WEPAB —  Wednesday Poster Session   (26-May-21   08:00—10:00)
Paper Title Page
WEPAB001 Accelerator Challenges of the LHeC Project 2570
 
  • B.J. Holzer, K.D.J. André, O.S. Brüning
    CERN, Geneva, Switzerland
  • S.A. Bogacz
    JLab, Newport News, Virginia, USA
  • M. Klein
    The University of Liverpool, Liverpool, United Kingdom
 
  The LHeC project studies the design of a future electron-proton collider at CERN that will run in parallel to the standard LHC operation. For this purpose, the existing LHC storage ring will be combined with an Energy Recovery Linac (ERL), to accelerate electrons up to kinetic energy of 50 GeV. This concept - also applicable to the FCC-eh collider and studied at the PERLE project as prototype version - allows a peak luminosity of 1034 cm-2 s-1. A sophisticated design of the RF structures, linacs, arcs, and interaction region is required. The electrons are accelerated and, after the interaction point, their energy is recovered through the same RF structures. While this energy recovery concept is a very promising approach, severe challenges are set by the layout of the interaction region, the beam separation concept and the design of the linac and arc lattice for the highest possible momentum acceptance. Emittance control and beam-beam effect of both, electron and proton beams, have been studied in front-to-end simulations and will be presented. We summarise the design principles of the ERL, the optimization of the arc lattice, and the main parameters of the project.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB001  
About • paper received ※ 17 May 2021       paper accepted ※ 21 June 2021       issue date ※ 31 August 2021  
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WEPAB002 The Interaction Region of the Electron-Ion Collider EIC 2574
 
  • H. Witte, J. Adam, M. Anerella, E.C. Aschenauer, J.S. Berg, M. Blaskiewicz, A. Blednykh, W. Christie, J.P. Cozzolino, K.A. Drees, D.M. Gassner, K. Hamdi, C. Hetzel, H.M. Hocker, D. Holmes, A. Jentsch, A. Kiselev, P. Kovach, H. Lovelace III, Y. Luo, G.J. Mahler, A. Marone, G.T. McIntyre, C. Montag, R.B. Palmer, B. Parker, S. Peggs, S.R. Plate, V. Ptitsyn, G. Robert-Demolaize, C.E. Runyan, J. Schmalzle, K.S. Smith, S. Tepikian, P. Thieberger, J.E. Tuozzolo, F.J. Willeke, Q. Wu, Z. Zhang
    BNL, Upton, New York, USA
  • B.R. Gamage, T.J. Michalski, V.S. Morozov, M.L. Stutzman, W. Wittmer
    JLab, Newport News, Virginia, USA
  • M.K. Sullivan
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
This paper presents an overview of the Interaction Region (IR) design for the planned Electron-Ion Collider (EIC) at Brookhaven National Laboratory. The IR is designed to meet the requirements of the nuclear physics community *. The IR design features a ±4.5 m free space for the detector; a forward spectrometer magnet is used for the detection of hadrons scattered under small angles. The hadrons are separated from the neutrons allowing detection of neutrons up to ±4 mrad. On the rear side, the electrons are separated from photons using a weak dipole magnet for the luminosity monitor and to detect scattered electrons (e-tagger). To avoid synchrotron radiation backgrounds in the detector no strong electron bending magnet is placed within 40 m upstream of the IP. The magnet apertures on the rear side are large enough to allow synchrotron radiation to pass through the magnets. The beam pipe has been optimized to reduce the impedance; the total power loss in the central vacuum chamber is expected to be less than 90 W. To reduce risk and cost the IR is designed to employ standard NbTi superconducting magnets, which are described in a separate paper.
* An Assessment of U.S.-Based Electron-Ion Collider Science. (2018). Washington, D.C.: National Academies Press. https://doi.org/10.17226/25171
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB002  
About • paper received ※ 18 May 2021       paper accepted ※ 25 June 2021       issue date ※ 27 August 2021  
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WEPAB003 Overview of the Magnets Required for the Interaction Region of the Electron-Ion Collider (EIC) 2578
 
  • H. Witte, K. Amm, M. Anerella, J. Avronsart, A. Ben Yahia, J.P. Cozzolino, R.C. Gupta, H.M. Hocker, P. Kovach, G.J. Mahler, A. Marone, R.B. Palmer, B. Parker, S.R. Plate, C.E. Runyan, J. Schmalzle
    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.
The planned electron-ion collider (EIC) at Brookhaven National Laboratory (BNL) is designed to deliver a peak luminosity of 1x1034 cm-2 s-1. This paper presents an overview of the magnets required for the interaction region of the BNL EIC. To reduce risk and cost the IR is designed to employ conventional NbTi superconducting magnets. In the forward direction the magnets for the hadrons are required to pass a large neutron cone and particles with a transverse momentum of up to 1.3 GeV/c, which leads to large aperture requirements. In the rear direction the synchrotron radiation fan produced by the electron beam must not hit the magnet apertures, which determines their aperture. For the forward direction a mostly interleaved scheme is used for the optics, whereas for the rear side 2-in-1 magnets are employed. We present an overview of the EIC IR magnet design including the forward spectrometer magnet B0.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB003  
About • paper received ※ 18 May 2021       paper accepted ※ 01 July 2021       issue date ※ 15 August 2021  
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WEPAB004 Electron-Ion Luminosity Maximization in the EIC 2582
 
  • W. Fischer, E.C. Aschenauer, M. Blaskiewicz, K.A. Drees, A.V. Fedotov, H. Huang, C. Montag, V. Ptitsyn, D. Raparia, V. Schoefer, K.S. Smith, P. Thieberger, F.J. Willeke
    BNL, Upton, New York, USA
  • Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The electron-ion luminosity in EIC has a number of limits, including the ion intensity available from the injectors, the total ion beam current, the electron bunch intensity, the total electron current, the synchrotron radiation power, the beam-beam effect, the achievable beta functions at the interaction points (IPs), the maximum angular spreads at the IP, the ion emittances reachable with stochastic or strong cooling, the ratio of horizontal to vertical emittance, and space charge effects. We map the e-A luminosity over the center-of-mass energy range for some ions ranging from deuterons to uranium ions. For e-Au collisions the present design provides for electron-nucleon (e-Au) peak luminosities of 1.7x1033 cm-2s−1 with stochastic cooling, and 4.7x1033 cm-2s−1 with strong hadron cooling.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB004  
About • paper received ※ 18 May 2021       paper accepted ※ 21 June 2021       issue date ※ 02 September 2021  
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WEPAB005 Design Status Update of the Electron-Ion Collider 2585
 
  • C. Montag, E.C. Aschenauer, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A. Blednykh, J.M. Brennan, S.J. Brooks, K.A. Brown, Z.A. Conway, K.A. Drees, A.V. Fedotov, W. Fischer, C. Folz, D.M. Gassner, X. Gu, R.C. Gupta, Y. Hao, A. Hershcovitch, C. Hetzel, D. Holmes, H. Huang, W.A. Jackson, J. Kewisch, Y. Li, C. Liu, H. Lovelace III, Y. Luo, M. Mapes, D. Marx, G.T. McIntyre, F. Méot, M.G. Minty, S.K. Nayak, R.B. Palmer, B. Parker, S. Peggs, B. Podobedov, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, S. Seletskiy, V.V. Smaluk, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, S. Verdú-Andrés, E. Wang, D. Weiss, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman, W. Zhang
    BNL, Upton, New York, USA
  • S.V. Benson, J.M. Grames, F. Lin, T.J. Michalski, V.S. Morozov, E.A. Nissen, J.P. Preble, R.A. Rimmer, T. Satogata, A. Seryi, M. Wiseman, W. Wittmer, Y. Zhang
    JLab, Newport News, Virginia, USA
  • Y. Cai, Y.M. Nosochkov, G. Stupakov, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  • K.E. Deitrick, C.M. Gulliford, G.H. Hoffstaetter, J.E. Unger
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • E. Gianfelice-Wendt
    Fermilab, Batavia, Illinois, USA
  • T. Satogata
    ODU, Norfolk, Virginia, USA
  • D. Xu
    FRIB, East Lansing, Michigan, USA
 
  Funding: Work supported by BSA, LLC under Contract No. DE-SC0012704, by JSA, LLC under Contract No. DE-AC05-06OR23177, and by SLAC under Contract No. DE-AC02-76SF00515 with the U.S. Department of Energy.
The design of the electron-ion collider EIC to be constructed at Brookhaven National Laboratory has been continuously evolving towards a realistic and robust design that meets all the requirements set forth by the nuclear physics community in the White Paper. Over the past year activities have been focused on maturing the design, and on developing alternatives to mitigate risk. These include improvements of the interaction region design as well as modifications of the hadron ring vacuum system to accommodate the high average and peak beam currents. Beam dynamics studies have been performed to determine and optimize the dynamic aperture in the two collider rings and the beam-beam performance. We will present the EIC design with a focus on recent developments.
 
poster icon Poster WEPAB005 [2.095 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB005  
About • paper received ※ 14 May 2021       paper accepted ※ 22 June 2021       issue date ※ 17 August 2021  
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WEPAB006 EIC Crab Cavity Multipole Analysis 2589
 
  • Q. Wu, Y. Luo, B.P. Xiao
    BNL, Upton, New York, USA
  • S.U. De Silva
    ODU, Norfolk, Virginia, USA
  • J.A. Mitchell
    CERN, Geneva, Switzerland
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Crab cavities are specialized RF devices designed for colliders targeting high luminosities. It is a straightforward solution to retrieve head-on collision with crossing angle existing to fast separate both beams after collision. The Electron Ion Collider (EIC) has a crossing angle of 25 mrad, and will use local crabbing to minimize the dynamic aperture requirement throughout the rings. The current crab cavity design for the EIC lacks axial symmetry. Therefore, their higher order components of the fundamental deflecting mode have a potential of affecting the long-term beam stability. We present here the multipole analysis and preliminary particle tracking results from the current crab cavity design.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB006  
About • paper received ※ 18 May 2021       paper accepted ※ 25 June 2021       issue date ※ 12 August 2021  
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WEPAB008 Numerical Noise Study in EIC Beam-Beam Simulations 2592
 
  • D. Xu, Y. Hao
    FRIB, East Lansing, Michigan, USA
  • Y. Luo, C. Montag
    BNL, Upton, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  In the Electron-Ion Collider (EIC) design, a flat beam collision scheme is adopted to achieve 1e34 luminosity. We found that the vertical growth of the proton beam is much larger than of the round beam. In this article we present the numerical noise study about the number of macroparticles, the electron slice number, and the electron bunch length. Both weak-strong and strong-strong simulation methods are used. It turns out the proton emittance growth in the strong-strong simulation mainly comes from the numberical noise. This study helps us to perform beam-beam simulation correctly for EIC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB008  
About • paper received ※ 17 May 2021       paper accepted ※ 16 August 2021       issue date ※ 31 August 2021  
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WEPAB009 Study of Harmonic Crab Cavity in EIC Beam-Beam Simulations 2595
 
  • D. Xu, Y. Hao
    FRIB, East Lansing, Michigan, USA
  • Y. Luo, C. Montag
    BNL, Upton, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  In the Electron-Ion Collider (EIC) design, crab cavities are adopted to compensate the geometric luminosity loss from the crossing angle. From previous studies, higher-order synchro-betatron resonances are excited since the hadron beam is long and the crossing angle is large. To reduce the luminosity degradation rate, different combinations of harmonic crab cavities are studied with both weak-strong and strong-strong simulation methods. The frequency map analysis (FMA) is also used for comparison. This study helps determine the crab cavity parameters for the future EIC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB009  
About • paper received ※ 17 May 2021       paper accepted ※ 23 June 2021       issue date ※ 30 August 2021  
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WEPAB010 Full Range Tune Scan Studies Using Graphics Processing Units with CUDA in EIC Beam-Beam Simulations 2598
 
  • D. Xu, Y. Hao
    FRIB, East Lansing, Michigan, USA
  • Y. Luo, C. Montag
    BNL, Upton, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  The hadron beam in the Electron-Ion Collider (EIC) suffers high order betatron and synchro-betatron resonances. In this paper, we present a weak-strong full range (0.0~0.5) fractional tune scan with a step size as small as 0.001. Multiple Graphics Processing Units (GPUs) are used to speed up the simulation. A code parallelized with MPI and CUDA is implemented. The good tune region from weak-strong scan is further checked by the self-consistent strong-strong simulation. This study provides beam dynamics guidance in choosing proper working points for the future EIC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB010  
About • paper received ※ 17 May 2021       paper accepted ※ 23 June 2021       issue date ※ 23 August 2021  
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WEPAB011 Update on the Low Emittance Tuning of the e⁺/e⁻ Future Circular Collider 2601
 
  • T.K. Charles
    The University of Liverpool, Liverpool, United Kingdom
  • B.J. Holzer, F. Zimmermann
    CERN, Geneva, Switzerland
  • K. Oide
    KEK, Ibaraki, Japan
 
  The FCC-ee project studies the design of a future 100 km e+/e circular collider for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 1035 cm-2 s−1. To achieve ultra-low vertical emittance a highly effective emittance tuning scheme is required. In this paper, we describe a comprehensive correction strategy used for the low emittance tuning. The strategy includes Dispersion Free Steering, linear coupling compensation based on Resonant Driving Terms and beta beat correction utilising response matrices.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB011  
About • paper received ※ 18 May 2021       paper accepted ※ 23 June 2021       issue date ※ 16 August 2021  
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WEPAB012 Preliminary Investigation into Accelerators for In-Situ Cultural Heritage Research 2605
 
  • T.K. Charles
    The University of Liverpool, Liverpool, United Kingdom
  • A. Castilla
    CERN, Meyrin, Switzerland
  • A. Castilla
    Lancaster University, Lancaster, United Kingdom
 
  Ion Beam Analysis (IBA) centres have provided researchers with powerful techniques to analyse objects of cultural significance in a non-destructive and non-invasive manner. However, in some cases it is not be feasible to remove an object from the field or museum and transport it to the laboratory. In this conference proceedings, we report the initial results of an investigation into the feasibility of a compact accelerator that can be taken to sites of cultural significance, for PIXE analysis. In particular, we consider the application of a compact, robust accelerator that is capable to producing 2 MeV protons that can be taken into the field to perform PIXE measurements on rock art. We detail the main challenges and considerations for such a device, as well as highlighting the potential benefits of this new accelerator application.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB012  
About • paper received ※ 18 May 2021       paper accepted ※ 25 June 2021       issue date ※ 29 August 2021  
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WEPAB013 A New Algorithm for Positron Source Parameter Optimisation 2609
 
  • Y. Zhao, L. Ma
    SDU, Shandong, People’s Republic of China
  • S. Döbert, A. Latina
    CERN, Geneva, Switzerland
 
  In this report, we proposed a new simple and efficient algorithm for positron source parameter optimisation, which is based on iterations of scan of free parameters in the simulation. The new algorithm is fast, simple and convincing since the results can be visually drawn and flexibly tuned and it has an advantage that it can easily handle realistic parametric problems with more than one objective quantities to optimise. The optimisation of the main parameters of the CLIC positron source at the 380 GeV stage is presented as an example to demonstrate how the algorithm works.  
poster icon Poster WEPAB013 [1.352 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB013  
About • paper received ※ 15 May 2021       paper accepted ※ 24 June 2021       issue date ※ 19 August 2021  
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WEPAB014 Optimisation of the CLIC Positron Source 2613
 
  • Y. Zhao, L. Ma
    SDU, Shandong, People’s Republic of China
  • H.M.A. Bajas, S. Döbert, A. Latina
    CERN, Geneva, Switzerland
 
  In this report, we reoptimised the CLIC positron source at all collision energy stages. Simulation, optimisation algorithm and results were all improved compared with previous studies. Two different target schemes were studied and compared in terms of the advantages and disadvantages. The spot size of the injected electron beam was also optimised to achieve a compromise between large positron yields and safe energy deposition. The matching device for the capture of positrons was simulated and optimised with both improved analytic and realistic field maps. Conical aperture and front and rear gaps of the matching device were also considered for the first time. The optimised positron source is expected to have the lowest cost.  
poster icon Poster WEPAB014 [1.825 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB014  
About • paper received ※ 15 May 2021       paper accepted ※ 21 June 2021       issue date ※ 23 August 2021  
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WEPAB015 Comparison of Different Matching Device Field Profiles for the FCC-ee Positron Source 2617
 
  • Y. Zhao, L. Ma
    SDU, Shandong, People’s Republic of China
  • B. Auchmann, P. Craievich, J. Kosse, R. Zennaro
    PSI, Villigen PSI, Switzerland
  • I. Chaikovska, R. Chehab
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • S. Döbert, A. Latina
    CERN, Meyrin, Switzerland
  • P.V. Martyshkin
    BINP SB RAS, Novosibirsk, Russia
 
  In this report, we compared different matching device field profiles for the FCC-ee positron source. The matching device is used to capture positrons with magnetic field. A flux concentrator was designed with a conical inner chamber. A smaller aperture and a larger aperture were studied. An analytic field profile was also studied using an adiabatic formula. The peak field of the analytic profile as well as beam and target parameters was optimised to achieve a maximum positron yield. A safe energy deposition in the target was guaranteed by requiring a constraint on the deposited power and peak energy deposition density.  
poster icon Poster WEPAB015 [3.066 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB015  
About • paper received ※ 15 May 2021       paper accepted ※ 23 June 2021       issue date ※ 12 August 2021  
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WEPAB016 Snowmass’21 Accelerator Frontier 2621
 
  • V.D. Shiltsev
    Fermilab, Batavia, Illinois, USA
  • S.A. Gourlay
    LBNL, Berkeley, California, USA
  • T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
 
  Snowmass’21 is decadal particle physics community planning study. It provides an opportunity for the entire particle physics community to come together to identify and document a scientific vision for the future of particle physics in the U.S. and its international partners. Snowmass will define the most important questions for the field of particle physics and identify promising opportunities to address them. The P5, Particle Physics Project Prioritization Panel, will take the scientific input from Snowmass and develop a strategic plan for U.S. particle physics that can be executed over a 10 year timescale, in the context of a 20-year global vision for the field. Here we present the goals, progress and plans of the Snowmass’21 Accelerator Frontier.  
poster icon Poster WEPAB016 [1.108 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB016  
About • paper received ※ 17 May 2021       paper accepted ※ 23 June 2021       issue date ※ 18 August 2021  
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WEPAB017 General Approach to Physics Limits of Ultimate Colliders 2624
 
  • V.D. Shiltsev
    Fermilab, Batavia, Illinois, USA
 
  The future of the particle physics is critically dependent on feasibility of future energy frontier colliders. The concept of the feasibility is complex and includes at least three factors: feasibility of energy, feasibility of luminosity, and feasibility of cost and construction time. Here we discuss major beam physics limits of ultimate accelerators, take a look into ultimate energy reach of possible future colliders. We also foresee a looming paradigm change for the HEP research as the thrust for higher energies by necessity will mean lower luminosity.  
poster icon Poster WEPAB017 [1.720 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB017  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 14 August 2021  
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WEPAB018 Space-Charge Effects in Ionization Beam Profile Monitors 2628
 
  • V.D. Shiltsev
    Fermilab, Batavia, Illinois, USA
 
  Ionization profile monitors (IPMs) are widely used in accelerators for non-destructive and fast diagnostics of high energy particle beams. At high beam intensities, the space-charge forces make the measured IPM profiles significantly different from those of the beams. We analyze dynamics of the secondaries in IPMs and develop an effective algorithm to reconstruct the beam sizes from the measured IPM profiles. Efficiency of the developed theory is illustrated in application to the Fermilab 8 GeV proton Booster IPMs.  
poster icon Poster WEPAB018 [0.731 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB018  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 19 August 2021  
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WEPAB019 RF Harmonic Kicker R&D Demonstration and Its Application to the RCS Injection of the EIC 2632
 
  • G.-T. Park, M.W. Bruker, J.M. Grames, J. Guo, R.A. Rimmer, S.O. Solomon, H. Wang
    JLab, Newport News, Virginia, USA
 
  The Rapid Cycling Synchrotron (RCS) of the Electron-Ion Collider (EIC) at Brookhaven National Laboratory (BNL) * is an accelerating component of the electron injection complex, which provides polarized electrons in electron-ion collisions in the main Electron Storage Ring (ESR). We present the injection scheme into the RCS based on an ultra-fast harmonic kicker, whose "five odd-harmonic modes" prototype was developed in the context of the Jefferson Lab EIC (JLEIC) conceptual design **. In its early stage of R&D, the sharp (~3 ns width) waveform construction, beam dynamics, and pulsed power operation with short ramping time (~10 us) will be discussed together with the fabrication work of the JLEIC prototype ***.
* BNL, "Electron Ion Collider Conceptual Design Report", 2020
** G. Park et. al, JLAB-TN-044
*** G. Park et. al., JLAB-TN-046
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB019  
About • paper received ※ 17 May 2021       paper accepted ※ 22 June 2021       issue date ※ 27 August 2021  
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WEPAB020 The Relation Between Field Flatness and the Passband Frequency in the Elliptical Cavities 2636
 
  • G.-T. Park, R.A. Rimmer, H. Wang
    JLab, Newport News, Virginia, USA
 
  A technique that predicts the field flatness of the operating pi-mode based on the passband frequency is highly desirable when the direct measurement of the field is not available. Such a technique was developed for the SNS-PPU cavity, a 6-cell SRF cavity whose field flatness is important for cold operation. In this paper, we will present the theory on the relations between field profile and passband frequencies of the arbitrary deformed cavities, the simulation studies, and comparison with the experimental measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB020  
About • paper received ※ 17 May 2021       paper accepted ※ 24 June 2021       issue date ※ 31 August 2021  
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WEPAB021 Development and Testing of a Cherenkov Beam Loss Monitor in CLEAR Facility 2640
 
  • S. Benitez Berrocal, E. Effinger, W. Farabolini, A. Gilardi, P. Korysko, E. Lima, B. Salvachua, W. Viganò
    CERN, Geneva 23, Switzerland
  • P. Lane
    University of Huddersfield, Huddersfield, United Kingdom
 
  Beam Loss Monitors are fundamental diagnostic systems in particle accelerators. Beam losses are measured by a wide range of detectors with excellent results; most of these devices are used to measure local beam losses. However, in some accelerators there is the need to measure beam losses continuously localized over longer distances i.e., several tens of meters. For this reason, a beam loss detector based on long optical fibres is now under study. As part of the design, several simulations, comparing different possible detection scenarios, have been performed in FLUKA and bench-marked with experimental data. An experimental campaign was performed with an electron beam in the CERN Linear Electron Accelerator for Research (CLEAR) in November 2020. The light emitted from the optical fibre was captured using Silicon Photo-Multipliers (SiPM) coupled at each fibre’s end. In this poster, the first results of a beam loss detector based on the capture of Cherenkov photons generated by charged particles inside multimode silica fibres are presented.  
poster icon Poster WEPAB021 [0.724 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB021  
About • paper received ※ 18 May 2021       paper accepted ※ 21 June 2021       issue date ※ 28 August 2021  
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WEPAB023 Crystal Collimation of 20 MJ Heavy-Ion Beams at the HL-LHC 2644
 
  • M. D’Andrea, R. Bruce, M. Di Castro, I. Lamas Garcia, A. Masi, D. Mirarchi, S. Redaelli, R. Rossi, B. Salvachua, W. Scandale
    CERN, Geneva, Switzerland
  • F. Galluccio
    INFN-Napoli, Napoli, Italy
  • L.J. Nevay
    Royal Holloway, University of London, Surrey, United Kingdom
 
  The concept of crystal collimation at the Large Hadron Collider (LHC) relies on the use of bent crystals that can deflect halo particles by a much larger angle than the standard multi-stage collimation system. Following an extensive campaign of studies and performance validations, a number of crystal collimation tests with Pb ion beams were performed in 2018 at energies up to 6.37 Z TeV. This paper describes the procedure and outcomes of these tests, the most important of which being the demonstration of the capability of crystal collimation to improve the cleaning efficiency of the machine. These results led to the inclusion of crystal collimation into the LHC baseline for operation with ion beams in Run 3 as well as for the HL-LHC era. A first set of operational settings was defined.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB023  
About • paper received ※ 19 May 2021       paper accepted ※ 23 June 2021       issue date ※ 29 August 2021  
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WEPAB024 Release of Crystal Routine for Multi-Turn Proton Simulations within SixTrack v5 2648
 
  • M. D’Andrea, A. Mereghetti, D. Mirarchi, V.K.B. Olsen, S. Redaelli
    CERN, Geneva, Switzerland
 
  Crystal collimation is studied as a possible scheme to further improve the efficiency of ion collimation at the High Luminosity Large Hadron Collider (HL-LHC), as well as for possible applications in the CERN program of Physics Beyond Colliders. This concept relies on the use of bent crystals that can deflect high-energy halo particles at large angles, of the order of tens of urad. In order to reproduce key experimental results of crystal collimation tests and predict the performance of this system when applied to present and future machines, a dedicated simulation routine was developed. This routine is capable of modeling both coherent and incoherent interactions of beam particles with crystal collimators, and is fully integrated into the magnetic tracking and collimator modeling provided by the single-particle tracking code SixTrack. This paper describes the implementation of the routine in the latest version of SixTrack and its most recent improvements, in particular regarding the treatment of the crystal miscut angle.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB024  
About • paper received ※ 19 May 2021       paper accepted ※ 23 June 2021       issue date ※ 20 August 2021  
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WEPAB025 Collimation Strategies for Secondary Beams in FCC-hh Ion-Ion Operation 2652
 
  • J.R. Hunt, R. Bruce, F. Carra, F. Cerutti, J. Guardia, J. Molson
    CERN, Geneva, Switzerland
 
  The target peak luminosity of the CERN FCC-hh during Pb-Pb collisions is more than a factor of 50 greater than that achieved by the LHC in 2018. As a result, the intensity of secondary beams produced in collisions at the interaction points will be significantly higher than previously experienced. With up to 72 kW deposited in a localised region by a single secondary beam type, namely the one originated by Bound Free Pair Production (BFPP), it is essential to develop strategies to safely intercept these beams, including the ones from ElectroMagnetic Dissociation (EMD), in order to ensure successful FCC-hh Pb-Pb operation. A series of beam tracking and energy deposition simulations were performed to determine the optimal solution for handling the impact of such beams. In this contribution the most advanced results are presented, with a discussion of different options.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB025  
About • paper received ※ 18 May 2021       paper accepted ※ 02 July 2021       issue date ※ 31 August 2021  
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WEPAB026 Optics Measurements and Correction Plans for the HL-LHC 2656
 
  • T.H.B. Persson, X. Buffat, F.S. Carlier, R. De Maria, J. Dilly, E. Fol, D. Gamba, H. Garcia Morales, A. García-Tabarés Valdivieso, M. Giovannozzi, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, P.K. Skowroński, F. Soubelet, R. Tomás García, F.F. Van der Veken, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt
    CERN, Geneva, Switzerland
  • J.M. Coello de Portugal
    PSI, Villigen PSI, Switzerland
 
  The High Luminosity LHC (HL-LHC) will require stringent optics correction to operate safely and deliver the design luminosity to the experiments. In order to achieve this, several new methods for optics correction have been developed. In this article, we outline some of these methods and we describe the envisioned strategy of how to use them in order to reach the challenging requirements of the HL-LHC physics program.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB026  
About • paper received ※ 17 May 2021       paper accepted ※ 27 July 2021       issue date ※ 16 August 2021  
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WEPAB027 Optics Correction Strategy for Run 3 of the LHC 2660
 
  • T.H.B. Persson, R. De Maria, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, F. Soubelet, R. Tomás García, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt
    CERN, Geneva, Switzerland
  • J.F. Cardona
    UNAL, Bogota D.C, Colombia
 
  The Run 3 of the LHC will continue to provide new challenges for optics corrections. In order to succeed and go beyond what was achieved previously, several new methods to measure and correct the optics have been developed. In this article we describe these methods and outline the plans for the optics commissioning in 2022.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB027  
About • paper received ※ 17 May 2021       paper accepted ※ 12 July 2021       issue date ※ 30 August 2021  
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WEPAB028 MAD-X for Future Accelerators 2664
 
  • T.H.B. Persson, H. Burkhardt, L. Deniau, A. Latina, P.K. Skowroński
    CERN, Geneva, Switzerland
 
  The feasibility and performance of the future accelerators must, to a large extent, be predicted by simulation codes. This implies that simulation codes need to include effects that previously played a minor role. For example, in large electron machines like the FCC-ee the large energy variation along the ring requires that the magnets strength is adjusted to the beam energy at that location, normally referred to as tapering. In this article, we present new features implemented in the MAD-X code to enable and facilitate simulations of future colliders.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB028  
About • paper received ※ 17 May 2021       paper accepted ※ 06 July 2021       issue date ※ 11 August 2021  
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WEPAB029 Challenges for the Interaction Region Design of the Future Circular Collider FCC-ee 2668
 
  • M. Boscolo, A. Ciarma, F. Fransesini, L. Pellegrino
    INFN/LNF, Frascati, Italy
  • N. Bacchetta
    INFN- Sez. di Padova, Padova, Italy
  • M. Benedikt, H. Burkhardt, M.A. Jones, R. Kersevan, M. Lueckhof, E. Montbarbon, K. Oide, L. Watrelot, F. Zimmermann
    CERN, Meyrin, Switzerland
  • L. Brunetti, M. Serluca
    IN2P3-LAPP, Annecy-le-Vieux, France
  • M. Dam
    NBI, København, Denmark
  • M. Koratzinos
    MIT, Cambridge, Massachusetts, USA
  • M. Migliorati
    INFN-Roma1, Rome, Italy
  • A. Novokhatski, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  • F. Poirier
    CNRS - DR17, RENNES, France
 
  Funding: This work was partially supported by the EC HORIZON 2020 project FCC-IS, grant agreement n.951754, and by the U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-76SF-00515.
The FCC-ee is a proposed future high-energy, high-intensity and high precision lepton collider. Here, we present the latest developments for the FCC-ee interaction regions, which shall ensure optimum conditions for the particle physics experiments. We discuss measures of background reduction and a revised interaction region layout including a low impedance compact beam chamber design. We also discuss the possible impact of the radiation generated in the interaction region including beamstrahlung.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB029  
About • paper received ※ 11 May 2021       paper accepted ※ 23 June 2021       issue date ※ 18 August 2021  
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WEPAB031 Frequency Dependence of Plasma Cascade Amplification 2672
 
  • G. Wang, V. Litvinenko, J. Ma
    BNL, Upton, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A new type of amplifier, plasma cascade amplifier (PCA) has been proposed for a coherent electron cooling (CeC) system. Previously, the 1D model for PCA assumes that the transverse distribution of the density perturbation in the electrons is uniform and consequently, the plasma frequency does not depend on the wavelength of the perturbation. This assumption is valid if the longitudinal wavelength of the beam frame is much shorter than the transverse width of perturbation. In this work, we explore the PCI gain at a long wavelength by assuming the perturbation in the electron density has a non-uniform transverse profile. Specifically, we solve the 3D Poisson equation for given charge distribution (longitudinal sinusoidal, transversely Gaussian, or Beer-can), average the electric field over the transverse plane, and then apply it to 1D Vlasov equation. Similar to the previous calculation, the Vlasov equation can be reduced to a Hill’s equation but the plasma frequency now depends on the longitudinal wavelength of the density perturbation in the electrons. By numerically solving Hill’s equation, we obtain the gain of a PCA and compare it with the results from 3D SPACE simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB031  
About • paper received ※ 20 May 2021       paper accepted ※ 23 June 2021       issue date ※ 17 August 2021  
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WEPAB032 Studies of the Short-Range Wakefields for the Electron Storage Ring in the Electron Ion Collider 2675
 
  • G. Wang, M. Blaskiewicz, A. Blednykh, M.P. Sangroula
    BNL, Upton, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
During the estimates of impedance budget for the Electron Storage Ring (ESR) of Electron-Ion Collider (EIC), various codes, including GdfidL, CST and ECHO3D, have been used to calculate the short-range wake-fields due to the vacuum components. The ECHO 3D code demonstrates more reliable results for the tapered type of structures rather than the GdfidL code, where the stepsize needs to be dramatically decreased to achieve a high-performance calculation. Impedance of the following components are discussed and compared in details: Interaction Region (IR) chamber, bellows, and synchrotron radiation mask (flange absorber).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB032  
About • paper received ※ 19 May 2021       paper accepted ※ 10 June 2021       issue date ※ 16 August 2021  
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WEPAB033 Lattice Design of the CEPC Collider Ring for a High Luminosity Scheme 2679
 
  • Y. Wang, S. Bai, J. Gao, B. Wang, D. Wang, Y. Wei, J. Wu, C.H. Yu, J.Y. Zhai, Y. Zhang, Y.S. Zhu
    IHEP, Beijing, People’s Republic of China
  • Y. Zhang
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  A high luminosity scheme of the CEPC has been proposed aiming to increase the luminosity mainly at Higgs and Z modes. In this paper, the high luminosity scheme will be introduced briefly, including the beam parameters and RF staging. Then, the lattice design of the CEPC collider ring for the high luminosity scheme will be presented, including the bare lattice design and dynamic aperture optimization at Higgs energy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB033  
About • paper received ※ 20 May 2021       paper accepted ※ 05 July 2021       issue date ※ 24 August 2021  
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WEPAB038 Commissioning of a New X-Band, Low-Noise LLRF System 2683
 
  • A.V. Edwards, M. Boronat Arevalo, N. Catalán Lasheras, G. McMonagle
    CERN, Meyrin, Switzerland
  • A.C. Dexter
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
 
  To increase beam energy in the CLEAR facility at CERN and study the CLIC accelerating structure prototype in operating conditions, the first X-band test facility at CERN was upgraded in 2020. Both, the acquisition and software systems at X-band test stand 1 (Xbox1) were upgraded to exhibit low phase noise which is relevant to klystron based CLIC and to the use of crab cavities in the beam delivery system. The new LLRF uses down-conversion which necessitates a local oscillator which can be produced by two different methods. The first is a PLL, a commonly used technique which has been previously employed at the other X-band facilities at CERN. The second is a novel application of a single sideband up-convertor. The up-convertor system has demonstrated reduced phase noise when compared with the PLL. The commissioning of the new system began in late 2020 with the conditioning of a 50 MW Klystron. Measurements of the quality of the new LLRF will be shown. These will compare the PLL and up-convertor with particular attention on the quality of the phase measurements. Also, a preliminary study of phase shifts in the waveguide network due to temperature changes will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB038  
About • paper received ※ 13 May 2021       paper accepted ※ 05 July 2021       issue date ※ 23 August 2021  
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WEPAB039 Construction of a Compact Electron Injector Using a Gridded RF Thermionic Gun and a C-Band Accelerator 2687
 
  • T. Inagaki, T. Asaka, T. Hara, T. Hiraiwa, N. Hosoda, E. Iwai, C. Kondo, H. Maesaka, T. Ohshima, H. Tanaka
    RIKEN SPring-8 Center, Hyogo, Japan
  • H. Dewa, T. Magome, Y. Minagawa, T. Sakurai
    JASRI/SPring-8, Hyogo-ken, Japan
  • T. Fukui
    RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan
  • S. Hashimoto
    LASTI, Hyogo, Japan
  • S.I. Inoue, K. Kajimoto, S. Nakata, T. Seno, H. Sumitomo, R. Takesako, S. Tanaka, R. Yamamoto, M. Yoshioka
    SES, Hyogo-pref., Japan
  • K. Yanagida
    JASRI, Hyogo, Japan
 
  A compact and low-cost 1 GeV injector linac was designed and constructed to provide injection beams to the soft X-ray synchrotron radiation facility NewSUBARU instead of the SPring-8 injector system, which will be shutdown. The total length of the injector linac needs to be less than 70 m to fit into the existing tunnel. To this end, an RF electron gun with a gridded thermionic cathode directly attached to a 238 MHz RF cavity was developed and adopted. The 500 keV, 0.6 ns, 1 nC beam emitted from the cavity is compressed to 3 ps by velocity bunching driven by a 476 MHz RF cavity and a S-band RF structure. The short-pulsed beams are accelerated up to 1 GeV with 16 C-band RF structures. In the C-band accelerator section, the klystron output of 50 MW is multiplied 4 times by a pulse compressor and fed to the 4 RF structures to generate a high accelerating field of 31 MV/m. A low-level RF system consisting of a MTCA.4 based high-speed digitizers and RF frontend boards has been constructed. This injector system is used at the 3 GeV SR facility currently under construction in Sendai. In this paper, we report the design outline and the operational performance of the injector system.  
poster icon Poster WEPAB039 [2.419 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB039  
About • paper received ※ 20 May 2021       paper accepted ※ 02 July 2021       issue date ※ 29 August 2021  
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WEPAB040 Characterization of Low Emittance Electron Beams Generated by Transverse Laser Beam Shaping 2690
 
  • M. Groß, N. Aftab, P. Boonpornprasert, G.Z. Georgiev, J. Good, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, D. Melkumyan, S.K. Mohanty, R. Niemczyk, A. Oppelt, H.J. Qian, G. Shu, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
  • Y. Chen, G. Loisch
    DESY, Hamburg, Germany
  • I. Will
    MBI, Berlin, Germany
 
  Linac based X-ray free electron laser demand a high beam quality from the electron source, therefore RF photoinjectors are used to generate the electron bunches for state of the art beam brightness. One important figure of merit for these injectors is the transverse emittance of the generated electron beam, which can be minimized by shaping the photocathode laser pulses. Best performance can be achieved with ellipsoidal laser pulses, but 3D shaping is technically challenging. Typically, a quasi-uniform transverse laser profile is truncated from the Gaussian profile generated by the laser with an aperture to reduce the transverse nonlinear space charge forces. This is investigated in detail by optimizing the laser transverse profile at the Photoinjector Test facility at DESY in Zeuthen (PITZ), where photoinjector R&D is conducted for the E-XFEL and FLASH free electron lasers at DESY in Hamburg. In this contribution we present experimental results at high acceleration gradients (up to 60 MV/m) for both 250 pC and 500 pC. For a bunch charge of 500 pC an emittance reduction of about 30% compared to the commonly used transverse flat-top laser distribution was achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB040  
About • paper received ※ 17 May 2021       paper accepted ※ 02 June 2021       issue date ※ 31 August 2021  
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WEPAB041 Testing of the Milliampere Booster Prototype Cavity 2693
 
  • R.G. Heine
    KPH, Mainz, Germany
 
  The Milliampere Booster (MAMBO) is the injector linac for the Mainz Energy-recovering Superconducting Accelerator MESA. MESA is a multi-turn energy recovery linac with beam energies in the 100 MeV regime currently designed and built at Institut für Kernphysik (KPH) of Johannes Gutenberg-Universität Mainz. The main accelerator consists of two superconducting Rossendorf type modules, while the injector MAMBO relies on normal conducting technolgy. The MAMBO RF cavities are bi-periodic pi/2 structures with 33 cells and 37 cells, respectively. In this paper we present the results of the commissioning and testing of a 13 cell prototype structure.  
poster icon Poster WEPAB041 [2.824 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB041  
About • paper received ※ 18 May 2021       paper accepted ※ 23 June 2021       issue date ※ 23 August 2021  
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WEPAB042 Linac-200: A New Electron Test Beam Facility at JINR 2697
 
  • M.A. Nozdrin, M. Gostkin, V. Kobets, Y.A. Samofalova, G. Shirkov, A. Trifonov, K. Yunenko, A. Zhemchugov
    JINR, Dubna, Moscow Region, Russia
 
  Commissioning of a new electron test beam facility Linac-200 comes to the end at JINR (Dubna, Russia). The core of the facility is a refurbished MEA accelerator from NIKHEF. The key accelerator subsystems including controls, vacuum, precise temperature regulation were redesigned or deeply upgraded. The facility provides electron beams with energy up to 200 MeV while the beam current varying smoothly from 40 mA down to almost zero (single electrons in a bunch). The main goal of the facility is providing test beams for particle detector R&D, studies of novel approaches to the beam diagnostics, and education and training of graduate and postgraduate students. The current status and operation parameters of the facility will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB042  
About • paper received ※ 18 May 2021       paper accepted ※ 23 June 2021       issue date ※ 25 August 2021  
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WEPAB043 Consolidation and Future Upgrades to the CLEAR User Facility at CERN 2700
 
