-ring, photon 1478
 
  • S.K. Tian, Y. Jiao, G. Xu
    IHEP, Beijing, People's Republic of China
  
  The electron storage ring's beam lifetime is determined by scattering of the electrons at the nucleus and the shell of the atoms of the residual gas (gas lifetime) and the scattering of electrons within a bunch (Touschek lifetime).Beam lifetime studies have been performed at the 6 GeV electron storage ring HEPS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB067  
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TUPAB110 Possible Limits of Plasma Linear Colliders plasma, electron, emittance, collider 1576
 
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  Plasma linear colliders have been proposed as next or next-next generation energy-frontier machines for high-energy physics. I investigate possible fundamental limits on energy and luminosity of such type of colliders, considering acceleration, multiple scattering off plasma ions, intrabeam scattering, bremsstrahlung, and betatron radiation. The question of energy efficiency will also be addressed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB110  
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TUPVA044 Modelling and Measurements of Bunch Profiles at the LHC emittance, synchrotron, radiation, luminosity 2167
 
  • S. Papadopoulou, F. Antoniou, T. Argyropoulos, M. Hostettler, Y. Papaphilippou
    CERN, Geneva, Switzerland
  • M. Fitterer
    Fermilab, Batavia, Illinois, USA
  
  The bunch profiles in the LHC are often observed to be non-Gaussian, both at Flat Bottom (FB) and Flat Top (FT) energies. Especially at FT, an evolution of the tail population in time is observed. In this respect, the Monte-Carlo Software for IBS and Radiation effects (SIRE) is used to track different types of beam distributions. The impact of the distribution shape on the evolution of bunch characteristics is studied. The results are compared with observations from the LHC Run 2 data.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA044  
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TUPVA079 Model of Statistical Errors in the Search for the Deuteron EDM in the Storage Ring detector, simulation, experiment, dipole 2258
 
  • A.E. Aksentyev, V. Senichev
    FZJ, Jülich, Germany
  
  In this work we investigate the standard error of the spin precession frequency estimate in an experiment for the search for the electric dipole moment (EDM) of the deuteron using the polarimeter. The basic principle of polarimetry is the scattering of a polarized beam on a carbon target. Since the number of particles in one fill is limited, we must maximize the utility of the beam. This raises the question of sampling efficiency, as the signal, being an oscillating function, varies in informational content. To address it, we define a numerical measurement model, and compare two sampling strategies (uniform and frequency-modulated) in terms of beam-use efficiency. The upshot is the formulation of the conditions necessary for the effective use of the modulated sampling strategy, and the evaluation of its advantage over the uniform strategy. The simulation results are also used to compare two competing analytical models for the standard error of the frequency estimate.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA079  
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TUPVA133 Thin Internal Target Studies in a Compact FFAG target, simulation, emittance, proton 2411
 
  • D. Bruton, R.J. Barlow, T.R. Edgecock
    University of Huddersfield, Huddersfield, United Kingdom
  • C. Johnstone
    PAC, Batavia, Illinois, USA
  
  The production of radioisotopes using a thin internal target and recycled beam within a compact FFAG design has been studied. Radioisotopes have a wide range of uses in medicine, and recent disruption to the supply chain has seen a renewed effort to find alternative isotopes and production methods. The FFAG design features separate sector magnets with non-scaling, non-linear field gradients which are optimized with magnet geometry to achieve isochronisity at the level of 0.3%, sufficient for Continuous Wave (CW) operation. Simulations have demonstrated that beam currents of up to 10mA can comfortably be achieved with this design. To further improve production efficiency a thin internal target, where the beam passes through the target and is recirculated, may be used. This setup ensures that production takes place within a narrow energy range, potentially increasing production rates and reducing impurities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA133  
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WEOBA1 A Comparison of Interaction Physics for Proton Collimation Systems in Current Simulation Tools collimation, simulation, proton, collider 2478
 
  • J. Molson, A. Faus-Golfe
    LAL, Orsay, France
  • R.B. Appleby, S.C. Tygier
    UMAN, Manchester, United Kingdom
  • R.J. Barlow
    IIAA, Huddersfield, United Kingdom
  • R. Bruce, F. Cerutti, A. Ferrari, A. Mereghetti, S. Redaelli, K.N. Sjobak, V. Vlachoudis
    CERN, Geneva, Switzerland
  • H. Rafique
    University of Manchester, Manchester, United Kingdom
  • Y. Zou
    IHEP, Beijing, People's Republic of China
  
  Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305.
High performance collimation systems are required for current and proposed high energy hadron accelerators in order to protect superconducting magnets and experiments. In order to ensure that the collimation system designs are sufficient and will operate as expected, precision simulation tools are required. This paper discusses the current status of existing collimation system tools, and performs a comparison between codes in order to ensure that the simulated interaction physics between a proton and a collimator jaw is accurate. 		 
slides icon Slides WEOBA1 [7.235 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOBA1  
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WEOBA3 Studies of a Scheme for Low Emittance Muon Beam Production From Positrons on Target target, positron, emittance, simulation 2486
 
  • M. Boscolo, M. Antonelli, M.E. Biagini, O.R. Blanco-García, A. Variola
    INFN/LNF, Frascati (Roma), Italy
  • A. Bacci
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • I. Chaikovska, R. Chehab
    LAL, Orsay, France
  • F. Collamati
    INFN-Roma1, Rome, Italy
  • M. Iafrati
    ENEA, Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile, Frascati, Italy
  • L. Keller
    SLAC, Menlo Park, California, USA
  • S.M. Liuzzo, P. Raimondi
    ESRF, Grenoble, France
  • P. Sievers
    CERN, Geneva, Switzerland
  
  We are studying a new scheme to produce very low emittance muon beams using a positron beam of about 45 GeV interacting on electrons on target. This is a challenging and innovative scheme that needs a full design study. One of the innovative topics to be investigated is the behaviour of the positron beam stored in a low emittance ring with a thin target, that is directly inserted in the ring chamber to produce muons. Muons will be immediately collected at the exit of the target and transported to two mu+ and mu- accumulator rings. We focus in this paper on the simulation of the e+ beam interacting with the target, its degradation in the 6-D phase space and the optimization of the e+ ring design mainly to maximize the energy acceptance. We will investigate the performances of this scheme, ring optics plus target system, comparing different multi-turn simulations.  
slides icon Slides WEOBA3 [3.737 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOBA3  
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WEPAB067 Electron Beam Lifetime in SOLARIS Storage Ring electron, storage-ring, vacuum, damping 2731
 
  • M.B. Jaglarz, P.B. Borowiec, A. Kisiel, A.I. Wawrzyniak
    Solaris, Kraków, Poland
  • A.M. Marendziak
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
  
  Solaris storage ring is a recently constructed and commissioned machine. At the beginning of storage ring operation the lifetime was very short mostly dominated by the ion trapping and residual gas scattering. After a 390 A·h of beam cleaning the measured total lifetime has reached 20 h for 100mA of a stored current. Since the main contribution to the total lifetime in the storage ring comes from single Coulomb and Touschek scattering the dependence of the residual gas pressure and the vertical aperture of storage ring is investigated. Moreover to improve the Touschek lifetime the 3rd harmonic cavities were installed. Recently the cavities were tuned close to the resonance and the total lifetime increased significantly. This presentation will report on the lifetime measurements and calculations carried out for Solaris 1.5 GeV storage ring at different vacuum and RF conditions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB067  
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WEPAB130 First Results from MICE Step IV emittance, detector, simulation, solenoid 2878
 
  • P. Franchini
    University of Warwick, Coventry, United Kingdom
  
  Funding: STFC, DOE, NSF, INFN, CHIPP and more
Muon beams of low emittance provide the basis for the intense, well characterised neutrino beams of the Neutrino Factory and for lepton-antilepton collisions at energies of up to several TeV at a Muon Collider. The international Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling - the technique by which it is proposed to reduce the phase-space volume occupied by the muon beam. MICE is being constructed in a series of Steps. The configuration currently in operation at the Rutherford Appleton Laboratory is optimised for the study the properties of liquid hydrogen and lithium hydride that affect cooling. The data taken in the present configuration have been partially analyzed and the available results will be described in detail.
submitted by the Speakers Bureau of the collaboration, in charge of
finding later a member to prepare and present the contribution 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB130  
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WEPAB133 A Wedge Absorber Experiment at MICE emittance, collider, experiment, optics 2888
 
  • D.V. Neuffer
    Fermilab, Batavia, Illinois, USA
  • T.A. Mohayai
    IIT, Chicago, Illinois, USA
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • 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 beam line could serve as a demonstration of the type of emittance exchange needed for 6-D cooling, including the configurations needed for muon colliders, as well as configurations for low-energy muon sources. Parameters for this test are explored in simulation and possible experimental configurations with simulated results are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB133  
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WEPAB134 Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices plasma, simulation, emittance, electron 2891
 
