Keyword: scattering
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MOPAB003 Machine Learning Analysis of Electron Cooler Operation for RHIC luminosity, electron, operation, GUI 45
 
  • X. Gu, A.V. Fedotov, D. Kayran
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A regression machine learning algorithm was applied to analyze the operation data of RHIC with electron cooler LEReC during the 2020 physics run. After constructing a black-box surrogate model from the XGBoost algorithm and plotting their partial dependency plots for different operation parameters, we can find the effects of an individual parameter on the RHIC luminosity and optimize it accordingly offline. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB003  
About • paper received ※ 14 May 2021       paper accepted ※ 25 May 2021       issue date ※ 11 August 2021  
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MOPAB004 JSPEC - A Simulation Program for IBS and Electron Cooling electron, simulation, experiment, emittance 49
 
  • H. Zhang, S.V. Benson, M.W. Bruker, Y. Zhang
    JLab, Newport News, Virginia, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Intrabeam scattering is an important collective effect that can deteriorate the properties of a high-intensity beam, and electron cooling is a method to mitigate the IBS effect. JSPEC (JLab Simulation Package for Electron Cooling) is an open-source program developed at Jefferson Lab, which simulates the evolution of the ion beam under the IBS and/or the electron cooling effect. JSPEC has been benchmarked with BETACOOL and experimental data. In this report, we will introduce the features of JSPEC, including the friction force calculation, the IBS expansion rate and electron cooling rate calculation, and the beam-dynamic simulations for the electron cooling process; explain how to set up the simulations in JSPEC; and demonstrate the benchmarking results. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB004  
About • paper received ※ 19 May 2021       paper accepted ※ 21 May 2021       issue date ※ 27 August 2021  
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MOPAB006 Optics Configurations for Improved Machine Impedance and Cleaning Performance of a Multi-Stage Collimation Insertion optics, collimation, impedance, collider 57
 
  • R. Bruce, R. De Maria, M. Giovannozzi, N. Mounet, S. Redaelli
    CERN, Geneva, Switzerland
  
  For a two-stage collimation system, the betatron phase advance between the primary and secondary stages is usually set to maximise the absorption of secondary particles outscattered from the primary. Another constraint is the contribution to the ring impedance of the collimation system, which can be decreased through an optimized insertion optics, featuring large values of the beta functions. In this article we report on first studies of such an optics for the CERN LHC. In addition to a gain in impedance, we show that the cleaning efficiency can be improved thanks to the large beta functions, even though the phase advance is not set at the theoretical optimum.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB006  
About • paper received ※ 17 May 2021       paper accepted ※ 28 May 2021       issue date ※ 11 August 2021  
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MOPAB027 Improving the Luminosity Burn-Off Estimate by Considering Single-Diffractive Effects luminosity, proton, collider, simulation 130
 
  • F.F. Van der Veken, H. Burkhardt, M. Giovannozzi, V.K.B. Olsen
    CERN, Geneva, Switzerland
  
  Collisions in a high-luminosity collider result in a continuous burn-off of the circulating beams that is the dominant effect that reduces the instantaneous luminosity over time. In order to obtain a good estimate of the luminosity evolution, it is imperative to have an accurate understanding of the burn-off. Typically, this is calculated based on the inelastic cross-section, as it provides a direct estimate of the number of protons that participate in inelastic collisions, and are hence removed. Likewise, protons that participate in elastic collisions will remain in the machine acceptance, still contributing to luminosity. In between these two regimes lie diffractive collisions, for which the protons have a certain probability to remain in the machine acceptance. Recent developments of the SixTrack code allow it to interface with Pythia, thus allowing for more precise simulations to obtain a better estimate of the diffractive part of the cross-section. In this paper, we will mainly concentrate on slowly-drifting protons that are close to the acceptance limit, resulting from single-diffractive scattering.  
poster icon Poster MOPAB027 [1.193 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB027  
About • paper received ※ 18 May 2021       paper accepted ※ 31 May 2021       issue date ※ 11 August 2021  
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MOPAB042 Beam Dynamics Investigation for a New Project of Compton Back Scattering Photon Source at NRNU MEPhI linac, photon, electron, laser 186
 
  • V.S. Dyubkov, I.A. Ashanin, M. Gusarova, Yu.D. Kliuchevskaia, M.V. Lalayan, S.M. Polozov, A.I. Pronikov, V.I. Rashchikov
    MEPhI, Moscow, Russia
  
  Funding: This project is supported by Russian Foundation for Basic Research, Grant no. 19-29-12036.
The activities on physical models design of a compact monochromatic radiation source in the x-ray range based on inverse Compton scattering are started at NRNU MEPhI. There are comparison of two schemes of the photon source here: one of them is considered to be based on linac with variable energy of 20-60 MeV only and the other one is considered as accelerator complex where linac is supposed to be used as injector to medium size storage ring (energy up to 60 MeV). Preliminary results of linac structures and storage ring design as well as electron dynamics simulation are discussed 		 
poster icon Poster MOPAB042 [0.962 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB042  
About • paper received ※ 13 May 2021       paper accepted ※ 20 May 2021       issue date ※ 10 August 2021  
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MOPAB061 Comparison Simulation Results of the Collimator Aperture in HEPS Storage Ring lattice, simulation, ECR, storage-ring 257
 