  • L.A. Dyks, P. Korysko
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  • P. Burrows
    JAI, Oxford, United Kingdom
  • R. Corsini, S. Curt, W. Farabolini, D. Gamba, L. Garolfi, A. Gilardi, E. Granados, G. McMonagle, H. Panuganti
    CERN, Geneva, Switzerland
  • W. Farabolini
    CEA-DRF-IRFU, France
  • A. Gilardi
    University of Napoli Federico II, Napoli, Italy
  • K.N. Sjobak
    University of Oslo, Oslo, Norway
 
  The CERN Linear Electron Accelerator for Research (CLEAR) at CERN has been operating since 2017 as a dedicated user facility providing beams for a varied range of experiments. CLEAR consists of a 20 m long linear accelerator (linac), able to produce beams from a Cs2Te photocathode and accelerate them to energies of between 60 MeV and 220 MeV. Following the linac, an experimental beamline is located, in which irradiation tests, wakefield and impedances tudies, plasma lens experiments, beam diagnostics development, and terahertz (THz) emission studies, are performed. In this paper, we present recent upgrades to the entire beamline, as well as the design of future upgrades, such as a dogleg section connecting to an additional proposed experimental beamline. The gain in performance due to these upgrades is presented with a full range of available beam properties documented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB043  
About • paper received ※ 18 May 2021       paper accepted ※ 24 June 2021       issue date ※ 29 August 2021  
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WEPAB044 Status of VHEE Radiotherapy Related Studies at the CLEAR User Facility at CERN 2704
 
  • R. Corsini, W. Farabolini, A. Gilardi
    CERN, Geneva, Switzerland
  • L.A. Dykspresenter, P. Korysko
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  • W. Farabolini
    CEA-DRF-IRFU, France
  • A. Gilardi
    University of Napoli Federico II, Napoli, Italy
  • K.N. Sjobak
    University of Oslo, Oslo, Norway
 
  Despite the increase in interest in using Very High Energy Electron (VHEE) beams for cancer radiotherapy many unanswered questions in its development remain. The use of test facilities will be an essential tool used to solve these issues. The 200 MeV electron beam from the CERN Linear Accelerator for Research (CLEAR) has been used extensively, in collaboration with several research institutes, to perform dosimetry studies and explore potential applications of VHEE beams to radiotherapy, including the exploitation of the so called FLASH effect. In this paper, we present an overview of past studies with emphasis on the more recent results. We describe methods, techniques and equipment developed at CERN in this framework, and give an outlook on future activities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB044  
About • paper received ※ 18 May 2021       paper accepted ※ 23 June 2021       issue date ※ 13 August 2021  
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WEPAB045 European XFEL High-Power RF System - the First 4 Years of Operation 2708
 
  • M. Bousonville, S. Choroba, T. Grevsmühl, S. Göller, A. Hauberg, V.V. Katalev, K. Machau, V. Vogel, B. Yildirim
    DESY, Hamburg, Germany
 
  In 2016, the installation of the European XFEL was completed and its 26 RF stations started operation in 2017. Each RF station consists of a 10 MW-1.3 GHz-multibeam klystron, a HV pulse modulator and a waveguide system to supply the superconducting cavities and the normal-conducting electron gun with RF power. During commissioning and subsequent operation, the RF stations were closely monitored and causes of failures were investigated. For the optimisation of the RF systems, the various RF station failures were evaluated according to their impact on accelerator operation and the measures to eliminate them were prioritised accordingly. This report describes the operation experience and improvements of the high-power RF stations during the first 4 years of operation.  
poster icon Poster WEPAB045 [6.887 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB045  
About • paper received ※ 19 May 2021       paper accepted ※ 07 June 2021       issue date ※ 13 August 2021  
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WEPAB048 Design of an Optical Cavity for Generating Intense THz Pulse Based on Coherent Cherenkov Radiation 2711
 
  • P. Wang, Y. Koshiba, T. Murakami, K. Murakoshi, K. Sakaue, Y. Tadenuma, M. Washio
    Waseda University, Tokyo, Japan
  • R. Kuroda
    AIST, Tsukuba, Japan
  • K. Sakaue
    The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan
 
  We have been studying terahertz (THz) generation via Cherenkov radiation with high-quality electron beams from a photocathode rf (radio frequency) gun. In our early studies, we have succeeded in the generation of coherent Cherenkov radiation by controlling the tilt of the electron beam using an rf-deflector. For further enhancement, we are planning to stack the THz pulses in an optical cavity. Multi-bunch operation of the rf-gun will generate electron beams with a repetition rate of 119 MHz, and THz pulses as well. These pulses will be accumulated in the cavity for up to 150 pulses. In this conference, we report the design study of the enhancement cavity and discuss the performance of the THz source.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB048  
About • paper received ※ 19 May 2021       paper accepted ※ 02 June 2021       issue date ※ 22 August 2021  
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WEPAB051 Beam Dynamics for a High Field C-Band Hybrid Photoinjector 2714
 
  • L. Faillace, F. Bosco, M. Carillo, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • R.B. Agustsson, I.I. Gadjev, S.V. Kutsaev, A.Y. Murokh
    RadiaBeam, Marina del Rey, California, USA
  • M. Behtouei, A. Giribono, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati, Italy
  • A. Fukasawa, N. Majernik, J.B. Rosenzweig, O. Williams
    UCLA, Los Angeles, California, USA
  • S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National Committee V through the ARYA project.
In this paper, we present a new class of a hybrid photoinjector in C-Band. This project is the effort result of a UCLA/Sapienza/INFN-LNF/SLAC/RadiaBeam collaboration. This device is an integrated structure consisting of an initial standing-wave 2.5-cell gun connected to a traveling-wave section at the input coupler. Such a scheme nearly avoids power reflection back to the klystron, removing the need for a high-power circulator. It also introduces strong velocity bunching due to a 90° phase shift in the accelerating field. A relatively high cathode electric field of 120 MV/m produces a ~4 MeV beam with ~20 MW input RF power in a small foot-print. The beam transverse dynamics are controlled with a ~0.27 T focusing solenoid. We show the simulation results of the RF/magnetic design and the optimized beam dynamics that shows 6D phase space compensation at 250 pC. Proper beam shaping at the cathode yields a ~0.5 mm-mrad transverse emittance. A beam waist occurs simultaneously with a longitudinal focus of <400 fs rms and peak current >600 A. We discuss application of this injector to an Inverse-Compton Scattering system and present corresponding start-to-end beam dynamics simulations.
 
poster icon Poster WEPAB051 [0.827 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB051  
About • paper received ※ 18 May 2021       paper accepted ※ 01 July 2021       issue date ※ 22 August 2021  
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WEPAB052 Development of an EO Sampling System for the Analysis of THz Waves Generated by Coherent Cherenkov Radiation 2718
 
  • K. Murakoshi, Y. Koshiba, T. Murakami, K. Sakaue, Y. Tadenuma, P. Wang, M. Washio
    Waseda University, Tokyo, Japan
  • R. Kuroda
    AIST, Tsukuba, Japan
  • K. Sakaue
    The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan
 
  THz waves, located between microwaves and light waves, have transparency, directionality and fingerprint spectrum of specific materials. Therefore, they are expected to be useful for various applications. We have been studying THz waves generation via Cherenkov radiation with electron beams from a photocathode rf-gun. In our early studies, we have succeeded in the generation of coherent Cherenkov radiation by tilted electron beams using an rf-deflector. Furthermore, we have generated quasi-monochromatic THz waves by spatially modulated electron beams and have succeeded in its measurement by bandpass filters. This study aims to obtain the THz wave form in time domain by electro-optic (EO) sampling, which is an useful detection system for obtaining the information of the electric field and the phase simultaneously with high S/N. In this conference, we report about our probe laser system, results of the time-domain spectroscopy measurement of THz waves by EO sampling, and future prospects.  
poster icon Poster WEPAB052 [0.861 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB052  
About • paper received ※ 19 May 2021       paper accepted ※ 07 June 2021       issue date ※ 26 August 2021  
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WEPAB054 Electromagnetic and Beam Dynamics Studies of the ThomX LINAC 2721
 
  • M. Alkadi, C. Bruni, M. El Khaldi, M. Jacquet
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • H. Monard
    IJCLab, ORSAY, France
 
  ThomX is a new generation compact Compton source. The machine is composed of a 50/70 MeV injector linac and a storage ring where an electron bunch collides with a laser pulse accumulated in a Fabry-Perot resonator. The compact source, built at Irene Joliot-Curie Laboratory (IJCLAB) in the Orsay campus of Paris-Saclay University, is designed to produce a total flux of 1013 ph/s and a brightness of 1011 ph / (s.mm2.mrad2) in 0.1% of bandwidth with a tunable energy ranging from 45 keV to 90 keV on the X-ray beam axis. The photo-injector is composed of a homemade 2.5 cell photocathode RF-gun, placed between two solenoids. An energy of 5 MeV is reached with a 80 MV/m electric field gradient. During the commissioning phase, a 4.8 m S-band LIL section will be used to achieve a 50 MeV corresponding to a 45 keV X-ray energy. The LIL accelerating section is a quasi-constant gradient traveling wave structure. The energy gain in the section is 45 MeV, corresponding to an average effective accelerating gradient of 10 MV/m for an input RF power of 9 MW. Here we present the electromagnetic and beam dynamics studies of the ThomX LINAC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB054  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 31 August 2021  
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WEPAB055 Development of a Linac for Injection of Ultrashort Electron Bunches Into Laser Plasma Electron Accelerators 2725
 
  • S. Masuda, N. Kumagai, T. Masuda, Y. Otake
    JASRI, Hyogo, Japan
  • Y. Koshiba, S. Otsuka
    Waseda University, Tokyo, Japan
  • T. Sakai, T. Tanaka
    LEBRA, Funabashi, Japan
  • K. Sakaue
    The University of Tokyo, The School of Engineering, Tokyo, Japan
 
  Funding: This work is supported by JST-Mirai Program Grant Number JPMJMI17A1, Japan.
We are developing a C-band linac that produces ultrashort electron bunches as an injector for laser plasma accelerators. A plasma wave excited by a high intense ultrashort laser pulse has a wavelength of the order of 10 to 100 fs and transverse dimensions of the order of 10 to 100 um. To inject the bunch into a proper phase of the plasma wave, a length and transverse sizes of the bunch must be much smaller than the plasma wave structure. A laser triggered photo cathode electron RF-gun and a 2pi/3 mode traveling wave buncher with 24 cells for ultrashort electron bunch production have been developed based on electron beam tracking simulations that show the bunch length is less than 10 fs with a charge of 100 fC at a focus on the plasma wave. The simulations also show that sufficiently small transverse sizes of the bunch at the focus can be obtained by a Q triplet. A highly accurate timing lower than the plasma wavelength (~10fs) is required for the synchronization between the electron bunch injection and the plasma wave excitation. An RF master oscillator with low SSB phase noise (-150dBc/Hz@10MHz) has been developed for the synchronization. We will report present development status.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB055  
About • paper received ※ 19 May 2021       paper accepted ※ 15 July 2021       issue date ※ 26 August 2021  
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WEPAB056 Advanced Photoinjector Development at the UCLA SAMURAI Laboratory 2728
 
  • A. Fukasawa, G. Andonian, O. Camacho, C.E. Hansel, G.E. Lawler, W.J. Lynn, N. Majernik, P. Manwani, B. Naranjo, J.B. Rosenzweig, Y. Sakai, O. Williams
    UCLA, Los Angeles, California, USA
  • Z. Li, R. Robles, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • J.I. Mann
    PBPL, Los Angeles, USA
  • M. Yadav
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: This work was supported by the US Department of Energy under the contract No. DE-SC0017648, DE-SC0009914, and DE-SC0020409, and by National Science Foundation Grant No. PHY-1549132
UCLA has recently constructed SAMURAI, a new radiation bunker and laser infrastructure for advanced accelerator research. In its first phase, we will build a 30 MeV photoinjector with an S-band hybrid gun. The beam dynamics simulation for this beamline showed the generation of the beam with the emittance 2.4 um and the peak current 270 A. FIR-FEL experiments are planned in this beamline. The saturation peak power was expected at 170 MW.
 
poster icon Poster WEPAB056 [0.939 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB056  
About • paper received ※ 28 May 2021       paper accepted ※ 01 July 2021       issue date ※ 25 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 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 ※ 11 August 2021  
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WEPAB063 Status of the Polarized Source and Beam Preparation System at MESA 2736
 
  • S. Friederich, K. Aulenbacher, C. Matejcek
    IKP, Mainz, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
  • K. Aulenbacher
    GSI, Darmstadt, Germany
 
  Funding: This work is supported by the DFG excellence initiative PRISMA+.
The MESA Low-energy Beam Apparatus (MELBA) connects the DC photoemission source STEAM with the injector accelerator MAMBO. MELBA is capable of adjusting the longitudinal phase space for the requirements of the pre-acceleration by using a chopper and buncher while providing small transverse emittances. Measurements of the transverse phase space and longitudinal beam dimension taken at a test setup are presented. These results serve now for further improvements, e.g design changes in our corrector magnets. In addition, the revised MELBA will include two Wien filters and a solenoid for spin manipulation. A double scattering Mott polarimeter for spin diagnostics and a second source for the extraction of high bunch charges is foreseen using a branched off beam line. RF-synchronized laser diodes will be used with infrared wavelength as a driver for the spin-polarized photoemission. In this report we present the latest layout of MELBA and simulation results.
 
poster icon Poster WEPAB063 [1.752 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB063  
About • paper received ※ 19 May 2021       paper accepted ※ 16 July 2021       issue date ※ 25 August 2021  
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WEPAB064 Front-to-End Simulations of the Energy Recovery Linac for the LHeC Project 2740
 
  • K.D.J. André, B.J. Holzer
    CERN, Geneva, Switzerland
 
  The LHeC project aims to study the electron-proton deep inelastic scattering at the TeV energy scale with an innovative accelerator program. It exploits the promising energy recovery technology in order to collide an intense 50 GeV lepton beam with one hadron beam from the High Luminosity Large Hadron Collider (HL-LHC) in parallel to the hadron-hadron operation. The paper presents the studies that have been performed to assess the performance of the machine and the efficiency of the energy recovery process for different scalings of the ERL. The studies include emittance blow-up due to synchrotron radiation emission and beam-disruption created by the strong beam-beam force at the interaction point. The design principles of the ERL structure are discussed, including the particle detector bypass and the interaction region, and the results of the tracking simulations are presented, considering the complete multi-turn ERL process. Special attention is turned to the lepton beam emittance budget and the resulting energy recovery performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB064  
About • paper received ※ 18 May 2021       paper accepted ※ 24 June 2021       issue date ※ 12 August 2021  
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WEPAB065 Studies of the Energy Recovery Performance of the PERLE Project 2744
 
  • K.D.J. André, B.J. Holzer
    CERN, Geneva, Switzerland
  • S.A. Bogacz
    JLab, Newport News, Virginia, USA
 
  The Powerful Energy Recovery Linac for Experiments (PERLE) is an accelerator facility for the development and application of the energy recovery technique for an intense 500 MeV electron beam. The paper presents the studies that have been performed to assess the quality of the ERL lattice design and beam optics. The studies include the Coherent Synchrotron Radiation (CSR) emission and wakefields in the superconducting radio-frequency structures of the linacs. The lattice design and optics principles of the ERL structure are discussed, involving the vertical deflection system and the 180° arcs. Finally, the results of the front-to-end tracking simulations that consider the complete multi-turn energy recovery process are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB065  
About • paper received ※ 18 May 2021       paper accepted ※ 24 June 2021       issue date ※ 14 August 2021  
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WEPAB067 High Duty Cycle EUV Radiation Source Based on Inverse Compton Scattering 2748
 
  • R. Huang, Q.K. Jia, C. Li
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: Work supported by the National Natural Science Foundation of China Grant Number 11805200, and National Key Research and Development Program of China No. 2016YFA0401901.
ICS can obtain quasi-monochromatic and directional EUV radiation via a MeV-scale energy electron beam and a micron-scale wavelength laser beam, which enables a dramatic reduction in dimension and expense of the system, and makes it an attractive technology in research, industry, medicine and homeland security. Here we describe an EUV source based on high repetition ICS system. The scheme exploits the output from the laser-electron interaction between a MW-ps laser at MHz repetition-rate and a high quality electron beam with an energy of a few MeV at MHz repetition-rate.
 
poster icon Poster WEPAB067 [1.551 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB067  
About • paper received ※ 23 May 2021       paper accepted ※ 24 June 2021       issue date ※ 11 August 2021  
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WEPAB071 Design and Construction of an Intense Terahertz-Wave Source Based on Coherent Cherenkov Radiation Matched to Circle Plane Wave 2751
 
  • N. Sei, H. Ogawa
    AIST, Tsukuba, Ibaraki, Japan
  • K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Sumitomo, Y. Takahashi, T. Tanaka
    LEBRA, Funabashi, Japan
  • T. Takahashi
    Kyoto University, Research Reactor Institute, Osaka, Japan
 
  Funding: This work was supported by Japan Society for the Promotion of Science KAKENHI JP19H04406 and the Visiting Researchers Program of Kyoto University Research Reactor Institute (R2013).
National Institute of Advanced Industrial Science and Technology has been studied terahertz (THz) coherent radiation in collaboration with Nihon University and Kyoto University. We have been developed a coherent transition radiation (CTR) source with macropulse power of 1 mJ using a screen monitor in the parametric X-ray line at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University. However, to obtain a THz-wave source with higher intensity, we have undertaken a development of a new THz-wave source based on coherent Cherenkov radiation (CCR) matched to circle plane wave. Bypassing an electron beam through a hollow conical dielectric having an apex angle equal to the Cherenkov angle, the wavefront of the CCR generated on the inner surface of the hollow conical dielectric matches on the basal plane. Therefore, it is possible to obtain a high-power beam that is easy to transport. We have already produced a hollow conical dielectric made of high-resistivity silicon and considered a position controller for the hollow conical dielectric. In this presentation, the status of the new THz-wave source will be reported.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB071  
About • paper received ※ 18 May 2021       paper accepted ※ 22 June 2021       issue date ※ 15 August 2021  
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WEPAB072 PAX: A Plasma-Driven Attosecond X-Ray Source 2755
 
  • C. Emma, J. Cryan, M.J. Hogan, K. Larsen, J.P. MacArthur, A. Marinelli, G.R. White, X.L. Xu
    SLAC, Menlo Park, California, USA
  • A.C. Fisher, R.M. Hessami, P. Musumeci
    UCLA, Los Angeles, California, USA
  • R. Robles
    Stanford University, Stanford, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. This work was also partially supported by DOE grant DESC0009914
Plasma accelerators can generate ultra high brightness electron beams which open the door to light sources with smaller physical footprint and properties unachievable with conventional accelerator technology. In this work * we show that electron beams from Plasma WakeField Accelerators (PWFAs) can generate coherent tunable soft X-ray pulses with TW peak power and duration of tens of attoseconds in a meter-length undulator. These X-ray pulses are an order of magnitude more powerful, shorter and can be produced with better stability than state-of-the-art X-ray Free Electron Lasers (XFELs). The X-ray emission in this approach is driven by coherent radiation from a pre-bunched, near Mega Ampere (MA) current electron beam of attosecond duration rather than the SASE FEL process starting from noise. This approach significantly relaxes the restrictive requirements on emittance, energy spread, and pointing stability which has thus far hindered the realization of a high-gain FEL driven by a plasma accelerator. We discuss the approach and progress towards the experimental realization of this concept at the FACET-II accelerator facility.
* C. Emma, X. Xu, A. Fisher, J. P. MacArthur, J. Cryan, M. J. Hogan, P. Musumeci, G. White, A. Marinelli, "Terawatt attosecond X-ray source driven by a plasma accelerator", arXiv:2011.07163 (2020)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB072  
About • paper received ※ 20 May 2021       paper accepted ※ 24 June 2021       issue date ※ 23 August 2021  
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WEPAB073 An Overview of the Radio-Frequency System for an Inverse Compton X-Ray Source Based on CLIC Technology 2759
 
  • T.G. Lucas, O.J. Luiten, P.H.A. Mutsaers, X.F.D. Stragier, H.A. Van Doorn, F.M. van Setten, H.J.M. van den Heuvel, M.L.M.C. van der Sluis
    TUE, Eindhoven, The Netherlands
 
  Funding: This project is financed by the "Interreg V programme Flanders-Netherlands" with financial support of the European Fund for Regional Development.
Compact inverse Compton scattering X-ray sources are gaining in popularity as the future of lab-based x-ray sources. Smart*Light is one such facility, under commissioning at Eindhoven University of Technology (TU/e), which is based on high gradient X-band technology originally designed for the Compact Linear Collider (CLIC) and its test stands located at CERN. Critical to the beam quality is the RF system which aims to deliver 10-24 MW RF pulses at repetition rates up to 1 kHz with a high amplitude and phase stability of <0.5\% and <0.65~° allowing it to adhere to strict synchronicity conditions at the interaction point. This work overviews the design of the high power and low level RF systems for Smart*Light.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB073  
About • paper received ※ 19 May 2021       paper accepted ※ 23 June 2021       issue date ※ 18 August 2021  
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WEPAB074 A Distributed Sextupoles Lattice for the ALBA Low Emittance Upgrade 2762
 
  • G. Benedetti, M. Carlà, U. Iriso, Z. Martí, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  The first lattice studied in 2019 for the ALBA upgrade was a 7BA lattice with two dispersion bumps, for localised chromatic correction. That lattice had limited dynamic aperture and momentum acceptance. In 2020 we started to explore a different approach to find an MBA lattice with distributed chromatic correction that meets the same emittance goal with larger dynamic aperture and momentum acceptance. The choice of the number of bendings per cell, as well as the tuning of the magnet gradients, is carried out by developing a light weight solver that performs both the emittance and chromaticity optimisation of the arcs and the matching of the linear optics in the straight sections. We present the status of the storage ring upgrade studies, the performance of the new developed lattice, together with the issues related with the injection scheme.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB074  
About • paper received ※ 19 May 2021       paper accepted ※ 16 June 2021       issue date ※ 31 August 2021  
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WEPAB075 Xenos: X-Ray Monte Carlo Code Suite 2766
 
  • S. Humphries
    Field Precision, Albuquerque, New Mexico, USA
 
  Xenos is an integrated 3D code suite for the design of X-ray sources and electron beam devices. The component programs run under all versions of Windows. This paper describes unique features of Xenos compared to other Monte Carlo packages: 1) representation of geometry and deposited dose on a finite-element mesh supported by an interactive mesh generator, 2) inclusion of full 3D electric and magnetic fields in Monte Carlo simulations, 3) an integrated user environment for input and output calculations (e.g., electron gun design, target heating, …) and 4) extended parallel-computing support for high-accuracy solutions. Xenos employs the full capabilities of multi-core computers and allows parallel computations on an unlimited number of independent computers.
* Sempau J., et.al. (2003), "Experimental benchmarks of the Monte Carlo code PENELOPE", Nucl. Instrum. Meth. B 207, 107-123.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB075  
About • paper received ※ 10 May 2021       paper accepted ※ 23 June 2021       issue date ※ 13 August 2021  
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WEPAB077 High Power Terahertz Cherenkov Free Electron Laser from a Waveguide with a Thin Dielectric Layer by a Near-Relativistic Electron Beam 2769
 
  • W.W. Li, T.L. He, Z.G. He, R. Huang, Q.K. Jia, S.M. Jiang, L. Wang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: National Natural Science Foundation of China (11705198, 11775216, 11805200) Fundamental Research Funds for the Central Universities (No. WK2310000082 and No. WK2310000090)
Corrugated and dielectric structures have been widely used for producing accelerator based terahertz radiation source. Recently, the novel schemes of the sub-terahertz free electron laser (FEL) from a metallic waveguide with corrugated walls and a normal dielectric loaded waveguide driven by a near-relativistic (beam energy of a few MeV) picosecond electron beam were studied respectively. Such a beam is used for driving resonant modes in the waveguide, and if the pipe is long enough, the interaction of these modes with the co-propagating electron beam will result in micro-bunching and the coherent enhancement of the wakefield radiation. It offers a promising candidate for compact accelerator-based high power terahertz source which can be realized with relatively low energy and low peak-current electron beams. However the choices of the waveguide above is less effective in order to obtain high power with frequency around 1THz. In this paper, we propose to use the waveguide with a thin dielectric layer instead, and high power radiation (>~10 MW) around 1 THz is expected to obtain in the proposed structure according to the simulation results.
 
poster icon Poster WEPAB077 [1.332 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB077  
About • paper received ※ 12 May 2021       paper accepted ※ 23 June 2021       issue date ※ 19 August 2021  
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WEPAB079 Optics Studies on the Operation of a New Wiggler and Bunch Shortening at the DELTA Storage Ring 2772
 
  • B. Büsing, P. Hartmann, A. Held, S. Khan, C. Mai, D. Schirmer, G. Schmidt
    DELTA, Dortmund, Germany
 
  Funding: Work supported by Deutsche Forschungsgemeinschaft via project INST 212/330-1 AOBJ: 619186
The 1.5-GeV electron storage ring DELTA is a synchrotron light source operated by the TU Dortmund University. Radiation from hard X-rays to the THz regime is provided by dipole magnets and insertion devices like undulators and wigglers. To provide even shorter wavelengths, a new 22-pole superconducting 7-T wiggler has been installed. The edge focusing of the wiggler has a large impact on the linear optics of the storage ring. Measurements regarding its influence and simulations were performed. In addition, a second radiofrequency (RF) cavity has been installed to compensate the increased energy loss per turn due to the new wiggler. As a consequence of the higher RF power, the electron bunches are shorter compared to the old setup with only one cavity. In view of reducing the bunch length even more, studies of the storage ring optics with reduced momentum compaction factor were performed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB079  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 22 August 2021  
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WEPAB080 Near Threshold Pion Photoproduction on Deuterons 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 ※ 11 August 2021  
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WEPAB081 The Broad-Band Impedance Budget in the Storage Ring of the ALS-U Project 2779
 
  • D. Wang, K.L.F. Bane, R. Bereguer, T. Cui, S. De Santis, P. Gach, D. Li, T.H. Luo, T. Miller, T. Oliver, O. Omolayo, C. Steier, T.L. Swain, M. Venturini, G. Wang
    LBNL, Berkeley, California, USA
 
  Design work is underway for the upgrade of the Advanced Light Source (ALS-U) to a diffraction-limited soft x-rays radiation source. Like other 4th-generation light source machines, the ALS-U multiple-bend achromat storage-ring (SR) is potentially sensitive to beam-coupling impedance effects. This paper presents the SR broad-band impedance budget in both the longitudinal and transverse planes. In our modeling we follow the commonly accepted approach of separating the resistive-wall and the geometric parts of the impedance, the former being described by analytical formulas and the latter obtained by numerical electromagnetic codes (primarily CST Studio software) assuming perfectly conducting materials. We discuss the main sources of impedance. Results of our analysis are the basis for the single bunch instability study and would feedback on the design of critical vacuum components.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB081  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 14 August 2021  
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WEPAB082 Single Bunch Instability Simulations in the Storage Ring of the ALS-U Project 2783
 
  • D. Wang, K.L.F. Bane, S. De Santis, M.P. Ehrlichman, D. Li, T.H. Luo, O. Omolayo, G. Penn, C. Steier, M. Venturini
    LBNL, Berkeley, California, USA
 
  As the broad-band impedance modeling and the vacuum chamber design of the new Advanced Light Source storage ring (ALS- U) reach maturity, we report on progress in single-bunch collective effects studies. A pseudo-Green function wake representing the entire ring was earlier obtained by numerical and analytical methods. Macroparticle simulations using the computer code "elegant" and this wake function are used to determine the instability thresholds for longitudinal and transverse motion. We consider various operating conditions, such as without/with higher-harmonic RF cavities, zero/finite linear chromaticity, and without/with a transverse bunch-by-bunch feedback system. Results show enough margin for the broadband impedance budget when the single-bunch instability thresholds are compared with the design bunch charge.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB082  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 18 August 2021  
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WEPAB083 Effect of Negative Momentum Compaction Operation on the Current-Dependent Bunch Length 2786
 
  • P. Schreiber, T. Boltz, M. Brosi, B. Härer, A. Mochihashi, A.-S. Müller, A.I. Papash, R. Ruprecht, M. Schuh
    KIT, Karlsruhe, Germany
 
  Funding: Funded by the European Union’s Horizon 2020 Research and Innovation programme, Grant Agreement No 730871. P.S, T.B are supported by DFG-funded Karlsruhe School of Elementary and Astroparticle Physics.
New operation modes are often considered during the development of new synchrotron light sources. An understanding of the effects involved is inevitable for a successful operation of these schemes. At the KIT storage ring KARA (Karlsruhe Research Accelerator), new modes can be implemented and tested at various energies, employing a variety of performant beam diagnostics devices. Negative momentum compaction optics at various energies have been established. Also, the influence of a negative momentum compaction factor on different effects has been investigated. This contribution comprises a short report on the status of the implementation of a negative momentum compaction optics at KARA. Additionally, first measurements of the changes to the current-dependent bunch length will be presented.
 
poster icon Poster WEPAB083 [1.129 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB083  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 01 September 2021  
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WEPAB087 Observation of Undulator Radiation Generated by a Single Electron Circulating in a Storage Ring and Possible Applications 2790
 
  • I. Lobach
    University of Chicago, Chicago, Illinois, USA
  • A. Halavanau, Z. Huang
    SLAC, Menlo Park, California, USA
  • K. Kim
    ANL, Lemont, Illinois, USA
  • S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev
    Fermilab, Batavia, Illinois, USA
 
  An experimental study into the undulator radiation, generated by a single electron was carried out at the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab. The individual photons were detected by a Single Photon Avalanche Diode (SPAD) at an average rate of 1 detection per 300 revolutions in the ring. The detection events were continuously recorded by a picosecond event timer for as long as 1 minute at a time. The collected data were used to test if there is any deviation from the classically predicted Poissonian photostatistics. It was motivated by the observation * of sub-Poissonian statistics in a similar experiment. The observation * could be an instrumentation effect related to low detection efficiency and long detector dead time. In our experiment, the detector (SPAD) has a much higher efficiency (65%) and a much lower dead time. In addition, we show that the collected data (recorded detection times) can be used to study the synchrotron motion of a single electron and infer some parameters of the ring. For example, by comparing the results of simulation and measurement for the synchrotron motion we were able to estimate the magnitude of the RF phase jitter.
* Teng Chen and John M. J. Madey, Phys. Rev. Lett. 86, 5906, June 2001
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB087  
About • paper received ※ 17 May 2021       paper accepted ※ 24 June 2021       issue date ※ 27 August 2021  
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WEPAB088 Transverse Beam Emittance Measurement by Undulator Radiation Power Noise 2794
 
  • I. Lobach
    University of Chicago, Chicago, Illinois, USA
  • A. Halavanau, Z. Huang
    SLAC, Menlo Park, California, USA
  • K. Kim
    ANL, Lemont, Illinois, USA
  • V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev
    Fermilab, Batavia, Illinois, USA
 
  Generally, turn-to-turn power fluctuations of incoherent spontaneous synchrotron radiation in a storage ring depend on the 6D phase-space distribution of the electron bunch. In some cases, if only one parameter of the distribution is unknown, this parameter can be determined from the measured magnitude of these power fluctuations. In this contribution, we report the results of our experiment at the Integrable Optics Test Accelerator (IOTA) storage ring, where we carried out an absolute measurement (no free parameters or calibration) of a small vertical emittance (5–15 nm rms) of a flat beam by this new method, under conditions, when the small vertical emittance is unresolvable by a conventional synchrotron light beam size monitor.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB088  
About • paper received ※ 17 May 2021       paper accepted ※ 24 June 2021       issue date ※ 20 August 2021  
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WEPAB089 Conceptual Design of Booster Synchrotron for Siam Photon Source II 2795
 
  • S. Krainara, S. Klinkhieo, P. Klysubun, T. Pulampong, P. Sudmuang
    SLRI, Nakhon Ratchasima, Thailand
 
  Funding: Synchrotron Light Research Institute (Public organization)
A project on a 3.0 GeV Siam Photon Source II (SPS-II) has been started. The storage ring of SPS-II was designed to obtain an electron beam with a low-emittance below 1 nm-rad. The SPS-II injector mainly consists of a 150 MeV linac and a full-energy booster synchrotron. The booster synchrotron will be installed in the same tunnel as the storage ring, with a total circumference of 304.829 meters. The proposed lattice of the booster contains 40 modified FODO cells with combined function magnets. This lattice achieves a small beam emittance less than 10 nm-rad at 3 GeV, which can provide a high injection efficiency for top-up operation. The conceptual design for SPS-II booster synchrotron is presented in this work.
 
poster icon Poster WEPAB089 [1.187 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB089  
About • paper received ※ 19 May 2021       paper accepted ※ 08 June 2021       issue date ※ 19 August 2021  
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WEPAB090 Higher Order Mode Damping for 166 MHz and 500 MHz Superconducting RF Cavities at High Energy Photon Source 2798
 
  • H.J. Zheng, Z.Q. Li, F. Meng, N. Wang, H.S. Xu, P. Zhangpresenter, X.Y. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Funding: This work was supported in part by High Energy Photon Source, in part by the National Natural Science Foundation of China under Grant No. 11905232.
Superconducting rf cavities have been chosen for High Energy Photon Source, a 6 GeV diffraction-limited synchrotron light source under construction in Beijing. The main accelerating cavity adopted a quarter-wave β=1 structure operating at 166 MHz while the third harmonic cavity utilized the single-cell elliptical geometry at 500 MHz for the storage ring. The high beam current (200 mA) requires a strong damping of higher order modes (HOMs) excited in the superconducting cavities. To meet the beam stability requirements, enlarged beam pipes with a diameter of 505 mm for the 166 MHz cavity and 300 mm for the 500 MHz cavity were chosen to allow all HOMs to propagate along the beam tubes and to be damped by beam-line absorbers. This paper presents the HOM damping scheme and the cavity impedance analysis results. In addition, power losses due to HOMs were also evaluated for various operation modes (high charge and high luminosity) of the HEPS.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB090  
About • paper received ※ 17 May 2021       paper accepted ※ 22 June 2021       issue date ※ 11 August 2021  
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WEPAB092 Redesign of the Jefferson Lab -300 kV DC Photo-Gun for High Bunch Charge Operations 2802
 
  • S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft, G.G. Palacios Serrano
    ODU, Norfolk, Virginia, USA
  • J.F. Benesch, J.R. Delayen, C. Hernandez-Garcia, G.A. Krafft, M.A. Mamun, M. Poelker, R. Suleiman
    JLab, Newport News, Virginia, USA
 
  Funding: The U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177, JSA initiatives fund program and Laboratory Directed Research and Development program.
Production of high bunch charge beams for the Electron-Ion Collider (EIC) is a challenging task. High bunch charge (a few nC) electron beam studies at Jefferson Lab using an inverted insulator DC high voltage photo-gun showed evidence of space charge limitations starting at 0.3 nC, limiting the maximum delivered bunch charge to 0.7 nC for beam at -225 kV, 75 ps (FWHM) pulse width, and 1.64 mm (rms) laser spot size. The low extracted charge is due to the modest longitudinal electric field (Ez) at the photocathode leading to beam loss at the anode and downstream beam pipe. To reach the few nC high bunch charge goal, and to correct the beam deflection exerted by the non-symmetric nature of the inverted insulator photo-gun the existing photo-gun was modified. This contribution discusses the electrostatic design of the modified photo-gun obtained using CST Studio Suite’s electromagnetic field solver. Beam dynamics simulations performed using General Particle Tracer (GPT) with the resulting electrostatic field map obtained from the modified electrodes confirmed the validity of the new design.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB092  
About • paper received ※ 20 May 2021       paper accepted ※ 02 June 2021       issue date ※ 19 August 2021  
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WEPAB093 Space Charge Effects in Low Energy Magnetized Electron Beam 2806
 
  • S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • J.F. Benesch, G.A. Krafft, M.A. Mamun, M. Poelker, R. Suleiman, S. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Laboratory Directed Research and Development program.
Magnetized electron cooling is one of the major approaches towards obtaining the required high luminosity in the proposed Electron-Ion Collider (EIC). In order to increase the cooling efficiency, a bunched electron beam with a high bunch charge and high repetition rate is required. At Jefferson Lab, we generated magnetized electron beams with high bunch charge using a new compact DC high voltage photogun biased at -300 kV with bialkali-antimonide photocathode and a commercial ultra-fast laser. This contribution discusses how magnetization affects space charge dominated beams as a function of magnetic field strength, gun high voltage, and laser pulse width, and spot size in comparison with simulations performed using General Particle Tracer.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB093  
About • paper received ※ 19 May 2021       paper accepted ※ 08 June 2021       issue date ※ 23 August 2021  
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WEPAB096 RF Testbed for Cryogenic Photoemission Studies 2810
 
  • G.E. Lawler, A. Fukasawa, N. Majernik, J.B. Rosenzweig, A. Suraj, M. Yadav
    UCLA, Los Angeles, California, USA
  • Z. Li
    SLAC, Menlo Park, California, USA
  • M. Yadav
    The University of Liverpool, Liverpool, United Kingdom
  • M. Yadav
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409
Producing higher brightness beams at the cathode is one of the main focuses for future electron beam applications. For photocathodes operating close to their emission threshold, the cathode lattice temperature begins to dominate the minimum achievable intrinsic emittance. At UCLA, we are designing a radiofrequency (RF) test bed for measuring the temperature dependence of the mean transverse energy (MTE) and quantum efficiency for a number of candidate cathode materials. We intend to quantify the attainable brightness improvements at the cathode from cryogenic operation and establish a proof-of-principle cryogenic RF gun for future studies of a 1.6 cell cryogenic photoinjector for the UCLA ultra compact XFEL concept (UC-XFEL). The test bed will use a C-band 0.5-cell RF gun designed to operate down to 40K, producing an on-axis accelerating field of 120 MV/m. The cryogenic system uses conduction cooling and a load-lock system is being designed for transport and storage of air-sensitive high brightness cathodes.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB096  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 21 August 2021  
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WEPAB097 Initial Nanoblade-Enhanced Laser-Induced Cathode Emission Measurements 2814
 
  • G.E. Lawler, J.I. Mann, J.B. Rosenzweig, V.S. Yu
    UCLA, Los Angeles, California, USA
  • R.J. Roussel
    University of Chicago, Chicago, Illinois, USA
 
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE HEP Grant DE-SC0009914
Nanostructured photocathodes offer a unique functionality not possible in traditional photocathodes, increasing beam brightness by reducing the effective emission area. Inspired by field emitter tips, we examine a possible extension for higher current operation, an extended nanoblade capable of producing asymmetric emittance electron beams. A full understanding of emission is necessary to establish the effectiveness of nanoblades as usable cathode for electron accelerators. Utilizing wet etching of silicon wafers, we arrive at a robust sample capable of dissipating incident laser fields in excess of 20 GV/m without permanent damage. Initial predictions and experiments from the nanotip case predict energies up to the keV scale from electron rescattering and fine features on the order of the photon quantum. We will present initial electron data from 800 nm Ti:S laser illumination and measurements of a focused 1 keV beam.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB097  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 26 August 2021  
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WEPAB098 Cryogenic Component and Material Testing for Compact Electron Beamlines 2818
 
  • G.E. Lawler, N. Majernik, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
 
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409
Cryogenic regimes of operation are, for various reasons, highly advantageous for normal conducting accelerator structures. Liquid cryogen-based systems are costly to implement and maintain. As a result, developing cryogenic test facilities at a smaller more cost effective scale using cryo-coolers is attractive. Before real implementations of a cryo-cooler based beamline, a significant amount of information is necessary regarding the behavior and properties of various components and materials at cryogenic temperatures. Finding this information lacking for our particular beamline case and by extension similar electron beamlines, we endeavor to generate a thorough beamline-relevant material and component properties down to the range of a liquid nitrogen temperatures (77 K) and the nominal operating temperature of a modest Gifford-McMahon cryocooler (45 K).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB098  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 18 August 2021  
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WEPAB099 Near-Threshold Nonlinear Photoemission From Cu(100) 2822
 
  • C.J. Knill, S.S. Karkare
    Arizona State University, Tempe, USA
  • H.A. Padmore
    LBNL, Berkeley, California, USA
 