  • J.S. Ellison
    IIT, Chicago, Illinois, USA
  • P. Snopok
    Fermilab, Batavia, Illinois, USA
  • P. Snopok
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Funding: Work supported by the U.S. 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 progress of developing the required simulation tools and applying them to study 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-IPAC2017-WEPAB134  
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WEPIK081 The Logitudinal Broadband Impedance and Energy Spread Measurements at the VEPP-4M Electron-Positron Collider impedance, electron, synchrotron, collider 3117
 
  • V.M. Borin, V.A. Kiselev, G.Y. Kurkin, S.A. Nikitin, P.A. Piminov, S.V. Sinyatkin
    BINP SB RAS, Novosibirsk, Russia
  • V.L. Dorokhov, O.I. Meshkov
    BINP, Novosibirsk, Russia
  
  The paper presents measurements of the longitudinal broadband impedance and beam energy spread of the beam at the VEPP-4M electron-positron collider in an energy range of 1.0 - 3.5 GeV. In order to measure the longitudinal bunch size at various beam currents we used PS-1/S1 streak camera with picosecond temporal resolution. The dependence of bunch length from the bunch current at different energies demonstrates a microwave instability threshold. The bunch lengthening was caused by potential well distortion as well. Potential well distortion lengthening was used to estimate a value of the reactive part of the longitudinal impedance of the vacuum chamber of the collider Observed microwave instability thresholds was used to measure the value of the broadband impedance. The impact of the Touschek effect in the beam energy spread is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK081  
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THOAB1 Study of Medical Applications of Compact Laser-Compton Light Source laser, electron, synchrotron, radiation 3656
 
  • Y. Hwang, T. Tajima
    UCI, Irvine, California, USA
  • G.G. Anderson, C.P.J. Barty, D.J. Gibson, R.A. Marsh
    LLNL, Livermore, California, USA
  
  Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Compton scattering of laser photons by a relativistic electron beam produces monoenergetic, tunable and small source size X-rays similar to synchrotron light sources in a very compact setting, due to the shorter undulator period of lasers. These X-ray sources can bring to every hospitals advanced radiology and radiotherapy that are currently only being conducted at synchrotron facilities. Few examples include phase contrast imaging utilizing the micron-scale source size, K-edge subtraction imaging from two monoenergetic X-rays at different energies and radiation therapy using radiosensitization of high-Z nanoparticles. At LLNL, 30 keV X-rays have been generated from the 30 MeV X-band linac, and the X-rays have been characterized and agree with the modeling very well. This source is being used to study the feasibility of aforementioned medical applications. Experimental setup of K-edge subtraction of contrast agents are presented, demonstrating the low-dose, high-contrast imaging potential of the light source. Plans to study enhanced radiotherapy using Gold nanoparticles with the upgrade of the machine to higher energies are discussed. 		 
slides icon Slides THOAB1 [2.818 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THOAB1  
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THPAB024 Emittance Growth at Charge-Exchanging Multi-Turn Injection in KURRI FFAG injection, emittance, acceleration, simulation 3747
 
  • T. Uesugi, Y. Ishi, Y. Kuriyama, Y. Mori
    Kyoto University, Research Reactor Institute, Osaka, Japan
  
  In the fixed field alternating gradient (FFAG) synchrotron in Kyoto university research reactor institute (KURRI), rapid beam loss of factor 100 is observed right after the injection. In the synchrotron, charge-exchanging multi-turn injection is adopted with a stripping foil located on the closed orbit of the injection energy. No bump orbit system is used and the injected beams escape from the foil according to the closed-orbit shift by acceleration. The particles hit the foil many times and that is why the emittance grows up during the injection. In this paper, simulation studies are done to estimate the emittance growth and beam losses. The scattering effect at the foil is modeled by GEANT4.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB024  
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THPAB046 SixTrack for Cleaning Studies: 2017 Updates collimation, ion, coupling, collider 3811
 
  • A. Mereghetti, R. Bruce, F. Cerutti, R. De Maria, A. Ferrari, M. Fiascaris, P.D. Hermes, D. Mirarchi, P.G. Ortega, D. Pastor Sinuela, E. Quaranta, S. Redaelli, K.N. Sjobak, V. Vlachoudis
    CERN, Geneva, Switzerland
  • J. Molson
    LAL, Orsay, France
  • Y. Zou
    IHEP, Beijing, People's Republic of China
  