  • Y.L. Zhao, Y. Jiao, N. Li
    IHEP, Beijing, People’s Republic of China
  
  The High Energy Photon Source (HEPS) is a 6 GeV diffraction-limited storage ring light source, which is under construction and planned to be in operation in 2025. To protect the sensitive elements from being damaged and reduce the radiation level of the site, collimators will be installed in the storage ring to localize the particle losses. The Touschek scattering is the main cause of particle losses during daily nominal operations. Based on the elegant simulations, we evaluate the physical design of the collimators, especially analysis the collimator performance with different collimator apertures. The simulation results will be introduced in this paper.  
poster icon Poster MOPAB061 [0.701 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB061  
About • paper received ※ 13 May 2021       paper accepted ※ 17 August 2021       issue date ※ 21 August 2021  
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MOPAB174 Foil Hits Reduction by Minimizing Injection Beam Size at the Foil in J-PARC RCS injection, proton, beam-losses, operation 590
 
  • P.K. Saha, H. Harada, K. Okabe, F. Tamura, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • H. Hotchi
    KEK, Tokai, Ibaraki, Japan
  
  Funding: Pranab Kumar Saha
The uncontrolled beam loss caused by the foil scattering of the circulating beam during multi-turn charge-exchange injection is one of the main sources for high residual radiation at the injection area of J-PARC 3-GeV rapid cycling synchrotron. We studied to reduce foil hits of the circulating beam by minimizing the vertical injection beam size at the foil and using a smaller vertical foil size. The vertical foil size was reduced according to the injection beam size by maintaining the stripping efficiency. As a result, the number of circulating beam passing through foil was significantly reduced due to smaller foil size. The simulation and measurement results of the foil hits reduction are presented in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB174  
About • paper received ※ 20 May 2021       paper accepted ※ 31 May 2021       issue date ※ 28 August 2021  
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MOPAB419 Acceleration and Measurement of Alpha Particles and Hydrogen Molecular Ions with the HZB Cyclotron cyclotron, radiation, proton, vacuum 1264
 
  • G. Kourkafas, J. Bundesmann, A. Denker, T. Fanselow, J. Röhrich
    HZB, Berlin, Germany
  • J. Heufelder, A. Weber
    Charite, Berlin, Germany
  
  The HZB cyclotron has treated more than 4000 patients with eye tumors using protons. The accelerator can also provide heavier ions which could be suitable for ocular radiation therapy. Helium ions exhibit less lateral spread, increased relative biological effectiveness and a sharper Bragg-Peak compared to protons of the same range, while minimizing nuclear fragmentation and thus excessive dose downstream the irradiated volume compared to more heavy ions. When accelerating fully stripped helium ions (alpha particles), hydrogen molecular ions can also be accelerated to the same energy with a small tuning of the machine due to having almost the same mass-to-charge ratio, yielding a proton beam of double current after the beam exits the vacuum window towards the target. The acceleration and characterization of these two ion species are described in this paper, suggesting the feasibility of a corresponding clinical cyclotron for ocular or even deep-seated tumors.  
poster icon Poster MOPAB419 [0.806 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB419  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 13 August 2021  
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TUPAB177 Simulating Magnetized Electron Cooling for EIC with JSPEC electron, simulation, target, HOM 1813
 
  • S.J. Coleman, D.L. Bruhwiler, B. Nash, I.V. Pogorelov
    RadiaSoft LLC, Boulder, Colorado, USA
  • H. Zhang
    JLab, Newport News, Virginia, USA
  
  We present a possible electron cooling configuration for the proposed Electron Ion Collider (EIC) facility, developed using a Nelder-Mead Simplex optimization procedure built into JSPEC, an electron cooling code developed at Jefferson Lab. We show the time evolution of the emittance of the ion beam in the presence of this cooler evaluated assuming the ion distribution remains Gaussian. We also show that bi-gaussian distributions emerge in simulations of ion macro-particles. We show how intra-beam scattering can be treated with a core-tail model in simulations of ion macro-particles. The Sirepo/JSPEC* and Sirepo/Jupyter** apps will be presented, with instructions enabling the community to reproduce our simulations.
* https://www.sirepo.com/jspec
** https://www.sirepo.com/jupyter 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB177  
About • paper received ※ 19 May 2021       paper accepted ※ 15 June 2021       issue date ※ 16 August 2021  
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TUPAB323 Modular Type Quick Splicing Method for TPS Beamline Radiation Shielding Hutch radiation, shielding, synchrotron, neutron 2252
 
  • C.Y. Chang, C.H. Chang, S.H. Chang, C.L. Chen, Y.C. Lin, J.C. Liu, D.G. Liu, H.Y. Yan
    NSRRC, Hsinchu, Taiwan
  