  Funding: National Science Foundation Grant No. PHY-1549132
Photocathodes that have a low mean transverse energy (MTE) are crucial to the development of compact X-ray Free Electron Lasers (XFEL) and ultrafast electron diffraction (UED) experiments. For FELs, low MTE cathodes result in a lower requirement for electron energy when lasing at a defined energy, and for a defined electron energy result in lasing at higher energy. For UED experiments, low MTE cathodes give a longer coherence length, allowing measurements on larger unit cell materials. A record low MTE of 5 meV has been recently demonstrated from a Cu (100) surface when measured near the photoemission threshold and cooled down to 30 K with liquid Helium [*]. For UED and XFEL applications that require a high charge density, the low quantum efficiency of Cu (100) near threshold necessitates the use of a high laser fluence to achieve the desired charge density [**]. At high laser fluences the MTE is limited by nonlinear effects, and therefore it is necessary to investigate near photoemission threshold at these high laser fluences. In this paper we report on nonlinear, near-threshold photoemission from a Cu (100) cathode, and its effect on the MTE.
* S. Karkare et al, Phys. Rev. Lett. 125, 054801 (2020)
** J. Bae et al, J. Appl. Phys., 124, 244903 (2018)
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB099  
About • paper received ※ 19 May 2021       paper accepted ※ 21 July 2021       issue date ※ 20 August 2021  
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WEPAB100 Heat Dissipation of Photocathodes at High Laser Intensities for a New DC Electron Source 2826
 
  • M.A. Dehn, K. Aulenbacher
    IKP, Mainz, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
  • K. Aulenbacher
    GSI, Darmstadt, Germany
 
  Funding: This project was supported by the German science ministry BMBF through the Verbundforschung
Laser intensities of 1W or more are required to extract average beam currents of more than 10mA from photocathodes. Most of this laser power is converted into thermal load within the cathode and has to be dissipated to avoid excessive heating of the cathode and thus a significant reduction in lifetime. At Johannes Gutenberg-University Mainz, we are developing a new high current DC electron source operating at an energy of 100keV, where an efficient heat dissipation of the photocathode is achieved by a mechanical design of the supporting structure.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB100  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 26 August 2021  
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WEPAB101 An Improved Model for Photoemission of Space Charge Dominated Picosecond Electron Bunches: Theory and Experiment 2829
 
  • S.M. Polozov, V.I. Rashchikov
    MEPhI, Moscow, Russia
  • M. Krasilnikov
    DESY Zeuthen, Zeuthen, Germany
 
  The emission of a short highly charged electron bunch in a radiofrequency photogun is discussed. The traditional space charge limited emission numerical model is extended by an introduction of positively charged ions arising in the cathode region and dynamically changing during the emission. Estimates on the time characteristics of the charge migrating process in the semiconductor region are given. The numerical results are compared with the results of other numerical models and with experimental observations at the Photo Injector Test facility at DESY in Zeuthen (PITZ).  
poster icon Poster WEPAB101 [1.601 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB101  
About • paper received ※ 08 May 2021       paper accepted ※ 07 June 2021       issue date ※ 29 August 2021  
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WEPAB102 Half-Metal Spin Filter for Highly Polarized Emission from GaAs Photocathodes 2833
 
  • S. Poddar, C.-J. Jing, E.J. Montgomery
    Euclid Beamlabs, Bolingbrook, USA
  • P. Lukashev
    University of Northern Iowa, Cedar Falls, Iowa, USA
  • C. Palmstrøm
    UCSB, Santa Barbara, California, USA
  • M.L. Stutzman, S. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by Department of Energy grant number DE-SC0020564.
GaAs-based photocathodes are one of the major sources of spin-polarized electrons and are crucial for the upcoming Electron-Ion collider experiments which includes study of proton spin and spin parity violation in the standard model. The theoretical polarization limit in unstrained GaAs photocathodes is 50 % but only 35 % is routinely achieved in experiments. Spin selective filtering allows to boost the spin polarization beyond the 50 % theoretical limit. In this work, first-principle electronic calculations using standard Density Functional Theory are performed to predict possible Heusler alloy half-metal candidates to be used as spin-filter. Simulations are also performed to investigate the half-metallicity as function of the magnetic spin direction. Several devices are experimentally fabricated using dedicated Molecular Beam Epitaxy growth system. We implemented Quantum Efficiency and Polarization testing of these half-metal/GaAs heterostructures using a dedicated Mott polarimeter system. Photoemission can also be seen on magnetically switching the spin-filter direction accompanied by a change in sign of the asymmetry which is a qualitative proof of the spin-filtering effect.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB102  
About • paper received ※ 20 May 2021       paper accepted ※ 28 July 2021       issue date ※ 18 August 2021  
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WEPAB103 Systematic Beam Parameter Studies at the Injector Section of FLUTE 2837
 
  • T. Schmelzer, E. Bründermann, D. Hoffmann, I. Križnar, S. Marsching, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski, T. Windbichler
    KIT, Karlsruhe, Germany
 
  Funding: This work is supported by the DFG-funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology (KSETA)"
FLUTE (Ferninfrarot Linac- und Test-Experiment) is a compact linac-based test facility for accelerator R&D and source of intense THz radiation for photon science. In preparation for the next experiments, the electron beam of the injector section of FLUTE has been characterized. In systematic studies the electron beam parameters, e.g., beam energy and emittance, are measured with several diagnostic systems. This knowledge allows the establishment of different operation settings and the optimization of electron beam parameters for future experiments.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB103  
About • paper received ※ 19 May 2021       paper accepted ※ 26 August 2021       issue date ※ 01 September 2021  
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WEPAB104 Improving the Operational Lifetime of the CEBAF Photo-Gun by Anode Biasing 2840
 
  • J.T. Yoskowitz, G.A. Krafft, G.G. Palacios Serrano, S.A.K. Wijethunga
    ODU, Norfolk, Virginia, USA
  • J.M. Grames, J. Hansknecht, C. Hernandez-Garcia, M. Poelker, M.L. Stutzman, R. Suleiman
    JLab, Newport News, Virginia, USA
  • S.B. van der Geer
    Pulsar Physics, Eindhoven, The Netherlands
 
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
The operating lifetime of GaAs-based photocathodes in DC high voltage electron photo-guns is dominated by the ionization rate of residual beamline gas molecules. In this work, experiments were performed to quantify the improvement in photocathode charge lifetime by biasing the photo-gun anode with a positive voltage, which repels ions generated downstream of the anode. The photo-cathode charge lifetime improved by almost a factor of two when the anode was biased compared to the usual grounded configuration. Simulations were performed using the particle tracking code General Particle Tracer (GPT) with a new custom element. The simulation results showed that both the number and energy of ions play a role in the pattern of QE degradation. The experiment results and conclusions supported by GPT simulations will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB104  
About • paper received ※ 20 May 2021       paper accepted ※ 02 June 2021       issue date ※ 24 August 2021  
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WEPAB105 Simulating Electron Impact Ionization Using a General Particle Tracer (GPT) Custom Element 2843
 
  • J.T. Yoskowitz, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • J.M. Grames
    JLab, Newport News, Virginia, USA
  • G.R. Montoya Soto
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
  • C.A. Valerio
    ECFM-UAS, Culiacan, Sinaloa, Mexico
  • S.B. van der Geer
    Pulsar Physics, Eindhoven, The Netherlands
 
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177, Consejo Nacional de Ciencia y Tecnología (CONACYT).
A new C++ custom element has been developed with the framework of General Particle Tracer (GPT) to simulate electron impact ionization of residual gas molecules. The custom element uses Monte-Carlo routines to determine both the ion production rate and the secondary electron kinetic energy based on user-defined gas densities and theoretical values for the ionization cross section and the secondary electron differential cross section. It then uses relativistic kinematics to track the secondary electron, the scattered electron, and the newly formed ion after ionization. The ion production rate and the secondary electron energy distribution determined by the custom element have been benchmarked against theoretical calculations and against simulations made using the simulation package IBSimu. While the custom element was originally built for particle accelerator simulations, it is readily extensible to other applications. The custom element will be described in detail and examples of applications at the Thomas Jefferson National Accelerator Facility will be presented for ion production in a DC high voltage photo-gun.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB105  
About • paper received ※ 20 May 2021       paper accepted ※ 25 June 2021       issue date ※ 02 September 2021  
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WEPAB106 Study on Durability Improvement of Cs-Te Photocathode by Means of Alkali Halide Protective Films 2847
 
  • K. Ezawa, R. Fukuoka, Y. Koshiba, T. Tamba, M. Washio
    Waseda University, Tokyo, Japan
  • K. Sakaue
    The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan
 
  We have been conducting basic and applied research for generating high quality electron beams, using 1.6 cell laser photocathode RF-gun. In our laboratory, Cesium Telluride (Cs-Te), one of the semiconductor photocathodes, is used as an electron source for accelerator experiments. This semiconductor photocathode is known for high quantum efficiency (Q.E.) about 5~10% and 3-month 1/e lifetime. High Q.E. photocathodes can reduce the power requirement of the laser system, and long lifetime photocathodes can decrease the maintenance frequency, contributing to an efficient experimental environment. For these reasons, high Q.E. and long lifetime photocathodes are necessary in accelerator experiments. In order to produce robust photocathodes and extend the lifetime, we have conducted covering Cs-Te photocathodes with CsBr and CsI protective films. In this conference, we report the thickness dependency on the lifetime of Cs-Te photocathodes when we intentionally exposed oxygen gas to coated and non-coated Cs-Te photocathodes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB106  
About • paper received ※ 19 May 2021       paper accepted ※ 02 June 2021       issue date ※ 01 September 2021  
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WEPAB109 Initial Study of GaN Thin Films for Photocathodes Prepared by Magnetron Sputtering on Copper Substrates 2850
 
  • M. Vogel, X. Jiang, C. Wangpresenter
    University Siegen, Siegen, Germany
  • P. Murcek, J. Schaber, R. Xiang
    HZDR, Dresden, Germany
 
  Funding: This research is funded by the Federal Ministry of Education and Research of Germany in the framework of BETH (project number 05K19PSB).
On the path for high brightness electron beams, Gallium Nitride (GaN) is one promising candidate for a photo-cathode material. In this contribution, we report on the continuation of the study to optimize the crystallization quality and crystallography of Mg-doped GaN samples on copper substrates that are synthesized by RF magnetron sputtering. SEM and XRD results show that the pretreatment methods and the sputtering conditions (temperature, sputtering power, and partial pressure of the reactive gas) can both affect the morphology and crystal quality of GaN films. The initial QE measurements of these samples are done in our newly build in-situ QE measurement system and the first results of QE analyses done at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) are presented in a dedicated contribution.
Part of this work was performed at the Micro- and Nanoanalytics Facility (MNaF) of the University of Siegen.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB109  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 29 August 2021  
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WEPAB110 Solid-State Driven X-Band Linac for Electron Microscopy 2853
 
  • A. Dhar, E.A. Nanni, M.A.K. Othman, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515.
Microcrystal electron diffraction (MicroED) is a technique used by scientists to image molecular crystals with cryo-electron microscopy (cryo-EM)*. However, cryo-EMs remain expensive, limiting MicroED’s accessibility. Current cryo-EMs accelerate electrons to 200-300 keV using DC electron guns with a nA of current and low emittance. However at higher voltages these DC guns rapidly grow in size. Replacing these electron guns with a compact linac powered by solid-state sources could lower cost while maintaining beam quality, thereby increasing accessibility. Utilizing compact high shunt impedance X-band structures ensures that each RF cycle contains at most a few electrons, preserving beam coherence. CW operation of the RF linac is possible with distributed solid-state architectures** that use 100W solid-state amplifiers at X-band frequencies. We present an initial design for a prototype low-cost CW RF linac for high-throughput MicroED producing 200 keV electrons with a standing-wave architecture where each cell is individually powered by a solid-state amplifier. This design also provides an upgrade path for future compact MeV-scale sources on the order of 1 meter in size.
* Jones, C. G. et al. ACS central science 4, 1587-1592 (2018).
** D. C. Nguyen et al, Proc. 9th International Particle Accelerator Conference (IPAC’18), no. 9, pp. 520-523
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB110  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 19 August 2021  
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WEPAB111 Controlled Degradation by Oxygen Exposure in the Performance of a Ag (100) Single-Crystal Photocathode 2856
 
  • L.A.J. Soomary, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • L.B. Jones, T.C.Q. Noakes
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  The search for high-performance photocathode electron sources is a priority in the accelerator science community. The surface characteristics of a photocathode define many important factors of the photoemission including the work function, intrinsic emittance, and quantum efficiency of the photocathode. These factors in turn define the electron beam performance which is measurable as normalized emittance, brightness, and energy spread*. Strategies for improving these parameters vary, but understanding and influencing the relevant cathode surface physics which underpin these attributes is a primary focus for the electron source community**. As such, pure metal photocathodes and their performance at UV wavelengths are of interest as seen at the LCLS at SLAC and CLARA at Daresbury. We present performance data for an Ag (100) single-crystal photocathode under illumination at 266 nm wavelength, with known levels of surface roughness, using our Transverse Energy Spread Spectrometer (TESS)*** both at room and cryogenic temperatures. Crucially our data shows the effect of progressive degradation in the photo-cathode performance as a consequence of exposure to controlled levels of oxygen.
* D.H. Dowell, et al., Nucl. Instr. and Meth. A (2010), doi:10.1016/j.nima.2010.03.104
** Appl. Phys. Lett. 89, 224103 (2006); doi:10.1063/1.2387968
*** Proc. FEL’13, TUPPS033, 290-293
 
poster icon Poster WEPAB111 [0.866 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB111  
About • paper received ※ 20 May 2021       paper accepted ※ 22 June 2021       issue date ※ 21 August 2021  
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WEPAB112 Performance Characterisation of a Cu (100) Single-Crystal Photocathode 2860
 
  • L.A.J. Soomary, D.P. Juarez-Lopez, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • L.B. Jones, T.C.Q. Noakes
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  The search for high performance photocathode electron sources is a priority in the accelerator science community. The surface characteristics of a photocathode define important factors of the photoemission including the intrinsic emittance, the quantum efficiency and the work function of the photocathode. These factors in turn define the electron beam performance which are measurable as emittance, brightness and energy spread. We have used ASTeC’s Multiprobe (SAPI)* to characterise and analyse photocathode performance using multiple techniques including XPS, STM, and LEED imaging, and their Transverse Energy Spread Spectrometer (TESS)** to measure mean transverse energy (MTE). We present characterisation measurements for a Cu (100) single-crystal photocathode sample with data from SAPI confirming the crystallographic face and showing surface composition and roughness, supported by data from TESS showing the photocathode electron beam energy spread.
* B.L. Militsyn, 4-th EuCARD2 WP12.5 meeting, Warsaw, 14-15 March 2017
**Proc. FEL’13, TUPPS033, 290-293
 
poster icon Poster WEPAB112 [0.814 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB112  
About • paper received ※ 19 May 2021       paper accepted ※ 12 July 2021       issue date ※ 25 August 2021  
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WEPAB113 Stripline Kickers for Injection Into PETRA IV 2863
 
  • G. Loisch, I.V. Agapov, S.A. Antipov, J. Keil, F. Obier
    DESY, Hamburg, Germany
  • M.A. Jebramcik
    CERN, Meyrin, Switzerland
 
  PETRA IV is the planned ultralow-emittance upgrade of the PETRA III synchrotron light source at DESY, Hamburg. The current design includes an on-axis beam injection scheme using fast stripline kickers. These kickers have to fulfill the requirements on kick-strength, field quality, pulse rise-rate and a matched beam impedance. 3D finite element simulations in conjunction with Bayesian optimisation are used to meet these requirements simultaneously. Here, we will discuss the requirements on the PETRA IV injection kickers and the current design status.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB113  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 23 August 2021  
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WEPAB115 Beam Preparation with Temporally Modulated Photocathode Laser Pulses for a Seeded THz FEL 2866
 
  • G.Z. Georgiev, N. Aftab, P. Boonpornprasert, J. Good, M. Groß, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, A. Lueangaramwong, D. Melkumyan, S.K. Mohanty, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko, T. Weilbach
    DESY Zeuthen, Zeuthen, Germany
  • N. Chaisueb
    Chiang Mai University, Chiang Mai, Thailand
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  The need for carrier-envelope-phase (CEP) stable THz pump pulses is recognized at many pump-probe experiments at the European XFEL. At the Photo Injector Test Facility at DESY in Zeuthen (PITZ), a proof-of-principle experiment of an accelerator-based THz FEL source is in preparation. Since the CEP stability of FEL pulses is not guaranteed in the SASE regime, a seeding scheme is needed. A common scheme for seeding is to drive the microbunching process with external laser pulses, which are power-limited in the THz range. Alternatively, a pre-bunched beam, generated for example by applying a temporally modulated photocathode laser pulse, can be used to drive the FEL. The beam dynamics with such a seeding method are studied with ASTRA tracking code simulations with space-charge forces as well as experimentally. The results of these studies are shown and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB115  
About • paper received ※ 19 May 2021       paper accepted ※ 27 July 2021       issue date ※ 21 August 2021  
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WEPAB117 Injection Feedback for a Storage Ring 2870
 
  • A. Moutardier, C. Bruni, I. Chaikovska, S. Chancé, N. Delerue, E.E. Ergenlik, V. Kubytskyi, H. Monard
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
 
  Funding: Research Agency under the Equipex convention ANR-10-EQPX-0051.
We report on an injection feedback scheme for the ThomX storage ring project. ThomX is a 50-MeV-electron accelerator prototype which will use Compton backscattering in a storage ring to generate a high flux of hard X-rays. Given the slow beam damping (in the ring), the injection must be performed with high accuracy to avoid large betatron oscillations. A homemade analytic code is used to compute the corrections that need to be applied before the beam injection to achieve a beam position accuracy of a few hundred micrometers in the first beam position monitors (BPMs). In order to do so the code needs the information provided by the ring’s diagnostic devices. The iterative feedback system has been tested using MadX simulations. Our simulations show that a performance that matches the BPMs’ accuracy can be achieved in less than 50 iterations in all cases. Details of this feedback algorithm, its efficiency and the simulations are discussed.
 
poster icon Poster WEPAB117 [2.422 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB117  
About • paper received ※ 28 May 2021       paper accepted ※ 01 July 2021       issue date ※ 25 August 2021  
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WEPAB118 Loss Maps Along the ThomX Transfer Line and the Ring First Turn 2874
 
  • A. Moutardier, C. Bruni, I. Chaikovska, S. Chancé, N. Delerue, E.E. Ergenlik, V. Kubytskyi, H. Monard
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
 
  Funding: Research Agency under the Equipex convention ANR-10-EQPX-0051.
We report on studies of the loss maps for particles travelling from the end of the ThomX’s linac along the transfer line to the end of the ring first turn in preparation of the machine commissioning. ThomX is a 50-MeV-electron accelerator prototype which will use Compton backscattering to generate a high flux of hard X-rays. The accelerator tracking code MadX is used to simulate electrons’ propagation and compute losses. These maps may be projected at any localisation along the bunch path or plotted along the bunch path. This information is particularly relevant at the locations of the monitoring devices (screens, position monitors,…) where loss predictions will be compared with measurements.
 
poster icon Poster WEPAB118 [3.173 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB118  
About • paper received ※ 28 May 2021       paper accepted ※ 28 July 2021       issue date ※ 25 August 2021  
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WEPAB119 Beam Injection with a Pulsed Nonlinear Magnet Into the HALF Storage Ring 2878
 
  • G. Liu, W. Li, L. Wang, P.N. Wang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  The nonlinear optics of the HALF storage ring are well optimized to make it possible to inject the beam with the pulsed multipole injection scheme. In this paper, the injection scheme is studied with an innovatively designed pulsed nonlinear magnet. The layout and parameters of the injection system are well designed based on the acceptance analysis. The injection process is simulated with particle tracking is presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB119  
About • paper received ※ 20 May 2021       paper accepted ※ 29 July 2021       issue date ※ 25 August 2021  
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WEPAB120 Upgrades to the Booster to Storage Ring Transfer Line at the Canadian Light Source 2881
 
  • W.A. Wurtz, T. Batten, B.E. Bewer, M. Bree, S.R. Carriere, A.M. Duffy, B. Fogal, L.X. Lin, C.M. Randall, B.A. Schneider, J.M. Vogt, J. Willard, T. Wilson
    CLS, Saskatoon, Saskatchewan, Canada
  • P. Kuske
    HZB, Berlin, Germany
 
  Investigations into the booster to storage ring transfer process identified non-linear fields in the booster extraction septum as the cause for the poor transfer efficiency. We found that by correcting the trajectory through the septum, the transfer efficiency improved substantially. This motivated an upgrade project to reliably control the trajectory through the septum and transfer line, to provide improved diagnostics and to implement a set of four horizontal scrapers to reduce the horizontal emittance of the beam before it reaches the storage ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB120  
About • paper received ※ 10 May 2021       paper accepted ※ 24 June 2021       issue date ※ 13 August 2021  
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WEPAB121 Design and Simulation of Transparent Injection Upgrade for the CLS Storage Ring 2885
 
  • P.J. Hunchak, M.J. Boland
    University of Saskatchewan, Saskatoon, Canada
  • D. Bertwistle, M.J. Boland
    CLS, Saskatoon, Saskatchewan, Canada
 
  The Canadian Light Source (CLS) synchrotron uses four fast kicker magnets to inject electrons into the storage ring from a 2.9 GeV booster ring. The injection occurs over several turns of the stored beam, which is also perturbed by the injection kickers. The resultant oscillations of the stored beam can negatively affect beamline experiments, so it is desirable to implement an injection scheme which does not disturb the stored beam. Injection schemes of this type allow for transparent injection and are beneficial for planned top-up operations of the CLS storage ring. Many alternative injection techniques were examined as they apply to the CLS storage ring. Pulsed multipole magnets and a non-linear kicker (NLK) are the most viable options for integration with the current ring. Non-linear kicker designs are also being considered for the proposed CLS2 and studying the NLK in the limitations of the current machine provides insight to guide the work on the new machine. Simulation with the accelerator code ELEGANT shows the viability of the non-linear kicker design as developed at BESSY, MAX IV and SOLEIL for transparent injection at the CLS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB121  
About • paper received ※ 19 May 2021       paper accepted ※ 16 July 2021       issue date ※ 22 August 2021  
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WEPAB122 Development of Fast and Super-Fast Kicker System for SLS 2.0 Injection 2889
 
  • M. Paraliev, M. Aiba, S. Dordevic, C.H. Gough, A. Streun
    PSI, Villigen PSI, Switzerland
 
  Swiss Light Source plans a major upgrade to turn the existing Storage Ring (SR) into a modern diffraction-limited light source called SLS 2.0. As part of this project, the injection system has to be upgraded as well in order to ensure reliable and efficient injection in the reduced beam aperture. A 4 kicker bump and a new thin septum will ensure the conventional injection in the SR. To further minimize the perturbation of the stored beam during injection two new schemes are in development: "Fast" and "Super-fast" one. The "Fast" injection scheme should be able to ensure single-bunch off-axis top-up injection affecting only 10 to 20 SR bunches that are 2 ns apart. The "Super-fast" one should bring the perturbed bunches down to only one. In on-axis mode it should be able to inject a top-up bunch between two SR bunches with minimum disturbance of the adjacent ones. To do this a combination of special beam injection schemes and an extremely fast (ns) kicker system is required. We will discuss the status of the development, the problems, and the solutions for reaching such a challenging goal.  
poster icon Poster WEPAB122 [1.371 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB122  
About • paper received ※ 18 May 2021       paper accepted ※ 09 June 2021       issue date ※ 02 September 2021  
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WEPAB123 Multi-Bunch Resistive Wall Wake Field Tracking via Pseudomodes in the ALS-U Accumulator Ring 2893
 
  • M.P. Ehrlichman, S. De Santis, T. Hellert, S.C. Leemann, G. Penn, C. Steier, C. Sun, M. Venturini, D. Wang
    LBNL, Berkeley, USA
 
  For the ALS-U project, particles will be injected from the booster to the accumulator ring utilizing an injection scheme that leaves the stored and injected particles with a non-trivial transient. This transient requires that multibunch feedback be masked for those buckets into which charge is injected. The masking significantly diminishes the damping capability of the multibunch feedback system. This problem is exacerbated by the large injection transient. The higher order resistive wall wake fields in the accumulator ring exceed the radiation damping time. To study whether the beam will remain multibunch stable during an injection cycle, a multibunch tracking simulation is used that simulates the multibunch feedback system and also pseudomode representation of resistive wall wake fields.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB123  
About • paper received ※ 20 May 2021       paper accepted ※ 28 August 2021       issue date ※ 01 September 2021  
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WEPAB124 The Three Dipole Kicker Injection Scheme for the ALS-U Accumulator Ring 2896
 
  • M.P. Ehrlichman, T. Hellert, S.C. Leemann, G. Penn, C. Steier, C. Sun, M. Venturini, D. Wang
    LBNL, Berkeley, California, USA
 
  The ALS-U light source will implement on-axis swap-out injection of individual trains employing an accumulator between the booster and storage rings. The accumulator ring design is a twelve period triple-bend achromat that will be installed along the inner circumference of the storage-ring tunnel. A non-conventional injection scheme will be utilized for top-off off-axis injection from the booster into the accumulator ring meant to accommodate a relatively narrow vacuum-chamber aperture while maximizing injection efficiency. The scheme incorporates three dipole kickers distributed over three sectors, with two kickers perturbing the stored beam and the third affecting both the stored and the injected beam trajectories. This paper describes this ‘‘3DK’’ injection scheme, how it was chosen, designed and optimized, and how we evaluated its fitness as a solution for booster-to-accumulator ring injection against alternate injection schemes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB124  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 30 August 2021  
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WEPAB125 Acceptance Analysis Method for the Scheme Design of Multipole Kicker Injection 2900
 
  • P.N. Wang, W. Li, G. Liu, L. Wang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  A pulsed multipole kicker has zero magnetic field at the center, consequently, this injection scheme can be transparent to the stored beam and users. In general, multipole kicker injection schemes are derived from the method of phase space analysis. In this paper, a new method of acceptance analysis based on multi-particles tracking is proposed. Using this method, we can quickly obtain multiple kicker injection schemes and easily make adjustments to them. The details of this method are presented and we apply it to the HALF storage ring as an example. A series of tracking simulations are carried out and results are also discussed.  
poster icon Poster WEPAB125 [0.930 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB125  
About • paper received ※ 18 May 2021       paper accepted ※ 09 June 2021       issue date ※ 13 August 2021  
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WEPAB126 Pulsed Wire Magnetic Field Measurement System for Short-Period Long Undulators 2903
 
  • J.E. Baader, S. Casalbuoni
    EuXFEL, Schenefeld, Germany
 
  The pulsed wire method is an attractive option to measure the magnetic field in insertion devices, mainly for those with restricted access (e.g., small gaps, in-vacuum/cryogenic environments, etc.). Besides first and second field integrals, experiments have proved the feasibility of reconstructing the magnetic field profile. Undulators with a small gap and short period are - and are planned to be - used at diffraction-limited storage rings and free-electron lasers. This contribution outlines the pulsed wire system’s requirements to perform magnetic field reconstruction in such undulators. We examine the main expected limitations, particularly the dispersive, finite pulse-width, discretization error, and sag effects. Furthermore, we present the current status of developing the pulsed wire system at the European XFEL.  
poster icon Poster WEPAB126 [1.184 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB126  
About • paper received ※ 19 May 2021       paper accepted ※ 07 July 2021       issue date ※ 11 August 2021  
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WEPAB127 Accurate Measurements of Undulator Particle Beam Entrance/Exit Angles Using Improved Hall Probes and Calibration Process 2907
 
  • I. Vasserman, R.J. Dejus, Y. Piao, M.F. Qian, J.Z. Xu
    ANL, Lemont, Illinois, USA
 
  Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
The Advanced Photon Source Upgrade (APS-U) undulator requirements were changed from the first and second field integrals to the entrance and exit angles of the particle beam. This provides the user with the best radiation view angle by the storage ring closed orbit correction system. To satisfy such requirements we use improved Senis Hall probes and calibration process. In addition to the normal NMR calibration of the sensors, the calibration was further refined using stretch-coil integrals to make accurate measurements.
 
poster icon Poster WEPAB127 [0.620 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB127  
About • paper received ※ 15 May 2021       paper accepted ※ 09 June 2021       issue date ※ 23 August 2021  
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WEPAB128 Recent Experience with Magnet Sorting for APS-U Hybrid Undulators 2910
 
  • I. Vasserman, R.J. Dejus, Y. Piao, M.F. Qian, J.Z. Xu
    ANL, Lemont, Illinois, USA
 
  Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
The quality of permanent magnets plays a particularly important role in undulator performance. Many different types of magnet sorting to enhance undulator performance have been carried out at different facilities. Meanwhile, progress in improving magnet quality has been made by different vendors. At the Advanced Photon Source (APS) we have assembled, measured, and analyzed over 14 new undulators of the same mechanical design, some of them with sorted magnets and some unsorted. The performance differences appear to be insignificant in meeting the tight APS Upgrade (APS-U) undulator requirements.
 
poster icon Poster WEPAB128 [0.395 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB128  
About • paper received ※ 16 May 2021       paper accepted ※ 09 June 2021       issue date ※ 27 August 2021  
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WEPAB129 A New Method of Undulator Phase Tuning with Mechanical Shimming 2912
 
  • M.F. Qian, R.J. Dejus, Y. Piao, I. Vasserman, J.Z. Xu
    ANL, Lemont, Illinois, USA
 
  Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DEAC02-06CH11357.
We developed a new method for tuning the undulator phase errors by shimming the undulator gap profile mechanically. First, the phase errors of a device are calculated based on the initial field measurement; then the desired field strength modulation along the device length is derived from the phase errors; and finally, the gap profile is mechanically shimmed to produce the desire field strength modulation. The method has been successfully applied to the tuning of many new and reused APS Upgrade (APS-U) hybrid permanent magnet undulators. The method is especially effective for tuning the legacy undulators with large phase errors. For instance, an old 33-mm-period undulator with a 23 degree initial rms phase error largely due to radiation damage has been tuned to better than 3 degrees.
 
poster icon Poster WEPAB129 [0.500 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB129  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 16 August 2021  
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WEPAB130 Experience with Algorithm-Guided Tuning of APS-U Undulators 2915
 
  • M.F. Qian, R.J. Dejus, Y. Piao, I. Vasserman, J.Z. Xu
    ANL, Lemont, Illinois, USA
 
  Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE AC02-06CH11357.
The Advanced Photon Source (APS) is undergoing a major upgrade to its storage ring. The APS Upgrade (APS-U) project plans to build over 40 new hybrid permanent magnet undulators (HPMUs) and rebuild over 20 existing HPMUs. To meet the APS-U undulator requirements, the quality of the undulator magnetic field needs to be fine-tuned to the specifications. The traditional methods that depend on the tuning specialist experience are not desirable for tuning large quantities of undulators. We developed algorithms that automate the tuning of permanent magnet undulators. For tuning of the undulator trajectory and phase, the algorithms optimize the tuning parameters with differential evolution-based global optimization. The algorithms have been successfully applied to over 18 APS HPMUs. The results and experiences of the tuning are reported in detail.
 
poster icon Poster WEPAB130 [0.543 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB130  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 31 August 2021  
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WEPAB131 Magnetic Tuning and Installation Modifications of U48 Undulator for the Delhi Light Source (DLS) 2918
 
  • M. Tischer, P. Neumann, A. Schöps, P. Vagin, T. Vielitz, T. Wohlenberg
    DESY, Hamburg, Germany
  • M. Aggarwalpresenter, R.N. Dutt, S. Ghosh, J. Karmakar, S. Sahu
    IUAC, New Delhi, India
  • J. Bahrdt, E.C.M. Rial
    HZB, Berlin, Germany
 
  A compact THz radiation facility based on the principle of a pre-bunched Free Electron Laser, called Delhi Light Source (DLS) is at the final stage of commissioning at IUAC, New Delhi, India. For generation of THz radiation in DLS, an undulator with period length of 48 mm (U48), built by HZB and refurbished at DESY will be used. The magnetic tuning and the field measurements have been done on the U48 along with the design and installation of correction coils at the entrance/exit of the U48. In addition, horizontal and vertical ambient field correction coils were integrated into the magnet girders. A quadrupole correction coil along the vacuum chamber in order to mitigate the defocusing effect of the U48 on the electron beam has been designed. The current through all coils has been adjusted as a function of the gap by the new control system designed for the U48. In addition, an extruded aluminium vacuum chamber was designed and fabricated and will be aligned with the the undulator soon.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB131  
About • paper received ※ 19 May 2021       paper accepted ※ 05 July 2021       issue date ※ 16 August 2021  
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WEPAB132 Towards a Superconducting Undulator Afterburner for the European XFEL 2921
 
  • S. Casalbuoni, J.E. Baader, G. Geloni, V. Grattoni, D. La Civita, C. Lechner, B. Marchetti, S. Serkez, H. Sinn
    EuXFEL, Schenefeld, Germany
  • W. Decking, L. Lilje, S. Liu, T. Wohlenberg, I. Zagorodnov
    DESY, Hamburg, Germany
 
  We propose to develop, characterize and operate a superconducting undulator (SCU) afterburner consisting of 5 undulator modules (1 module = 2 times SCU coil of 2 m length and 1 phase shifter) at the SASE2 hard X-ray beamline of European XFEL. This afterburner has the potential to produce an output of more than 1010 ph/pulse at photon energies above 30 keV. The project is divided into the production of a pre-series prototype module and a small-series production of 5 modules. Central goals of this R&D activity are: the demonstration of the functionality of SCUs at an X-ray FEL, the set up of the needed infrastructure to characterize and operate SCUs, the industrialization of such undulators, and the reduction of the price per module. In this contribution, the main parameters and specifications of the pre-series prototype module (S-PRESSO) are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB132  
About • paper received ※ 15 May 2021       paper accepted ※ 05 July 2021       issue date ※ 28 August 2021  
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WEPAB133 First Numerical Wakefield Studies of New In-Vacuum Cryogenic and APPLE II Undulators for BESSY II 2925
 
  • M. Huck, J. Bahrdt, A. Meseck
    HZB, Berlin, Germany
  • A. Meseck
    KPH, Mainz, Germany
 
  While the new in-vacuum cryogenic undulator is in its last commissioning stages, a worldwide new in-vacuum APPLE II undulator is being designed and constructed for BESSY II storage ring. Besides the challenging mechanical design of these small-gap and short-period undulators, challenges arise due to interaction with the electron beam. Therefore, detailed studies of this interaction is required to minimize the adverse effects on beam dynamics and the device itself. For this purpose, the wakefield effects have been computed numerically for critical parts of these devices i.e. the RF-shields, flexible tapers and taper sections. A brief overview of simulation results and discussions are presented in this paper.  
poster icon Poster WEPAB133 [0.795 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB133  
About • paper received ※ 19 May 2021       paper accepted ※ 23 July 2021       issue date ※ 10 August 2021  
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WEPAB134 Experimental Studies of the In-Vacuum-Cryogenic Undulator Effect on Beam Instabilities at BESSY II 2929
 
  • M. Huck, J. Bahrdt, A. Meseck, G. Rehm, M. Ries, A. Schälicke
    HZB, Berlin, Germany
 
  A new in-vacuum cryogenic permanent magnet undulator (CPMU17) has been installed in summer 2018 in the BESSY II storage ring at HZB. Such a small gap in-vacuum undulator device increases the impedance of the storage ring and can contribute to the instabilities that adversely affect the beam quality and the device itself. To identify and explore the effects of CPMU17 on the instabilities at BESSY II, grow-damp and drive-damp experiments have been conducted using the installed bunch-by-bunch feedback system. In this paper, the first results of the mode and gap analysis of these studies with a brief overview of other impedance studies will be presented.  
poster icon Poster WEPAB134 [1.079 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB134  
About • paper received ※ 17 May 2021       paper accepted ※ 02 July 2021       issue date ※ 13 August 2021  
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WEPAB135 Progress of the Development of a Superconducting Undulator as a THz Source for FELs 2933
 
  • J. Gethmann, S. Casalbuoni, N. Glamann, A.W. Grau, A.-S. Müller, D. Saez de Jauregui
    KIT, Karlsruhe, Germany
  • D. Astapovych, H. De Gersem, E. Gjonaj
    TEMF, TU Darmstadt, Darmstadt, Germany
  • S. Casalbuoni
    EuXFEL, Schenefeld, Germany
 
  Funding: This work is supported by the BMBF project 05K19VK2 SCUXFEL (Federal Ministry of Education and Research) and by the DFG-funded Doctoral School KSETA: Science and Technology.
To produce radiation in the THz frequency range at X-ray Free Electron Lasers, undulators with large period length, high fields, and large gaps are required. These demands can be fulfilled by superconducting undulators. In this contribution, the actual requirements on the main parameters of such a superconducting undulator will be discussed and the progress of the design will be discussed. In addition, beam impedance and heat load results obtained analytically as well as by large-scale wakefield simulations will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB135  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 24 August 2021  
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WEPAB138 Superconducting RF Gun with High Current and the Capability to Generate Polarized Electron Beams 2936
 
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • S.A. Belomestnykh, S. Kazakov, T.N. Khabiboulline, M. Martinello, Y.M. Pischalnikov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • J.C. Brutus, P. Inacker, Y.C. Jing, V. Litvinenko, J. Skaritka, E. Wang
    BNL, Upton, New York, USA
  • J.M. Grames, M. Poelker, R. Suleiman, E.J-M. Voutier
    JLab, Newport News, Virginia, USA
 
  High-current low-emittance CW electron beams are indispensable for nuclear and high-energy physics fixed target and collider experiments, cooling high energy hadron beams, generating CW beams of monoenergetic X-rays (in FELs) and gamma-rays (in Compton sources). Polarization of electrons in these beams provides extra value by opening a new set of observables and frequently improving the data quality. We report on the upgrade of the unique and fully functional CW SRF 1.25 MeV SRF gun, built as part of the Coherent electron Cooling (CeC) project, which has demonstrated sustained CW operation with CsK2Sb photocathodes generating electron bunches with record-low transverse emittances and record-high bunch charge exceeding 10 nC. We propose to extend the capabilities of this system to high average current of 100 milliampere in two steps: increasing the current 30-fold at each step with the goal to demonstrate reliable long-term operation of the high-current low-emittance CW SRF guns. We also propose to test polarized GaAs photocathodes in the ultra-high vacuum (UHV) environment of the SRF gun, which has never been successfully demonstrated in RF accelerators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB138  
About • paper received ※ 25 May 2021       paper accepted ※ 29 July 2021       issue date ※ 23 August 2021  
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WEPAB139 Beam Tracking Simulations for Stage 1 of the Laser-Hybrid Accelerator for Radiobiological Applications (LhARA) 2939
 
  • H.T. Lau
    Imperial College London, London, United Kingdom
 
  The Laser-hybrid Accelerator for Radiobiological Applications (LhARA) is a unique and flexible facility proposed for radiobiological studies. The first stage of LhARA consists of an intense laser source interacting with a thin foil target producing a large flux of protons with energies up to 15 MeV. Particles will propagate through a combination of plasma (Gabor) lenses and magnetic elements to an achromat arc delivering the beam vertically to an in-vitro end station. An end-to-end simulation from the laser source to the end station is required to verify the conceptual design of the beamline. The laser-plasma interaction is simulated with Smilei (a particle-in-cell code) to produce a two-dimensional (2D) distribution of particles. Whilst it is possible to simulate the laser-plasma interaction in three dimensions (3D), access to the computing resources needed to run highly resolved simulations was not available. A sampling routine will be described which samples the 2D distribution to generate a 3D beam. The Monte Carlo simulation programs BDSIM and GPT were used to track the beam. Results of the simulations will be shown and compared to the results of an idealized Gaussian beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB139  
About • paper received ※ 18 May 2021       paper accepted ※ 01 July 2021       issue date ※ 19 August 2021  
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WEPAB140 Second Beam Test and Numerical Investigation of the Imperial College Plasma (Gabor) Lens Prototype 2943
 
  • T.S. Dascalu
    Imperial College London, London, United Kingdom
  • R. Bingham, C.G. Whyte
    USTRAT/SUPA, Glasgow, United Kingdom
  • C.L. Cheung, H.T. Lau, K.R. Long, T. Nonnenmacher, J.K. Pozimski
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
 