  SixTrack is a single particle tracking code for simulating beam dynamics in ultra-relativistic accelerators. It is widely used at the European Organisation for Nuclear Research (CERN) for predicting dynamic aperture and cleaning inefficiency in large circular machines like the Super Proton Synchrotron (SPS), the Large Hadron Collider (LHC) and the Future Circular Collider (FCC). The code is under continuous development, to both extend its physics models, and enhance performance. The present work gives an overview of developments, specifically aimed at extending the code capabilities for cleaning studies. They mainly involve: the online aperture check; the possibility to perform simulations coupled to advanced Monte Carlo codes like Fluka or using the scattering event generator of the Merlin code; the generalisation of tracking maps to ion species; the implementation of composite materials of relevance for the future upgrades of the LHC collimators; the physics of interactions with bent crystals. Plans to merge these functionalities into a single version of the SixTrack code will be outlined.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB046  
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THPAB066 Modeling Cathode Roughness, Work Function, and Field Enhancement Effects on Electron Emission electron, emittance, simulation, photon 3869
 
  • D.A. Dimitrov, G.I. Bell, D.N. Smithe, S.A. Veitzer
    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 is supported by the US DOE Office of Science, department of Basic Energy Sciences under grant DE-SC0013190.
Recent developments in material design and growth have resulted in photocathodes that can deliver high quantum efficiency and are sufficiently robust to use in high electric field gradient photoinjectors and free electron lasers. The growth process usually produces photoemissive material layers with rough surface profiles that lead to transverse accelerating fields and possible work function variation resulting in emittance growth. To better understand the effects of surface roughness on emitted electron beams, we have developed realistic three-dimensional models for photocathode materials with grated surface structures. They include general modeling of electron excitation due to photon absorption, charge transport and emission from rough surfaces taking into account image charge and field enhancement effects. We implemented these models in the VSim particle-in-cell code. We report results from simulations using different photocathode materials with grated and flat surfaces to investigate how controlled roughness, work function variation, and field enhancement affect emission properties. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB066  
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THPAB088 Comparison of Theory, Simulation, and Experiment for Dynamical Extinction of Relativistic Electron Beams Diffracted Through a Si Crystal Membrane electron, simulation, experiment, emittance 3924
 
  • L.E. Malin, W.S. Graves, J. Spence, C. Zhang
    Arizona State University, Tempe, USA
  • R.K. Li, C. Limborg, E.A. Nanni, X. Shen, S.P. Weathersby
    SLAC, Menlo Park, California, USA
  
  Diffraction in the transmission geometry through a single-crystal silicon slab is exploited to control the intensity of a relativistic electron beam. The choice of crystal thickness and incidence angle can extinguish or maximize the transmitted beam intensity via coherent multiple Bragg scattering; thus, the crystal acts as a dynamical beam stop through the Pendel'sung effect, a well-known phenomenon in X-ray and electron diffraction. In an initial experiment, we have measured the ability of this method to transmit or extinguish the primary beam and diffract into a single Bragg peak. Using lithographic etching of patterns in the crystal we intend to use this method to nanopattern an electron beam for production of coherent x-rays. We compare the experimental results with simulations using the multislice method to model the diffraction pattern from a perfect silicon crystal of uniform thickness, considering multiple scattering, crystallographic orientation, temperature effects, and partial coherence from the momentum spread of the beam. The simulations are compared to data collected at the ASTA UED facility at SLAC for a 340 nm thick Si(100) wafer with a beam energy of 2.35 MeV.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB088  
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THPIK054 The X-Band Pulse Compressor for Tsinghua Thomson Scattering X-Ray Source cavity, coupling, simulation, klystron 4214
 
  • Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, X.W. Wu, H. Zha
    TUB, Beijing, People's Republic of China
  
  An X-band (11.424 GHz) high-power RF station is being built for Tsinghua Thomson scattering X-ray Source (TTX). The station aims to feed several X-band accelerating structures working at a high gradient of 80 MV/m. An X-band pulse compressor is designed to compress the RF pulse from 1.5 us to 100 ns and to generate more than 250 MW peak power from a 50MW klystron. This pulse compressor implements a resonate cavity housing the HE11-mode as the energy storage cavity, with a high quality factor Q of more than 105. The detailed design of the high-Q cavity as well as the dedicate couplers of this pulse compressor are present in this work.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK054  
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THPIK057 Development of a High-Power X-Band RF Rotary Joint simulation, linac, network, insertion 4224
 
  • J. Liu, H.B. Chen, J. Shi, X.W. Wu, H. Zha
    TUB, Beijing, People's Republic of China
  
  RF rotary joints allow the independent movement be-tween the RF power source and the accelerating tube of a linear accelerator (linac). In this paper, the design of a compact X-band (9.3 GHz) high-power RF rotary joint is presented. Simulation results illustrate that RF parameters (the scattering matrix) of this rotary joint keep stable in the arbitrary rotation angle. The maximum return loss is about -30 dB, the insert loss is less than 0.11 dB, and the variance of output phase shifts is below 1 degree while rotating the joint. RF measurement on the rotary joint using Vector-Network analyser is also conducted and presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK057  
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THPIK064 Beam Lifetime Analysis of HLS-II Storage Ring storage-ring, vacuum, operation, emittance 4242
 