  The synchrotron light source is transported to the experimental station through a beamline with specified optics, such as mask, mirror, slit, monochromator. Generally, standard beamline should use solid materials (stainless steel, tungsten, lead, and PE) to block bremsstrahlung and synchrotron radiations, even the neutron. The radiation-shielded hutch surrounds the peripheral area of the beamline with iron and lead panels. It requires blocking the scattering radiation to protect the person against radiation hazards. A modularized radiation shielding hutch includes the frame, wall, and ceiling cover that can assemble on-site through splicing. This method could greatly shorten the installation. Besides, we designed the modular ceiling cover units with a quick mounting/opening function to easily enable the maintenance and installation of large optical components. The details of the concept design for the fixed-point radiation shielding hutch in the TPS beamline are also reported that includes the configurations of the radiation shielding wall panels, frames, and pipes/cables arrangements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB323  
About • paper received ※ 13 May 2021       paper accepted ※ 10 June 2021       issue date ※ 21 August 2021  
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TUPAB392 Conceptual Design of the Vacuum System for the Future Circular Collider FCC-ee Main Rings vacuum, photon, collider, quadrupole 2438
 
  • R. Kersevan, C. Garion
    CERN, Geneva, Switzerland
  
  The Future Circular Collider study program comprises several machine concepts for the future of high-energy particle physics. Among them there is a twin-ring e−e+ collider capable to run at beam energies between 45.6 and 182.5 GeV, i.e. the energies corresponding to the resonances of the Z, W, H bosons and the top quark. The conceptual design of the two 100-km rings has advanced to what is believed to be a working solution, i.e. capability to deal with low-energy (45.6 GeV) high-current (1390 mA) version as well as the high-energy (182.5 GeV) low-current (5.4 mA) one, with intermediate energy and current steps for the other 2 resonances. The limit for all of the versions is given by the 50 MW/beam allotted to the synchrotron radiation (SR) losses. The paper will outline the main beam/machine parameters, the vacuum requirements, and the choices made concerning the vacuum chamber geometry, material, surface treatments, pumping system, and the related pressure profiles. The location of lumped SR photon absorbers for the generic arc cell has been determined. An outline of the studies needed and envisaged for the near future will also be given.  
poster icon Poster TUPAB392 [3.036 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB392  
About • paper received ※ 19 May 2021       paper accepted ※ 31 May 2021       issue date ※ 25 August 2021  
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TUPAB413 Rapid Browser-Based Visualization of Large Neutron Scattering Datasets neutron, experiment, network, detector 2494
 
  • D.L. Bruhwiler, K. Bruhwiler, P. Moeller, R. Nagler
    RadiaSoft LLC, Boulder, Colorado, USA
  • C.M. Hoffmann, Z.J. Morgan, A.T. Savici, M.G. Tucker
    ORNL, Oak Ridge, Tennessee, USA
  • A. Kuhn, J. Mensmann, P. Messmer, M. Nienhaus, S. Roemer, D. Tatulea
    NVIDIA, Santa Clara, USA
  
  Funding: This work is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0021551.
Neutron scattering makes invaluable contributions to the physical, chemical, and nanostructured materials sciences. Single crystal diffraction experiments collect volumetric scattering data sets representing the internal structure relations by combining datasets of many individual settings at different orientations, times and sample environment conditions. In particular, we consider data from the single-crystal diffraction experiments at ORNL.* A new technical approach for rapid, interactive visualization of remote neutron data is being explored. The NVIDIA IndeX 3D volumetric visualization framework** is being used via the HTML5 client viewer from NVIDIA, the ParaView plugin***, and new Jupyter notebooks, which will be released to the community with an open source license.
* L. Coates et al., Rev. Sci. Instrum. 89, 092802 (2018).
** https://developer.nvidia.com/nvidia-index
*** https://blog.kitware.com/nvidia-index-plugin-in-paraview-5-5 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB413  
About • paper received ※ 18 May 2021       paper accepted ※ 21 July 2021       issue date ※ 26 August 2021  
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WEXA07 Beam Background Measurements at SuperKEKB/Belle-II in 2020 background, luminosity, injection, detector 2532
 
  • H.N. Nakayama, T. Koga
    KEK, Ibaraki, Japan
  • K. Kojima
    Nagoya University, Nagoya, Japan
  • A. Natochii, S. Vahsen
    University of Hawaii, Honolulu,, USA
  
  The SuperKEKB electron-positron collider began collision operation in 2018 and achieved the world-record luminosity of 2.4x1034~cm-2s-1 in June 2020. We pursue higher luminosity by squeezing beam sizes and increasing beam currents. Beam backgrounds induced by stray particles will also increase and might cause severe radiation damage to Belle II detector components and worsen the quality of collected physics data. To mitigate these backgrounds, we have carefully designed our interaction region and installed movable collimators in the machine. We present recent measurements of beam background at SuperKEKB. We have performed dedicated machine studies to measure each background component separately and found that beam-gas scattering and Touschek scattering in the positron ring are the dominant sources of background rates in Belle II. We also present the latest observations of injection background, which determines the timing of a required Belle II data acquisition trigger veto and therefore affects the integrated luminosity. We show the beam background extrapolation toward the expected higher-luminosity operation and our plans for further background mitigation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA07  
About • paper received ※ 20 May 2021       paper accepted ※ 25 June 2021       issue date ※ 13 August 2021  
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WEPAB062 Investigation of the Thomson Scattering Influence on Electron Beam Parameters in an Energy-Recovering Linear Accelerator on the Example of MESA electron, photon, HOM, laser 2732
 