  Funding: STFC through the Imperial Impact Acceleration Account
The design of the Laser-hybrid Accelerator for Radiobiological Applications (LhARA) is based on a series of plasma lenses to capture, focus, and select the energy of the ions produced in the laser-target interaction. A second beam test of the first plasma lens prototype, built at the Imperial College London, took place in October 2017 at the Ion Beam Centre of the University of Surrey. 1.4 MeV proton pencil beams were imaged 0.67m downstream of the lens on a scintillator screen over a wide range of settings. On top of the focusing effect, the electron plasma converted pencil beams into rings. The intensity of each ring shows a different degree of modulation along its circumference. Analysis of the results indicates non-uniformity and an off-axis rotation of the electron plasma. The effect on the beam is presented and compared to the results of a simulation of the plasma dynamics and proton beam transport through the lens. A particle-tracking code was used to study the impact of plasma instabilities on the focusing forces produced by the lens. The m = 1 diocotron instability was associated with the formation of rings from the pencil beams.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB140  
About • paper received ※ 19 May 2021       paper accepted ※ 21 August 2021       issue date ※ 29 August 2021  
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WEPAB141 Preliminary Simulation of CERN’s Linac4 H⁻ Source Beam Formation 2947
 
  • A. Vnuchenko, J. Lettry
    CERN, Geneva, Switzerland
  • U. Fantz, S. Mochalskyy, D. Wünderlich
    MPI/IPP, Garching, Germany
  • T. Minea, A. Revel
    CNRS LPGP Univ Paris Sud, Orsay, France
 
  Linac4 is the new (H) linear injector of CERN’s accelerator complex. This contribution describes the modelling activities required to get insight into H beam formation processes and their impact on beam properties. The simulation region starts from a homogeneous hydrogen plasma, the plasma then expands through the magnetic filter field. H ions and electrons are electrostatically extracted through the meniscus (line of separation between the plasma and the extracted beam) and eventually accelerated. The physics is simulated via the 3D PIC code ONIX. This code, originally dedicated to ITER’s neutral injector sources, has been modified to match single aperture sources. A new type of boundary condition is described, as well as the field distribution and geometry of the standard IS03 and a dedicated proto-type of CERN’s Linac4 H source. A plasma electrode prototype designed to provide metallic boundary conditions was produced and tested. This plasma electrode geometry enables Optical Emission Spectroscopy in the region closest to meniscus. A set of plasma parameters was chosen as input characterizing the plasma. Preliminary simulation results of beam formation region are presented.  
poster icon Poster WEPAB141 [0.710 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB141  
About • paper received ※ 18 May 2021       paper accepted ※ 02 June 2021       issue date ※ 24 August 2021  
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WEPAB143 Sub-MeV Ion Generation by Standing Wave Excitation of Ionized Gases 2951
 
  • Sz. Turnár, G. Almási, J. Hebling, Cs. Korpa, M.I. Mechler, L. Pálfalvi, Z. Tibai
    University of Pecs, Pécs, Hungary
 
  Funding: Hungarian Scientific Research Fund (OTKA) (125808, 129134) ÚNKP-20-3 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research
Many ion acceleration techniques have been suggested and thoroughly studied in the last two decades*. One of the promising techniques is the Coulomb explosion acceleration (CEA)**. Using CEA in clusters could result in symmetric acceleration if there are not any other significant mechanisms. We proposed a THz-driven accelerator scheme that is based on CEA in proton, deuterium and heavy water gas plasmas. Two counter-propagating THz pulses are focused to the ionized region of the gas jet. Following the ripping of the electrons from the gas plasmas by ultrafast standing waves, the Coulomb explosion accelerates the positive ions. According to our calculation, using 2 x 34 mJ THz pulses electrons and protons with 1.1 nC charge are accelerated up to 0.4 MeV and 0.1 MeV, respectively. The total energy of the particles is 0.7 % of the energy of the THz pulses. We examined the effect of the initial bunch charge, bunch size and shape on the final energy spectra and the directional distribution of the particles. Our presented technique is scalable from a few µm to a few thousand µm driving wavelengths and can be used for electron and heavy-ion acceleration.
*J. Badziak, IOP Conf. Series: J Phys: Conf. Series 959, 012001 (2018).
** M. Murakami and K. Mima, Phys. of Plasmas 16, 103108 (2009).
 
poster icon Poster WEPAB143 [3.467 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB143  
About • paper received ※ 19 May 2021       paper accepted ※ 07 June 2021       issue date ※ 21 August 2021  
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WEPAB144 A New Flux Concentrator Made of Cu Alloy for the SuperKEKB Positron Source 2954
 
  • Y. Enomoto, K. Abe, N. Okada, T. Takatomi
    KEK, Ibaraki, Japan
 
  Flux concentrator (FC) is one of important device for positron source which translates position and momentum spread of the particles adiabatically to match them to the acceptance of the following section. To realize higher positron yield, higher magnetic field is desired. However, higher field by higher current generate stronger force on the coil. Since the gap between each turn of the coil is as narrow as 0.2 mm and the voltage across them is about as high as 1 kV at the design current, slight deformation of the coil cause discharge between the gap. To avoid such problem, a new FC made of Cu alloy which has 40 times higher yield strength than that of pure Cu was designed and tested. Finally, during summer shutdown in 2020, the old FC made of pure Cu was replaced by the new one made of Cu alloy in the KEK electron positron injector linac. The new one has been working stably at the design current, 12 kA, since Oct. 2020, and positron yield of 0.5 was realized. There were no discharge and other trouble till now.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB144  
About • paper received ※ 08 May 2021       paper accepted ※ 01 July 2021       issue date ※ 31 August 2021  
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WEPAB147 Simulations of Nanoblade-Enhanced Laser-Induced Cathode Emissions and Analyses of Yield, MTE, and Brightness 2957
 
  • J.I. Mann, G.E. Lawler, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • T. Arias, J.K. Nangoi
    Cornell University, Ithaca, New York, USA
 
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE HEP Grant DE-SC0009914.
Laser-induced field emission of electrons from metallic nanotips has been well studied. Unfortunately, nanotips suffer low damage thresholds with enhanced fields around 10 GV/m. The nanoblade, akin to a nanotip extruded in one lateral dimension, may reach upwards of 40 GV/m due to its robust thermomechanical properties. This increased surface field promises brighter electron emissions. We perform simulations of strong-field emissions from metallic nanoblades via the 1-D time-dependent Schr\"odinger equation with effective Jellium and nonlinear collective image charge potentials, including the strong field gradients induced by the nanostructure. We measure spectra and yields and compare to recent experiments. Potential analytical forms of image potential limited yield for a spectrally rich emission are presented. Calculations of mean transverse energy are provided as well as a prospective method of mitigation with the goal of increasing brightness.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB147  
About • paper received ※ 19 May 2021       paper accepted ※ 06 July 2021       issue date ※ 31 August 2021  
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WEPAB148 RF Design of an X-Band TM02 Mode Cavity for Field Emitter Testing 2961
 
  • Z. Li, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • S.V. Baryshev, T. Posos, M.E. Schneider
    Michigan State University, East Lansing, Michigan, USA
 
  Funding: Work at SLAC was supported by DOE under contract No. DE-AC02-76SF00515. Work at MSU was supported by DOE under Award No. DE-SC0020429 and under Cooperative Agreement Award No. DE-SC0018362.
Planar polycrystalline synthetic diamond with nitrogen-doping/incorporation was found to be a remarkable field emitter. It is capable of generating a high charge beam and handling moderate vacuum conditions. Integrating it with an efficient RF cavity could therefore provide a compact electron source for RF injectors. Understanding the performance metrics of the emitter in RF fields is essential toward developing such a device. We investigated a test setup of the field emitter at the X-band frequency. The setup included an X-band cavity operating at the TM02 mode. The field emitter material will be plated on the tip of a insertion rod on the cavity back plate. Part of the back plate and the emitter rod are demountable, allowing for exchange of the field emitters. The TM02 mode was chosen such that the design of the demountable back plate does not induce field enhancement at the installation gap. The cavity were optimized to achieve a high surface field at the emitter tip and a maximum energy gain of the emitted electrons at a given input power. We will present the RF and mechanical design of such a TM02 X-band cavity for field emitter testing.
 
poster icon Poster WEPAB148 [1.642 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB148  
About • paper received ※ 14 May 2021       paper accepted ※ 12 July 2021       issue date ※ 25 August 2021  
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WEPAB149 The RF Gun for the Siberian Circular Light Source "SKIF" 2965
 
  • V. Volkov, A.M. Batrakov, S.M. Gurov, S.E. Karnaev, A.A. Kondakov, S.A. Krutikhin, G.Y. Kurkin, A.E. Levichev, O.I. Meshkov, V.K. Ovchar, A.V. Pavlenko, O.A. Pavlov, A.G. Tribendis, N.G. Vasileva
    BINP SB RAS, Novosibirsk, Russia
  • A.E. Levichev, A.V. Pavlenko
    NSU, Novosibirsk, Russia
  • A.G. Tribendis
    NSTU, Novosibirsk, Russia
 
  The Siberian Circular Light Source is a new medium-energy high brightness synchrotron light facility that is under construction on the Budker Institute of Nuclear Physics (BINP) in Russia, Novosibirsk. The accelerator facility is divided for convenience into three components; a 3 GeV storage ring, a full-energy booster synchrotron, and a 200 MeV injector linac with a thermionic gridded RF gun electron source. This paper describes the RF gun design and plans for operations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB149  
About • paper received ※ 19 May 2021       paper accepted ※ 07 June 2021       issue date ※ 10 August 2021  
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WEPAB150 Monotron Beam Break Up Instability Analysis 2968
 
  • V. Volkov, V.M. Petrov
    BINP SB RAS, Novosibirsk, Russia
 
  New features of monotron beam break up (BBU) instability such as the typing of high order monopole modes (HOMs)in each cavity by two classes one of them are stable and other ones are unstable, HOM effective quality factor depending on average beam current, and normalized invariable threshold current individually characterizes each HOM are investigated in this article in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB150  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 10 August 2021  
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WEPAB151 Regenerative Beam Break Up Instability Analysis 2971
 
  • V. Volkov, V.M. Petrov
    BINP SB RAS, Novosibirsk, Russia
 
  New features of regenerative beam break up (BBU) instability such as the typing of high order dipole modes (HOMs)in each cavity by two classes, one of them are stable and other ones are unstable, HOM effective quality factor depending on average beam current, and normalized invariable threshold current individually characterizes each HOM are investigated in this article in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB151  
About • paper received ※ 19 May 2021       paper accepted ※ 22 June 2021       issue date ※ 10 August 2021  
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WEPAB152 Carbon Nanotubes as Cold Electron Field Emitters for Electron Cooling in the CERN Extra Low Energy Antiproton (ELENA) Ring 2975
 
  • B. Galante, G. Tranquille
    CERN, Meyrin, Switzerland
  • O. Apsimon, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • J. Resta-López
    IFIC, Valencia, Spain
 
  In ELENA electron cooling reduces the emittance of the antiproton beam allowing to deliver a high-quality beam to the experiments at the unprecedented low energy of 100 keV. To cool the antiproton beam at this low energy, the electron gun must emit electrons with as monoenergetic a distribution as possible. The currently used thermionic gun limits the cooling performance due to the relatively high transverse energy spread of the emitted electrons. Optimization is therefore being studied, aiming at developing a cold-cathode electron gun. This has led to the investigation of carbon nanotubes (CNTs) as cold electron field emitters. CNTs are considered the most promising field emitter material due to their high aspect ratio, chemical stability, and capability to deliver high current densities. To assess the feasibility of using such material operationally a full characterization is required, focussing on key parameters such as emitted current, emission stability, and lifetime. This contribution will present the status of ongoing experiments reporting on the conditioning process necessary to reach good stability over time and the emitting performance of different CNT arrays.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB152  
About • paper received ※ 18 May 2021       paper accepted ※ 25 June 2021       issue date ※ 17 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 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 ※ 01 September 2021  
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WEPAB158 Compact Terahertz-Powered Electron Photo-Gun 2983
 
  • T. Kroh, H. Çankaya, U. Demirbas, M. Fakhari, N.H. Matlis, M. Pergament, T. Rohwer
    CFEL, Hamburg, Germany
  • R.W. Aßmann, H. Dinter, M.J. Kellermeier
    DESY, Hamburg, Germany
  • M. Hemmer, F.X. Kärtner
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • F.X. Kärtner
    The Hamburg Center for Ultrafast Imaging, University of Hamburg, Hamburg, Germany
 
  Funding: This work is supported by the Cluster of Excellence "CUI: Advanced Imaging of Matter" of the Deutsche Forschungsgemeinschaft (DFG) - EXC 2056 - project ID 390715994.
Novel accelerator concepts such as all-optical THz based compact accelerators promise to enable new science due to unique features such as reduced timing-jitter and improved space-charge broadening of the generated electron bunches. However, multi-keV electron photo-guns based on short single-cycle THz pulses for acceleration have not been demonstrated experimentally so far. Here, we present a modular THz-driven electron gun with both tunable interaction length and output orifice allowing optimization of the sub-mm interaction volume. First extraction of multi-keV electrons is demonstrated and the parameter space as well as resulting performance of the THz-driven gun by varying the timing of the two single-cycle THz pulses and the UV photo-excitation pulse are explored. Such compact gun prototypes are not only promising as injectors for compact THz-based LINACs but also as source for ultrafast electron diffraction experiments.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB158  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 10 August 2021  
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WEPAB163 An X-Band Ultra-High Gradient Photoinjector 2986
 
  • S.V. Kuzikov, S.P. Antipov, P.V. Avrakhov, E. Dosov, C.-J. Jing, E.W. Knight
    Euclid TechLabs, Solon, Ohio, USA
  • G. Ha, C.-J. Jing, W. Liu, P. Piot, J.G. Power, D.S. Scott, J.H. Shao, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • C.-J. Jing
    Euclid Beamlabs, Bolingbrook, USA
  • X. Lu
    MIT/PSFC, Cambridge, Massachusetts, USA
  • X. Lu
    SLAC, Menlo Park, California, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  • P. Piot, W.H. Tan
    Northern Illinois University, DeKalb, Illinois, USA
  • E.E. Wisniewski
    IIT, Chicago, Illinois, USA
 
  Funding: This work was supported by DoE SBIR grant # DE-SC0018709.
High brightness beams appealing for XFELs and UEM essentially imply a high current and a low emittance. To obtain such beams we propose to raise the accelerating voltage in the gun mitigating repealing Coulomb forces. An ultra-high gradient is achieved utilizing a short-pulse technology. We have designed a room temperature X-band 1,5 cell gun that is able to inject 4 MeV, 100 pC bunches with as low as 0.15 mcm normalized transverse emittance. The gun is operated with as high gradients as 400 MV/m and fed by 200 MW, 10 ns RF pulses generated with Argonne Wakefield Accelerator (AWA) power extractor. We report results of low RF power tests, laser alignment test results, and successful gun conditioning results carried out at nominal RF power.
 
poster icon Poster WEPAB163 [5.427 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB163  
About • paper received ※ 18 May 2021       paper accepted ※ 02 June 2021       issue date ※ 13 August 2021  
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WEPAB164 Electrodeless Diamond Beam Halo Monitor 2990
 
  • S.V. Kuzikov, S.P. Antipov, P.V. Avrakhov, E. Dosov, E.W. Knight, Y. Zhao
    Euclid TechLabs, Solon, Ohio, USA
  • J.G. Power, J. Shao
    ANL, Lemont, Illinois, USA
 
  Funding: This work was supported by DoE SBIR grant # DE-SC0019642.
Beam halo measurement is important for novel x-ray free-electron lasers which have remarkably high repetition rate and average power. We propose diamond as a radiation hard material that can be used to measure the flux of passing particles based on a particle-induced conductivity effect. Our diamond electrodeless monitor is based on a microwave measurement of the change in the resonator coupling and eigenfrequency. For measurements, we put a sensitive diamond sample in a resonator that intercepts the halo. By measuring the change in RF properties of the resonator, one can infer the beam halo parameters scanning across the beam to map its transverse distribution. In recent experiments we used a Vertical Beam Test Stand (VBS), delivered DC electron beam of the 20-200 keV energy with the current up to 50 µA, to characterize several diamond samples. We have designed and fabricated a scanning diamond monitor, based on an X-band resonator, which was tested at Argonne Wakefield Accelerator (AWA) with a multi-MeV electron beam.
 
poster icon Poster WEPAB164 [5.138 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB164  
About • paper received ※ 14 May 2021       paper accepted ※ 07 June 2021       issue date ※ 11 August 2021  
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WEPAB165 Metamaterial Waveguide HOM Loads for SRF Accelerating Cavities 2994
 
  • S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
 
  Suppression of beam induced HOMs is necessary for most SRF accelerating cavities driven with high currents. One of the problems in design of a HOM load is that vacuum compatible materials with high enough imaginary part of the dielectric permittivity, which provides absorption, have also a high real part of the permittivity. This does not allow absorbing RF radiation at short distance and in broad frequency band. We propose considering artificial metamaterials where besides lossy dielectric pieces, an absorber with high magnetic permeability is included. In our proposal, we suggest composing a waveguide HOM load of a metamaterial consisted of well-known ceramic and ferrite plates placed periodically in a stack. Such a design provides low return losses, compactness and broad frequency range of the operation.  
poster icon Poster WEPAB165 [1.844 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB165  
About • paper received ※ 19 May 2021       paper accepted ※ 02 June 2021       issue date ※ 15 August 2021  
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WEPAB166 Concept of an Accelerator-Driven Neutron Source for the Production of Atmospheric Radiations 2998
 
  • P. Lee, N.-W. Kang
    Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
  • M. Moon
    KAERI, Daejon, Republic of Korea
 
  Funding: This work has been supported through KOMAC operation fund of KAERI and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2021R1C1C1007100).
At the Korea Multi-purpose Accelerator Complex (KOMAC) of Korea Atomic Energy Research Institute (KAERI), we are studying an accelerator-driven neutron source for the production of white neutron beams that resemble the atmospheric radiations on the earth. In the concept of the neutron source, high-energy neutrons are generated by using a 200-MeV proton beam on a heavy-metal target in a target station, which is consisted of a target, moderator, reflector, and biological shields, and a part of the high-energy neutrons are guided in a forward direction to make neutron beams with the atmospheric-like energy spectrum. The conceptual design has 6 more thermal-neutron beamlines at the separation of 30 degrees for the fundamental research on neutron science. Here, we present the concepts of the target station and basic parameters regarding the neutron source.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB166  
About • paper received ※ 18 May 2021       paper accepted ※ 01 July 2021       issue date ※ 24 August 2021  
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WEPAB169 Towards Ultra-Smooth Alkali Antimonide Photocathode Epitaxy 3001
 
  • E.J. Montgomery
    Private Address, Bolingbrook, USA
  • O. Chubenko, G.S. Gevorkyan, S.S. Karkare, P. Saha
    Arizona State University, Tempe, USA
  • R.G. Hennig, J.T. Paul
    University of Florida, Gainesville, Florida, USA
  • C. Jing, S. Poddar
    Euclid Beamlabs, Bolingbrook, USA
  • H.A. Padmore
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by Department of Energy, Office of Science, Office of Basic Energy Sciences, under grant number DE-SC0020575.
Photocathodes lead in brightness among electron emitters, but transverse momenta are unavoidably nonzero. Ultra-low transverse emittance would enable brighter, higher energy x-ray free-electron lasers (FEL), improved colliders, and more coherent, detailed ultrafast electron diffraction/microscopy (UED/UEM). Although high quantum efficiency (QE) is desired to avoid laser-induced nonlinearities, the state-of-the-art is 100 pC bunches from copper, 0.4 mm-mrad emittance. Advances towards 0.1 mm-mrad require ultra-low emittance, high QE, cryo-compatible materials. We report efforts towards epitaxial growth of cesium antimonide on lattice matched substrates. DFT calculations were performed to downselect from a list of candidate lattice matches. Co-evaporations achieving >3% QE at 532 nm followed by atomic force and Kelvin probe microscopy (AFM and KPFM) show ultra-low 313 pm rms (root mean square) physical and 2.65 mV rms chemical roughness. We simulate roughness-induced mean transverse energy (MTE) to predict <1 meV from roughness effects at 10 MV/m in as-grown optically thick cathodes, promising low emittance via epitaxial growth.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB169  
About • paper received ※ 19 May 2021       paper accepted ※ 02 June 2021       issue date ※ 13 August 2021  
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WEPAB172 Recent Developments of the IDEAS-Halo Detector 3005
 
  • A. Liu, J.R. Callahan, B.T. Freemire
    Euclid TechLabs, Solon, Ohio, USA
  • J.F. Power, J.H. Shao
    ANL, Lemont, Illinois, USA
 
  Funding: This work was performed at Euclid and Argonne National Laboratory, and was supported by the US DOE Office of Science under contract number DE-SC0019538.
Euclid Techlabs has been designing and testing a cost-effective iris diaphragm beam halo/profile detector, which can be easily configured to work with various primary beam energies and sites. Besides working as a measurement device, it can also work as a controllable beam scraper/collimator. This novel iris diaphragm detector utilizes the current signal produced by the beam charge deposition on the moveable conductive iris blades, to accurately measure the beam distribution from the outlier to the beam core. In this paper, we discuss the recent developments of our iris diaphragm e-beam apparatus series (IDEAS)-halo detector, including its geometry upgrades and newest beam experiments done at the AWA cathode testbed (ACT) of Argonne National Laboratory.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB172  
About • paper received ※ 03 June 2021       paper accepted ※ 22 July 2021       issue date ※ 27 August 2021  
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WEPAB174 Study of the Electron Seeded Proton Self-Modulation Using FBPIC 3008
 
  • L. Liang, G.X. Xia
    The University of Manchester, Manchester, United Kingdom
  • A. Bonatto
    Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
  • L. Liang, G.X. Xia
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This work is supported by the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1
In order to make a full use of the whole proton bunch to drive large amplitude plasma wakefields and suppress the uncontrolled growth of any possible instabilities at the head of the proton bunch, the AWAKE Run 2 experiment plans to use an electron bunch to seed the formation of the proton bunch self-modulation. Additionally, a density step in the plasma channel will be used to freeze the selfmodulation process to keep the wakefield amplitude. In this work, numerical simulations performed with FBPIC are used to investigate the electron seeded proton self-modulation and the effect of the plasma density step as well.
 
poster icon Poster WEPAB174 [1.751 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB174  
About • paper received ※ 10 May 2021       paper accepted ※ 28 June 2021       issue date ※ 27 August 2021  
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WEPAB175 Simulation Study of Electron Beam Acceleration with Non-Gaussian Transverse Profiles for AWAKE Run 2 3012
 
  • L. Liang, G.X. Xia
    The University of Manchester, Manchester, United Kingdom
  • J.P. Farmer
    MPI-P, München, Germany
  • L. Liang, G.X. Xia
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: The authors would like to acknowledge the support from the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1
In the physics plan for AWAKE Run 2, two known effects, beam loading the longitudinal wakefield and beam matching to the pure plasma ion channel, will be implemented for the better control of electron acceleration. It is founded in our study of beam matching that the transverse profile of the initial witness beam have a significant impact on its acceleration quality. In this paper, particle-in-cell (PIC) simulations are used to study factors that affect the acceleration quality of electron beams with different transverse profiles.
 
poster icon Poster WEPAB175 [1.860 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB175  
About • paper received ※ 10 May 2021       paper accepted ※ 25 June 2021       issue date ※ 14 August 2021  
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WEPAB176 Acceleration of He⁺ Beams for Injection Into NICA Booster During its First Run 3016
 
  • K.A. Levterov, V.P. Akimov, D.S. Letkin, D.O. Leushin, V.V. Mialkovskiy
    JINR/VBLHEP, Dubna, Moscow region, Russia
  • A.M. Bazanov, A.V. Butenko, D.E. Donets, D. Egorov, A.R. Galimov, B.V. Golovenskiy, A. Govorov, V.V. Kobets, A.D. Kovalenko, D.A. Lyuosev, A.A. Martynov, V.A. Monchinsky, D.O. Ponkin, I.V. Shirikov, A.O. Sidorin, E. Syresin, G.V. Trubnikov, A. Tuzikov
    JINR, Dubna, Moscow Region, Russia
  • H. Höltermann, H. Podlech
    BEVATECH, Frankfurt, Germany
  • U. Ratzinger, A. Schempp
    IAP, Frankfurt am Main, Germany
 
  Heavy Ion Linear Accelerator (HILAC) is designed to accelerate the heavy ions with ratio A/Z<=6.25 produced by ESIS ion source up to the 3.2 MeV for the injection into superconducting synchrotron (SC) Booster. HILAC was commissioned in 2018 using the carbon beams from Laser Ion Source (LIS). The project output energy was verified. Transmission could be estimated only for DTL structure because of the presence at the RFQ input the mixture of ions with different charge states extracted from laser-plasma. To estimate transmission through the whole linac the ion source producing the only species He+ was designed. The beams of He+ ions were used for the first run of SC Booster. The design of the helium ion source and results of the He+ beam acceleration and injection are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB176  
About • paper received ※ 19 May 2021       paper accepted ※ 11 June 2021       issue date ※ 19 August 2021  
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WEPAB177 Consideration of Triple-Harmonic Operation for the J-PARC RCS 3020
 
  • H. Okita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • M. Furusawa, Y. Sugiyama
    KEK, Tokai, Ibaraki, Japan
  • K. Hara, K. Hasegawa, M. Nomura, C. Ohmori, T. Shimada, F. Tamura, M. Yamamoto, M. Yoshii
    KEK/JAEA, Ibaraki-Ken, Japan
 
  The wideband magnetic alloy (MA) cavities are employed in the J-PARC RCS. The dual-harmonic operation, in which each MA cavity is driven by superposition of the fundamental accelerating voltage and the second harmonic voltage, significantly improves the bunching factor and is indispensable for acceleration of the high intensity beams. The original LLRF control system was replaced with the new system in 2019, which can control the amplitudes of the higher harmonics as well as the fundamental and second harmonics. Therefore we consider to use additionally the third harmonic voltage for further improvement of the bunching factor during acceleration. By the triple-harmonic operation, the flat RF bucket can be realized with a higher synchronous phase and improvement of the bunching factor is expected. In this presentation, we describe the longitudinal simulation studies of the triple-harmonic operation. Also the preliminary test results are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB177  
About • paper received ※ 18 May 2021       paper accepted ※ 25 June 2021       issue date ※ 18 August 2021  
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WEPAB178 Non-Adiabatic Longitudinal Bunch Manipulation at Flattop of the J-PARC MR 3023
 
  • F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • C. Ohmori, Y. Sugiyama, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
 
  The J-PARC MR delivers the high-intensity proton beams for the neutrino experiment. Eight bunches of high peak current are extracted by the extraction kickers, therefore the neutrino beam has a similar time structure. The new Intermediate Water Cherenkov Detector (IWCD) will be constructed for the future neutrino experiment and a low peak time structure is desired by the IWCD. Thus, we consider bunch manipulation at flattop of the MR for reducing the peak current. The manipulation requires a longer repetition period to extend the flattop. This reduces the output beam power. The manipulation should be quickly done to minimize the loss of the beam power. Also, the beam gap must be kept for the rise time of the extraction kicker. We propose a non-adiabatic bunch manipulation using the multiharmonic rf voltage. By using the neighbor harmonic of the accelerating harmonic, the first and eighth bunches can be decelerated and accelerated, respectively. After a certain period, the rf phase is flipped to pi for debunching. Thanks to the initial deceleration and acceleration, the beam gap for the kickers is kept. We present the concept and the longitudinal simulation result.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB178  
About • paper received ※ 17 May 2021       paper accepted ※ 25 June 2021       issue date ※ 11 August 2021  
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WEPAB179 Recent Status of J-PARC Rapid Cycling Synchrotron 3027
 
  • K. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The 3 GeV rapid cycling synchrotron (RCS) at the Ja-pan Proton Accelerator Research Complex (J-PARC) provides more than 500 kW beams to the Material and Life Science Facility (MLF) and Main Ring (MR). In such a high-intensity hadron accelerator, even losing less than 0.1% of the beam can cause many problems. Such lost protons can cause serious radio-activation and accelerator component malfunctions. Therefore, we have been continuing a beam study to achieve high-power operation. In addition, we have also improved and maintained the accelerator components to enable stable operation. This paper reports the status of the J-PARC RCS over the last two years.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB179  
About • paper received ※ 13 May 2021       paper accepted ※ 25 June 2021       issue date ※ 22 August 2021  
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WEPAB180 Design and Beam Dynamics Studies of a Novel Compact Recoil Separator Ring for Nuclear Research with Radioactive Beams 3031
 
  • J. Resta-López
    UVEG, Burjasot (Valencia), Spain
  • A.P. Foussat, G. Kirby
    CERN, Geneva, Switzerland
  • I. Martel
    University of Huelva, Huelva, Spain
  • V. Rodin
    The University of Liverpool, Liverpool, United Kingdom
  • V. Rodin
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This work was supported by the Generalitat Valenciana under grant agreement CIDEGENT/2019/058
The recent development of radioactive beam facilities has significantly expanded the capabilities for investigating the structure of the atomic nucleus and the nuclear interaction. For instance, the HIE-ISOLDE facility at CERN delivers presently the largest range of low-energy radioactive beam available worldwide. This energy range is ideal for the study of nuclear structure, low-energy dynamics and astrophysics by using nucleon transfer, Coulomb excitation and deep inelastic reactions. All these studies require an efficient and high-resolution recoil separator for the clear identification of medium and large mass reaction fragments. To meet these needs, we propose a versatile recoil separator for radioisotopes based on a compact storage ring, the Isolde Superconducting Recoil Separator (ISRS) formed of superconducting combined-function nested magnets with both, bending and focusing/defocusing functions. The ISRS is designed to operate in high momentum acceptance and isochronous modes. In this paper, we present the optics design and detailed beam dynamics studies for the performance characterisation.
 
poster icon Poster WEPAB180 [3.619 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB180  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 20 August 2021  
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WEPAB181 New Opportunities in Low Energy Antiproton Research 3035
 
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 721559.
Experiments with low-energy antiprotons are at the cutting edge of science and offer unique opportunities to test some of the fundamental laws of physics. The experiments are, however, very difficult to realize. They critically depend on high-performance numerical tools that can model realistic beam transport and storage and also require advanced beam monitors and detectors that can fully characterize the beam. Finally, novel experiments need to be designed that exploit the enhanced beam quality that the new ELENA ring at CERN provides. This paper presents some selected findings from the pan-European AVA network’s three scientific work packages. It shows results from studies into electron cooling at the new ELENA storage ring, research into carbon nanotubes as cold electron field emitters for electron cooling, and how antiproton-atom collision experiments can be optimized using GEANT4. Finally, the paper gives an overview of the network’s interdisciplinary training program.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB181  
About • paper received ※ 16 May 2021       paper accepted ※ 11 June 2021       issue date ※ 02 September 2021  
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WEPAB183 Big Data Techniques for Accelerator Optimization 3039
 
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This project has received funding from STFC under grant reference ST/P006752/1.
Accelerators and the experiments that they enable are some of the largest, most data-intensive, and most complex scientific systems in existence. The interrelations between machine subsystems are complicated and often nonlinear. The system dynamics involve large parameter spaces that evolve over multiple relevant time scales and accelerator systems. Any accelerator-based experiments and applications are almost always difficult to model. LIV. DAT, the Liverpool Centre for Doctoral Training in Data-intensive science, was established in 2017 as a hub for training students in Big Data science. The centre currently has 36 PhD students that are working across nuclear, particle and astrophysics, as well as in accelerator science. This paper presents results from R&D into betatron radiation models and beam parameter reconstruction for plasma acceleration experiments at FACET-II, simulations for MeV energy gain in dielectric structures driven by a CO2 laser, and modelling of seeded self-modulation of long elliptical bunches in plasma. It also gives an overview of the training program offered to the LIV. DAT students.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB183  
About • paper received ※ 16 May 2021       paper accepted ※ 16 June 2021       issue date ※ 21 August 2021  
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WEPAB184 Optimization of Medical Accelerators 3042
 
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sk’odowska-Curie grant agreement No 675265.
Between 2016 and 2020, 15 Fellows have carried out collaborative research within the 4 MEUR Optimization of Medical Accelerators (OMA) EU-funded innovative training network. Based at universities, research and clinical facilities, as well as industry partners in several European countries, the Fellows have successfully developed a range of beam and patient imaging techniques, improved biological and physical models in Monte Carlo codes, and also help improve the design of existing and future clinical facilities. This paper gives an overview of the research outcomes of this network. It presents results from tracking and LET measurements with the MiniPIX-TimePIX detector for 60 MeV clinical protons, a new treatment planning approach accounting for prompt gamma range verification and interfractional anatomical changes, and summarizes findings from high-gradient testing of an S-band, normal-conducting low phase velocity accelerating structure. Finally, it gives a brief over-view of the scientific and training events organized by the OMA consortium.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB184  
About • paper received ※ 16 May 2021       paper accepted ※ 14 July 2021       issue date ※ 19 August 2021  
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WEPAB185 Target Bypass Beam Optics for Future High Intensity Fixed Target Experiments in the CERN North Area 3046
 
  • G.L. D’Alessandro, D. Banerjee, J. Bernhard, M. Brugger, N. Doble, L. Gatignon, A. Gerbershagen, B. Rae, F.M. Velotti
    CERN, Meyrin, Switzerland
  • S.M. Gibson
    JAI, Egham, Surrey, United Kingdom
 
  Several of the proposed experiments for operation at the K12 beam line would profit from significant beam intensity increase. Among those, there is the KLEVER experiment that would require an intensity of 2x1013 protons per 4.8 s long spill. The main goal of the experiment is to measure BR(KL->pi0 nu nu) to test the Standard Model structure by itself, and in combination with results from NA62 for BR(K±>pi+ nu nu). NA62 could also profit from higher intensities, and could be run in a new configuration called NA62HI(gher intensity). In the current configuration the beam is transported from the SPS to the TT24 beamline. This beamline leads to the T4 target that attenuates the beam for P42. After T4 the beam is directed into the P42 beamline before impinging on the T10 target and creating the particles necessary for the experiment. Those are finally transported to the detector via K12. This paper presents the idea of partially bypassing T4 and changing the P42 beamline configuration in order to have a sufficiently small beam size at the T10 target for both KLEVER and NA62-HI. Optics studies are developed in MADX and the AppLE.py, software developed at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB185  
About • paper received ※ 17 May 2021       paper accepted ※ 01 July 2021       issue date ※ 10 August 2021  
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WEPAB186 Studies for the K12 High-Intensity Kaon Beam at CERN 3049
 
  • G.L. D’Alessandro, D. Banerjee, J. Bernhard, M. Brugger, N. Doble, L. Gatignon, A. Gerbershagen, R. Marchevski, B. Rae, S. Schuchmann, F.W. Stummer, M.W.U. Van Dijk
    CERN, Meyrin, Switzerland
  • S.T. Boogert, S.M. Gibson, L.J. Nevay
    JAI, Egham, Surrey, United Kingdom
 
  The NA62 experiment is a fixed target experiment located in the North Area of CERN and has as main goal the measurement of the branching ratio of the rare decay K±>pi+vv. The primary proton beam from the SPS accelerator interacts with the T10 beryllium target and the generated 75 GeV/c secondary particles, containing about 6% of positive kaons, are transported by the K12 beamline to the NA62 experiment. Studies in this paper present detailed simulations of the K12 beamline developed in both FLUKA and BDSIM codes, which reproduce the current configuration of K12 for the NA62 experiment. The beam optics parameters of K12 are studied in BDSIM and compared to MADX optics and tracking calculations. The models in FLUKA and BDSIM are used for beam studies and muon production at various locations along the beamline, and the parameters obtained from simulations are benchmarked against data recorded by the experiment. The impact of the Cherenkov kaon tagging detector (CEDAR) on the beam quality is calculated for two different gas compositions in view of a possible upgrade of the detector.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB186  
About • paper received ※ 17 May 2021       paper accepted ※ 01 July 2021       issue date ※ 10 August 2021  
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WEPAB187 The ENUBET Multi Momentum Secondary Beamline Design 3053
 
  • E.G. Parozzi, N. Charitonidis
    CERN, Geneva, Switzerland
  • G. Brunetti, E.G. Parozzi, F. Terranova
    Universita Milano Bicocca, MILANO, Italy
  • A. Longhin, M. Pari, F. Pupilli
    INFN- Sez. di Padova, Padova, Italy
  • A. Longhin, M. Pari
    Univ. degli Studi di Padova, Padova, Italy
  • E.G. Parozzi, F. Terranova
    INFN MIB, MILANO, Italy
 
  The aim of neutrino physics for the next decades is to detect effects due to CP violation, mass hierarchy, and search for effects beyond the Standard Model predictions. Future experiments need precise measurements of the neutrino interaction cross-sections at the ~GeV/c regime, currently limited by the exact knowledge of the initial neutrino flux on a ~10-20% uncertainty level. The ENUBET project is proposing a novel facility, capable of constraining the neutrino flux normalization through the precise monitoring of the Ke3 (K±>e+pi0nu) decay products in an instrumented decay tunnel. ENUBET can also monitor muons from the two body kaon and pion decays (nu flux) and measure the neutrino energy with a 10% precision without relying on the event reconstruction at the neutrino detector. We present here a novel design based on a broad (4-8.5 GeV/c) momentum range secondary beamline, that widen the cross-section energy range that can be explored by ENUBET. In this poster, we discuss the target optimization studies and we show the early results on the new line’s optics and the layout design. We discuss the expected performance of this line and the forthcoming activities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB187  
About • paper received ※ 13 May 2021       paper accepted ※ 29 July 2021       issue date ※ 11 August 2021  
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WEPAB188 New Method to Search for Axion-Like Particles Demonstrated with Polarized Beam at the COSY Storage Ring 3057
 
  • S. Karanth
    Jagiellonian University, Kraków, Poland
 
  The axion was originally proposed to explain the small size of CP violation in quantum chromodynamics. It might be a candidate for dark matter in the universe. Axions or axion-like particles (ALPs) when coupled to gluons induce an oscillating Electric Dipole Moment (EDM) along the nucleon’s spin direction. At the Cooler Synchrotron (COSY) in Jülich, this principle was used to perform a first test experiment to search for ALPs using an in-plane polarized deuteron beam. If the spin precession frequency equals the EDM oscillation frequency, a resonance occurs that accumulates the rotation of the polarization out of the ring plane. Since the axion frequency is unknown, the beam momentum was ramped to search for a vertical polarization jump that would occur when the resonance is crossed. At COSY, four beam bunches with different polarization directions were used to make sure that no resonance was missed because of the unknown relative phase between the polarization precession and the EDM oscillations. We scanned a frequency window of about a 1-kHz width around the spin precession frequency of 121 kHz. This talk will describe the experiment and show preliminary results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB188  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 31 August 2021  
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WEPAB189 EIC Hadron Beamline Vacuum Studies 3060
 
  • D. Weiss, M. Mapes, J.E. Tuozzolo, S. Verdú-Andrés
    BNL, Upton, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Ninety percent of the EIC hadron ring beamline is cold-bore comprising strings of interconnected 4.55 K RHIC superconducting (SC) magnets. The EIC operating specification requires shorter bunches and 3x higher intensity beams which are not appropriate for the present RHIC stainless steel cold-bore beam tube. The intensity and emittance of the hadron beams will degrade due to interactions with residual gas or vacuum instabilities arising from the expected resistive-wall (RW) heating, electron clouds, and beam-induced desorption mechanisms. Without strategies to limit RW heating, major cryogenic system modifications are needed to prevent SC magnet quenches. The SC magnet cold-bore beam tubes will be equipped with a high RRR copper clad stainless steel sleeve to significantly reduce RW heating and so the effect on the SC magnet cryogenic heat load and temperature. A thin amorphous carbon film applied to the beam facing copper surface will suppress electron cloud formation. This paper discusses the vacuum requirements imposed by the EIC hadron beams and the plans to achieve the necessary vacuum and thermal stability that ensure acceptable beam quality and lifetime.
 
poster icon Poster WEPAB189 [3.321 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB189  
About • paper received ※ 17 May 2021       paper accepted ※ 21 August 2021       issue date ※ 25 August 2021  
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WEPAB190 DC Break Design for a 2.45 GHz ECR Ion Source 3064
 
  • M.S. Dmitriyev, M.V. Dyakonov, S.A. Tumanov, M.I. Zhigailova
    MEPhI, Moscow, Russia
 
  New 2.45 GHz Electron Cyclotron Resonance Ion Source (ECRIS) is under development at NRNU MEPhI. The transmission line is designed for transmitting the microwave power into the ECRIS. A DC break up to 80 kV was designed for the electrical insulation between the microwave supply system and the plasma chamber applied to high DC voltage. Current study considers the investigation results as well as the optimization of numerical simulations of the 2.45 GHz DC break with low losses and low emission into the surrounding space.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB190  
About • paper received ※ 20 May 2021       paper accepted ※ 08 June 2021       issue date ※ 20 August 2021  
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WEPAB191 Magnet System for a Proton/helium ECR Ion Source 3066
 