  • K. Xuan, C. Li, J.Y. Li, G. Liu, G. Liu, J.G. Wang, L. Wang, W. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Beam lifetime is one of the important parameters of electron storage rings, which can describe the particle loss rate quantitatively and is restrict by quantum lifetime, beam-gas scattering and Touschek effect. The upgrade project of Hefei light source, named HLSII, has greatly improved the performance of the light source. The beam lifetime has been maintained at more than 5 hours. In this paper, a combined analysis method is derived by the analysis of the beam lifetime, and the method is applied to the HLSII storage ring. The experimental results show that this method is simple and reliable for the analysis of the Touschek lifetime and beam-gas scattering lifetime.

 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK064  
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THPIK093 Blow-Up Due to Intra Beam Scattering during Deceleration in ELENA emittance, simulation, electron, antiproton 4303
 
  • C. Carli, M. Martini
    CERN, Geneva, Switzerland
  
  Intra Beam Scattering (IBS) is expected to be the main performance limitation of the Extra Low Energy Antiproton ring (ELENA), a small synchrotron equipped with electron cooling under construction at CERN to decelerate antiprotons from 5.3 MeV to 100 keV. Thus, the duration of the ramps must not be too long to avoid excessive blow up due to IBS. On the other hand, the bending magnets are C-shaped and the vacuum chambers are without insulated junctions, which are difficult for fully baked machines; thus, the ramps must not be too short. The evolution of transverse and longitudinal emittances along the ramps have been estimated assuming that IBS is the main phenomenon leading to blow-up. The blow-up due to IBS found along the ramps have been found to be acceptable.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK093  
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THPVA002 Numerical Investigation of Beam Halo From Beam Gas Scattering in KEK-ATF emittance, simulation, vacuum, damping 4410
 
  • R.J. Yang, P. Bambade
    LAL, Orsay, France
  • K. Kubo, T. Okugi, N. Terunuma, D. Zhou
    KEK, Ibaraki, Japan
  
  To demonstrate the final focus schemes of the Future Linear Collider (FLC), the Accelerator Test Facility 2 (ATF2) at KEK is devoted to focus the beam to a RMS size of a few tens of nanometers (nm) vertically and to provide stability at the nm level at the virtual Interaction Point (IP). However, the loss of halo particles upstream will introduce background to the diagnostic instrument measuring the ultra-small beam, using a laser interferometer monitor. To help the realization of the above goals and beam operation, understanding and mitigation of beam halo are crucial. In this paper, we present the systematical simulation of beam halo formation from beam gas Coulomb scattering (BGS) in the ATF damping ring. The behavior of beam halo with various machine parameters is also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA002  
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THPVA084 Evaluation of Collective Effects in Iranian Light Source Facility (ILSF) Storage Ring impedance, storage-ring, vacuum, emittance 4650
 
  • E. Ahmadi, S. Ahmadiannamin, J. Rahighi
    ILSF, Tehran, Iran
  • S.M. Jazayeri
    IUST, Narmac, Tehran, Iran
  
  In this paper, we present the calculations of various collective effects in the storage ring of ILSF, a synchrotron light source under design in Iran. The ILSF storage ring is based on 5-BA lattice structure and emittance of 270 pm-rad which is optimized to provide high brightness and flux photons for the users. Because of design features, small radius vacuum pipe and small momentum compaction factor of lattice, it is expected that instabilities emerging from collective effects will affect significantly the beam quality and make it is challenging to reach maximum designed beam current. We will address the results of beam quality degradation and threshold calculations for different singlebunch and multibunch instabilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA084  
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THPVA112 Progress of the Beamline and Energy Selection System for HUST Proton Therapy Facility optics, proton, cyclotron, dipole 4719
 
  • B. Qin, Q.S. Chen, K. Fan, M. Fan, X.Y. Fang, D. Li, Z.K. Liang, K.F. Liu, X. Liu, P. Tan, J. Yang
    HUST, Wuhan, People's Republic of China
  • W. Chen
    Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China
  
  Funding: Work supported by The National Key Research and Development Program of China, with grant No. 2016YFC0105305
HUST proton therapy facility is a 5 years National Key Research and Development Program of China. This facil-ity is based on an isochronous superconducting cyclotron with two gantry treatment-rooms and one fixed beamline treatment station. The status for physical and technical design of the beamline and Energy Selection System (ESS) will be introduced in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA112  
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