  • C.L. Lorey, K. Aulenbacher, A. Meseck
    KPH, Mainz, Germany
  
  Funding: funded by DFG through GRK2128 ACCELENCE
At the Johannes Gutenberg University (JGU) in Mainz, the Mainz Energy-recovering Superconducting Accelerator (MESA) is currently under construction. It is designed to deliver electron beams of up to 155 MeV. As it can be operated in an energy-recovery (ER) mode thus allowing for high repetition rate, it is a promising candidate for a high flux Thomson scattering based gamma source. This paper will provide a status update on the study of the impact of Thomson scattering on electron beam parameters and the underlying mechanics. Further, the implementation into a simulation code will be discussed. 		 
poster icon Poster WEPAB062 [1.307 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB062  
About • paper received ※ 19 May 2021       paper accepted ※ 12 July 2021       issue date ※ 02 September 2021  
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WEPAB080 Near Threshold Pion Photoproduction on Deuterons photon, experiment, multipole, polarization 2775
 
  • V. Shastri, V. Aswathi, S.P. Shilpashree
    Christ University, School of Engineering and Technology, Bangalore, India
  
  The study of photoproduction of mesons is a prime tool in understanding the properties of strong interactions. The only photoproduction reaction on deuteron with two-body final state is coherent pion photoproduction reaction. Several theoretical studies are being carried out on the pion photoproduction on deuterons since several decades. On the experimental side, the accelerator and detector technology has improved the developments. In the recent years, measurements of tensor analyzing powers associated with coherent and incoherent pion photoproduction are also being carried out at the VEPP-3 electron storage ring. In one of the recent measurements, Rachek et al"*" have observed discrepancy between theory and experiment at higher photon energies and have suggested for improvement of the theoretical models. In a more recent analysis,"**" the role of D-wave component on spin asymmetries have been identified. In view of these developments, the purpose of the present contribution is to study coherent pion photoproduction on deuterons using model independent irreducible tensor formalism developed earlier to study the photodisintegration of deuterons."***"
*I A Rachek et al., Few-Body Syst., 58, 29 (2017)
**H M Al Ghamdi et al, Brazillian Journal of Physics, 50, 615 (2020)
*** G Ramachandran, S P Shilpashree Phys. Rev. C 74, 052801(R) (2006) 		 
poster icon Poster WEPAB080 [0.203 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB080  
About • paper received ※ 29 May 2021       paper accepted ※ 01 July 2021       issue date ※ 16 August 2021  
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WEPAB157 Understanding the Growth Dynamics Cs-Sb Thin Films via In-Situ Characterization Techniques: Towards Epitaxial Alkali Antimonide Photocathodes electron, cathode, brightness, lattice 2979
 
  • A. Galdi, I.V. Bazarov, L. Cultrera, J.M. Maxson
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J. Balajka, W.J.I. DeBenedetti, M. Hines, C. Hu, L. Moreschini, H. Paik, C.T. Parzyck, K.M. Shen
    Cornell University, Ithaca, New York, USA
  
  Funding: National Science Foundation award PHY-1549132, the Center for Bright Beams and PARADIM, Cooperative Agreement No.DMR-1539918.
Alkali antimonide photocathodes, such as Cs3Sb, have attractive properties, such as low emittance and high quantum efficiency, which makes them excellent candidates for next-generation high-brightness electron sources. A large number of studies in literature focus on quantum efficiency and lifetime, and fewer report chemical and structural analysis, despite the latter ultimately determine the brightness at the photocathode. Epitaxial, single-crystalline films would allow to study the intrinsic properties of alkali antimonide photocathodes and to optimize them for maximum brightness, but this goal remains elusive. A strong limiting factor is the extreme air sensitivity, preventing ex-situ structural and chemical analysis. We report a study on the growth of Cs-Sb films via molecular beam epitaxy with reflection high-energy electron diffraction to monitor the growth in real time. The samples were characterized via in-situ ultraviolet photoelectron spectroscopy, x-ray photoelectron spectroscopy and scanning tunneling microscopy. Cs3Sb and CsSb phases can be stabilized on appropriate single crystal substrates, with the latter reproducibly resulting in atomically smooth surfaces. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB157  
About • paper received ※ 19 May 2021       paper accepted ※ 30 June 2021       issue date ※ 10 August 2021  
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WEPAB192 Simulation Study on Double Diffuser for Loss Reduction in Slow Extraction at J-PARC Main Ring simulation, extraction, operation, proton 3069
 
  • R. Muto, Y. Arakaki, T. Kimura, S. Murasugi, K. Okamura, Y. Shirakabe, M. Tomizawa, E. Yanaoka
    KEK, Tokai, Ibaraki, Japan
  • A. Matsumura
    Nihon Advanced Technology Co., Ltd, Ibaraki, Nakagun, Tokaimura, Japan
  