  • M.S. Dmitriyev, K.G. Artamonov, M.V. Dyakonov, M.I. Zhigailova
    MEPhI, Moscow, Russia
 
  The study of the magnetic system of ECRIS with operating frequency of 2.45 GHz for producing protons and double-charged helium ions has been carried out. The results of the numerical simulation of the ECRIS magnetic system based on permanent magnets have been performed. The possibility of shifting the ring magnets in both injection and extraction regions is considered to adjust maximum and minimum values of the axial distribution of a magnetic field in a plasma chamber. The possibility of shifting the bar magnets of the hexapole is shown to provide the adjustment of the radial magnetic field Brad at the chamber wall. Additional solenoids are introduced to the system for providing the required Binj and Bext adjustment and tuning the axial magnetic field distribution including the minimum on the axis Bmin. Furthermore, the magnetic system allows to switch the operation mode of the ECR source to the microwave mode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB191  
About • paper received ※ 20 May 2021       paper accepted ※ 08 June 2021       issue date ※ 30 August 2021  
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WEPAB192 Simulation Study on Double Diffuser for Loss Reduction in Slow Extraction at J-PARC Main Ring 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 ※ 10 August 2021  
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WEPAB193 Optimization of the Hadron Ring Stripline Injection Kicker for the EIC 3073
 
  • M.P. Sangroula, C.J. Liaw, C. Liu, N. Tsoupas, B.P. Xiao, W. Zhang
    BNL, Upton, New York, USA
  • X. Sun
    ANL, Lemont, Illinois, USA
  • S. Verdú-Andrés
    Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
The Electron-Ion Collider (EIC) at Brookhaven National Laboratory is a high luminosity, (  ∼  1034  \textrm{cm}-2 \textrm{s}-1 ) accelerator facility colliding polarized electron beam with different ion species ranging from lighter nuclei (proton, deuterium) to heavier nuclei (gold, uranium). Design of a stripline injection kicker for the Hadron Storage Ring (HSR) of EIC for beams with the rigidity of  ∼  81 T-m poses some technical challenges due to expected shorter bunch spacing and higher peak current of EIC. This paper focuses on the optimization of the EIC hadron ring injection kicker. Starting from the 2D cross-section design which includes the selection of electrodes shape, we describe the optimization of the kicker’s cross-section. Then we discuss converting this 2D geometry to 3D by adding essential components for the stripline kicker and the 3D optimization techniques that we employed. Finally, we show simulation results for the optimized geometry including wakefields and Time Domain Reflection (TDR) from one feedthrough to another.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB193  
About • paper received ※ 21 May 2021       paper accepted ※ 28 June 2021       issue date ※ 22 August 2021  
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WEPAB194 Feasibility of Using the Existing RHIC Stripline BPMs for the EIC 3077
 
  • M.P. Sangroula, C. Liu, M.G. Minty, P. Thieberger
    BNL, Upton, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The design of the Electron-Ion Collider (EIC) at Brookhaven National Laboratory (BNL) will utilize portions of the existing Relativistic Heavy Ion Collider (RHIC) for the EIC hadron ring. The EIC design calls for up to 10-times shorter ion bunches compared to the present RHIC operation. Higher single bunch peak currents will result in higher voltages to the output ports of the BPMs consequently producing more heating of the cryogenic signal cables connected to these output ports. Therefore, the existing stripline BPMs should be either upgraded or replaced with new ones. In this paper, we explore the potentially cost-effective approach by incorporating an RF-shielding piece into the existing BPMs as opposed to replacing them completely. Starting with the power delivered to the output ports, we present the proposed BPM modification with the RF-shielding piece. Then we discuss in detail the RF-shielding piece geometry including the dimension of RF slot and RF-fingers configuration. Finally, we present the optimization of the shielding piece and the mechanical tolerances required for its fabrication.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB194  
About • paper received ※ 21 May 2021       paper accepted ※ 28 June 2021       issue date ※ 14 August 2021  
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WEPAB195 Design and Optimization of a Low Frequency RF-Input Coupler for the IsoDAR RFQ 3081
 
  • M.P. Sangroula, J.M. Conrad, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
  • M. Schuett
    BEVATECH, Frankfurt, Germany
 
  Funding: The RFQ-DIP project is supported by National Science Foundation grant \# PHY-1626069 and the Heising-Simons Foundation.
The Isotope Decay-At-Rest experiment (IsoDAR) is a proposed underground experiment which is expected to be a definitive search for sterile neutrinos. IsoDAR uses an especially designed low-frequency spilt-coaxial radio frequency quadrupole (RFQ) to accelerate H2+ ions directly from the ion source into the main cyclotron accelerator. This paper mainly focuses on the design and optimization of a low frequency (32.8 MHz) RF-input coupler for the IsoDAR RFQ. Starting with a basic design, we determine its appropriate position for this coupler in the RFQ. Finally, we optimized the design to lower the input power without compromising the coupling efficiency.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB195  
About • paper received ※ 21 May 2021       paper accepted ※ 30 June 2021       issue date ※ 17 August 2021  
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WEPAB198 Beam Dynamics Design of a Synchrotron Injector with Laser-Accelerated Ions 3085
 
  • M.Z. Tuo, X. Guan, W. Lu, P.F. Ma, Y. Wan, X.W. Wang, Q.Z. Xing, H.J. Yao, S.X. Zheng
    TUB, Beijing, People’s Republic of China
 
  We present, in this paper, the beam dynamics design of a linac injector with laser-accelerated carbon-ions for a medical synchrotron. In the design, the initial transverse divergence is reduced by two apertures. The beam is focused transversely through a quadrupole triplet lens downstream the apertures. The output energy spread of the extracted beam at the exit of the injector is compressed from ±6% to ±0.6% by a debuncher and a bend magnet system to meet the injection requirement for the synchrotron. By changing the width of imaging slit of the bend magnet system, the beam with energy of 4±0.024 MeV/u is extracted, and the particle number per shot and transverse emittances of the beam at the exit of the injector can be regulated through adjusting the slit height. The dynamics design can pave the way for the future concept research of the synchrotron injector.  
poster icon Poster WEPAB198 [1.034 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB198  
About • paper received ※ 16 May 2021       paper accepted ※ 16 June 2021       issue date ※ 14 August 2021  
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WEPAB199 Study on the Important Technologies of 300MeV Upgrade for the CSNS Injection System 3089
 
  • M.Y. Huang, C.D. Deng, L. Kang, L. Liu, Y. Liu, X. Qi, S. Wang, Q.B. Wu, Y.W. Wu, S.Y. Xupresenter, W.Q. Zhang, Y.L. Zhang
    IHEP, Beijing, People’s Republic of China
  • J.X. Chen, T. 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. U1832210 and 12075134).
The China Spallation Neutron Source (CSNS-I) have achieved the design goal of 100kW beam power on the target in Feb., 2020. As the second phase of the CSNS, CSNS-II will achieve a beam power on the target of 500 kW. The injection energy of CSNS-II will be increased from 80 MeV to 300 MeV and the average beam current of the Linac will increase 5 times. Therefore, the injection system will require a complete upgrade. In this paper, the design scheme of the injection system for CSNS-II will be introduced. The key technologies of the upgrade injection system will be carefully analyzed and pre-developed, such as the pulse power supplies and their magnets, the special-shaped ceramic vacuum chambers, the main stripping foil, the stripped electron collection, and so on.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB199  
About • paper received ※ 17 May 2021       paper accepted ※ 09 June 2021       issue date ※ 26 August 2021  
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WEPAB200 Study on the Measurement and Residual Dose of the CSNS Stripping Foil 3093
 
  • M.Y. Huang, L. Kang, S. Wang, Q.B. Wu, S.Y. Xupresenter, 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 ※ 21 August 2021       issue date ※ 25 August 2021  
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WEPAB202 Thermal Analysis of a Compact Split-Coaxial CW RFQ for the IsoDAR RFQ-DIP 3097
 
  • D. Koser, J.M. Conrad, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
  • H. Podlech, U. Ratzinger, M. Schuett
    BEVATECH, Frankfurt, Germany
 
  The RFQ direct injection project (RFQ-DIP) for the neutrino physics experiment IsoDAR aims at an efficient injection of a high-current H2+ beam into the dedicated 60 MeV driver cyclotron. Therefore, it is intended to use a compact 32.8 MHz RFQ structure of the split-coaxial type as a pre-buncher. To determine the thermal elongation of the 1.4 m long electrode rods as well as the thermal frequency detuning of the RF structure at a maximum nominal power load of 3.6 kW, an extensive thermal and structural mechanical analysis using COMSOL Multiphysics was conducted. The water heating along the cooling channels as well as the properties of heat transfer from the copper structure to the cooling water were taken into account, which required CFD simulations of the cooling water flow in the turbulent regime. Here we present the methods and results of the sophisticated thermal and structural mechanical simulations using COMSOL and provide a comparison to more simplistic simulations conducted with CST Studio Suite.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB202  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 27 August 2021  
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WEPAB203 RFQ Beam Dynamics Optimization Using Machine Learning 3100
 
  • D. Koser, J.M. Conrad, L.H. Waites, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
  • A. Adelmann, M. Frey, S. Mayani
    PSI, Villigen PSI, Switzerland
 
  To efficiently inject a high-current H2+ beam into the 60 MeV driver cyclotron for the proposed IsoDAR project in neutrino physics, a novel direct-injection scheme is planned to be implemented using a compact radio-frequency quadrupole (RFQ) as a pre-buncher, being partially inserted into the cyclotron yoke. To optimize the RFQ beam dynamics design, machine learning approaches were investigated for creating a surrogate model of the RFQ. The required sample datasets are generated by standard beam dynamics simulation tools like PARMTEQM and RFQGen or more sophisticated PIC simulations. By reducing the computational complexity of multi-objective optimization problems, surrogate models allow to perform sensitivity studies and an optimization of the crucial RFQ beam output parameters like transmission and emittances. The time to solution might be reduced by up to several orders of magnitude. Here we discuss different methods of surrogate model creation (polynomial chaos expansion and neural networks) and identify present limitations of surrogate model accuracy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB203  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 12 August 2021  
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WEPAB204 Layout of the New Septum Magnets for Fast Extraction in J-PARC Main Ring 3103
 
  • S. Iwata, K. Ishii, H. Matsumoto, N. Matsumoto, Y. Sato, T. Shibata, T. Sugimoto
    KEK, Ibaraki, Japan
 
  At J-PARC Main Ring (MR), we are pursuing to improve the beam power from 500 kW to 1.3 MW by reducing the repetition cycle from 2.48 to 1.16 seconds (1 Hz operation). Additionally, we are considering the beam particles increasing by selecting a more optimal tune. The fast extraction (FX) equipment to the neutrino facility (NU) is needed to upgrade for the 1 Hz operation. We plan to replace most FX septum magnets with new ones in 2021. We report a layout of the FX line in confirmation of new beam optics and mention the beam loss during the fast extraction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB204  
About • paper received ※ 20 May 2021       paper accepted ※ 09 June 2021       issue date ※ 10 August 2021  
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WEPAB205 XiPAF Synchrotron Slow Extraction Commissioning 3106
 
  • W.B. Ye, X. Guan, Y. Li, X.Y. Liu, M.W. Wang, X.W. Wang, Y. Yang, H.J. Yao, H.J. Zeng, S.X. Zheng
    TUB, Beijing, People’s Republic of China
  • W.L. Liu, D. Wang, M.C. Wang, Z.M. Wang, Y. Yang, M.T. Zhao
    NINT, Shannxi, People’s Republic of China
 
  Xi’an 200 MeV Proton Application Facility (XiPAF) is a project to fulfill the need for the experimental simulation of the space radiation environment. It comprises a 7 MeV H linac, a 60~230 MeV proton synchrotron, and experimental stations. Slow extraction commissioning for 60 MeV proton beam in XiPAF synchrotron has been finished. After commissioning, the maximal experiment extraction efficiency with the RF-knockout (RF-KO) method can up to 85%. The reason for beam loss has been analyzed and presented in this paper. Besides, an experiment of multiple energy extraction has been conducted in XiPAF synchrotron. The proton beams of 3 different energies were successfully extracted in 1.54 s.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB205  
About • paper received ※ 18 May 2021       paper accepted ※ 07 July 2021       issue date ※ 23 August 2021  
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WEPAB208 Energy Sweeping Beam Extraction by the Septum Magnet Assisted with Charge Exchange for a Hadron Therapy 3109
 
  • T.S. Dixit, A. Shaikh
    SAMEER, Mumbai, India
  • T. Adachi, T. Kawakubo, K. Takayama
    KEK, Ibaraki, Japan
 
  An energy sweeping compact rapid cycling hadron therapy based on a fast cycling induction synchrotron has been proposed by KEK and SAMEER as the next generation of hadron therapy machine *. For energy sweep extraction, a C+5 beam is injected, captured and trapped in the barrier bucket. A fraction of the beam is continuously released from the barrier bucket by controlling the timing of barrier pulse generation. Released C+5 ions merge into the coasting beam and moves inwards with ramping of the guiding main magnets. Ions in the coasting beam eventually hit the carbon foil placed inside the beam chamber wall. As a result, C+5 is converted to C+6 and beam orbit is largely changed as it traverses through the downstream bending magnet. This notably facilitates C+6 beam extraction, resulting in a relatively small kick angle of the septum magnet. When the septum is excited in the same way as that of the main magnets, the extracted C+6 beam always places on the center of the irradiation beam line. LISE++ simulations demonstrated the charge exchange efficiency of almost 100 % for expected beam energy. The feasibility of the switching power supply for the septum magnet has been studied.
* PRAB 24, 011601 (2021)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB208  
About • paper received ※ 14 May 2021       paper accepted ※ 22 June 2021       issue date ※ 27 August 2021  
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WEPAB209 Review of Medical Accelerator Development at Sameer, India 3113
 
  • T.S. Dixit, N. Bansode, A.P. Bhagwat, S.T. Chavan, A.P. Deshpande, G. Gaikwad, S. Ghosh, R. Krishnan, C.S. Nainwad, G.D. Panchal, S.N. Pethe, K.A. Thakur, V.B. Ukey, M.M. Vidwans
    SAMEER, Mumbai, India
 
  Funding: Ministry of Electronics and Information Technology (MeitY), Government of India
At the Medical Electronics Division of SAMEER, R&D for the development of a 4 MeV energy electron linac for Cancer therapy was taken up in the late ’80s. An S-band standing wave side coupled structure operating at pi/2 mode was developed for electron acceleration. The linac was integrated with other subsystems in collaboration with CSIO and PGIMER and the first machine was commissioned at PGI, Chandigarh in 1990. Thereafter, a lot of modifications like energy, dose rate, iso-center height etc. were made in the system, and later 4 more machines were commissioned in hospitals for treatment. More than 1,50,000 patients have been treated using SAMEER’s 6 MeV oncology system. Subsequently, development of dual-mode and variable energy electron and photon output machines was undertaken. Two-photon energies of 6 and 15 MV and multiple electron energies starting from 6 to 18 MeV for treatment was offered from the linac. The electron energy variation was done using plunger mechanism in the side coupling cavity. This linac was successfully baked and RF tested for various parameters. This paper describes the experimental parameters achieved for both low and high energy dual-mode linac.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB209  
About • paper received ※ 14 May 2021       paper accepted ※ 07 July 2021       issue date ※ 01 September 2021  
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WEPAB210 Beam Commissioning of the New 160 MeV H⁻ Injection System of the CERN PS Booster 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 ※ 19 August 2021  
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WEPAB211 Lattice Design of the Beam Transfer Line (BTL) from PIP-II LINAC to the Booster at Fermilab 3120
 
  • M. Xiao
    Fermilab, Batavia, Illinois, USA
 
  PIP-II beam transfer line (BTL) to transport the beam from PIP-II Linac to the Booster ring at Fermilab. The latest design eliminates rolling the dipoles in the beam line to cross over the Tevatron tunnel. Also re-designed is the lattice in the region of the Booster Injection to meet the request of the civil construction needs and accommodate the constrains of the Booster injection request. A beam line to the beam absorber (BAL) is designed based on the request from the results of Mars simulations and ANASYS calculation of the absorber. Simulations with dipole and quadrupole field errors for the Beam Transport Line (BTL) to the Booster, which provides the specifications for all the magnets and Power supplies, will be presented too.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB211  
About • paper received ※ 20 May 2021       paper accepted ※ 08 July 2021       issue date ※ 18 August 2021  
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WEPAB212 Physics Studies for the LBNF Graphite Target Design 3123
 
  • J.J. Back
    University of Warwick, Coventry, United Kingdom
 
  We present the simulated physics performance of the Long-Baseline Neutrino Facility (LBNF) graphite target that is being designed by the RAL High Power Targets Group for the Deep Underground Neutrino Experiment (DUNE). We first compare three conceptual cylindrical target design options as a function of target length (up to 2.2 m): downstream supported, two individual targets and an upstream-supported cantilever. Choosing the cantilever design as the baseline, we show the effect of widening the upstream inner conductor of the first focusing horn to provide extra space for supporting the target. We also give estimates of the expected performance of the 1.5 m prototype and 1.8 m production cantilevered targets. Furthermore, we show the effects of the main engineering updates made to the other two focusing horns since the DUNE TDR.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB212  
About • paper received ※ 17 May 2021       paper accepted ※ 05 July 2021       issue date ※ 26 August 2021  
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WEPAB213 Optimization of Antiproton-Atom Collision Studies Using GEANT4 3126
 
  • V. Rodin, A. Farricker, N. Kumar, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • N. Kumar, 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 programme under the Marie Sklodowska-Curie grant agreement No 721559.
The interaction between antiprotons and hydrogen or helium atoms is a fundamental problem in many-particle atomic physics, attracting strong interest from both theory and experiments. Atomic collisions are ideal to study the three and four-body Coulomb problem as the number of possible reaction channels is limited. Currently, only the total cross-sections of such interactions have been measured in an energy range between keV and a few MeV. This contribution investigates the discrepancies between different theories and available experimental data. It also describes a pathway for obtaining differential cross-sections. A purpose-designed experimental setup is presented and detailed Geant4 simulations provide an insight into the interaction between short (ns) antiproton bunches and a dense gas-jet target.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB213  
About • paper received ※ 23 May 2021       paper accepted ※ 30 June 2021       issue date ※ 28 August 2021  
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WEPAB214 Realistic Simulations of Stray Field Impact on Low Energy Transfer Lines 3130
 
  • V. Rodin, S. Padden, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • A. Farricker, S. Padden, V. Rodin, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • J. Resta-López
    UVEG, Burjasot (Valencia), Spain
 
  Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559.
Low energy (~100 keV) facilities working with antiprotons, heavy ions, or charged molecules may experience severe beam transport instabilities caused by field imperfections. For example, long (~10 m), unshielded beamlines will not be able to transfer particles due to the natural Earth magnetic field or stray fields from closely located experiments. Currently, only a limited number of simulation codes allow a simplified representation of such field errors, limiting capabilities for beam delivery optimization. In this contribution, a new simulation approach is presented that can provide detailed insight into 4D beam transport. It illustrates the impact of imperfections and stray fields on beam stability and quality through simulations of two antiproton experiments located in the Antimatter Factory (AD) at CERN in Geneva, Switzerland. Magnetic field imperfections are examined in two different ways, providing greater flexibility and an opportunity to benchmark all outcomes. Simulation performance is analyzed as a function of the level of detail and efficiency.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB214  
About • paper received ※ 19 May 2021       paper accepted ※ 12 July 2021       issue date ※ 11 August 2021  
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WEPAB215 Simulation of Intra-Beam Scattering in PyHEADTAIL 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 ※ 29 August 2021  
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WEPAB216 6D Simulations of PIP-II Booster Injection 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 ※ 22 August 2021  
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WEPAB221 H⁰ Stark Stripping and Component Irradiation in Fermilab Booster 3142
 
  • J.A. Johnstone, D.E. Johnson
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by Fermi Research Alliance, LLC under contract no. DE-AC02-07CH11359
In foil stripping of H some fraction of the emerging neutral H0 will be in excited states, which can then strip through the Stark effect in the magnetic field of the downstream orbit bump magnet. The resultant H+ will experience a depleted net kick compared to protons emerging from the foil and will track on trajectories different from the nominal circulating beam. This will lead to irradiation of downstream machine components. An analysis of these processes is of particular importance looking forward to the much higher beam power of the Fermilab PIP-II era. This study investigates where these errant protons will be lost, how much power is deposited, and whether this will be a shielding concern.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB221  
About • paper received ※ 11 May 2021       paper accepted ※ 09 June 2021       issue date ※ 27 August 2021  
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WEPAB222 Impedance Evaluation of Masks in the HEPS Storage Ring 3145
 
  • N. Wang, S.K. Tian, J.Q. Wang
    IHEP, Beijing, People’s Republic of China
  • J.Q. Wang
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  Masks are commonly used in photon light sources to protect sensitive elements from synchrotron radiations. In the ultra-low emittance rings, small aperture vacuum chambers are adopted in order to reach the very high gradient in the quadrupoles, while many masks are required due to the high radiation power density. Therefore, the impedance of the masks becomes one of the dominant contributors to the impedance budget. In this paper, the impedance is evaluated among different mask designs. Meanwhile, the impedance cross-talk between adjacent masks is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB222  
About • paper received ※ 18 May 2021       paper accepted ※ 06 July 2021       issue date ※ 01 September 2021  
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WEPAB224 Update of the Transverse Proton Synchrotron Impedance Model 3149
 
  • S. Joly, N. Mounet, B. Salvant
    CERN, Geneva, Switzerland
  • S. Joly
    La Sapienza University of Rome, Rome, Italy
  • M. Migliorati
    INFN-Roma1, Rome, Italy
  • M. Migliorati
    Sapienza University of Rome, Rome, Italy
 
  The CERN Proton Synchrotron (PS) was recently upgraded to allow reaching the ambitious performance goal of the High-Luminosity LHC Project. This upgrade is part of the LHC Injectors Upgrade project. The final part of the upgrade was performed during Long Shutdown 2 (LS2) to allow injection at higher energy from the PS Booster and a twofold increase in beam intensity and brightness. These changes must be considered in the PS impedance model. The effect on the impedance of the removal of obsolete injection equipment, changes of several accelerator components and new injection energy will be reviewed, as well as the wall impedance of the elliptic beam pipe, thanks to a newly developed code that allows taking into account both the ellipticity and the non-ultra-relativistic nature of the beam.  
poster icon Poster WEPAB224 [0.654 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB224  
About • paper received ※ 17 May 2021       paper accepted ※ 27 July 2021       issue date ※ 25 August 2021  
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WEPAB225 Transverse and Longitudinal Single Bunch Instabilities in FCC-ee 3153
 
  • E. Carideo, D. Quartullo, F. Zimmermann
    CERN, Geneva, Switzerland
  • D. De Arcangelis
    Sapienza University of Rome, Rome, Italy
  • M. Migliorati, M. Zobov
    INFN/LNF, Frascati, Italy
 
  Improving the accuracy of the impedance model of an accelerator is important for keeping beam instabilities and power loss under control. Here, by means of the PyHEAD- TAIL tracking code, we first review the longitudinal mi- crowave instability threshold for FCC-ee by taking into ac- count the longitudinal impedance model evaluated so far. Moreover, we present the results of beam dynamics simula- tions, including both the longitudinal and transverse wake- fields due to the resistive wall, in order to evaluate the influ- ence of the bunch length on the transverse mode coupling instability. The results of the transverse beam dynamics are also compared with the Vlasov solver DELPHI.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB225  
About • paper received ※ 10 May 2021       paper accepted ※ 01 July 2021       issue date ※ 26 August 2021  
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WEPAB226 Investigation of Vlasov Systems with a Certain Class of Linearly-Collective Hamiltonians 3157
 
  • Ph. Amstutz, M. Vogt
    DESY, Hamburg, Germany
 
  In many cases the Vlasov equation cannot be solved exactly due its inherent non-linearity arising from collective terms in the Hamiltonian. Based on the analysis of the Hamiltonian’s dependence on the phase-space density and the requirement for self-consistency in this contribution a class of Hamiltonians is defined and characterized. For members of this class the corresponding expansion of the Vlasov equation terminates. The new, potentially non-autonomous, Hamiltonian of the resulting Liouville equation depends only on the initial condition of the phase-space density. Prominent members of this class are Poisson-type kick-Hamiltonians, which we show as an example. We expect these investigations to be a potential starting point for the analysis and conception of operator-splitting schemes or splitting-free methods for beam-dynamics simulation codes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB226  
About • paper received ※ 18 May 2021       paper accepted ※ 01 July 2021       issue date ※ 13 August 2021  
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WEPAB227 Mechanism of Longitudinal Single-Bunch Instability in the CERN SPS 3161
 
  • I. Karpov
    CERN, Meyrin, Switzerland
  • M. Gadioux
    UCD, Dublin, Ireland
 
  Understanding the origin of beam instabilities is essential for reaching the highest performance of proton synchrotrons. In the present work, the Oide-Yokoya eigenvalue method of solving the linearised Vlasov equation was used to shed light on the mechanism of longitudinal single-bunch instability in the CERN SPS. In particular, semi-analytical calculations were done for the full longitudinal impedance model, taking into account the RF nonlinearity. The obtained results agree well with macro-particle simulations and are consistent with available beam measurements. For the first time, the instability has been interpreted as a coupling of radial modes within a single azimuthal mode, due to a strong potential-well distortion of the synchrotron-frequency distribution. To avoid this instability, a higher RF voltage is required at a given emittance. Thus, the instability mechanism is very different from the loss of Landau damping, which, in contrast, is mitigated by a lower RF voltage. This understanding also allowed us to optimise the RF voltage programmes during the acceleration cycle for high-intensity bunches used in the AWAKE experiment at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB227  
About • paper received ※ 12 May 2021       paper accepted ※ 01 July 2021       issue date ※ 19 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 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 ※ 10 August 2021  
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WEPAB229 Transverse Density Pileup and Pattern Formation in Dense Ultracold Electron Beamlets under Coulomb Expansion 3169
 
  • A.J. Tencate, K. Bhuyan, B. Erdélyi
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: This work was sponsored by the US Department of Energy Office of Science under Grant DE-SC0020241.
Dynamic Coulomb expansion of dense particle bunches can lead to transverse density shock-like propagation for nonuniform bunch distributions. Furthermore, under favorable circumstances, multiple bunches in close proximity can collide without crossing to form wheel-and-spoke patterns. This process has been observed experimentally for Rubidium ions, but not yet for electrons, where the dynamics occur over far shorter length scales. We simulate the interaction of electron bunches while varying the initial transverse temperature and density profiles to determine the thresholds that characterize this pattern formation. Additionally, we consider the effects of asymmetries and the impact of a low-density halo on the overall process. The simulations are conducted using a novel high-fidelity algorithm for collisional particle dynamics.
 
poster icon Poster WEPAB229 [7.411 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB229  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 22 August 2021  
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WEPAB233 Excitation of Micro-Bunching in Short Electron Bunches Using RF Amplitude Modulation 3173
 
  • T. Boltz, E. Blomley, M. Brosi, E. Bründermann, B. Härer, A. Mochihashi, A.-S. Müller, P. Schreiber, M. Schuh, M. Yan
    KIT, Karlsruhe, Germany
 
  In its short-bunch operation mode, the KIT storage ring KARA provides picosecond-long electron bunches, which emit coherent synchrotron radiation (CSR) up to the terahertz frequency range. Due to the high spatial compression under these conditions, the self-interaction of the bunch with its own emitted CSR induces a wake-field, which significantly influences the longitudinal charge distribution. Above a given threshold current, this leads to the formation of dynamically evolving micro-structures within the bunch and is thus called micro-bunching instability. As CSR is emitted at wavelengths corresponding to the spatial dimension of the emitter, these small structures lead to an increased emission of CSR at higher frequencies. The instability is therefore deliberately induced at KARA to provide intense THz radiation to dedicated experiments. To further increase the emitted power in the desired frequency range, we consider the potential of RF amplitude modulations to intentionally excite this form of micro-bunching in short electron bunches. This work is supported by the BMBF project 05K19VKC TiMo (Federal Ministry of Education and Research).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB233  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 23 August 2021  
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WEPAB234 Simulating Two Dimensional Coherent Synchrotron Radiation in Python 3177
 
  • W. Lou, Y. Cai, C.E. Mayes, G.R. White
    SLAC, Menlo Park, California, USA
 
  Coherent Synchrotron Radiation (CSR) in bending magnets poses an important limit for electron beams to reach high brightness in novel accelerators. While the longitudinal wakefield has been well studied in one-dimensional CSR theory and implemented in various simulation codes, transverse wakefields have received less attention. Following the recently developed two-dimensional CSR theory, we developed a Python code simulating the steady-state two-dimensional CSR effects. The computed CSR wakes have been benchmarked with theory and other simulation codes. To speed up computation speed, the code applies vectorization, parallel processing, and Numba in Python.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB234  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 14 August 2021  
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WEPAB235 TMCI Theory of Flat Chambers Revisited 3181
 
  • T.F. Günzel
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  By accounting for the transverse impedance’ quadrupolar component according to the work of R.Lindberg *, no TMCI-instability can be observed in case of a pure horizontal resistive wall impedance of flat vacuum chambers. In order to study this effect more closely, TMCI-theory is reviewed and Lindberg’s work is further developed by including the resonator model as impedance type. The theory is applied to the ALBA-impedance model for the calculation of horizontal TMCI-detuning and threshold. Moreover, a couple of example cases are presented including vertical TMCI-detuning and threshold. Results on both planes are compared to simpler descriptions which account for the quadrupolar impedance effect only by tune shift.
* Ryan Lindberg, Fokker-Planck analysis of transverse collective instabilities in electron storage rings, Phy. Rev. Acc. Beams 19, 124402 (2016)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB235  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 20 August 2021  
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WEPAB238 Modeling Short Range Wakefield Effects in a High Gradient Linac 3185
 
  • F. Bosco, M. Carillo, L. Faillace, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • M. Behtouei, L. Faillace, A. Giribono, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati, Italy
  • F. Bosco, M. Migliorati
    INFN-Roma1, Rome, Italy
  • L. Giuliano, A. Mostacci, L. Palumbo
    INFN-Roma, Roma, Italy
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
 
  Funding: This work is supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
The interaction of charged beams with the surrounding accelerating structures requires a thorough investigation due to potential negative effects on the phase space quality. Indeed, the wakefields acting back on the beam are responsible for emittance dilution and instabilities, such as the beam break-up, which limit the performances of electron-based radiation sources and linear colliders. Here we introduce a new tracking code which is meant to investigate the effects of short-range transverse wakefields in linear accelerators. The tracking is based on quasi-analytical models for the beam dynamics which, in addition to the basic optics specified by the applied fields, include dipole wakefield forces and a simple approach to account for space-charge effects. Such features provide a reliable tool which easily allows to inspect the performances of a linac. To validate the model, a parallel analysis for a reference case is performed with well-known beam dynamics codes, and comparisons are shown. As an illustrative application, we discuss a study on alignment tolerances evaluating the emittance growth induced by misaligned accelerating sections.
 
poster icon Poster WEPAB238 [1.747 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB238  
About • paper received ※ 18 May 2021       paper accepted ※ 07 July 2021       issue date ※ 17 August 2021  
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WEPAB239 Effect of Chromaticity and Feedback on Transverse Head-Tail Instability 3189
 
  • V.V. Smaluk, G. Bassi, A. Blednykh, A. Khan
    BNL, Upton, New York, USA
 
  Funding: This work was supported by the US Department of Energy under contract DE-SC0012704.
The head-tail instability caused by the beam interaction with short-range wakefields is a major limitation for the single-bunch beam intensity in circular accelerators. The combined effect of the transverse feedback systems and chromaticity suppressing the instability is discussed. Theoretical and experimental studies of the head-tail instability and methods of its mitigation are reviewed. Results of experimental studies of the transverse mode coupling carried out at NSLS-II are compared with the theoretical model and numerical simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB239  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 24 August 2021  
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WEPAB240 Increasing the Single-Bunch Instability Threshold by Bunch Splitting Due to RF Phase Modulation 3193
 
  • J.L. Steinmann, E. Blomley, M. Brosi, E. Bründermann, A. Mochihashi, A.-S. Müller, M. Schuh, P. Schönfeldt
    KIT, Karlsruhe, Germany
 
  Funding: This work is funded by the BMBF contract number: 05K16VKA.
RF phase modulation at twice the synchrotron frequency can be used to split a stored electron bunch into two or more bunchlets orbiting each other. We report on time-resolved measurements at the Karlsruhe Research Accelerator (KARA), where this bunch splitting was used to increase the threshold current of the microbunching instability, happening in the short-bunch operation mode. Turning the modulation on and off reproducibly affects the sawtooth behavior of the emitted coherent synchrotron radiation.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB240  
About • paper received ※ 19 May 2021       paper accepted ※ 08 July 2021       issue date ※ 02 September 2021  
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WEPAB243 Longitudinal Microwave Instability Study at Transition Crossing with Ion Beams in the CERN PS 3197
 
  • A. Lasheen, H. Damerau, A. Huschauer, B.K. Popovic
    CERN, Meyrin, Switzerland
 
  The luminosity of lead ion collisions in the Large Hadron Collider (LHC) was significantly increased during the 2018 ion run by reducing the bunch spacing from 100 ns to 75 ns, allowing to increase the total number of bunches. With the new 75 ns variant, three instead of four bunches are generated each cycle in the Low Energy Ion Ring (LEIR) and the Proton Synchrotron (PS) with up to 30% larger intensity per bunch. The beam was produced with satisfactory quality but at the limit of stability in the injectors. In particular, the minimum longitudinal emittance in the PS is limited by a strong longitudinal microwave instability occurring just after transition crossing. The uncontrolled blow-up generates tails, which translate into an unacceptably large satellite population following the RF manipulations prior to extraction from the PS. In this paper, instability measurements are compared to particle simulations using the latest PS impedance model to identify the driving impedance sources. Moreover, means to mitigate the instability are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB243  
About • paper received ※ 19 May 2021       paper accepted ※ 06 July 2021       issue date ※ 14 August 2021  
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WEPAB244 Optimization and Machine Learning Applied to the RF Manipulations of Proton Beams in the CERN PS 3201
 
  • A. Lasheen, H. Damerau, S.C. Johnston
    CERN, Meyrin, Switzerland
 
  The 25 ns bunch spacing in the LHC is defined by a sequence of RF manipulations in the Proton Synchrotron (PS). Multiple RF systems covering a large range of revolution harmonics (7 to 21, 42, 84, 168) allow performing RF manipulations such as beam splitting, and non-adiabatic bunch shortening. For the nominal beam sent to LHC, each bunch is split in 12 in the PS. The relative amplitude and phase settings of the RF systems need to be precisely adjusted to minimize the bunch-by-bunch variations in intensity, longitudinal emittance, and bunch shape. However, due to transient beam-loading, the ideal settings, as well as the best achievable beam quality, vary with beam intensity. Slow drifts of the hardware may also affect beam quality. In this paper, automatized optimization routines based on particle simulations with intensity effects are presented, together with the first considerations of machine learning. The optimization routines are used to assess the best achievable longitudinal beam quality expected with the PS RF systems upgrades, in the framework of the LHC Injector Upgrade project.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB244  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 19 August 2021  
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WEPAB245 A Possible Modification of Ceramic Chambers in the Injection Area at the RCS in J-PARC 3205
 
  • Y. Shobuda, K. Horino, J. Kamiya, K. Kotoku, T. Takayanagi, T. Ueno, T. Yanagibashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The J-PARC RCS is composed of ceramic chambers covered over copper stripes to suppress the eddy current on the chamber. The inductance, comprising the copper stripes and flanges, in combination with the capacitors makes an LCR electric circuit with the chamber and can cause field modulation in the chamber. Though most chambers are not harmful at the RCS, the chambers at the injection area excite beam losses, because a trapezoid field pattern is excited to accumulate LINAC beam during the injection period. In this report, we consider several types of ceramic chambers to suppress the field modulation. One type is a ceramic chamber covered over copper stripes in parallel with damping resistors. Another is that covered over spiral copper stripes with only capacitors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB245  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 21 August 2021  
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WEPAB246 Influence of Different Beam Energies on the Micro-Bunching Instability 3209
 
  • M. Brosi, A.-S. Müller, P. Schreiber, M. Schuh
    KIT, Karlsruhe, Germany
 
  During the operation of an electron synchrotron with short electron bunches, the beam dynamics are influenced by the occurrence of the micro-bunching instability. This collective instability is caused by the self-interaction of a short electron bunch with its own emitted coherent synchrotron radiation (CSR). Above a certain threshold bunch current dynamic micro-structures start to occur on the longitudinal phase space density. The resulting dynamics depend on various parameters and were previously investigated in relation to, amongst others, the momentum compaction factor and the acceleration voltage. In this contribution, the influence of the energy of the electrons on the dynamics of the micro-bunching instability is studied based on measurements at the KIT storage ring KARA (Karlsruhe Research Accelerator).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB246  
About • paper received ※ 19 May 2021       paper accepted ※ 08 July 2021       issue date ※ 24 August 2021  
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WEPAB248 Kurth Vlasov-Poisson Solution for a Beam in the Presence of Time-Dependent Isotropic Focusing 3213
 
  • C.E. Mitchell, K. Hwang, R.D. Ryne
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The well-known K-V distribution provides an exact solution of the self-consistent Vlasov-Poisson system describing an unbunched charged particle beam with nonzero temperature in the presence of time-dependent linear transverse focusing. We describe a lesser-known exact solution of the Vlasov-Poisson system that is based on the work of Kurth in stellar dynamics. Unlike the K-V distribution, the Kurth distribution is a true function of the phase space variables, and the solution may be constructed on either the 4D or 6D phase space, for the special case of isotropic linear focusing. Numerical studies are performed for benchmarking simulation codes, and the stability properties of a 4D Kurth distribution are compared with those of a K-V distribution.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB248  
About • paper received ※ 19 May 2021       paper accepted ※ 14 July 2021       issue date ※ 21 August 2021  
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WEPAB249 Model of Curvature Effects Associated with Space Charge for Long Beams in Dipoles 3217
 
  • C.E. Mitchell, K. Hwang, R.D. Ryne
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
For modeling the dynamics within a dipole of a bunch whose length is much larger than the vacuum pipe radius, it is typical to use a 2D (or 2.5D) Poisson solver, with arc length taken as the independent variable. However, sampled at a fixed time, the beam is curved, space charge is not truly 2D, and the usual cancellation between E and B contributions to the Lorentz force need not exactly hold. The size of these effects is estimated using an idealized model of a uniform torus of charge rotating inside a toroidal conducting pipe. Simple expressions are provided for the correction of the electric and magnetic fields to first order in the reciprocal of the curvature radius.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB249  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 27 August 2021  
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WEPAB250 Interplay Between Space Charge, Intra-Beam Scattering, and Synchrotron Radiation Effects 3220
 
  • M. Zampetakis, F. Antoniou, H. Bartosik, Y. Papaphilippou
    CERN, Geneva, Switzerland
  • M. Zampetakis
    University of Crete, Heraklion, Crete, Greece
 
  The objective of this research is to study the interplay of synchrotron radiation, intra-beam scattering, and space charge in the vicinity of excited resonances. In this respect, two modules were developed to simulate intra-beam scattering and synchrotron radiation effects and plugged into pyORBIT to be used together with its space charge module. Different regimes of synchrotron motion were used to study the response of the beam to a lattice resonance when space charge, intra-beam scattering and synchrotron radiation are present.  
poster icon Poster WEPAB250 [0.536 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB250  
About • paper received ※ 17 May 2021       paper accepted ※ 21 July 2021       issue date ※ 13 August 2021  
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WEPAB251 Beam Dynamics Optimization of LCLS-II HE Linear Accelerator Design 3224
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  • T.O. Raubenheimer, M.D. Woodley
    SLAC, Menlo Park, California, USA
 
  The LCLS-II-HE as a high energy upgrade of the high repetition rate X-ray FEL under construction at SLAC will provide great opportunities for scientific discovery by generating coherent, high brightness hard X-ray radiation. In this paper, we report on beam dynamics optimization of the LCLS-II HE linear accelerator design with a 100pC and a 20pC charge beam to attain high quality electron beam for X-ray FEL radiation. We also present preliminary results of beam dynamics optimization of a 100pC beam from a low emittance superconducting injector.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB251  
About • paper received ※ 18 May 2021       paper accepted ※ 21 June 2021       issue date ※ 18 August 2021  
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WEPAB252 Transient Beam-Beam Effect During Electron Bunch Replacement in the EIC 3228
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  • M. Blaskiewicz, Y. Luo, C. Montag, F.J. Willeke, D. Xu
    BNL, Upton, New York, USA
  • Y. Hao
    FRIB, East Lansing, Michigan, USA
 