  J-PARC (Japan Proton Accelerator Research Complex) Main Ring delivers slow-extracted 30~GeV proton beam to various nuclear and particle physics experiments. In the slow extraction the beam loss at the electrostatic septum (ESS) is inevitable, and the beam loss reduction is a key issue to realize the high-intensity beam delivery. We carried out simulation studies on the effectiveness of the beam diffusers at the upstream of the ESS for the beam loss reduction with various materials and dimensions of the diffusers. We found out that putting two diffusers simultaneously on the beam was effective for the beam loss reduction, and the expected beam loss was 0.35 times as high as the operation without diffusers. According to the simulation results we installed the diffusers in the J-PARC Main Ring. We performed beam test with one diffuser and beam loss reduction of 60% was observed, which was in good agreement with the simulation results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB192  
About • paper received ※ 19 May 2021       paper accepted ※ 28 June 2021       issue date ※ 21 August 2021  
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WEPAB200 Study on the Measurement and Residual Dose of the CSNS Stripping Foil injection, MMI, neutron, simulation 3093
 
  • M.Y. Huang, L. Kang, S. Wang, Q.B. Wu, S.Y. Xu, Y.L. Zhang
    IHEP, Beijing, People’s Republic of China
  • J.X. Chen, W.L. Huang, H.C. Liu
    IHEP CSNS, Guangdong Province, People’s Republic of China
  
  Funding: This work was supported by National Natural Science Foundation of China (Project Nos. 12075134 and U1832210).
In this paper, firstly, the application and service life of the main stripping foil for the China Spallation Neutron Source (CSNS) were introduced. The stripping efficiency of the main stripping foil have been measured and studied. Then, by using the codes FLUKA and ORBIT, the particle scattering of the main stripping foil has been simulated and the theoretical residual doses in the injection region caused by the foil scattering were obtained. By weekly measurement of the residual doses in the injection region, the actual residual doses near the main stripping foil were given. The residual doses comparison results have confirmed that the particle scattering of the main stripping foil is the most important source of the residual doses in the injection region. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB200  
About • paper received ※ 09 May 2021       paper accepted ※ 25 August 2021       issue date ※ 23 August 2021  
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WEPAB210 Beam Commissioning of the New 160 MeV H− Injection System of the CERN PS Booster injection, emittance, simulation, brightness 3116
 
  • E. Renner, S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, G.P. Di Giovanni, L.O. Jorat, E.H. Maclean, M. Meddahi, B. Mikulec, T. Prebibaj, G. Rumolo, P.K. Skowroński, W.J.M. Weterings
    CERN, Meyrin, Switzerland
  
  A key component to meeting the brightness targets of the LHC Injectors Upgrade (LIU) project at CERN is the new 160 MeV H− charge exchange injection system into the Proton Synchrotron Booster. This system has been in beam commissioning since December 2020, optimizing the beam production schemes for tailoring different beams to the respective user-defined brightness targets. In this paper, selected measurements from the beam commissioning period are presented, characterizing the system’s flexibility to produce the required wide range of transverse emittances. The discussion focuses on the essential optimization of the injection set-up to minimize space charge driven emittance blow-up and injection errors. The results are completed by selected comparisons with multi-particle simulation models of the injection process.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB210  
About • paper received ※ 19 May 2021       paper accepted ※ 19 July 2021       issue date ※ 29 August 2021  
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WEPAB215 Simulation of Intra-Beam Scattering in PyHEADTAIL emittance, simulation, space-charge, proton 3134
 
  • V. Rodin, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • A. Oeftiger
    GSI, Darmstadt, Germany
  • V. Rodin, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 721559
High-intensity beams in low-energy synchrotrons are subject to space charge as well as intra-beam scattering (IBS). Accurate modelling of both effects becomes essential when the transverse emittances and minimum bunch length are determined through heating processes and resonances induced by machine errors. To date, only very few tools available to the general public allow to simultaneously study space charge and IBS in self-consistent simulations. In this contribution, we present our recent development of an IBS module for PyHEADTAIL, an open-source 6D multi-particle tracking tool, which already includes various 2.5D and 3D space-charge models based on the self-consistent particle-in-cell algorithm. A simulation example of high-intensity bunch rotation demonstrates the joint impact of applied heating effects. Our model is based on the Martini and Bjorken-Mitingwa theories. Benchmarks of our implementation against IBS modules provided in the MAD-X and JSPEC codes are shown. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB215  
About • paper received ※ 23 May 2021       paper accepted ※ 14 July 2021       issue date ※ 13 August 2021  
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WEPAB216 6D Simulations of PIP-II Booster Injection injection, controls, booster, closed-orbit 3138
 
  • J.-F. Ostiguy, D.E. Johnson
    Fermilab, Batavia, Illinois, USA
  
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The PIP-II superconducting linac will deliver 2 mA average H- beam current at 800 MeV to the existing Booster synchrotron over a period of 0.55 ms (285 turns). As a result, the injected beam power will quadruple to 17 kW. Safe operation at the increased beam power implies careful attention to the origin, magnitude, and distribution of both controlled and uncontrolled losses. Uncontrolled losses are due to neutral ions in excited states stripped in downstream magnets and large angle scattered protons from parasitic foil hits. The relative magnitudes of these loss mechanisms is used to determine the optimal foil thickness. A transverse painting scheme involving closed orbit motion will be used to mitigate space charge effects and minimize parasitic foil hits. Using a detailed full 6D simulation of the injection process, we compute large angle scattering losses and compare results to back of the envelope estimates. We investigate possible impact of space charge on the emittance and beam distribution both during and at the conclusion of the injection period. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB216  
About • paper received ※ 20 May 2021       paper accepted ※ 24 June 2021       issue date ※ 10 August 2021  
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WEPAB228 Modelling and Counteracting Microbunching Instability in Spreader Lines of Radiofrequency and Plasma-Based Accelerators for Free-Electron Lasers electron, bunching, laser, free-electron-laser 3165
 
  • G. Perosa
    Università degli Studi di Trieste, Trieste, Italy
  • S. Di Mitri
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  
  High energy radiofrequency and plasma-driven accelerators target electron beam brightness suitable for x-ray free-electron lasers. Microbunching instability can be enhanced during beam transport through the spreader line from the accelerator to the undulator, degrading the brightness of the accelerated beam and therefore reducing the lasing efficiency. We present a semi-analytical model of the instability, benchmarked with experimental data at the FERMI free-electron laser, in the presence of intrabeam scattering and beam heating. Strategies for minimization of the instability both in conventional and plasma-based accelerators are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB228  
About • paper received ※ 19 May 2021       paper accepted ※ 08 July 2021       issue date ※ 02 September 2021  
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WEPAB272 Field-Off Multiple Coulomb Scattering in the MICE Liquid Hydrogen Absorber experiment, emittance, beam-cooling, radiation 3277
 
  • G.T. Chatzitheodoridis
    USTRAT/SUPA, Glasgow, United Kingdom
  
  It is anticipated that high brightness muon beams will be used primarily in two types of accelerators, a muon collider and a neutrino factory. The primary challenge posed by using muons as the working particle of an accelerator physics system, and the reason it has not been used extensively in modern particle physics experiments, is its short life-time (2.2μseconds at rest) and the relatively long cooling periods required by current cooling techniques. The Muon Ionization Cooling Experiment (MICE), is a multi-national accelerator physics initiative which has demonstrated Ionization Cooling (IC); a new, rapid beam-cooling technique suitable for the short-lived muon. The performance of IC depends on two key processes - energy loss due to collisional ionization, and Multiple Coulomb Scattering (MCS) - for which accurate models are crucial in parametrizing the method and enabling quantitative design of future muon accelerators. Experimental measurements of MCS of positive straight-track muons with momenta in the range 170-240 MeV/c in liquid H2 are reported in this study.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB272  
About • paper received ※ 19 May 2021       paper accepted ※ 19 July 2021       issue date ※ 31 August 2021  
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WEPAB360 Future Prospective for Bent Crystals in Accelerators lattice, collimation, experiment, SRF 3545
 
  • M. Romagnoni
    INFN-Ferrara, Ferrara, Italy
  • M. Romagnoni
    Universita’ degli Studi di Milano, Milano, Italy
  
  Super magnet dipoles employed to steer high energy particle beams are massive instruments requiring cryogenic cooling and featuring large energy consumption. A bent crystal has the potential in a few millimeters to deflect 100-1000 GeV particle beams as much as an hundreds-tesla magnetic dipole. Indeed, within the lattice of a crystal, large electric fields up to several GeV/cm are present. Positive charged particles can be efficiently channeled between two adjacent lattice planes, thus following their curvature. These features and the possibility to selectively affect only the portion of the beam intercepting the crystal led to the proposal of exploiting bent crystals for several purposes, such as the collimation of ions at LHC. In this scheme, the particles on the beam halo instead of being scattered by tens-centimeters long collimators are directly separated from the beam using a 4 mm long silicon crystal. The production of a bent crystal suitable for installation in the LHC beamline requires strict control over lattice features and bending apparatus. The results obtained by the years long research of the INFN research team in Ferrara are presented in this work.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB360  
About • paper received ※ 14 May 2021       paper accepted ※ 28 July 2021       issue date ※ 18 August 2021  
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WEPAB410 Finite Element Analyses of Synchrotron Radiation Induced Stress in Beryllium Synch-Light Mirrors dipole, simulation, synchrotron, operation 3664
 