  The high luminosity, high polarization electron-ion collider (EIC) will provide great opportunities in nuclear physics study. In order to maintain high polarization, the electron beam will be replaced every few minutes during the collider operation. This frequent replacement of electron beams can affect proton beam quality during the collision. In this paper, we report on the study of the transient effect of electron beam replacement on proton beam emittance growth through strong-strong beam-beam simulation. The effect of electron beam injection imperfection will be included in the study.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB252  
About • paper received ※ 17 May 2021       paper accepted ※ 21 June 2021       issue date ※ 26 August 2021  
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WEPAB254 Design of a 10 MeV Beamline at the Upgraded Injector Test Facility for e-Beam Irradiation 3232
 
  • X. Li, H. Baumgart, G. Ciovati
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, F.E. Hannon, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Jefferson lab LDRD.
Electron beam irradiation near 10 MeV is suitable for wastewater treatment. The Upgraded Injector Test Facility (UITF) at Jefferson Lab is a CW superconducting linear accelerator capable of providing an electron beam of energy up to 10 MeV and up to 100 µA current. This contribution presents the beam transport simulations for a beamline to be used for the irradiation of wastewater samples at the UITF. The simulations were done using the code General Particle Tracer with the goal of obtaining an 8 MeV electron beam of radius (3-σ) of ~2.4 cm. The achieved energy spread is ~74.5 keV. The space charge effects were investigated when the bunch charge is varied to be up to 1000 times and the results showed that they do not affect the beam quality significantly.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB254  
About • paper received ※ 20 May 2021       paper accepted ※ 25 June 2021       issue date ※ 18 August 2021  
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WEPAB255 Simulation Studies on the Interactions of Electron Beam with Wastewater 3236
 
  • X. Li, H. Baumgart, G. Ciovati
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, F.E. Hannon, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Jefferson Lab LDRD
The manufactured chemical pollutants, like 1,4 dioxane and PFAS (per- and polyfluroralkyl substances), found in the underground water and/or drinking water are challenging to be removed or biodegraded. Energetic electrons are capable of mediating and removing them. This paper utilizes FLUKA code to evaluate the beam-wastewater interaction effects with different energy, space and divergence distributions of the electron beam. With 8 MeV average energy, the electron beam exits from a 0.0127 cm thick titanium window, travels through a 4.3 cm distance air and a second 0.0127 cm thick stainless water container window with 2.43 cm radius, and finally is injected into the water area, where the volume of water is around 75 cubic cm. The distribution parameters of the electron beam are from the GPT (General Particle Tracer) simulations for UITF (Upgraded Injector Test Facility) in Jefferson lab. By varying the distributions, several measurements including the dose (or energy deposition) distribution, electron fluence, photon fluence are scored and compared. Taking the comparisons into consideration, this paper is aiming to find better electron beams for the wastewater irradiation.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB255  
About • paper received ※ 20 May 2021       paper accepted ※ 25 June 2021       issue date ※ 12 August 2021  
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WEPAB256 Three-Dimensional Space Charge Oscillations in a Hybrid Photoinjector 3240
 
  • M. Carillo, M. Behtouei, F. Bosco, L. Faillace, A. Giribono, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • L. Ficcadenti
    INFN-Roma, Roma, Italy
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati, Italy
 
  Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
A new hybrid C-band photo-injector, consisting of a standing wave RF gun connected to a traveling wave structure, operating in a velocity bunching regime, has shown to produce an extremely high brightness beam with very low emittance and a very high peak current through a simultaneous compression of the beam in the longitudinal and transverse dimensions. A beam slice analysis has been performed in order to understand the evolution of the relevant physical parameters of the beam in the longitudinal and transverse phase spaces along the structure. A simple model for the envelope equation has been developed to describe the beam behavior in this particular dynamics regime that we term "triple waist", since all three dimensions reach a minimum condition almost simultaneously. The model analyzes the transverse envelope dynamics at the exit of the hybrid photo-injector, in the downstream drift where the triple waist occurs. The analytical solutions obtained from the envelope equation are compared with the simulations, showing a good agreement. Finally, these results have been analyzed also in terms of plasma oscillation to obtain a further physical interpretation of the beam dynamics.
 
poster icon Poster WEPAB256 [1.162 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB256  
About • paper received ※ 19 May 2021       paper accepted ※ 21 July 2021       issue date ※ 12 August 2021  
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WEPAB257 Matching of a Space-Charge Dominated Beam into the Undulator of the THz SASE FEL at PITZ 3244
 
  • X. Li, Z. Aboulbanine, G.D. Adhikari, N. Aftab, Z.G. Amirkhanyan, P. Boonpornprasert, M.E. Castro Carballo, N. Chaisueb, G.Z. Georgiev, J. Good, M. Groß, C. Koschitzki, M. Krasilnikov, O. Lishilin, A. Lueangaramwong, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, G. Shu, F. Stephan, G. Vashchenko, T. Weilbach
    DESY Zeuthen, Zeuthen, Germany
 
  The Photo Injector Test facility at DESY in Zeuthen (PITZ) is developing a THz SASE FEL as a prototype high repetition rate accelerator-based source for the THz-pumped, X-ray-probed experiments at the European XFEL. For the generation of THz pulses of mJ-level energy from SASE, an electron beam with a high charge (up to 4 nC) and high peak current (~200 A) will be injected into an LCLS-I undulator, which is currently being installed at the end of the photo-injector. The narrow vacuum chamber (11x5 mm) between the magnetic poles and the strong vertical focusing from the undulator, as well as the lack of beam diagnostics, have made it a challenge to match the space-charge dominated beam into the undulator without beam loss during the following transport. In this paper, boundary conditions of a matched electron beam will be discussed and the simulation and experimental study on our matching strategy will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB257  
About • paper received ※ 08 May 2021       paper accepted ※ 02 July 2021       issue date ※ 24 August 2021  
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WEPAB258 Beam Dynamics Design of a 162.5 MHz Superconducting RFQ Accelerator 3248
 
  • Ying. Xia, H.P. Li, Y.R. Lu, Q.Y. Tan, Z. Wang
    PKU, Beijing, People’s Republic of China
  • Y.R. Lu
    IAP, Frankfurt am Main, Germany
 
  Superconducting(SC) RFQ has lower power consumption, larger aperture and higher accelerating gradient than room temperature RFQ. We plan to design a 162.5MHz SC RFQ to accelerate the 30 mA proton beams from 35 keV to 2.5 MeV, which will be used as a neutron source for BNCT and neutron imaging project. At an inter-vane voltage of 180kV, the beam dynamics design was carried out with acceptable peak surface electric field, high transmission efficiency, and relatively short cavity length.  
poster icon Poster WEPAB258 [1.251 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB258  
About • paper received ※ 17 May 2021       paper accepted ※ 06 July 2021       issue date ※ 13 August 2021  
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WEPAB259 Impact of the Magnet Alignment and Field Errors on the Output Uniform Beam at the DONES HEBT Line 3251
 
  • C. Oliver, A. Ibarra, J. Mollá, I. Podadera, R. Varela
    CIEMAT, Madrid, Spain
  • H. Dzitko
    F4E, Germany
  • O. Nomen, D. Sánchez-Herranz
    IREC, Sant Adria del Besos, Spain
 
  Funding: This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053
IFMIF-DONES will be a facility devoted to study the degradation of advanced materials for operation of fusion reactors. Motivated by the need of optimizing the neutron irradiation to the materials samples, the HEBT line of the deuteron DONES (DEMO Oriented Neutron Source) accelerator is based on non-linear magnetic fields. By using octupoles and dodecapoles magnets, it is possible to shape the beam profile to achieve the demanded rectangular uniform distribution across the flat top of the beam profile, with high edge peaks in the horizontal direction. Special optics conditions are obtained with a proper setting of quadrupole magnets to minimize the x-y coupling. Additionally, the high beam power (5 MW, for a 125 mA, 40 MeV deuteron beam) in conjunction with the huge space charge makes challenging the HEBT line design to avoid non-controlled losses, except in the devoted scrapers. A comprehensive beam dynamics analysis has been made using TraceWin code. It includes extensive error studies to define tolerances and verify the robustness of the design with respect to magnet misalignment, power supply instabilities and injection parameters.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB259  
About • paper received ※ 19 May 2021       paper accepted ※ 26 July 2021       issue date ※ 20 August 2021  
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WEPAB263 Complex Unit Lattice Cell for Low-Emittance Synchrotrons 3254
 
  • Z.L. Ren, Z.H. Bai, J.J. Tan, L. Wang, H. Xu, P.H. Yang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  To reach the real diffraction-limited emittance, it is generally required to increase the number of bends in multi-bend achromat (MBA) lattices that are used in the designs of fourth-generation synchrotron light sources. For an MBA lattice with distributed chromatic correction, more bends mean much tighter space and much stronger magnets. Inspired by the hybrid MBA lattice concept, in this paper we propose a new lattice concept called complex unit lattice cell, which can save space and reduce magnet strengths. A 17BA lattice based on the complex unit cell concept is designed for a 3 GeV synchrotron light source with a circumference of 537.6 m, which reaches a natural emittance of about 21 pm·rad. Comparison is also made between this 17BA lattice and the 17BA lattice with distributed chromatic correction to demonstrate the merit of the complex unit cell concept.  
poster icon Poster WEPAB263 [1.279 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB263  
About • paper received ※ 16 May 2021       paper accepted ※ 02 July 2021       issue date ※ 29 August 2021  
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WEPAB264 MOGA Optimization of Superconducting Longitudinal Gradient Bend Based on NbTi Wire 3257
 
  • C. Chen, Z.H. Bai, G.Y. Feng, Z.L. Renpresenter, Zh.X. Tang, L. Wang, H. Xu
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: Work supported by National Key Research and Development Program of China, (2016YFA0402001)
Multi-bend achromat lattices with unit cells have been used in diffraction-limited storage ring designs. The longitudinal gradient bend can reduce the horizontal emittance below the theoretical minimum of a given magnet structure, and generally the horizontal emittance reduces with the peak field grows. Therefore superconducting longitudinal gradient bend (SLGB) can produce higher peak field value and quasi-hyperbolic field profile to minimize emittance at location of radiation and generate better hard X-rays. NbTi conductor, rather than Nb3Sn conductor, is selected to keep the design and manufacture of SLGB magnet as simple as possible. In this paper, how the field profiles of race-track type coil and solenoid coil change with their geometric parameters is studied, and multi-objective genetic algorithm is used to optimize SLGB magnet structure considering Hefei Advanced Light Facility lattice design demand and NbTi critical current.
 
poster icon Poster WEPAB264 [1.476 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB264  
About • paper received ※ 14 May 2021       paper accepted ※ 05 July 2021       issue date ※ 15 August 2021  
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WEPAB265 Simulations of Cooling Rate for Coherent Electron Cooling with Plasma Cascade Amplifier 3261
 
  • J. Ma, V. Litvinenko, G. Wang
    BNL, Upton, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Coherent electron cooling (CeC) is a novel technique for rapidly cooling high-energy, high-intensity hadron beams. A plasma cascade amplifier (PCA) has been proposed for the CeC experiment in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). The cooling rate of CeC experiment with PCA has been predicted in 3D start-to-end CeC simulations using code SPACE.
 
poster icon Poster WEPAB265 [1.507 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB265  
About • paper received ※ 13 May 2021       paper accepted ※ 10 June 2021       issue date ※ 15 August 2021  
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WEPAB266 Simulation Studies of Plasma Cascade Amplifier 3265
 
  • J. Ma, V. Litvinenko, G. Wang
    BNL, Upton, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Plasma cascade amplifier (PCA) is an advanced design of amplifier for the coherent electron cooling (CeC) experiment in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Working principle of PCA is the new plasma cascadeμbunching instability occurring in electron beams propagating along a straight trajectory. PCA is cost-effective as it does not require separating electron and hadron beams. SPACE, a parallel, relativistic 3D electromagnetic Particle-in-Cell (PIC) code, has been used for simulation studies of PCA.
 
poster icon Poster WEPAB266 [2.317 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB266  
About • paper received ※ 13 May 2021       paper accepted ※ 10 June 2021       issue date ※ 16 August 2021  
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WEPAB270 Characterization and Simulation of Optical Delay System for the Proof-of-Principle Experiment of Optical Stochastic Cooling at IOTA 3269
 
  • A.J. Dick, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • J.D. Jarvis
    Fermilab, Batavia, Illinois, USA
  • P. Piot
    ANL, Lemont, Illinois, USA
 
  Funding: CBB NSF-PHY-1549132 DOE DE-SC0018656 DOE DE-AC02-07CH11359
The Optical Stochastic Cooling (OSC) experiment at Fermilab’s IOTA storage ring uses two undulators to cool the beam over many turns. The radiation emitted by electrons in the first undulator is delayed and imaged in the second undulator where it applies a corrective energy kick on the electrons. Imperfections in the manufacturing of the delay plates can lead to a source of error. This paper presents the experimental characterization of the absolute thickness of these delay plates using an interferometric technique. The measured "thickness maps" are implemented in the Synchrotron Radiation Workshop (SRW) program to assess their impact on the delayed radiation pulse.
 
poster icon Poster WEPAB270 [2.578 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB270  
About • paper received ※ 16 May 2021       paper accepted ※ 05 July 2021       issue date ※ 29 August 2021  
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WEPAB271 Numerical Modelling of the Optical Stochastic Cooling Experiment at IOTA 3273
 
  • A.J. Dick, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • J.D. Jarvis
    Fermilab, Batavia, Illinois, USA
  • P. Piot
    ANL, Lemont, Illinois, USA
 
  Funding: CBB NSF-PHY-1549132 DOE DE-SC0018656 DOE DE-AC02-07CH11359
A proof-of-principle optical-stochastic cooling (OSC) experiment is currently in its commissioning phase at the Fermilab’s IOTA ring. In support of this experiment, we recently implemented an OSC element in the ELEGANT tracking program. The model, based on a semi-analytic description of OSC [*], supports the simulation of a large number of macroparticles (104-106) over many turns (106). This paper showcases the simulation capabilities to investigate the beam dynamics in the presence of cooling (or self-interacting radiation field in general) and quantify the impact of various sources of error (e.g. transverse and phase jitter), guide data analysis.
* B. Andorf, V. A. Lebedev, J. Jarvis, and P. Piot Rev. Accel. Beams 21, 100702 (2018)
 
poster icon Poster WEPAB271 [1.649 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB271  
About • paper received ※ 16 May 2021       paper accepted ※ 06 July 2021       issue date ※ 14 August 2021  
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WEPAB272 Field-Off Multiple Coulomb Scattering in the MICE Liquid Hydrogen Absorber 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 ※ 14 August 2021  
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WEPAB273 Cooling and Diffusion Rates in Coherent Electron Cooling Concepts 3281
 
  • S. Nagaitsev, V.A. Lebedev
    Fermilab, Batavia, Illinois, USA
  • W.F. Bergan, E. Wang
    BNL, Upton, New York, USA
  • G. Stupakov
    SLAC, Menlo Park, California, 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.
We present analytic cooling and diffusion rates for a simplified model of coherent electron cooling (CEC), based on a proton energy kick at each turn. This model also allows to estimate analytically the rms value of electron beam density fluctuations in the "kicker" section. Having such analytic expressions should allow for better understanding of the CEC mechanism, and for a quicker analysis and optimization of main system parameters. Our analysis is applicable to any CEC amplification mechanism, as long as the wake (kick) function is available.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB273  
About • paper received ※ 10 May 2021       paper accepted ※ 28 July 2021       issue date ※ 15 August 2021  
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WEPAB274 Numerical Study of Beam Dynamics in PITZ Bunch Compressor 3285
 
  • A. Lueangaramwong, Z. Aboulbanine, G.D. Adhikari, N. Aftab, P. Boonpornprasert, N. Chaisueb, G.Z. Georgiev, J. Good, M. Groß, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, D. Melkumyan, H.J. Qian, G. Shu, F. Stephan, G. Vashchenko, T. Weilbach
    DESY Zeuthen, Zeuthen, Germany
  • H. Shaker
    CLS, Saskatoon, Saskatchewan, Canada
 
  A magnetic bunch compressor has been recently designed for an accelerator-based THz source which is under development at the Photo Injector Test facility at DESY in Zeuthen (PITZ). The THz source is assumed to be a prototype for an accelerator-based THz source for pump-probe experiments at the European XFEL. As an electron bunch is compressed to achieve higher bunch currents for the THz source, we investigate the beam dynamics in the bunch compressor by numerical simulations. A start-to-end simulation optimizer has been developed by combining the use of ASTRA, IMPACT-T, and OCELOT to support the design of the THz source prototype. Coherent synchrotron radiation effects degrade the compression performance for our study cases with bunch charges up to 4 nC and beam energy of 17 MeV at a bending angle of 19 degrees. Simulation and preliminary beam characteristic results will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB274  
About • paper received ※ 11 May 2021       paper accepted ※ 06 July 2021       issue date ※ 15 August 2021  
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WEPAB277 Transverse Emittance Change and Canonical Angular Momentum Growth in MICE ‘Solenoid Mode’ with Muon Ionization Cooling 3289
 
  • T.W. Lord
    University of Warwick, Coventry, United Kingdom
 
  Emittance reduction of muon beams is an important requirement in the design of a Neutrino Factory or Muon Collider. Ionization cooling, whereby beam emittance is reduced by passing a beam through an energy-absorbing material, requires tight focusing in the transverse plane which is achieved in many designs using solenoid focusing. In solenoid focusing, the beam acquires kinetic angular momentum due to the radial field in the solenoid fringe. Cooling in ‘flip’ mode, where the beam-focusing solenoid field changes polarity at the absorber, has already been demonstrated in the Muon Ionization Cooling Experiment (MICE). In this mode the absorber is near to the field flip, so the kinetic angular momentum is zero at the absorber. ‘Solenoid mode’ cooling, where the field polarity does not change across the absorber leading to a beam crossing the absorber with significant kinetic angular momentum, has been considered for the final section of the muon collider design due to potentially stronger focussing that it enables. In this paper, we present the performance of MICE in ‘solenoid mode’.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB277  
About • paper received ※ 19 May 2021       paper accepted ※ 06 July 2021       issue date ※ 10 August 2021  
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WEPAB278 Beam-Beam Simulations for Lepton-Hadron Colliders: ALOHEP Software 3293
 
  • B.B. Oner
    Gazi University, Faculty of Arts and Sciences, Teknikokullar, Ankara, Turkey
  • B. Dagli, S. Sultansoy
    TOBB ETU, Ankara, Turkey
  • B. Ketenoğlu
    Ankara University, Faculty of Engineering, Tandogan, Ankara, Turkey
 
  It is known that rough luminosity estimations for ll, lh, and hh colliders can be performed easily using nominal beam parameters. In principle, more precise results can be obtained by analytical solutions. However, beam dynamics is usually neglected in this case since it is almost impossible to cope with beam size fluctuations. In this respect, several beam-beam simulation programs for linear e+e and photon colliders have been proposed while no similar open-access simulation exists for all types of colliders (i.e. linac-ring ep colliders). Here, we present the software ALOHEP (A Luminosity Optimizer for High Energy Physics), a luminosity calculator for linac-ring and ring-ring lh colliders, which also computes IP parameters such as beam-beam tune shift, disruption arising out of electromagnetic interactions. In addition, the program allows taking crossing-angle effects on luminosity into account.
* Y.C. Acar et al., Nucl. Instrum. Meth. A, 871 (2017).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB278  
About • paper received ※ 19 May 2021       paper accepted ※ 26 July 2021       issue date ※ 21 August 2021  
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WEPAB279 On Wire-Corrector Optimization in the HL-LHC and the Appearance of Special Aspect Ratios 3297
 
  • D. Kaltchev
    TRIUMF, Vancouver, Canada
 
  For the two high-luminosity insertions of the Large Hadron Collider (HL-LHC) current bearing wire correctors are intended to mitigate the detrimental effect of long-range beam-beam interactions. With respect to finding the optimum longitudinal location of the wire, two special locations corresponding to the special values 2 and 1/2 of the beta-function aspect ratio have been previously shown to provide simultaneous cancellation of multiple two-dimensional Resonance Driving Terms. This paper attempts to explain the appearance of such special aspect ratios.  
poster icon Poster WEPAB279 [1.238 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB279  
About • paper received ※ 14 May 2021       paper accepted ※ 19 July 2021       issue date ※ 02 September 2021  
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WEPAB280 Two-Dimensional Beam-Beam Invariant with Applications to HL-LHC 3301
 
  • D. Kaltchev
    TRIUMF, Vancouver, Canada
 
  Long-range beam-beam interactions represent the most severe limitation on the performance and achievable luminosity of circular collider. The paper presents a two-dimensional nonlinear Courant Snyder Invariant derived to first order in the beam-beam perturbation and based on the two-dimensional coefficients in the Fourier expansion of the Beam-beam Hamiltonian. Its validity in case of HL-LHC lattices with realistic beam-beam setup is verified with MadX tracking.  
poster icon Poster WEPAB280 [1.235 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB280  
About • paper received ※ 14 May 2021       paper accepted ※ 06 July 2021       issue date ※ 23 August 2021  
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WEPAB281 The Precision Laser Inclinometer 3305
 
  • B. Di Girolamo, S. Vlachos
    CERN, Geneva, Switzerland
  • Ju. Boudagov, M.V. Lyablin
    JINR, Dubna, Moscow Region, Russia
 
  Earth surface movements, like earthquakes or human-produced (cultural) noise, can induce a degradation of the instantaneous luminosity of particle accelerators or even sudden beam losses. In the same way the presence of seismic and cultural noise limits the detection capabilities of interferometric antennas used for the observations of gravitational waves. This contribution discusses the importance of monitoring the effects of earth vibrations using a novel multi-purpose instrument, the Precision Laser Inclinometer (PLI). Few examples of recorded events are discussed along with ideas on PLI applications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB281  
About • paper received ※ 16 May 2021       paper accepted ※ 01 July 2021       issue date ※ 29 August 2021  
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WEPAB282 The Consolidation of the CERN Beam Interlock System 3309
 
  • R.L. Johnson, C. Martin, T. Podzorny, I. Romera, R. Secondo, J.A. Uythoven
    CERN, Geneva, Switzerland
 
  The Beam Interlock System (BIS) is a machine protection system that provides essential interlock control throughout the CERN accelerator complex. The current BIS has been in service since 2006; as such, it is approaching the end of its operational lifetime, with most components being obsolete. A second version of the Beam Interlock System, "BIS2", is currently under development and will replace the current system. BIS2 aims to be more flexible by supplying additional on-board diagnostic tools, while also improving the overall safety by adding more redundancy. Crucially, BIS2 increases the number of critical paths that can be interlocked by almost 50%, providing an important flexibility for future additional interlocking requests. BIS2 will come into operation for the LHC in run 4 (2027) and will remain in operation until the end of the planned lifetime of HL-LHC. In this paper, we will focus on the Beam Interlock Controller Manager board (CIBM), which is at the heart of BIS2. Since this module works closely with many other systems that are similar in design to those in BIS1, we will compare how BIS2 improves upon BIS1, and justify the reasons why these changes were made.  
poster icon Poster WEPAB282 [0.378 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB282  
About • paper received ※ 18 May 2021       paper accepted ※ 14 July 2021       issue date ※ 19 August 2021  
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WEPAB283 CERN SPS Sprinkler System: A Customized Industrial Solution for a Non-Conventional Site 3313
 
  • A. Suwalska, A. Arnalich, F. Deperraz, M. Munoz Codoceo, P. Ninin
    CERN, Meyrin, Switzerland
 
  Until 2018, the limited firefighting means in the SPS complex largely exposed it to the consequences of self-ignition or accidental fire. In 2015 the SPS Fire Safety project was launched with the objective of improving life safety and property protection by deploying a whole set of automatic actions to protect SPS in case of fire outbreak. If nothing was done, an unmanaged fire could be a threat to lives of those working underground and could mean losing a vast majority of the SPS machine and its equipment. In 2020, CERN has completed the consolidation of its SPS fire safety systems. Among these, a water based sprinkler system, following principles of standard industrial design but customized and tailor-made for SPS and its irradiated areas, is ready to operate. The system must take into account limitations related to the presence of fragile accelerator equipment, radioactive zones, integration constraints and comply with European norms, in particular EN12845. This paper presents the risk assessment, our experience from the planning and installation phase while discussing the custom-chosen and radiation tested equipment to end up with the lessons learned and outlook for the future.  
poster icon Poster WEPAB283 [2.224 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB283  
About • paper received ※ 13 May 2021       paper accepted ※ 14 June 2021       issue date ※ 30 August 2021  
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WEPAB284 Interlock System Upgrades at the CERN Accelerator Complex During Long Shutdown 2 3316
 
  • J.A. Uythoven, A. Antoine, C. Martin, A. Mirana Fontan, R. Mompo, I. Romera, R. Secondo
    CERN, Geneva, Switzerland
 
  The CERN accelerator complex stopped operation at the end of 2018 for the Long Shutdown 2 (LS2), allowing for the LHC Injector Upgrade program (LIU) and consolidation work to be accomplished. A gradual restart of the different accelerators is ongoing in 2021, culminating with the LHC foreseen to be back in operation early 2022. During LS2 a very large range of systems was modified throughout the accelerator complex. This includes the so-called Machine Interlock systems, which are at the heart of the overall machine protection system. This paper gives an overview of the Machine Interlock systems changes during LS2. It includes the installation of a Beam Interlock System (BIS) at the new linear accelerator LINAC4, at the PS-Booster and the installation of a new Injection BIS for the SPS synchrotron. New Safe Machine Parameter flags to protect the SPS transfer line mobile beam dumps against high intensity beams were put in place. The new Warm Magnet Controller (WIC) installations at LINAC4 the PS Booster and the different transfer lines and experimental areas are presented together with the modifications to the Power Interlock Controller protecting the LHC superconducting magnets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB284  
About • paper received ※ 17 May 2021       paper accepted ※ 02 July 2021       issue date ※ 02 September 2021  
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WEPAB285 High Resolution Arrival Time Measurement of the Seed Laser 3320
 
  • J.G. Wang, H.X. Deng, L. Feng, C.L. Li, B. Liu
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • X.T. Wang, W.Y. Zhang
    Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
 
  The Shanghai soft X-ray Free-Electron Laser facility (SXFEL) is a fourth-generation linac-based light source, capable of producing X-ray pulses with a duration of tens of femtosecond. The seed laser for external seeding FEL, therefore, has tight requirements for relative arrival time to the electron bunch. To reach the required energy and wavelength for external seeding FEL, further optical amplification and frequency conversion is needed. These include reflection and propagation in different material and in air, in addition, also include the long laser transport beamline to the undulator, make the laser pulses arrival time influenced by environmental variation. To reach the required specification, high-resolution measurement of the laser arrival time is necessary. In this paper, we present a general concept for the measurement of the laser arrival time.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB285  
About • paper received ※ 19 May 2021       paper accepted ※ 12 July 2021       issue date ※ 19 August 2021  
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WEPAB286 Design of the Laser-to-RF Synchronization at 1.3 GHz for SHINE 3323
 
  • J.G. Wang, H.X. Deng, L. Feng, C.L. Li, B. Liu
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • X.T. Wang, W.Y. Zhang
    Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
 
  A next-generation photo-science facility like Shanghai HIgh repetition rate XFEL aNd Extreme light facility (SHINE) is aiming to generate femtosecond X-ray pulses with unprecedented brightness to film chemical and physical reactions with sub-atomic level spatio-temporal resolution. To fulfill this scientific goal, high-precision timing synchronization is essential. The pulsed optical synchronization has become an indispensable scheme for femtosecond precision synchronization of X-ray free-electron lasers. One of the critical tasks of pulsed optical synchronization is to synchronize various microwave sources. For the future SHINE, ultralow-noise pulses generated by a mode-locked laser are distributed over large distances via stabilized fiber links to all critical facility end-stations. In order to achieve low timing jitter and long-term stability of 1.3 GHz RF reference signal for the accuracy Low-Level RF(RF) field control, an Electro-optical intensity Modulator (EOM) based scheme is being developed at SHINE. In this paper, we present the progress on the design of the optical part and the integrated electronics of the laser-to-RF synchronization.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB286  
About • paper received ※ 20 May 2021       paper accepted ※ 12 July 2021       issue date ※ 23 August 2021  
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WEPAB287 Upgrade of the ELBE Timing System 3326
 
  • M. Kuntzsch, M. Justus, A. Schwarz, K. Zenker
    HZDR, Dresden, Germany
  • L. Krmpotic, U. Legat, U. Rojec
    Cosylab, Ljubljana, Slovenia
  • Ž. Oven
    COSYLAB, Control System Laboratory, Ljubljana, Slovenia
 
  At the ELBE accelerator center a superconducting linac is operated to drive manifold secondary radiation sources like two infrared FELs, a positron source and a THz facility. The machine uses two injectors as electron sources that are accelerated in the main linac. The user experiments demand a large variety of bunch patterns from single shot to macro pulsed and cw beam at up to 26 MHz repetition rate. At ELBE a new timing system is being developed based on the MRF hardware platform and the MRF Timing System IOC. It uses two masters and a scalable number of connected receivers to generate the desired pulse patterns for operating the machine and to control user experiments. The contribution will show the architecture of the timing system, the control interfacing and performance measurements acquired on the test bench.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB287  
About • paper received ※ 21 May 2021       paper accepted ※ 01 July 2021       issue date ※ 29 August 2021  
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WEPAB288 A New Timing System for PETRA IV 3329
 
  • H. Lippek, A. Aghababyan, K. Brede, H.T. Duhme, M. Fenner, U. Hurdelbrink, H. Kay, H. Schlarb, T. Wilksen
    DESY, Hamburg, Germany
 
  At DESY an upgrade of the PETRA III synchrotron light source towards a fourth-generation, low emittance machine PETRA IV is currently being actively pursued. The realization of this new machine implies a new design of the timing and synchronization system since requirements on beam quality and controls will significantly change from the existing implementation at PETRA III. As of now the technical design phase of the PETRA IV project is in full swing. For the timing system the design process of the overall system as well as the evaluation of individual components has been started as of last year. Given the success of the at DESY developed MicroTCA.4-based timing system for the European XFEL accelerator it has been chosen to serve as a basis for the PETRA IV timing system developement as well. We present first design ideas of the major timing system hardware component, a MicroTCA.4-based AMC for distributing clocks, triggers and further bunch-synchronous information within the accelerator complex and to user experiments. First steps of an evaluation process for designing the AMC hardware are briefly illustrated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB288  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 31 August 2021  
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WEPAB289 Machine Learning Based Spatial Light Modulator Control for the Photoinjector Laser at FLUTE 3332
 
  • C. Xu, E. Bründermann, A.-S. Müller, M.J. Nasse, A. Santamaria Garcia, C. Sax, C. Widmann
    KIT, Karlsruhe, Germany
  • A. Eichler
    DESY, Hamburg, Germany
 
  Funding: C. Xu acknowledges the support by the DFG-funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology".
FLUTE (Ferninfrarot Linac- und Test-Experiment) at KIT is a compact linac-based test facility for novel accelerator technology and a source of intense THz radiation. FLUTE is designed to provide a wide range of electron bunch charges from the pC- to nC-range, high electric fields up to 1.2 GV/m, and ultra-short THz pulses down to the fs-timescale. The electrons are generated at the RF photoinjector, where the electron gun is driven by a commercial titanium sapphire laser. In this kind of setup the electron beam properties are determined by the photoinjector, but more importantly by the characteristics of the laser pulses. Spatial light modulators can be used to transversely and longitudinally shape the laser pulse, offering a flexible way to shape the laser beam and subsequently the electron beam, influencing the produced THz pulses. However, nonlinear effects inherent to the laser manipulation (transportation, compression, third harmonic generation) can distort the original pulse. In this paper we propose to use machine learning methods to manipulate the laser and electron bunch, aiming to generate tailor-made THz pulses. The method is demonstrated experimentally in a test setup.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB289  
About • paper received ※ 19 May 2021       paper accepted ※ 06 July 2021       issue date ※ 23 August 2021  
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WEPAB290 Pointing Stabilization Algorithms Explored and Implemented with the Low Energy RHIC Electron Cooling Laser 3336
 
  • L.K. Nguyen
    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.
The electron beam for the Low Energy RHIC electron Cooler (LEReC) at Brookhaven National Laboratory (BNL) is generated by a high-power fiber laser illuminating a photocathode, with a total propagation distance of 34 m separating the laser output and the photocathode. This propagation is facilitated by three independent laser tables that have varying responses to changes in time of day, weather, and season. Alignment drifts induced by these environmental changes are mitigated by an active "slow" pointing stabilization system found along the length of the transport, and this in-house system was commissioned as part of the full laser transport in 2019, as previously reported*. In 2020, the system became fully operational alongside LEReC, the world’s first electron cooler in a collider, and helped establish the transverse stability of the electron beam required for cooling. A summary of the different slow stabilization algorithms, which were continually refined during the run in order to achieve long-term center-of-mass stability of the laser spot on the photocathode to within 10 microns RMS, is provided.
* L. K. Nguyen et al., "Active Pointing Stabilization Techniques Applied to the Low Energy RHIC Electron Cooling Laser Transport at BNL", presented at NAPAC’19, paper THYBA6.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB290  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 30 August 2021  
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WEPAB292 Application of Machine Learning to Predict the Response of the Liquid Mercury Target at the Spallation Neutron Source 3340
 
  • L. Lin, S. Gorti, J.C. Mach, H. Tran, D.E. Winder
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: Basic Energy Sciences U.S. Department of Energy SC-22/Germantown Building 1000 Independence Avenue., SW Washington, DC 20585 P: (301) 903 - 3081 F: (301) 903 - 6594
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is currently the most powerful accelerator-driven neutron source in the world. The intense proton pulses strike on SNS’s mercury target to provide bright neutron beams, which also leads to severe fluid-structure interactions inside the target. Prediction of resultant loading on the target is difficult particularly when helium gas is intentionally injected into mercury to reduce the loading and mitigate the pitting damage on the target’s internal walls. Leveraging the power of machine learning and the measured target strain, we have developed machine learning surrogates for modeling the discrepancy between simulations and experimental strain data. We then employ these surrogates to guide the refinement of the high-fidelity mercury/helium mixture model to predict a better match of target strain response.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB292  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 19 August 2021  
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WEPAB293 The Trip Event Logger for Online Fault Diagnosis at the European XFEL 3344
 
  • J.H.K. Timm, J. Branlard, A. Eichler, H. Schlarb
    DESY, Hamburg, Germany
 
  The low-level RF (LLRF) system at the European XFEL, DESY, is of major importance for a high-performant and reliable operation. Faults here can jeopardize the overall operation. Therefore, the trip event logger is currently developped, - a fault diagnosis tool to detect errors online, inform the operators and trigger automatic supervisory actions. Further goals are to provide information for a fault tree and event tree analysis as well as a database of labeled faulty data sets for offline analysis. The tool is based on the C++ framework ChimeraTK Application Core. With this close interconnection to the control system it is possible not only to monitor but also to intervene as it is of great importance for supervisory tasks. The core of the tool consists of fault analysis modules ranging from simple ones (e.g., limit checking) to advanced ones (model-based, machine learning, etc.). Within this paper the architecture and the implementation of the trip event logger are presented.  
poster icon Poster WEPAB293 [7.919 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB293  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 21 August 2021  
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WEPAB294 LLRF Control and Synchronization System of the ARES Facility 3347
 
  • S. Pfeiffer, J. Branlard, F. Burkart, M. Hoffmann, T. Lamb, F. Ludwig, H. Schlarb, S. Schulz, B. Szczepanski, M. Titberidze
    DESY, Hamburg, Germany
 
  The linear accelerator ARES (Accelerator Research Experiment at SINBAD) is a new research facility at DESY. Electron bunches with a maximum repetition rate of 50 Hz are accelerated up to 155 MeV. The facility aims for ultra-stable sub-femtosecond arrival-times and high peak-currents at the experiment, placing high demands on the reference distribution and field regulation of the S-band RF structures. In this paper, we report on the current status of the RF reference generation, facility-wide distribution, and the LLRF systems of the RF structures.  
poster icon Poster WEPAB294 [2.394 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB294  
About • paper received ※ 18 May 2021       paper accepted ※ 05 July 2021       issue date ※ 11 August 2021  
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WEPAB295 Parameter Estimation of Short Pulse Normal-Conducting Standing Wave Cavities 3351
 
  • S. Pfeiffer, J. Branlard, F. Burkart, M. Hoffmann, H. Schlarb
    DESY, Hamburg, Germany
 
  The linear accelerator ARES (Accelerator Research Experiment at SINBAD) is a new research facility at DESY. Electron bunches with a maximum repetition rate of 50 Hz are accelerated to a target energy of 155 MeV. The facility aims for ultra-stable sub-femtosecond arrival-times and high peak-currents at the experiment, placing high demands on the reference distribution and field regulation of the RF structure. In this contribution, we present the physical parameter estimation of key RF properties such as cavity detuning not directly measurable on the RF field decay. The method can be used as a fast monitor of inner cell temperature. The estimated properties are finally compared with the measured ones.  
poster icon Poster WEPAB295 [0.860 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB295  
About • paper received ※ 19 May 2021       paper accepted ※ 05 July 2021       issue date ※ 10 August 2021  
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WEPAB296 A Klystron Phase Lock Loop for RF System at TPS Booster Ring 3354
 
  • F.Y. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.D. Li, M.-C. Lin, Z.K. Liu, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yupresenter
    NSRRC, Hsinchu, Taiwan
 
  In TPS booster ring, the DLLRF is used to controlled the ramping gap voltage and also the energy saving module is applied to save power while the ring does not inject beam. But we occurred to have a problem of PI saturation due to a large phase change when the energy saving module working. The energy saving module switches the anode voltage of the klystron from high to low level to decrease the cathode current while the ring does not inject and do the opposite while the ring injects. This action causes a large phase change of the transmitter and leads the PI controller to work in the wrong direction. We add a klystron phase loop to solve this situation.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB296  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 31 August 2021  
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WEPAB297 A Recent Upgrade on Phase Drift Compensation System for a Stable Beam Injection at J-PARC Linac 3357
 
  • E. Cicek, Z. Fang, Y. Fukui, K. Futatsukawa
    KEK, Ibaraki, Japan
  • T. Hirane, S. Shinozaki
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Sato
    Nippon Advanced Technology Co., Ltd., Tokai, Japan
 
  J-PARC linac, consisting of 324 MHz and 972 MHz acceleration sections, delivers H beam to the rapid cycling synchrotron (RCS). The drift in the beam injection momentum from linac to RCS was measured to be highly dependent on the humidity at the klystron gallery. Also, changes in both temperature and humidity strongly affect the rf field phase controlled within the digital feedback (DFB) system. To cope with this, a unique phase drift compensation system, namely the phase drift monitor (PDM) system, is implemented in the MEBT2B1 station as the first step at the linac. However, the compensation of the drift correction could not be achieved directly since two different frequencies were used. The new PDM, which adapts the direct sampling method using the Radio Frequency System-on-Chip (RFSoC), will pave the way to ensure rf phase stability at all stations simultaneously. Here we present the effects of temperature and humidity on the rf field phase, along with performance and preliminary test results concerning the phase drift compensation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB297  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 30 August 2021  
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WEPAB298 Design of an Accurate LLRF System for an Array of Two-Gap Resonators 3360
 
  • D.A. Liakin, S.V. Barabin, T. Kulevoypresenter, A.Y. Orlov
    ITEP, Moscow, Russia
 
  A particle accelerator based on an array of two-gap resonators requires a control system, which is responsible for precise setup and stabilization of the phase and magnitude of the electromagnetic field in resonators. We develop a cost-effective LLRF system for the array of more than 80 resonators and three different operating frequencies. The design is based on proved solution used for 5-resonators accelerator HILAC (project NICA, Dubna). This paper gives an overview of the basic structure and some specific features of the developing LLRF control system.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB298  
About • paper received ※ 18 May 2021       paper accepted ※ 23 June 2021       issue date ※ 20 August 2021  
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WEPAB299 Spallation Neutron Source Proton Power Upgrade Low-Level RF Control System Development 3363
 