  • Y. Lushtak, Y. Li, A. Lyndaker
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Air Force Research Laboratory Directorate for Mathematical and Physical Sciences National Institute of General Medical Sciences Empire State Development - NYSTAR
Mirrors made of high purity beryllium are used in particle accelerators to extract synchrotron radiation (SR) in the visible range for transverse and longitudinal particle beam profile measurements. Be is a high-strength, high thermal conductivity material. As a low-Z metal, it allows high-energy photons to penetrate the mirror body, so that majority of the SR power is dissipated, resulting in a significantly reduced thermal stress and distortion on the mirror surface. In this paper, we describe a Finite Element Analysis method of accurately simulating the SR-induced thermal stress on the beryllium mirrors at the Cornell Electron Storage Ring at various particle beam conditions. The simulations consider the energy dependence of X-ray attenuation in beryllium. The depth-dependent distribution of the power absorbed by the mirror is represented by separate heating zones within the mirror model. The results help set the operational safety limit for the mirrors-ensuring that the SR-induced thermal stress is below the elastic deformation limit and estimate the mirror surface distortion at high beam currents. The simulated surface distortion is consistent with optical measurements. 		 
poster icon Poster WEPAB410 [0.942 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB410  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 02 September 2021  
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THXA04 Microbunching Instability in the Presence of Intrabeam Scattering for Single-Pass Accelerators electron, bunching, FEL, simulation 3692
 
  • C.-Y. Tsai
    HUST, Wuhan, People’s Republic of China
  • W. Qin
    Lund University, Lund, Sweden
  
  Funding: This work is supported by the Fundamental Research Funds for the Central Universities under Project No. 5003131049 and National Natural Science Foundation of China under project No. 11905073.
Intrabeam scattering (IBS) has long been studied in lepton or hadron storage rings as a slow diffusion process, while the effects of IBS on single-pass or recirculating electron accelerators have drawn attention only in the recent two decades due to the emergence of linac-based or ERL-based 4th-generation light sources, which require high-quality electron beams during the beam transport. Recent experimental measurements indicate that in some parameter regimes, IBS can have a significant influence on microbunched beam dynamics. Here we develop a theoretical formulation* of microbunching instability (MBI) in the presence of IBS for single-pass accelerators. We start from the Vlasov-Fokker-Planck (VFP) equation, combining both collective longitudinal space charge and incoherent IBS effects. The linearized VFP equation with the corresponding coefficients is derived. The evolutions of the phase space density and energy modulations are formulated as a set of coupled integral equations. The formulation** is then applied to a simplified single-pass transport line. The results from the semi-analytical calculation are compared and show good agreement with particle tracking simulations.
* C.-Y. Tsai et al., Phys. Rev. Accel. Beams 23, 124401 (2020)
** C.-Y. Tsai and W. Q, Phys. Plasmas (2021), accepted for publication 		 
slides icon Slides THXA04 [2.699 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA04  
About • paper received ※ 13 May 2021       paper accepted ※ 19 July 2021       issue date ※ 13 August 2021  
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THXC05 Simulation of Imaging Using Accelerated Muon Beams acceleration, simulation, linac, radio-frequency 3740
 
  • M. Otani
    KEK, Tokai, Ibaraki, Japan
  • H.M. Miyadera
    LANL, Los Alamos, New Mexico, USA
  • T. Shiba
    Japan Atomic Energy Agency, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  
  Muons are elementary particles with strong penetrating power and cosmic-ray muons have been utilized to see through large structures such as the pyramids. Recently, we have succeeded in accelerating muons using a radio-frequency accelerator, opening the door to new imaging techniques using accelerated muon beams. Currently, imaging with cosmic-ray muons is limited in imaging time and resolution by their intensity and energy fluctuations. The muon beams can have high intensity and monochromatic energy, allowing for better resolution imaging in less time. In this poster, imaging of spent nuclear fuel in casks using cosmic rays and muon beams, as well as imaging in other cases, will be evaluated and compared.  
poster icon Poster THXC05 [2.560 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXC05  
About • paper received ※ 16 May 2021       paper accepted ※ 19 July 2021       issue date ※ 15 August 2021  
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THPAB009 A Hard X-Ray Compton Source at CBETA electron, photon, laser, brilliance 3765
 
  • K.E. Deitrick, C. Franck, G.H. Hoffstaetter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J. Crone, H.L. Owen
    UMAN, Manchester, United Kingdom
  • G.A. Krafft
    JLab, Newport News, Virginia, USA
  • G.A. Krafft, B. Terzić
    ODU, Norfolk, Virginia, USA
  • B.D. Muratori, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • B.D. Muratori, P.H. Williams
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  Inverse Compton scattering (ICS) holds the potential for future high flux, narrow bandwidth x-ray sources driven by high quality, high repetition rate electron beams. CBETA, the Cornell-BNL Energy recovery linac (ERL) Test Accelerator, is the world’s first superconducting radiofrequency multi-turn ERL, with a maximum energy of 150 MeV, capable of ICS production of x-rays above 400 keV. We present an update on the bypass design and anticipated parameters of a compact ICS source at CBETA. X-ray parameters from the CBETA ICS are compared to those of leading synchrotron radiation facilities, demonstrating that, above a few hundred keV, photon beams produced by ICS outperform those produced by undulators in term of flux and brilliance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB009  
About • paper received ※ 19 May 2021       paper accepted ※ 06 July 2021       issue date ※ 10 August 2021  
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THPAB063 Laser Transport System of Shanghai Laser Electron Gamma Source (SLEGS) laser, detector, controls, feedback 3897
 
  • H.H. Xu, G.T. Fan
    SSRF, Shanghai, People’s Republic of China
  
  Shanghai Laser Electron Gamma Source (SLEGS) *, based on laser Compton scattering (LCS), as one of beamlines of Shanghai Synchrotron Radiation Facility (SSRF) in phase II, is under construction now. The technical design of its laser injection system has been implemented and optimized consecutively over the last few years. In order to inject the 10640 nm CO2 laser into the interaction point from the laser hutch outside the storage ring’s shielding, a laser transport system longer than 20 m using relay-imaging telescopes is designed. There are two operation mode in SLEGS. One is backscattering mode, which will make the laser and electron bunch collide at 180° with flux higher than 107 gamma/s. The other mode is slanting mode, which mainly inherits the design used in the prototype**. In this paper, a brief summary of the laser transport system is given. The system contains several modules to perform beam expansion, combining, monitoring and real-time adjustment. The design models, simulation study of the laser quality through the transporta-tion, and the experimental results are presented.
* Y. Xu, W. Xu, et al., NIM A, 578, 457 (2007).
** H.H. Xu, J.H. Chen, et al., Transaction on Nuclear Science, IEEE, 63, 906 (2016). 		 
poster icon Poster THPAB063 [2.508 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB063  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 27 August 2021  
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THPAB176 Studies on Beam Collimation System for the ESSnuSB Accumulator collimation, proton, linac, simulation 4107
 
  • Y. Zou, M. Olvegård
    Uppsala University, Uppsala, Sweden
  
  Funding: This work is supported by the European Union Horizon 2020 research and innovation program under grant agreement No 777419.
The ESSnuSB, a neutrino facility based on the European Spallation Source, aims at measuring, with precision, the charge-parity (CP) violating lepton phase at the 2nd oscillation maximum. The ESS linac will have to be upgraded to provide an additional 5 MW beam for the ESSnuSB to produce an unprecedented high-intensity neutrino beam. An accumulator ring is employed to compress the 2.86 ms long pulse from the linac to around 1.5 µs in order to satisfy the target requirements and improve the physics performance. In the operation of a high-intensity proton accumulator, the most important issue is to minimize the uncontrolled beam loss to reduce component activation to make hands-on maintenance possible. For this purpose, a two-stage collimation system is designed, which consists of a thin scraper to scatter halo particles and secondary collimators to absorb those scattered particles. Phase advances between scraper and secondary collimators, together with the material, the thickness of collimators, have been detailed studied and numerical simulations have been performed to evaluate the performance of the collimation system. This paper presents the design of the collimation system. 		 
poster icon Poster THPAB176 [5.022 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB176  
About • paper received ※ 11 May 2021       paper accepted ※ 21 June 2021       issue date ※ 01 September 2021  
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THPAB203 Update of the Tracking Code RF-Track laser, wakefield, simulation, space-charge 4180
 
  • A. Latina
    CERN, Geneva, Switzerland
  
  During the last couple of years, the RF-Track particle tracking code has seen a tremendous increase in the number of its applications: medical linacs, compact injector electron guns, and positron sources are among the main ones. Following a work of consolidation of its internal structure, new simulation capabilities have been introduced, together with several new effects: arbitrary orientation of elements in space, full element overlap, short- and long-range wakefields, and laser-beam interaction through Compton scattering are the most significant ones. In this paper, some of these new features are presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB203  
About • paper received ※ 14 May 2021       paper accepted ※ 02 August 2021       issue date ※ 01 September 2021  
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THPAB270 Pair Spectrometer for FACET-II electron, positron, detector, photon 4336
 
  • B. Naranjo, G. Andonian, A. Fukasawa, N. Majernik, M.H. Oruganti, J.B. Rosenzweig, Y. Sakai, O. Williams, M. Yadav
    UCLA, Los Angeles, California, USA
  • N. Cavanagh, G. Sarri
    Queen’s University of Belfast, Belfast, Northern Ireland, United Kingdom
  • A. Di Piazza, C.H. Keitel
    MPI-K, Heidelberg, Germany
  • E. Gerstmayr, S. Meuren, D.A. Reis, D.W. Storey, V. Yakimenko
    SLAC, Menlo Park, California, USA
  • R. Holtzapple
    CalPoly, San Luis Obispo, California, USA
  • C. Nielsen
    AU, Aarhus, Denmark
  
  Funding: DARPA GRIT Contract 20204571, DOE HEP Grant DE-SC0009914
We present the design of a pair spectrometer for use at FACET-II, where there is a need for spectroscopy of photons having energies up to 10 GeV. Incoming gammas are converted to high-energy positron-electron pairs, which are then subsequently analyzed in a dipole magnet. These charged particles are then recorded in arrays of acrylic Cherenkov counters, which are significantly less sensitive to background x-rays than scintillator counters in this case. To reconstruct energies of single high-energy photons, the spectrometer has a sensitivity to single positron-electron pairs. Even in this single-photon limit, there is always some low-energy continuum present, so spectral deconvolution is not trivial, for which we demonstrate a maximum likelihood reconstruction. Finally, end-to-end simulations of experimental scenarios, together with anticipated backgrounds, are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB270  
About • paper received ※ 20 May 2021       paper accepted ※ 28 July 2021       issue date ※ 18 August 2021  
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