  • M.T. Crofford, J.A. Ball, J.E. Breeding, M.P. Martinez, J.S. Moss, M. Musrock
    ORNL, Oak Ridge, Tennessee, USA
  • L.R. Doolittle, C. Serrano, V.K. Vytla
    LBNL, Berkeley, California, USA
  • J. Graham, C.K. Roberts, J.W. Sinclair, Z. Sorrell, S. Whaley
    ORNL RAD, Oak Ridge, Tennessee, USA
 
  Funding: * This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725.
The Proton Power Upgrade (PPU) Project is approved for the Spallation Neutron Source at Oak Ridge National Laboratory and will double the proton beam power capability from 1.4 MW to 2.8 MW with 2 MW beam power available to the first target station. A second target station is planned and will utilize the remaining beam power in the future. The proton power increase will be supported with the addition of twenty-eight new superconducting cavities powered by 700 kW peak power klystrons to increase beam energy while increases to the beam current will be done with a combination of existing RF margin, and DTL HPRF upgrades. The original low-level RF control system has proven to be reliable over the past 15 years of operations, but obsolescence issues mandate a replacement system be developed for the PPU project. The replacement system is realized in a µTCA.4 platform using a combination of commercial off-the-shelf boards and custom hardware to support the requirements of PPU. This paper presents the prototype hardware, firmware, and software development activities along with preliminary testing results of the new system.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB299  
About • paper received ※ 18 May 2021       paper accepted ※ 21 June 2021       issue date ※ 12 August 2021  
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WEPAB300 Python Based Tools for FRIB LLRF Operation and Management 3367
 
  • S.R. Kunjir, D.G. Morris, S. Zhao
    FRIB, East Lansing, Michigan, USA
 
  Funding: This work is supported by the US Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
Some Python based tools have been developed at the Facility for Rare Isotope Beams (FRIB) for the ease of operation and management of the low level radio frequency (LLRF) controllers. Utilizing the rich features in Python, some tasks can be easily applied to a whole segment, one type of cryomodule (CM), a specific cryomodule or individual cavities grouped by a complex custom query. The tasks include, for example, 1) testing interface connections between various sub-systems prior to an operational run; 2) setting, checking and saving/restoring parameters during and after an operational run; 3) updating LLRF controller firmware and software during maintenance. With these tools, routine manual tasks are streamlined to achieve significantly greater efficiency in terms of scalability, time, memory and network resources. Considering channel access security, beam on/off status etc., the strategy of choosing either input/output controller (IOC) or Python for the implementation of certain tasks is also discussed in the paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB300  
About • paper received ※ 18 May 2021       paper accepted ※ 01 July 2021       issue date ※ 29 August 2021  
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WEPAB301 Design of an X-Band LLRF System for TEX Test Facility at LNF-INFN 3371
 
  • L. Piersanti, D. Alesini, M. Bellaveglia, S. Bini, B. Buonomo, F. Cardelli, C. Di Giulio, M. Diomede, A. Falone, G. Franzini, A. Gallo, A. Liedl, S. Pioli, S. Quaglia, L. Sabbatini, M. Scampati, G. Scarselletta, A. Stella
    INFN/LNF, Frascati, Italy
 
  Funding: Latino is a project co-funded by Regione Lazio within POR-FESR 2014-2020 program
In the framework of LATINO project (Laboratory in Advanced Technologies for INnOvation) funded by Lazio regional government, a TEst stand for X-band (TEX) is being commissioned at Frascati National Laboratories (LNF) of INFN. TEX is born as a collaboration with CERN, aimed at carrying out high power tests of X-band accelerating structure prototypes and waveguide components, and it is of paramount importance in view of the construction of EuPRAXIA@SPARC_LAB facility at LNF. In order to generate, manipulate and measure the RF pulses needed to feed the RF power unit (solid state ScandiNova K400 modulator, CPI 50 MW 50 Hz klystron) an X-band low level RF system has been developed, making use of a commercial S-band (2.856 GHz) Libera digital LLRF (manufactured by Instrumentation Technologies) with a newly designed up/down conversion stage and a reference generation/distribution system, which is able to produce coherent reference frequencies for the American S-band (2.856 GHz) and European X-band (11.994 GHz). In this paper the main features of such systems will be reviewed together with preliminary laboratory measurement results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB301  
About • paper received ※ 19 May 2021       paper accepted ※ 12 July 2021       issue date ※ 16 August 2021  
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WEPAB302 COSY Machine-Model Optimization 3375
 
  • I. Bekman, J.H. Hetzel
    FZJ, Jülich, Germany
 
  Funding: Helmholtz Association
Successful operation of a particle accelerator requires accompanying model calculations. The model helps in understanding the machine and predicts the impact of a change in the settings (e.g. current of magnetic elements). For the COoler SYnchrotron (COSY) at Research Center Jülich the accelerator simulation software MAD-X is used to model the machine. The model parameters are steadily being improved based on various manual adjustments and analytical studies, however are hardly optimized all at once. This can be improved with machine learning methods. The model is used to predict measurable quantities, like Orbit Response Matrix (ORM) or betatron tunes. Several observables for different particle energies have been measured recently and the corresponding machine settings are available. We describe the effort to improve the agreement between measured and calculated ORMs and hence improve the agreement between model and (real) machine and report on the optimization using a multivariate algorithm (e.g. genetic algorithm). This facilitates the setup of COSY and will allow to perform high precision experiments e.g. a measurement of an electric dipole moment of deuterons at COSY.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB302  
About • paper received ※ 14 May 2021       paper accepted ※ 28 July 2021       issue date ※ 11 August 2021  
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WEPAB303 Machine Learning Applied to Automated Tunes Control at the 1.5 GeV Synchrotron Light Source DELTA 3379
 
  • D. Schirmer
    DELTA, Dortmund, Germany
 
  Machine learning (ML) driven algorithms are finding more and more use cases in the domain of accelerator physics. Apart from correlation analysis in large data volumes, low and high level controls, like beam orbit correction, also non-linear feedback systems are possible application fields. This also includes monitoring the storage ring betatron tunes, as an important task for stable machine operation. For this purpose classical, shallow (non-deep), feed-forward neural networks (NNs) were investigated for automated adjusting the storage ring tunes. The NNs were trained with experimental machine data as well as with simulated data based on a lattice model of the DELTA storage ring. With both data sources comparable tune correction accuracies were achieved, both, in real machine operation and for the simulated storage ring model. In contrast to conventional PID methods, the trained NNs were able to approach the desired target tunes in fewer steps. The report summarizes the current status of this machine learning project and points out possible future improvements as well as other possible applications.  
poster icon Poster WEPAB303 [1.575 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB303  
About • paper received ※ 19 May 2021       paper accepted ※ 05 July 2021       issue date ※ 14 August 2021  
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WEPAB304 Multi-Objective Multi-Generation Gaussian Process Optimizer 3383
 
  • X. Huang, M. Song, Z. Zhangpresenter
    SLAC, Menlo Park, California, USA
 
  Funding: DOE, Office of Science, Office of Basic Energy Sciences, DE-AC02-76SF00515 and FWP 2018-SLAC-100469 Computing Science, Office of Advanced Scientific Computing Research, FWP 2018-SLAC-100469ASCR.
We present a multi-objective evolutionary optimization algorithm that uses Gaussian process (GP) regression-based models to select trial solutions in a multi-generation iterative procedure. In each generation, a surrogate model is constructed for each objective function with the sample data. The models are used to evaluate solutions and to select the ones with a high potential before they are evaluated on the actual system. Since the trial solutions selected by the GP models tend to have better performance than other methods that only rely on random operations, the new algorithm has much higher efficiency in exploring the parameter space. Simulations with multiple test cases show that the new algorithm has a substantially higher convergence speed and stability than NSGA-II, MOPSO, and some other recent preselection-assisted algorithms.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB304  
About • paper received ※ 17 May 2021       paper accepted ※ 12 July 2021       issue date ※ 10 August 2021  
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WEPAB305 Teeport: Break the Wall Between the Optimization Algorithms and Problems 3387
 
  • Z. Zhang, X. Huang, M. Song
    SLAC, Menlo Park, California, USA
 
  Funding: DOE, Office of Science, Office of Basic Energy Sciences, DE-AC02-76SF00515 and FWP 2018-SLAC-100469 Computing Science, Office of Advanced Scientific Computing Research, FWP 2018-SLAC-100469ASCR.
Optimization algorithms/techniques such as genetic algorithm (GA), particle swarm optimization (PSO) and Gaussian process (GP) have been widely used in the accelerator field to tackle complex design/online optimization problems. However, connecting the algorithm with the optimization problem can be difficult, sometimes even unrealistic, since the algorithms and problems could be implemented in different languages, might require specific resources, or have physical constraints. We introduce an optimization platform named Teeport that is developed to address the above issue. This real-time communication (RTC) based platform is particularly designed to minimize the effort of integrating the algorithms and problems. Once integrated, the users are granted a rich feature set, such as monitoring, controlling, and benchmarking. Some real-life applications of the platform are also discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB305  
About • paper received ※ 20 May 2021       paper accepted ※ 02 July 2021       issue date ※ 21 August 2021  
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WEPAB306 Applying Machine Learning to Optimization of Cooling Rate at Low Energy RHIC Electron Cooler 3391
 
  • Y. Gao, K.A. Brown, P.S. Dyer, S. Seletskiy, H. Zhao
    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.
The Low Energy RHIC electron Cooler (LEReC) is a novel, state-of-the-art, electron accelerator for cooling RHIC ion beams, which was recently built and commissioned. Optimization of cooling with LEReC requires fine-tuning of numerous LEReC parameters. In this work, initial optimization results of using Machine Learning (ML) methods - Bayesian Optimization (BO) and Q-learning are presented. Specially, we focus on exploring the influence of the electron trajectory on the cooling rate. In the first part, simulations are conducted by utilizing a LEReC simulator. The results show that both methods have the capability of deriving electron positions that can optimize the cooling rate. Moreover, BO takes fewer samples to converge than the Q-learning method. In the second part, Bayesian optimization is further trained on the historical cooling data. In the new samples generated by the BO, the percentage of larger cooling rates data is greatly enhanced compared with the original historical data.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB306  
About • paper received ※ 12 May 2021       paper accepted ※ 01 July 2021       issue date ※ 23 August 2021  
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WEPAB308 Measurement-Based Surrogate Model of the SLAC LCLS-II Injector 3395
 
  • L. Gupta, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • A.L. Edelen, C.E. Mayes, A.A. Mishra, N.R. Neveu
    SLAC, Menlo Park, California, USA
 
  Funding: This project was funded by the DOE SCGSR Program.
There is significant effort within particle accelerator physics to use machine learning methods to improve modeling of accelerator components. Such models can be made realistic and representative of machine components by training them with measured data. These models could be used as virtual diagnostics or for model-based control when fast feedback is needed for tuning to different user settings. To prototype such a model, we demonstrate how a machine learning based surrogate model of the SLAC LCLS-II photocathode injector was developed. To create machine-based data, laser measurements were taken at the LCLS using the virtual cathode camera. These measurements were used to sample particles, resulting in realistic electron bunches, which were then propagated through the injector via the Astra space charge simulation. By doing this, the model is not only able to predict many bulk electron beam parameters and distributions which are often hard to measure or not usually available to measure, but the predictions are more realistic relative to traditionally simulated training data. The methods for training such models, as well as model capabilities and future work are presented here.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB308  
About • paper received ※ 26 May 2021       paper accepted ※ 27 July 2021       issue date ※ 21 August 2021  
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WEPAB309 Study and Design of the Appropriate High-Performance Computing System for Beamline Data Analysis Application at Iranian Light Source Facility (ILSF) 3399
 
  • A. Khaleghi, M. Akbari
    ILSF, Tehran, Iran
  • H. Haedar, K. Mahmoudipresenter, M. Takhttavani
    IKIU, Qazvin, Iran
  • S. Mahmoudi
    Sharif University of Technology (SUT), Tehran, Iran
 
  Data analysis is a very important step in doing experiments at light sources, where multiple application and software packages are used for this purpose. In this paper we have reviewed some software packages that are used for data analysis and design at Iranian Light Source Facility then according to their processing needs, after taking in mind different HPC scenarios a suitable architecture for deployment of the ILSF HPC is presented. The proposed architecture is a cluster of 64 computing nodes connected through Ethernet and InfiniBand network running a Linux operating system with support of MPI parallel environment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB309  
About • paper received ※ 19 May 2021       paper accepted ※ 23 July 2021       issue date ※ 15 August 2021  
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WEPAB310 Study and Design of a High-Performance Computing Infrastructure for Iranian Light Source Facility Based on the Accelerator Physicists and Engineers’ Applications Requirements 3402
 
  • K. Mahmoudi, H. Haedar, A. Khaleghi
    IKIU, Qazvin, Iran
  • M. Akbari, A. Khaleghi
    ILSF, Tehran, Iran
  • S. Mahmoudi
    IUST, Narmac, Tehran, Iran
 
  Synchrotron design and operation are one of the complex tasks which requires a lot of precise computation. As an example, we could mention the simulations done for calculating the impedance budget of the machine which requires a notable amount of computational power. In this paper we are going to review different HPC scenarios suitable for this matter then we will present our design of a suitable HPC based on the accelerator physicists and engineers’ needs. Going through different HPC scenarios such as shared memory architectures, distributed memory architectures, cluster, grid and cloud computing we conclude implementation of a dedicated computing cluster can be desired for ILSF. Cluster computing provides the opportunity for easy and saleable scientific computation for ILSF also another advantage is that its resources can be used for running cloud or grid computing platforms as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB310  
About • paper received ※ 19 May 2021       paper accepted ※ 19 July 2021       issue date ※ 15 August 2021  
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WEPAB314 TEX - an X-Band Test Facility at INFN-LNF 3406
 
  • S. Pioli, D. Alesini, F.A. Anelli, M. Bellaveglia, S. Bini, B. Buonomo, S. Cantarella, F. Cardelli, G. Catuscelli, R. Ceccarelli, A. Cecchinelli, F. Chiarelli, P. Ciuffetti, R. Clementi, C. Di Giulio, E. Di Pasquale, G. Di Raddo, M. Diomede, A. Esposito, L. Faillace, A. Falone, G. Franzini, A. Gallo, S. Incremona, A. Liedl, D. Pellegrini, G. Piermarini, L. Piersanti, S. Quaglia, R. Ricci, L. Sabbatini, M. Scampati, G. Scarselletta, A. Stella, R. Zarlenga
    INFN/LNF, Frascati, Italy
 
  Funding: The LATINO project is co-funded by the Regione Lazio within POR-FESR 2014-2020 European activities (public call "Open Research Infrastructures").
We report the status of the development of an High Power RF Laboratory in X-Band called TEX (TEst-stand for X-Band). TEX is part of the LATINO (Laboratory in Advanced Technologies for INnOvation) initiative that is ongoing at the Frascati National Laboratories (LNF) of the Italian Institute for Nuclear Physics (INFN) that covers many different areas focused on particle accelerator technologies. TEX is a RF test facility based on solid-state K400 modulator from ScandiNova with a 50MW class X-band (11.996 GHz) klystron tube model vkx 8311a operating at 50 Hz. This RF source will operate as resource for test and research programs such as the RF breakdown on RF waveguide components as well as high power testing of accelerating structures for future high gradient linear accelerator such as EuPRAXIA and CLIC. The high power testing will be performed in a dedicated brand-new bunker that has been recently built. RF system, vacuum controls and safety equipments are currently being installed. The first accelerating structure testing is scheduled by beginning 2022. In this document design and tests for all the sub-systems of the facility will be presented and discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB314  
About • paper received ※ 19 May 2021       paper accepted ※ 28 July 2021       issue date ※ 19 August 2021  
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WEPAB315 360 Degree Panoramic Photographs During the Long Shutdown 2 of the CERN Machines and Facilities 3410
 
  • T.W. Birtwistle, A. Ansel, S. Bartolomé Jiménez, B. Feral, G. Lacerda, A.-L. Perrot, J.F. Piñera Ovejero
    CERN, Geneva, Switzerland
 
  Studies and preparation of activities are key to the success of short technical stops and longer shutdowns in CERN’s accelerator complex. The ’Panorama’ tool offers a virtual tour of our facilities, and thanks to integration with other CERN tools, further complementary information can be easily retrieved, including layout information, equipment detail, and a history of changes. The tool was used to support the preparation and the execution of works during the Long Shutdown 2. It helped to optimize machine (accelerator/decelerator) interventions and hence reduce potential radiation exposure, as well as to ease integration studies. Thanks to its user-friendliness, the tool is now also used for educational and outreach activities. The current instantiation of the ’Panorama’ tool and related processes is presented, alongside the benefits that the tool can bring to the accelerator complex community. A particular focus is on the Long Shutdown 2. Future planned developments and improvements are also described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB315  
About • paper received ※ 11 May 2021       paper accepted ※ 14 June 2021       issue date ※ 24 August 2021  
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WEPAB317 Online Model Developments for BESSY II and MLS 3413
 
  • P. Schnizer, J. Bengtsson, T. Birke, J. Li, T. Mertens, M. Ries, A. Schälicke, L. Vera Ramirez
    HZB, Berlin, Germany
 
  Digital models have been developed over a long time for preparing accelerator commissioning next to benchmarking theory predictions to machine measurements. These digital models are nowadays being realized as digital shadows or digital twins. Accelerator commissioning requires periodic setup and review of the machine status. Furthermore, different measurements are only practical by comparison to the machine model (e.g. beam based alignment). In this paper we describe the architecture chosen for our models, describe the framework Bluesky for measurement orchestration and report on our experience exemplifying on dynamic aperture scans. Furthermore we describe our plans to extend the models applied to BESSY~II and MLS to the currently planned machines BESSY~III and MLS~II.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB317  
About • paper received ※ 19 May 2021       paper accepted ※ 28 July 2021       issue date ※ 18 August 2021  
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WEPAB318 Prediction and Clustering of Longitudinal Phase Space Images and Machine Parameters Using Neural Networks and K-Means Algorithm 3417
 
  • M. Maheshwari
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • D.J. Dunning, J.K. Jones, M.P. King, H.R. Kockelbergh, A.E. Pollard
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Machine learning algorithms were used for image and parameter recognition and generation with the aim to optimise the CLARA facility at Daresbury, using start-to-end simulation data. Convolutional and fully connected neural networks were trained using TensorFlow-Keras for different instances, with examples including predicting Longitudinal Phase Space (LPS) images with machine parameters as input and FEL parameter prediction (e.g. pulse energy) from LPS images. The K-means clustering algorithm was used to cluster the LPS images to highlight patterns within the data. Machine learning techniques can enhance the way large amounts of data are processed and analysed and so have great potential for application in accelerator science R&D.  
poster icon Poster WEPAB318 [1.062 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB318  
About • paper received ※ 17 May 2021       paper accepted ※ 05 July 2021       issue date ※ 14 August 2021  
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WEPAB319 Open XAL Status Report 2021 3421
 
  • N. Milas, J.F. Esteban Mullerpresenter, E. Laface, Y. Levinsen
    ESS, Lund, Sweden
  • T.V. Gorlov, A.P. Shishlo, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
 
  The Open XAL accelerator physics software platform is being developed through international collaboration among several facilities since 2010. The goal of the collaboration is to establish Open XAL as a multi-purpose software platform supporting a broad range of tool and application development in accelerator physics and high-level control (Open XAL also ships with a suite of general-purpose accelerator applications). This paper discusses progress in beam dynamics simulation, new RF models, and updated application framework along with new generic accelerator physics applications. We present the current status of the project, a roadmap for continued development, and an overview of the project status at each participating facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB319  
About • paper received ※ 19 May 2021       paper accepted ※ 21 July 2021       issue date ※ 24 August 2021  
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WEPAB320 RecCeiver-ETCD: A Bridge Between ETCD and ChannelFinder 3424
 
  • G. Jhang, T. Ashwarya, A. Carriveau
    FRIB, East Lansing, Michigan, USA
 
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Managing EPICS Process Variables’~(PVs) metadata, such as the host and the contact, is one of the important tasks for the operation of large-scale accelerator facilities with minimal downtime. Record Sychronizer~(RecSync) provides a way to manage such crucial information in an EPICS Input-Output Controller~(IOC). RecCeiver-ETCD is the server component of the RecSync-ETCD, or an extension of RecCeiver for ETCD. In the previous work, the client component of RecSync, or RecCaster, has been extended to RecCaster-ETCD to store the metadata into an ETCD key-value store. An important remaining step to the production use is to introduce a connection between ETCD and ChannelFinder, which is achieved by RecCeiver in the RecSync system. RecCeiver-ETCD plays the role of the original RecCeiver in the RecSync-ETCD system. RecCeiver-ETCD is designed to perform the specific operation, bridging the communication between ETCD and ChannelFinder. In addition, its simple implementation does not hold it down to ChannelFinder and makes it easy to extend RecCeiver-ETCD out to the other applications.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB320  
About • paper received ※ 11 May 2021       paper accepted ※ 19 July 2021       issue date ※ 21 August 2021  
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WEPAB321 ALS-U Instrumentation Overview 3427
 
  • J.M. Weber, J.C. Bell, M.J. Chin, S. De Santis, R.F. Gunion, S. Murthy, W.E. Norum, G.J. Portmann, C. Serrano
    LBNL, Berkeley, California, USA
  • W.K. Lewis
    Osprey DCS LLC, Ocean City, USA
 
  Funding: Work supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The Advanced Light Source Upgrade (ALS-U) to a diffraction-limited storage ring with a small vacuum chamber diameter requires excellent orbit stability and a fast response orbit interlock for machine protection. The on-axis swap-out injection scheme and dual RF frequencies demand fast monitoring of pulsed injection magnets and a novel approach to timing. Recent development efforts at ALS and advances in PLLs, FPGAs, and RFSoCs that provide higher performance and mixed-signal integration can be leveraged for instrumentation solutions to these accelerator challenges. An overview of preliminary ALS-U instrumentation system designs and status will be presented.
 
poster icon Poster WEPAB321 [23.306 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB321  
About • paper received ※ 19 May 2021       paper accepted ※ 27 July 2021       issue date ※ 18 August 2021  
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WEPAB322 Status of Digital BPM Signal Processor for SHINE 3430
 
  • L.W. Lai, F.Z. Chen, Y.B. Leng, T. Wu, Y.M. Zhou
    SSRF, Shanghai, People’s Republic of China
  • J. Wan
    SINAP, Shanghai, People’s Republic of China
 
  Funding: Youth Innovation Promotion Association, CAS (Grant No. 2019290); The National Key Research and Development Program of China (Grant No. 2016YFA0401903).
Digital signal processors that can handle 1MHz bunch rate BPM signal processing are under development for SHINE. Two different processors have been developed at the same time, including an intermediate frequency signal processor with a sampling rate higher than 500MHz, which can be used in general BPM applications; and a direct RF sampling processor, which can directly sample the C band cavity BPM signal without analog down-conversion modules and greatly simplifies the cavity BPM system. This paper will introduce the design, development status, and performance evaluations of the processors.
 
poster icon Poster WEPAB322 [1.919 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB322  
About • paper received ※ 20 May 2021       paper accepted ※ 10 June 2021       issue date ※ 24 August 2021  
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WEPAB323 High Performance DAQ Infrastructure to Enable Machine Learning for the Advanced Photon Source Upgrade 3434
 
  • G. Shen, N.D. Arnold, T.G. Berenc, J. Carwardine, E. Chandler, T. Fors, T.J. Madden, D.R. Paskvan, C. Roehrig, S.E. Shoaf, S. Veseli
    ANL, Lemont, Illinois, USA
 
  Funding: Argonne National Laboratory’s work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract DE-AC02-06CH11357.
It is well known that the efficiency of an advanced control algorithm like machine learning is as good as its data quality. Much recent progress in technology enables the massive data acquisition from a control system of modern particle accelerator, and the wide use of embedded controllers, like field-programmable gate arrays (FPGA), provides an opportunity to collect fast data from technical subsystems for monitoring, statistics, diagnostics or fault recording. To improve the data quality, at the APS Upgrade project, a general-purpose data acquisition (DAQ) system is under active development. The APS-U DAQ system collects high-quality fast data from underneath embedded controllers, especially the FPGAs, with the manner of time-correlation and synchronously sampling, which could be used for commissioning, performance monitoring, troubleshooting, and early fault detection, etc. This paper presents the design and latest progress of APS-U high-performance DAQ infrastructure, as well as its preparation to enable the use of machine learning technology for APS-U, and its use cases at APS.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB323  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 01 September 2021  
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WEPAB327 Sheet Electron Probe for Beam Tomography 3437
 
  • V.G. Dudnikov, M.A. Cummingspresenter, G. Dudnikova
    Muons, Inc, Illinois, USA
 
  Funding: Work is funded by DOE SBIR grant DE-SC0021581
An electron beam probe has been successfully used for the determination of accelerated particle density distributions. However, the apparatus used for this diagnostic had a large size and complex design which limit the broad use of this diagnostic for tomography of accelerated bunches. We propose a new approach to electron beam tomography: we will generate a continuous sheet of electrons. As the ion beam bunches pass through the sheet, they cause distortions in the distribution of sheet electrons arriving at CCD device on the other side of the beam that is interpreted to give a continuous measurement of the beam profile. The apparatus to generate the sheet beam is a strip cathode, which, compared to the scanning electron beam probe, is smaller, has a simpler design and less expensive manufacturing, has better magnetic shielding, has higher sensitivity, higher resolution, has better accuracy of measurement and better time resolution. With this device, it is possible to develop almost ideal tomography diagnostics of bunches in linear accelerators and in circular accelerators and storage rings.
 
poster icon Poster WEPAB327 [0.640 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB327  
About • paper received ※ 19 May 2021       paper accepted ※ 15 July 2021       issue date ※ 25 August 2021  
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WEPAB328 Rapid Surface Microanalysis Using a Low Temperature Plasma 3440
 
  • V.G. Dudnikov, M.A. Cummingspresenter, R.P. Johnson
    Muons, Inc, Illinois, USA
 
  There is a need for rapid, high-resolution (micron or sub-micron) scanning of surfaces of special nuclear materials (SNM) and surrogate materials to locate and identify regions of abnormalities. One technique that is commonly used to analyze the composition of solid surfaces and thin films is secondary-ion mass spectrometry (SIMS). SIMS devices are very complex and expensive. We propose to develop simpler, less expensive surface analysis devices, based on glow-discharge optical emission spectroscopy (GOES) that can provide excellent spatial resolution. Ions from a plasma discharge sputtered atoms from the surface and the discharge electrons effectively excite and ionize the sputtered atoms. GOES uses the light emitted by the excited particles for quantitative analysis. In the GOES device, the ion flux is extracted from the gas-discharge plasma and focused to a micron size on the sample, providing very local sputtering and local elemental analysis. The radiation from the sputtered atoms is passed through an optical fiber to an optical spectrometer and recorded. To register the distribution of elements over the sample, the sample is scanned electro-mechanically.  
poster icon Poster WEPAB328 [0.385 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB328  
About • paper received ※ 19 May 2021       paper accepted ※ 29 July 2021       issue date ※ 24 August 2021  
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WEPAB329 LCLS-II Average Current Monitor 3443
 
  • P. Borchard, J.S. Hoh
    Dymenso LLC, San Francisco, USA
 
  The LCLS-II project at SLAC is a high power upgrade to the existing free-electron laser facility. The LCLS-II Accelerator System will include a new 4 GeV continuous-wave superconducting linear accelerator in the first kilometer of the SLAC linear accelerator tunnel and supplements the existing low power pulsed linac. Average Current Monitors (ACMs) are needed to protect against excessive beam power which might otherwise cause damage to the beam dumps. The ACM cavities are pillbox-shaped stainless steel RF cavity with two radial probe ports with couplers, one radial test port with a coupler, and a mechanism for mechanically fine-tuning the cavity resonant frequency. The ACM RF cavities will be located at points of known or constrained beam energy and will monitor the beam current, a safety system will trip off the beam if the beam power exceeds the allowed value.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB329  
About • paper received ※ 19 May 2021       paper accepted ※ 16 June 2021       issue date ※ 12 August 2021  
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WEPAB330 A Multirange Low Noise Transimpedance Amplifier for Sirius Beamlines 3447
 
  • L.Y. Tanio, F.H. Cardoso, M.M. Donatti
    LNLS, Campinas, Brazil
 
  In a typical synchrotron beamline, the interaction of photon beams with different materials generates free electric charges in devices such as ionization chambers, photodiodes, or even isolated metallic structures (e.g., blades, blocks, foils, wires). These free charges can be measured as electric current to diagnose the photon beam intensity, profile, position, or stability. Sirius, the new 3GeV fourth-generation Brazilian light source, may accommodate up to 38 beamlines, which combined will make use of hundreds of instruments to measure such low-intensity signals. This work reports on the design and test results of a transimpedance amplifier developed for low current measurements at Sirius’ beamlines. The device presents low noise, high accuracy, and good temperature stability providing 5 selectable ranges (from 500pA to 7.3mA) to measure bipolar currents achieving femtoampere resolution under certain conditions. Considering low bandwidth applications, the results suggest noise performance comparable to commercial bench instruments. Additionally, the project definitions and plans for the development of a family of low current ammeters will be discussed.  
poster icon Poster WEPAB330 [2.642 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB330  
About • paper received ※ 19 May 2021       paper accepted ※ 16 June 2021       issue date ※ 27 August 2021  
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WEPAB331 Application of KALYPSO as a Diagnostic Tool for Beam and Spectral Analysis 3451
 
  • M.M. Patil, E. Bründermann, M. Caselle, A. Ebersoldt, S. Funkner, B. Kehrer, A.-S. Müller, M.J. Nasse, G. Niehues, J.L. Steinmann, M. Weber, C. Widmann
    KIT, Karlsruhe, Germany
 
  Funding: This work is supported by the BMBF project 05K19VKD STARTRAC and DFG-funded Doctoral School ’Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology’
KALYPSO is a novel detector capable of operating at frame rates up to 12 MHz developed and tested at the institute of data processing and electronics (IPE) and employed at Karlsruhe Research Accelerator (KARA) which is part of the Test Facility and Synchrotron Radiation Source KIT. This detector consists of silicon, InGaAs, PbS, or PbSe line array sensor with spectral sensitivity from 350 nm to 5000 nm. The unprecedented frame rate of this detector is achieved by a custom-designed ASIC readout chip. The FPGA-readout architecture enables continuous data acquisition and real-time data processing. Such a detector has various applications in the fields of beam diagnostics and spectral analysis. KALYPSO is currently employed at various synchrotron facilities for electro-optical spectral decoding (EOSD) to study the longitudinal profile of the electron beam, to study the energy spread of the electron beam, tuning of free-electron lasers (FELs), and also in characterizing laser spectra. This contribution will present an overview of the results from the mentioned applications.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB331  
About • paper received ※ 19 May 2021       paper accepted ※ 22 July 2021       issue date ※ 02 September 2021  
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WEPAB333 Installation and Commissioning of the Sirius Vacuum System 3455
 
  • R.M. Seraphim, R.O. Ferraz, H.G. Filho, G.R. Gomes, P.H. Lima, R.F. Oliveira, B.M. Ramos, T.M. Rocha, D.R. Silva, M.B. Silva
    LNLS, Campinas, Brazil
 
  The installation of the Sirius accelerators was completed in 2019. The vacuum installation of the booster took place in October 2018. The booster vacuum chambers were baked-out ex-situ and the vacuum pumps, gauges and valves were assembled prior to the installation in the tunnel. The vacuum installation of the storage ring took place from May to August 2019. The vacuum system of the storage ring is based on fully NEG-coated chambers and each sector was baked-out in-situ for NEG activation. The average static pressure in the booster is in the range of low 10-9 mbar. In the storage ring, 95% of the pressures are in 10-11 mbar range and 5% are in 10-10 mbar range. The first beam was stored in the storage ring in December 2019. The vacuum system has been performing well, and an effective beam cleaning effect has been observed for the NEG-coated chambers. At a beam dose of 70 A-h, the storage ring already achieved the design normalized average dynamic pressure of 3x10 12 mbar/mA. A summary of the installation and the commissioning status of the vacuum system will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB333  
About • paper received ※ 20 May 2021       paper accepted ※ 14 June 2021       issue date ※ 29 August 2021  
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WEPAB334 Development of Diffusion Bonded Joints of AA6061 Aluminum Alloy to AISI 316LN Stainless Steel for Sirius Planar Undulators 3459
 
  • R.L. Parise, O.R. Bagnato, R. Defavari, M.W.A. Feitosa, F.R. Francisco, D.Y. Kakizaki, R.D. Ribeiro
    LNLS, Campinas, Brazil
 
  LNLS has been commissioning Sirius, a 4th-generation synchrotron light source. The commissioning of the beamlines has been mainly done by using planar undulator, which uses in-house built aluminum vacuum chambers with ultra-high vacuum tight bimetallic flanges. In order to manufacture these flanges, diffusion bonded joints of AA6061 aluminum alloy to AISI 316LN stainless steel were developed. Diffusion bonding was carried out at 400-500°C for 45-60 min, applying a load of 9.8MPa in a vacuum furnace. Also, the surface preparation for Al and SS was investigated. SEM observation revealed that an 1-3 µm reaction layer was formed at the AA6061/Ni-plated interface. The intermetallic compound Al3Ni was identified in the reaction layer. The obtained Al/SS joints showed mean ultimate strength of 84 MPa, with the fracture occurring in the Al/reaction layer interface. Bake-out cycles followed by leak tests were carried out to validate the process and approve their use on the planar undulator vacuum chambers. Two undulators with Al/SS flanges have been installed and are under operation in the storage ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB334  
About • paper received ※ 17 May 2021       paper accepted ※ 17 June 2021       issue date ※ 26 August 2021  
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WEPAB335 Aluminum Vacuum Chamber for the Sirius DELTA 52 Undulator 3463
 
  • T.M. Rocha, O.R. Bagnato, R.O. Ferraz, H.G. Filho, P.P.S. Freitas, G.R. Gomes, P.H. Lima, R.F. Oliveira, B.M. Ramos, F. Rodrigues, R.M. Seraphim, D.R. Silva, M.B. Silva
    LNLS, Campinas, Brazil
 
  Sirius is a 3 GeV fourth generation synchrotron light source under commissioning by the Brazilian Synchrotron Light Laboratory (LNLS). Delta Undulators with magnet vertical aperture of 13.6 mm, and period of 52.5 mm will be used for the generation of soft X rays to photoemission spectroscopy and X ray absorption experiments. Extruded aluminum vacuum chambers having small vertical aperture of 7.6 mm and horizontal aperture of 13 mm is proposed. This paper details the design and manufacturing processes of a complete chamber. Challenges regarding the TIG welding for aluminum and NEG coating for small aperture chambers will also be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB335  
About • paper received ※ 18 May 2021       paper accepted ※ 19 July 2021       issue date ※ 20 August 2021  
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WEPAB336 Aluminum Vacuum Chamber for the Sirius Commissioning Undulators 3467
 
  • B.M. Ramos, O.R. Bagnato, R.O. Ferraz, H.G. Filho, P.P.S. Freitas, G.R. Gomes, P.H. Lima, R.F. Oliveira, T.M. Rocha, F. Rodrigues, R.M. Seraphim, D.R. Silva, M.B. Silva
    LNLS, Campinas, Brazil
 
  Sirius is a 3 GeV fourth generation light source under commissioning by the Brazilian Synchrotron Light Laboratory (LNLS). Compact Linear Polarizing Undulators with magnet vertical aperture of 8 mm have been used for the commissioning of some beam lines. Extruded aluminum vacuum chambers having small vertical aperture of 6 mm and horizontal aperture of 40 mm, were built. This paper details the design and manufacturing processes of a complete chamber and its installation procedure at the storage ring. Challenges regarding the precision machining of the 0.5 mm wall thickness, TIG welding for aluminum, NEG coating for small apertures will also be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB336  
About • paper received ※ 18 May 2021       paper accepted ※ 17 August 2021       issue date ※ 25 August 2021  
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WEPAB337 Some Methods of Making Titanium Vacuum Chamber Act as Getter Pump for UHV/XHV 3471
 
  • J. Kamiya, T. Takano, H. Yuza
    JAEA/J-PARC, Tokai-mura, Japan
  • K. Wada
    Tokyo Electronics Co. Ltd., Kokubunji, Tokyo, Japan
 
  Funding: JSPS KAKENHI Grant Number JP18K11925
The non-evaporable getter (NEG) coating has been developed in CERN to make a beam pipe act as a distributed vacuum pump by coating the getter materials with the ability to adsorb/absorb gas molecules on the beam pipe surface. The NEG coating materials used in the LHC are alloys of titanium, zirconium, and vanadium. In high-power beam accelerators, titanium has been used as the beam pipe chamber material due to its low radio activation characteristics. The ordinal titanium surface has no getter function because it is covered with a titanium oxide film. The new technique, which removes the titanium-oxide surface by some methods, such as baking or sputtering, has been investigated. The dependence of the surface oxide film and the getter characteristics on the baking temperature have been measured. Also, by sputtering the inner surface of the titanium chamber, clear evidence that shows the chamber acts as a vacuum pump has been obtained. Furthermore, the NEG coating on the pure titanium surface can suppress the rapid decrease of the sticking probability by the repeated air purge and reactivation.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB337  
About • paper received ※ 14 May 2021       paper accepted ※ 25 June 2021       issue date ※ 22 August 2021  
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WEPAB338 Amorphous Carbon Coating in SPS 3475
 
  • W. Vollenberg, P. Chiggiato, P. Costa Pinto, P. Cruikshank, H. Moreno, C. Pasquino, J. Perez Espinos, M. Taborelli
    CERN, Meyrin, Switzerland
 
  Within the LHC Injector Upgrade (LIU) project, the Super Proton Synchrotron (SPS) needs to be upgraded to inject into the LHC higher intensity and brighter 25-ns bunch spaced beams. To mitigate the Electron Multipacting (E.M.) phenomenon, a well-known limiting factor for high-intensity positively charged beams, CERN developed carbon coatings with a low Secondary Electron Yield (SEY). During the 2016 & 2017 year-end technical stops, such coatings were deposited on the inner wall of the vacuum chambers of some SPS quadrupole and dipole magnets by a dedicated in-situ setup. A much larger scale deployment was implemented during the Long Shutdown 2 (2019-2020) to coat all beam pipes of focussing quadrupoles (QF) and their adjacent short straight sections. In this contribution, we remind the motivation of the project, and present the results and the quality control of the carbon coating campaign during the latter phase of implementation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB338  
About • paper received ※ 19 May 2021       paper accepted ※ 16 June 2021       issue date ※ 16 August 2021  
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WEPAB339 Beam-Induced Surface Modification of the LHC Beam Screens: The Reason for the High Heat Load in Some LHC Arcs? 3479
 
  • V. Petit, P. Chiggiato, M. Himmerlich, G. Iadarola, H. Neupert, M. Taborelli, D.A. Zanin
    CERN, Geneva, Switzerland
 
  All over Run 2, the LHC beam-induced heat load exhibited a wide scattering along the ring. Studies ascribed the heat source to electron cloud build-up, indicating an unexpectedly high Secondary Electron Yield (SEY) of the beam screen surface in some LHC regions. During the Long Shutdown 2, the beam screens of a low and a high heat load dipole were extracted. Their inner copper surface was analysed in the laboratory to compare their SEY and surface composition. While findings on the low heat load beam screens are compatible with expectations from laboratory studies of copper conditioning and deconditioning mechanisms, an extremely low carbon amount and the presence of CuO (non-native surface oxide) are observed on the high heat-load beam screens. The azimuthal distribution of CuO correlates with the density and energy of electron impingement. Such chemical modifications increase the SEY and inhibit the full conditioning of affected surfaces. This work shows a direct correlation between the abnormal LHC heat load and the surface properties of its beam screens, opening the door to the development of curative solutions to overcome this critical limitation.  
poster icon Poster WEPAB339 [2.247 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB339  
About • paper received ※ 19 May 2021       paper accepted ※ 22 June 2021       issue date ※ 26 August 2021  
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WEPAB340 Pressure Simulations for the EIC Interaction Region 3483
 
  • M.L. Stutzman
    JLab, Newport News, Virginia, USA
 
  Background detector rates in the Electron Ion Collider depend in part on the pressure in the interaction region. Materials choice, synchrotron radiation induced desorption, conditioning time and pumping configuration all affect the pressure in the system. Simulations of the region using Synrad and Molflow+ coupled simulation codes will be presented for various configruations and conditioning times.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB340  
About • paper received ※ 18 May 2021       paper accepted ※ 20 July 2021       issue date ※ 27 August 2021  
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WEPAB341 Injection and Extraction Kickers for the Advanced Light Source Upgrade Project (ALS-U) 3487
 
  • W.L. Waldron, D.A. Dawson, S. De Santis, T. Oliver, C. Steier
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Advanced Light Source upgrade project (ALS-U) at Lawrence Berkeley National Laboratory includes the construction of a new accumulator ring and the replacement of the existing storage ring. Both ferrite-loaded kickers and stripline kickers are used in the ALS-U design for injection, extraction, and decohering the beam before storage ring extraction. In the accumulator ring, the rise and fall time requirements are based on the single bunch revolution time of 608 ns which allows the use of ferrite-loaded kickers. The 10 ns spacing between bunch trains in the storage ring requires stripline kickers to meet the rise and fall time requirements. Both types of kickers are driven by solid-state inductive voltage adders using MOSFETs. Modeling and prototyping efforts have characterized the kicker impedance and beam-induced heating, and explored the effects of beam strike on electrodes.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB341  
About • paper received ※ 20 May 2021       paper accepted ※ 27 July 2021       issue date ※ 19 August 2021  
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WEPAB342 Beam Induced Power Deposition in CERN SPS Injection Kickers 3490
 
  • M.J. Barnes, O. Bjorkqvist
    CERN, Geneva 23, Switzerland
  • K. Kodama
    KEK, Ibaraki, Japan
 
  The SPS injection kicker magnets (MKP) were developed in the 1970’s, before beam power deposition was considered an issue and before any advanced tools for analysing beam coupling impedance were available in their current form. These magnets are very lossy from a beam impedance perspective, and the beam induced power deposition is highly non-uniform. This is expected to be an issue during SPS operation with the higher intensity beams needed in the future for HL-LHC. There is an existing design, with serigraphy, that will mitigate the heating issues, which is presently being implemented on a prototype for test and measurement. Models have been developed to aid in predicting the safe operating regions until the upgraded MKPs are installed in the SPS: these are reported herein. A novel measurement technique is also presented to confirm the non-uniform power deposition in the ferrite yoke. Beam coupling impedance, power deposition, field rise time and field uniformity data are also presented for an upgraded, prototype, MKP.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB342  
About • paper received ※ 16 May 2021       paper accepted ※ 02 July 2021       issue date ※ 22 August 2021  
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WEPAB343 Inductive Adder Prototype for FCC-hh Injection Kicker System 3494
 
  • D. Woog, M.J. Barnespresenter, T. Kramer
    CERN, Geneva, Switzerland
  • H. De Gersem
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  The future circular collider (FCC) requires a highly reliable injection kicker system. Present day kicker systems often rely on thyratron-based pulse generators and a pulse forming network or line: the thyratron is susceptible to self-triggering. Hence, an alternative pulse generator topology, based on fast semiconductor switches, is considered for the FCC. One possibility is an inductive adder (IA). A prototype IA has been designed and built: the main challenges are the fast rise time, high output current, low system impedance and a 2.3 us pulse duration combined with low droop. This paper presents the results of measurements on the prototype IA where the rated output current and output voltage were achieved separately. Suggested improvements to the IA hardware are identified and proposals are presented that could help improve the kicker system performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB343  
About • paper received ※ 16 May 2021       paper accepted ※ 01 July 2021       issue date ※ 20 August 2021  
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WEPAB344 Studies for Mitigating Flashover of CERN-LHC Dilution Kicker Magnets 3498
 
  • A.M. Loebner, M.J. Barnespresenter, W. Bartmann, C. Bracco, L. Ducimetière, V. Namora, V. Senaj
    CERN, Geneva 23, Switzerland
 
  The LHC beam dump system is used for extracting beam from the LHC and, as such, is a safety critical system whose proper functionality must be assured. Dilution kicker magnets (MKBs) sweep the extracted beam over the cross-sectional area of a dump block as the energy density would otherwise be too high and damage the block. In 2018, a high voltage flashover occurred in a vertical MKB (MKBV) vacuum tank, during a beam dump, which resulted in non-ideal sweep of the beam over the block. The location of the flashover could not be identified during a subsequent inspection of the magnet. Hence, electrical field simulations have been carried out to identify potentially critical regions, to determine the most probable region of the flashover. One potentially critical region is a rectangular beam pipe (RBP) between the end of the tank and the MKBV magnet, whose purpose is to reduce plasma propagation to the adjacent tank in the event of a flashover. Mitigating measures were studied and are reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB344  
About • paper received ※ 16 May 2021       paper accepted ※ 06 July 2021       issue date ※ 27 August 2021  
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WEPAB345 Impedance and Thermal Studies of the LHC Injection Kicker Magnet Upgrade 3502
 
  • M.J. Barnes, O. Bjorkqvist, F. Motschmann
    CERN, Geneva 23, Switzerland
 
  The bunch intensities of High Luminosity (HL) LHC are predicted to lead to heating of the ferrite yokes of the LHC injection kicker magnets (MKI), in their current configuration, to their Curie temperature. Hence, the MKIs are being upgraded to meet the requirements of HL-LHC, which is planned to start in the mid-2020s. The upgraded design features an RF damping ferrite loaded structure at the upstream end of each magnet, which will absorb a large portion of the beam induced power deposition of the magnet. The ferrite damper is cooled via a copper sleeve, brazed to the ferrite, and a set of water pipes. The thermal contact conductance (TCC) between ferrite and copper is very important, as are the properties of the ferrite. In this paper, we present measurements of the TCC and ferrite properties. This data is used to predict temperatures during operation of the LHC. In addition, a measurement and prediction is shown for the longitudinal impedance of the magnet. The models developed in this study will be benchmarked during run III of the LHC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB345  
About • paper received ※ 19 May 2021       paper accepted ※ 06 July 2021       issue date ※ 21 August 2021  
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WEPAB346 Electromagnetic Modelling of Kicker Magnets to Derive Equivalent Circuits 3506
 
  • M.J. Barnes, O. Bjorkqvist
    CERN, Geneva 23, Switzerland
  • L. Jensen, O.A. Nielsen
    Aarhus University, Aarhus, Denmark
 
  An equivalent circuit model of a kicker magnet system is an invaluable tool for predicting the performance, studying possible modifications and for helping to diagnose faults. The frequency content of pulses associated with a ferrite loaded transmission line kicker magnet generally extend up to a few tens of MHz: hence, it is feasible to accurately model such a kicker magnet using lumped elements. This modelling technique is powerful since it in general has a run time several orders of magnitude shorter than a full wave electromagnetic simulation. In this paper, we determine values, including those of parasitic components, using modern simulation tools, for use in the lumped equivalent circuit models. In addition, the paper describes a method to simulate coupling between beam and the electrical circuit of a kicker magnet at relatively low frequencies: this allows one to use circuit analysis tools to study means of mitigating beam induced resonances.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB346  
About • paper received ※ 16 May 2021       paper accepted ※ 02 July 2021       issue date ※ 16 August 2021  
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WEPAB347 Design, Construction and Testing of a Magnetic Probe for Fast Kicker Magnets 3510
 
  • N. Ayala, A. Ferrero Colomo, T. Kramer
    CERN, Geneva, Switzerland
 
  The CERN PS injection kicker has been modified in the framework of the LHC Injector Upgrade (LIU) project to allow injecting proton beams with an energy of 2 GeV. One of the most important items of the system parameter validation is the measurement and analysis of the magnetic field in the magnet aperture. To meet the required measurement precision without compromising the magnet vacuum performance, a dedicated magnetic probe has been designed, constructed and tested. The results are presented in this paper highlighting the mitigations of electrical, mechanical and vacuum complications. The paper concludes with an analysis of the probe performance during the first magnetic field measurements in the laboratory.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB347  
About • paper received ※ 19 May 2021       paper accepted ※ 07 July 2021       issue date ※ 19 August 2021  
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WEPAB348 Injection and Extraction Systems of the SIS100 Heavy Ion Synchrotron at FAIR 3514
 
  • I.J. Petzenhauser, U. Blell, S. Heberer
    GSI, Darmstadt, Germany
 
  The "Facility for Antiproton and Ion Research" (FAIR) is a new international accelerator complex, which is currently built in Darmstadt, Germany. Part of this complex is the SIS100 heavy ion synchrotron with a circumference of ~1086 m. To inject ions into the SIS100, an injection kicker system will we required. For fast extraction of the particle beam from the SIS100, an extraction kicker is used. This extraction kicker will be a bipolar system, this way it works as an emergency kicker at the same time. The fast kicker systems have to produce a current pulse >6 kA. To achieve this, energy storages are charged up to voltages >70 kV and are quickly discharged. The pulse durations vary from 0.5 us to 7 us, depending on the kicker type and the operation mode. Slow extraction of the ion beam will include an electrostatic septum, operating with voltages up to 160 kV. The requirements of these injection/extraction devices will be described in detail and the status of the projects will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB348  
About • paper received ※ 17 May 2021       paper accepted ※ 11 June 2021       issue date ※ 22 August 2021  
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WEPAB349 Design of a Circular Waveguide TM₀₁ Mode Launcher with Wire Loop Feed 3517
 
  • A. Chittora
    BITS Pilani, Sancoale, India
 
  In Accelerator technology, RF power couplers are important component to couple RF signal to travelling wave structure. Circular waveguide TM01 mode is one of the symmetric modes, that is suitable to use for RF coupling. TM01 mode launcher is used as an RF coupler in Accelerator technology*. Design of a compact circular waveguide TM01 mode-launcher is presented in this paper. The design is based on the principle of magnetic field coupling between a wire loop and TM01 mode of circular waveguide. The mode launcher exhibits high efficiency and 3.1% bandwidth at 3.2 GHz frequency with both circular and elliptical loop. Performance of the mode launcher is experimentally verified and simulated S-parameters agree with the measured results. The mode launcher is of compact size and is suitable for efficient excitation of TM01 mode in circular waveguide and travelling wave structures. The launcher is also useful for cold testing of high power microwave antennas and Radars.
* M. Forno, "Design of a high power TM01 mode launcher optimized for manufacturing by milling." 2016.
 
poster icon Poster WEPAB349 [1.135 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB349  
About • paper received ※ 19 May 2021       paper accepted ※ 21 June 2021       issue date ※ 23 August 2021  
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WEPAB351 Requirements for an Inductive Voltage Adder as Driver for a Kicker Magnet with Short Circuit Termination 3521
 
  • J. Ruf, M.J. Barnes, T. Kramer
    CERN, Geneva 23, Switzerland
  • M. Sack
    KIT, Karlsruhe, Germany
 
  At CERN pulse generators based on Thyratron switches and SF6 gas filled pulse forming lines, used for driving kicker magnets, are to be replaced with semiconductor technology. Preliminary investigations show the inductive voltage adder is suitable as a pulse generator for this application. To increase the magnetic field without raising the system voltage, a short-circuit termination is often applied to a kicker magnet. Because of the electrical length of a transmission line magnet, wave propagation needs to be considered. To allow for the wavefront reflected from the short-circuit termination back to the generator, a novel approach for an inductive adder architecture has been investigated. It is based on a modified generator interface, circulating the current back into the load, until the stored energy is absorbed at the end of the pulse. This approach allows for a smaller magnetic core size compared to a conventional design with a matched load. Moreover, it enables more energy-efficient operation involving smaller storage capacitors. This paper summarizes the conceptual design features and furthermore gives an overview of the parameter space for possible applications at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB351  
About • paper received ※ 18 May 2021       paper accepted ※ 11 June 2021       issue date ※ 19 August 2021  
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WEPAB353 Design and Commissioning of a Multipole Injection Kicker for the SOLEIL Storage Ring 3525
 
  • R. Ollier, P. Alexandre, R. Ben El Fekih, L.S. Nadolski
    SOLEIL, Gif-sur-Yvette, France
 
  In third-generation synchrotron light sources, achieving an orbit distortion below 10% of the stored beam size is very challenging. The standard injection scheme of SOLEIL is made of 2 septa and 4 kicker magnets installed in a 12 m long straight section. Tuning the 4 kickers, to reduce perturbations, revealed to be almost impossible since it requires having 4 identical magnets, electronics, and Ti coated ceramic chambers. To reach the position stability requirement of the stored beam, a single pulsed magnet with no field on the stored beam path can replace the 4 kickers. Such a device, called MIK (Multipole Injection Kicker), was developed by SOLEIL and successfully commissioned in the MAX-IV 3-GeV ring as the key device used in the standard injection scheme for user operation, reducing the beam orbit distortion below 1 micron in peak value in both planes. A copy of the MIK has been installed in a short straight section of the SOLEIL storage ring, in January 2021. We report MIK positioning studies, the constraints of the project, sapphire chamber coating challenges and the first commissioning results. The R&D MIK is a demonstrator for the injection scheme of SOLEIL upgrade as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB353  
About • paper received ※ 21 May 2021       paper accepted ※ 23 July 2021       issue date ※ 30 August 2021  
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WEPAB355 Series Production of the SIS100 Cryocatchers 3529
 
  • L.H.J. Bozyk, S. Ahmed, P.J. Spiller
    GSI, Darmstadt, Germany
 
  The superconducting heavy ion synchrotron SIS100, which is the main accelerator of the FAIR-facility will be equipped with cryocatcher to suppress dynamic vacuum effects and to assure a reliable operation of high intensity heavy-ion beams. Subsequent to the successful validation of the prototype in 2011 as well as a First-of-Series cryocatcher, the series production of 60 cryocatcher modules meanwhile has been completed. It was released in 2018 after further design optimizations. Key findings from the series production and acceptance tests are presented as well. The First-of-Series cryocatcher has been integrated into the First-of-Series quadrupole module and has undergone several tests. These results are also illustrated in this report.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB355  
About • paper received ※ 19 May 2021       paper accepted ※ 06 July 2021       issue date ※ 21 August 2021  
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WEPAB356 Proposal of an Alignment System for HALF: The Reference Network of Alignment 3533
 
  • X. Li, J.X. Chen, X.Y. He, W. Wang, Z.Y. Wang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  • J.X. Chen, T. Luo
    IHEP CSNS, Guangdong Province, People’s Republic of China
 
  As a fourth-generation light source based on the diffraction-limited storage ring, Hefei Advanced Light Facility (HALF) has higher requirements for magnets alignment in accuracy, efficiency, and reliability. In this paper, the Reference Network of Alignment (RNA) system is proposed to improve the magnetic axis alignment accuracy on the radial direction of the beamline. Herein, we mainly introduce the concept design and the theoretical analysis of the RNA system, which center on the novel fusion method of sensors. A simulation result shows that it is credible to assume the RNA system can achieve an alignment installation accuracy of 20 µm and a displacement monitoring accuracy of 10 µm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB356  
About • paper received ※ 16 May 2021       paper accepted ※ 21 June 2021       issue date ※ 23 August 2021  
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WEPAB358 Development of Low-Z Collimator for SuperKEKB 3537
 
  • S. Terui, T. Abe, Y. Funakoshi, T. Ishibashi, H.N. Nakayama, K. Ohmi, D. Zhou
    KEK, Ibaraki, Japan
  • A. Natochii
    University of Hawaii, Honolulu,, USA
 
  Collimator jaws for SuperKEKB main ring, which is an electron-positron collider, installed to suppress background noise in a particle detector complex named Belle II. The collimators are successful to reduce backgrounds when the collimator was closed. But, in high current operations with 500 mA or more, jaws were occasionally damaged by hitting abnormal beams. This trouble is a low-frequency, which is once-a-commissioning period currently, but a high-consequence one because we are not able to apply high voltage on detectors in Belle II by high backgrounds. Low-Z collimator jaw, that is durable through hitting uncontrollable beam, have been designed due to protect important component as the solution of the trouble. The low-Z collimator jaws are installable in a present collimator chamber, have a pair of vertically opposed movable jaws. One pair of low-Z collimator jaws was installed. The paper is to describe what did we calculate and measure to make a low-Z collimator, how did we make a low-Z collimator, the impact of the installed low-Z collimator, mainly transverse mode coupling instability.  
poster icon Poster WEPAB358 [0.788 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB358  
About • paper received ※ 16 May 2021       paper accepted ※ 22 July 2021       issue date ※ 31 August 2021  
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WEPAB359 Report on Collimator Damaged Event in SuperKEKB 3541
 
  • S. Terui, Y. Funakoshi, H. Hisamatsu, T. Ishibashi, K. Kanazawa, Y. Ohnishi, K. Shibata, M. Shirai, Y. Suetsugu, M. Tobiyama
    KEK, Ibaraki, Japan
 
  Collimator jaws for SuperKEKB main ring, which is an electron-positron collider, installed to suppress background noise in a particle detector complex named Belle II. In high current operations with 500 mA or more, jaws were occasionally damaged by hitting abnormal beams. This trouble is a low-frequency, which is once-a-commissioning period currently, but high-consequence one because we are not able to apply high voltage on detectors in Belle II by high backgrounds. At this moment this jaw damage event occurs, we observed pressure burst near the collimator with the beam abort, there was no sign of beam oscillation indicating instability, and the beam intensity suddenly decreased a few turns before the abort. I predict that the cause of this jaw damage was that a sudden change of the beam energy by the collision with dust. In this paper, the explanation of the observation result of this events and tracking simulation of beam colliding with dust are reported.  
poster icon Poster WEPAB359 [3.869 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB359  
About • paper received ※ 17 May 2021       paper accepted ※ 22 July 2021       issue date ※ 19 August 2021  
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WEPAB360 Future Prospective for Bent Crystals in Accelerators 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 ※ 29 August 2021  
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WEPAB361 New Generation CERN LHC Injection Dump - Assembly and Installation (TDIS) 3548
 
  • D. Carbajo Perez, E. Berthomé, C. Bertone, N. Biancacci, C. Bracco, G. Bregliozzi, B. Bulat, C. Cadiou, M. Calviani, G. Cattenoz, A. Cherif, P. Costa Pinto, A. Dallocchio, M. Di Castro, P. Fessia, M.I. Frankl, R. Franqueira Ximenes, J.-F. Fuchs, H. Garcia Gavela, J.-M. Geisser, L. Gentini, S.S. Gilardoni, M.A. Gonzalez De La Aleja Cabana, J.L. Grenard, J.M. Herediapresenter, S. Joly, A. Lechner, J. Lendaro, J. Maestre, E. Page, M. Perez Ornedo, A. Perillo-Marcone, D. Pugnat, E. Rigutto, B. Salvant, A. Sapountzis, K. Scibor, R. Seidenbinder, J. Sola Merino, M. Taborelli, E. Urrutia, A. Vieille, C. Vollinger, C. Yin Vallgren
    CERN, Meyrin, Switzerland
 
  Funding: Work supported by the Hilumi Project
During CERN’s LS2, several upgrades were performed to beam intercepting devices in the framework of the HL-LHC Project. Upgraded equipment includes two internal beam dumps (TDIS) intended for machine protection located at the injection points from the SPS to the LHC. These two devices have been assembled, tested, and installed around LHC Point 2 and Point 8 and are currently ready to get commissioned with the beam. They are 5.8m-long, three-module-segmented vacuum chambers, with large aperture to accommodate the injected and circulating beam and equipped with absorbing materials, These comprise graphite and higher Z alloys that are embedded on sub-assemblies reinforced with back-stiffeners made of TZM. The current contribution covers three main matters. First, it details the TDIS design and its key technical features. The second topic discussed is the outcome of an experiment where a prototype module was tested under high-energy beam impacts at CERN’s HiRadMat facility. To conclude it is presented the return of experience from the pre-series construction, validation and installation in the LHC tunnel.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB361  
About • paper received ※ 18 May 2021       paper accepted ※ 11 June 2021       issue date ※ 02 September 2021  
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WEPAB363 Dynamic Response of Spallation Volume to Beam Raster on the European Spallation Source Target 3552
 
  • Y. Lee
    ESS, Lund, Sweden
 
  To achieve a desirably low beam intensity on the target, the European Spallation Source (ESS) adopted a beam raster system at the high beta beam transport part of the linac. The raster system paints the beam on the target with frequencies up to 40 kHz within the 2.86 ms beam pulse, to form a uniformly expanded beam footprint. While the beam raster reduces the time-averaged beam current density to a level that the 5 years of design lifetime of the target system can be achieved with a high operational reliability, it could potentially induce deleterious dynamic excitations in the spallation volume made of tungsten. The stress wavelets created by raster sweeps can be amplified if the sweep frequency is in tune with a resonance mode of the tungsten volume. This coherent interference of the wavelets could lead to a high dynamic stress in tungsten, posing a risk of premature failure of the target. In this paper, the dynamic response of the spallation volume of the ESS target to different beam raster frequencies has been analysed, using multi-physics simulations based on measured material data. Finally, a safe operational range of the beam raster frequency band is proposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB363  
About • paper received ※ 12 May 2021       paper accepted ※ 02 July 2021       issue date ※ 11 August 2021  
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WEPAB364 Third-Generation CERN n_TOF Spallation Target: Final Design and Examinations of Irradiated Prototype 3555
 
  • R. Esposito, O. Aberle, M. Calviani, T. Coiffet, M.D. Crouvizier, R. Franqueira Ximenespresenter, V. Maire, A.T. Perez Fontenla, M.A. Timmins
    CERN, Geneva, Switzerland
 
  The new neutron spallation target for the CERN neutron Time-Of-Flight (n_TOF) facility is based on a nitrogen-cooled Pb core impacted by short high-intensity proton beam pulses. An extensive material characterization campaign has been carried out to define the constitutive behavior of lead and assess its response under pulsed proton beam irradiation. The activities carried out include a beam irradiation test in the CERN HiRadMat facility. The tests and inspections performed show a robust behavior of the core material during operation and prominent static hardening recovery already at room temperature.  
poster icon Poster WEPAB364 [1.011 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB364  
About • paper received ※ 18 May 2021       paper accepted ※ 11 June 2021       issue date ※ 21 August 2021  
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WEPAB365 CERN BDF Prototype Target Operation, Removal and Autopsy Steps 3559
 
  • R. Franqueira Ximenes, O. Aberle, C. Ahdida, P. Avigni, M. Battistin, L. Bianchi, L.R. Buonocore, S. Burger, J. Busom, M. Calviani, J.P. Canhoto Espadanal, M. Casolino, M. Di Castro, M.A. Fraser, S.S. Gilardoni, S. Girod, J.L. Grenard, D. Grenier, M. Guinchard, R. Jacobsson, M. Lamont, E. Lopez Sola, A. Ortega Rolo, A. Perillo-Marcone, Y. Pira, B. Riffaud, V. Vlachoudis, L. Zuccalli
    CERN, Meyrin, Switzerland
 
  The Beam Dump Facility (BDF), currently in the study phase, is a proposed general-purpose fixed target facility at CERN. Initially will host the Search for Hidden Particles (SHiP) experiment, intended to investigate the origin of dark matter and other weakly interacting particles. The BDF particle production target is located at the core of the facility and is employed to fully absorb the high intensity (400 GeV/c) Super Proton Synchrotron (SPS) beam. To validate the design of the production target, a downscaled prototype was tested with the beam at CERN in 2018 in the North Area primary area in a dedicated test at 35 kW average beam power. This contribution details the BDF prototype target operation, fully remote removal intervention, and foreseen post-irradiation examination plans.  
poster icon Poster WEPAB365 [1.691 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB365  
About • paper received ※ 18 May 2021       paper accepted ※ 15 June 2021       issue date ※ 20 August 2021  
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WEPAB366 Towards the Last Stages of the CERN’s AD-Target Area Consolidation Project and Recommissioning Plans to Resume Operation 3563
 
  • C. Torregrosa, C. Ahdida, A. Bouvard, A. Broche, S. Burger, M.E.J. Butcher, M. Calviani, V. Clerc, A. De Macedo, S. De Man, F.A. Deslande, M. Di Castro, T. Dobers, T. Feniet, R. Ferriere, E. Fornasiere, R. Franqueira Ximenespresenter, T.J. Giles, J.L. Grenard, E. Grenier-Boley, G. Gräwer, M. Guinchard, M.D. Jedrychowski, K. Kershaw, B. Lefort, E. Lopez Sola, J.M. Martin Ruiz, A. Martínez Sellés, G. Matulenaite, C.Y. Mucher, A. Newborough, M. Perez Ornedo, E. Perez-Duenas, A. Perillo-Marcone, L. Ponce, N. Solieri, M.B. Szewczyk, P.A. Thonet, M.A. Timmins, A. Tursun, W. Van den Broucke, F.M. Velotti, C. Vendeuvre, V. Vlachoudis
    CERN, Meyrin, Switzerland
  • J.C. Espadanal
    LIP, Lisboa, Portugal
 
  Antiprotons are produced at CERN at the Antiproton Decelerator (AD) Target Area by impacting 26 GeV/c proton beams onto a fixed target. Further collection, momentum selection, and transport of the secondary particles - including antiprotons - towards the AD ring is realised by a 400 kA pulsed magnetic horn and a set of magnetic dipoles and quadrupoles. A major consolidation of the area - in operation since the 80s - has taken place during the CERN Long Shutdown 2 (2019-2021). Among other activities, such upgrade included: (i) Installation of a new air-cooled target design and manufacturing of a new batch of magnetic horns, including a surface pulsing test-bench for their validation and fine-tuning (ii) Installation of a new positioning and maintenance system for the target and horn (iii) Refurbishment and decontamination of the Target Area and its equipment, (iv) Construction of a new surface service building to house new nuclear ventilation systems. This contribution presents an overview of such activities and lesson learnt. In addition, it provides the latest results from refractory metals R&D for the antiproton target and a summary of the recommissioning and optimization plans.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB366  
About • paper received ※ 18 May 2021       paper accepted ※ 21 June 2021       issue date ※ 18 August 2021  
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WEPAB367 Bubble Generation in the SNS 2 MW Mercury Target 3567
 
  • C.N. Barbier, M.P. Costa, K.C. Johns, D. Ottinger, F. Rasheed, B.W. Riemer, R.L. Sangrey, J.R. Weinmeister, D.E. Winder
    ORNL, Oak Ridge, Tennessee, USA
 
  The accelerator at the Spallation Neutron Source is currently being upgraded to increase the proton beam power from 1.4 MW to 2.8 MW. About 2 MW will go to the first target station, while the rest will go to the future second target station. The first target station uses a mercury target. When the short proton beam pulse hits it, strong pressure waves are developed inside the mercury and the vessel itself, causing weld failures and cavitation erosion. The pressure wave can be significantly mitigated by injecting small helium bubbles into the mercury. SNS has been injecting helium since 2017 using small orifices but has met challenges in fabrication and operations with them. Thus, for the 2 MW target, swirl bubblers will be used to increase gas injection and improve reliability. A 2 MW prototypical target was built and tested in a mercury process loop available at Oak Ridge National Laboratory. Acrylic viewports on the top of the target were used to determine the bubble size distribution (BSD) generated by the swirl bubblers. It was found that the bubblers were not only capable of generating small bubbles but that the BSD was independent of gas injection rate.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB367  
About • paper received ※ 10 May 2021       paper accepted ※ 22 June 2021       issue date ※ 25 August 2021  
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WEPAB368 Sigraflex® Studies for LHC CERN Beam Dump: Summary and Perspective 3571
 
  • J.M. Heredia, M. Calviani, R. Franqueira Ximenes, D. Grenier, K. Kershaw, A. Lechner, P. Andreu-Muñoz, F.-X. Nuiry, A. Perillo-Marcone, V. Rizzoglio, C. Torregrosa
    CERN, Geneva 23, Switzerland
  • A. Alvaro
    SINTEF, Trondheim, Norway
  • F. Berto, S. Solfiti
    NTNU, Trondheim, Norway
 
  The Large Hadron Collider (LHC) beam dump (TDE) is essential for safe and reliable operation of the collider. It absorbs particles extracted from the accelerator whenever required. The original design of the TDE dates from the mid 2000 and it is constituted of an eight-meter-long cylindrical stainless-steel tube, filled with low-Z carbon-based materials from different grades and densities. The Sigraflex®, an expanded low-density graphite, is employed in the middle section of the TDE core. Due to unexpected behaviour observed in the past LHC runs, several major upgrades were recently implemented in order for the TDE to be ready for LHC Run3 (2021-2024), where up to 555 MJ beam energy is expected to be dumped every few hours. According simulations, temperatures in the Sigraflex core will reach locally up to 1500°C in the regular dump cases, and above 2300°C for failure scenarios. The objective of this contribution is to summarize the LS2 hardware upgrades and the plan for the evaluation of the Sigraflex performance during LHC Run3. This work will also detail the last experimental and numerical findings applied to the Sigraflex®, and possible alternative materials for the future.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB368  
About • paper received ※ 18 May 2021       paper accepted ※ 11 August 2021       issue date ※ 29 August 2021  
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WEPAB370 Study of an L-Band CW Linac 3575
 
  • J. Gao, H.B. Chen, J.Y. Liupresenter, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
 
  We have studied an L-band linac based on a cheap industrial magnetron, which works at CW mode with 75kW averaged output-power. The designed energy-gain of electrons is 500keV. Low accelerating gradient was the dominant problem encountered during the structure design. We adopted a standing-wave structure with magnetically coupling and nose cones to increase the effective shunt impedance. A 7-cell design has been completed, of which the transverse dynamics and thermodynamics were simulated. Results showed that this accelerating structure could work stably at 59 C and 100 mA output beam current was achieved. This L-band design provided a cheap and efficient way to generate low-energy electrons for industrial irradiation processing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB370  
About • paper received ※ 19 May 2021       paper accepted ※ 21 June 2021       issue date ※ 02 September 2021  
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WEPAB371 Numerical Analysis on Nitrogen Injection Fire Extinguishing System in the LINAC Area at TPS 3578
 
  • J.-C. Chang, W.S. Chan, Y.F. Chiupresenter
    NSRRC, Hsinchu, Taiwan
 
  The Linear accelerator (LINAC) of Taiwan Photon Source (TPS) could generate electrons to 150 MeV. The main subsystems including an electron gun, buncher, accelerating sections, vacuum system, and focusing and steering magnets are located in the LINAC area of 223.5 m2 and 3 m in height. We designed a nitrogen injection fire extinguishing system for the LINAC area and performed Computational Fluid Dynamic (CFD) simulation to analyse the fire extinguishing performance with and without fresh air supplied from the air conditioning system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB371  
About • paper received ※ 16 May 2021       paper accepted ※ 21 June 2021       issue date ※ 19 August 2021  
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WEPAB372 Design and Construction of Uninterruptible Paralleling Transfer Switches for an Emergency Power System in Taiwan Light Source 3581
 
  • Y.F. Chiu, W.S. Chan, K.C. Kuo, Y.-C. Lin
    NSRRC, Hsinchu, Taiwan
 
  The ATS of an emergency power system in Utility Building II has operated over 18 years; in recent years the failure rate is gradually increasing because of aged components. To improve old switches, schemes of upgrading and developing new and efficient transfer switches have been conducted cautiously. A new device named an Uninterruptible Paralleling Transfer Switch (UPTS) is designed and implemented to replace an existing ATS to enhance the performance to meet the requirements of uninterrupted power transfer. The UPTS can uninterruptedly switch the grid power to emergency power of a backup generator during a planned utility power outage, and also exactly switch emergency power to the grid power uninterruptedly when the utility power is restored. If grid power is unexpectedly lost, UPTS acts like a typical ATS, automatically transferring power from a primary source to a backup source with switching duration a few seconds. A practical UPTS has been assembled and installed in Utility Building II and has performed well effectively to eliminate power-switching transients.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB372  
About • paper received ※ 11 May 2021       paper accepted ※ 02 July 2021       issue date ※ 12 August 2021  
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WEPAB373 The Energy Management System in NSRRC 3585
 
  • C.S. Chen, W.S. Chan, Y.Y. Cheng, Y.F. Chiu, Y.-C. Chung, K.C. Kuo, M.T. Lee, Y.C. Lin, C.Y. Liu, Z.-D. Tsai
    NSRRC, Hsinchu, Taiwan
 
  Taiwan has been suffering from a shortage of natural resources for more than two decades. As stated by the Energy Statistics Handbook 2019 of Taiwan, up to 97.90% of energy supply was imported from abroad. This kind of energy consumption structure is fragile relatively. Not mention to the total domestic energy consumption annual growth rate is 1.97% in twenty years. Either the semiconductor or the integrated circuit-related industry is developed vigorously in Taiwan. All the facts cause us to face the energy problems squarely. Therefore, an energy management system (EnMS) was installed in NSRRC in 2019 to pursue more efficient energy use. With the advantages of the Archive Viewer - a utility supervisory control and data acquisition system in NSRRC, the data of energy use could be traced conveniently and widely. The model of energy use has been built to review periodically, furthermore, it provides us the accordance to replace the degraded equipment and alerts us if the failure occurs.  
poster icon Poster WEPAB373 [0.497 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB373  
About • paper received ※ 21 May 2021       paper accepted ※ 22 July 2021       issue date ※ 22 August 2021  
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WEPAB374 The Southern Hemisphere’s First X-Band Radio-Frequency Test Facility at the University of Melbourne 3588
 
  • M. Volpi, R.P. Rassool, S.L. Sheehy, G. Taylor, S.D. Williams
    The University of Melbourne, Melbourne, Victoria, Australia
  • M.J. Boland
    CLS, Saskatoon, Saskatchewan, Canada
  • M.J. Boland
    University of Saskatchewan, Saskatoon, Canada
  • N. Catalán Lasheras, S. Gonzalez Anton, G. McMonagle, S. Stapnes, W. Wuensch
    CERN, Meyrin, Switzerland
  • R.T. Dowd, K. Zingre
    AS - ANSTO, Clayton, Australia
 
  The first Southern Hemisphere X-band Laboratory for Accelerators and Beams (X-LAB) is under construction at the University of Melbourne, and it will operate CERN X-band test stand containing two 12GHz 6MW klystron amplifiers. By power combination through hybrid couplers and the use of pulse compressors, up to 50 MW of peak power can be sent to any of 2 test slots at pulse repetition rates up to 400 Hz. The test stand is dedicated to RF conditioning and testing CLIC’s high gradient accelerating structures beyond 100 MV/m. It will also form the basis for developing a compact accelerator for medical applications, such as radiotherapy and compact light sources. Australian researchers working as part of a collaboration between the University of Melbourne, international universities, national industries, the Australian Synchrotron -ANSTO, Canadian Light Source and the CERN believe that creating a laboratory for novel accelerator research in Australia could drive technological and medical innovation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB374  
About • paper received ※ 18 May 2021       paper accepted ※ 06 July 2021       issue date ※ 12 August 2021  
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WEPAB376 The Inner Triplet String Facility for HL-LHC: Design and Planning 3592
 
  • M.B. Bajko, S. Bertolasi, C. Bertone, S. Blanchard, D. Bozzini, O.S. Brüning, P. Cruikshank, D. De Luca, N. Dos Santos, F. Dragoni, N. Heredia Garcia, A. Herty, A. Kosmicki, S. Le Naour, W. Maan, A. Martínez Sellés, P. Martinez Urios, P. Orlandi, A. Perin, M. Pojer, F. Rodriguez-Mateos, G. Rolando, L. Rossi, H. Thiesen, E. Todesco, E. Vergara Fernandez, D. Wollmann, S. Yammine, J.J. Zawilinski, M. Zerlauth
    CERN, Geneva, Switzerland
 
  In the framework of the HL-LHC project, full-scale integration and operational tests of the superconducting magnet chain, from the inner triplet quadrupoles up to the first separation/recombination dipole, are planned in conditions as similar as possible to the final set-up in the LHC tunnel. The IT String includes all of the required systems for operation at nominal conditions, such as vacuum, cryogenics, warm and cold powering equipment, and protection systems. The IT String is intended to be both an assembly, and an integration test stand, and a full rehearsal of the systems working in unison. It will, closely reproducing the mechanical, electrical, and thermo-hydraulic interfaces of the final installation, as well as allowing a full rehearsal of the systems working in unison. This paper describes the conceptual design, the test stand’s reference configuration, and the main goals. It also summarizes the status of the main activities, including the detailed design of the test infrastructure, procurement of main equipment, the baseline installation schedule, and major milestones. The first version of the experimental program and the associated planning are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB376  
About • paper received ※ 19 May 2021       paper accepted ※ 22 July 2021       issue date ※ 18 August 2021  
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WEPAB378 Near-Infrared Laser System for Dielectric Laser Acceleration Experiments at SINBAD 3596
 
  • C. Mahnke, U. Grosse-Wortmann, I. Hartl, C.M. Heyl, Y. Hua, T. Lamb, Y. Ma, C. Mohr, J. Müller, S.H. Salman, S. Schulz, C. Vidoli
    DESY, Hamburg, Germany
  • H. Çankaya
    CFEL, Hamburg, Germany
 
  The technique of dielectric laser acceleration (DLA) utilizes the strong field gradients generated by intense laser light near the surfaces of microscopic photonic structures, possibly allowing compact accelerator devices. We report on the infrared laser system at the SINBAD facility at DESY, where first DLA experiments with relativistic electrons pre-accelerated by the ARES linear accelerator started in late 2020. We constructed a low-noise Holmium fiber oscillator producing pulses at a wavelength of 2050 nm, seeding a Ho:YLF regenerative amplifier. Pulses of 2 mJ and 2 ps duration from the amplifier are transported over a distance of about 30 m to the DLA interaction point. The laser system is synchronized to the accelerator by locking the laser repetition rate to an RF master oscillator using an all-digital phase-locked loop, giving a residual timing jitter of about 45 fs. The digital locking scheme allows precise shifting of the relative timing between laser pulses and electrons without need for a dedicated optical delay line. It is planned to lock the system to the UV photocathode laser by means of an optical cross correlator further to improve the locking performance.  
poster icon Poster WEPAB378 [1.445 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB378  
About • paper received ※ 19 May 2021       paper accepted ※ 22 June 2021       issue date ※ 01 September 2021  
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WEPAB379 Photocathode Laser Development for Superconducting X-Ray Free Electron Lasers at DESY 3599
 
  • C. Li, O. Akcaalan, U. Grosse-Wortmann, I. Hartl, C. Mohr, M. Seidel, H. Tuennermann, C. Vidoli, L. Winkelmann
    DESY, Hamburg, Germany
  • M. Frede, O. Puncken
    neoLASE GmbH, Hanover, Germany
 
  Funding: Deutsches Elektronen-Synchrotron, Hamburg, 22609, Germany
Modern X-Ray Free-Electron Lasers (XFEL) are a key tool to enable a variety of scientific research. Those large-scale machines rely on robust and reliable deep ultraviolet (DUV) laser sources to drive electrons from their RF photocathode gun. In this paper we present a new photocathode laser prototype, which offers more flexibility in duration and shape of the 257.5 nm pulses for driving the CsTe Photocathodes of DESY’s superconducting burst-mode FELs. The laser matches the FEL pulse structure, which are 800 µs bursts at up to 4.5 MHz intraburst-rate with 10 Hz burst-repetition-rate. In a first version the system will offer variable DUV pulse durations, tunable from 1 ps to 20 ps to address different operational regimes of the XFEL. The laser system comprises a high-resolution spectral shaper with the option of generating flat-top DUV pulses for reducing electron-beam emittance at a later version. The laser is constructed in a hybrid Yb:fiber and Yb:YAG architecture. Our prototype delivers 180 uJ pulse energy at 1030 nm and 1 MHz intra-burst rate and we demonstrated conversion of 50µJ of the NIR beam to DUV, resulting 11.5µJ at 21ps (FWHM) and 6.15 µJ at 1.05 ps (FWHM) pulse duration.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB379  
About • paper received ※ 27 May 2021       paper accepted ※ 02 July 2021       issue date ※ 29 August 2021  
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WEPAB380 Measurements of Field Emission Induced Optical Spectra 3602
 
  • R.C. Peacock, G. Burt
    Lancaster University, Lancaster, United Kingdom
  • S. Calatroni, W. Wuensch
    CERN, Meyrin, Switzerland
 
  Field emission induced optical spectra in a dc electrode system have been measured using a spectrometer and CCD camera system in order to gain insight into the nature of field emissions sites. Spectra were measured from between 2 ridged parallel copper electrodes with a gap ranging from 60µm to 100µm and a bias voltage of up to 8000V under high vacuum conditions. A strong correlation between the light intensity of the spectra and the measured field emitted current was observed as a function of applied voltage. A characteristic broadband spectrum ranging from 550nm and 850nm wavelength was observed but there were important features which varied as a function of observation angle, polarity, and conditioning state and also with time. Possible causes of the optical spectra being considered include black body radiation, optical transition radiation and cathode luminescence of copper. Further experiments are ongoing with an improved optical setup to increase optical alignment for measurements with different materials of electrodes, developing further understanding of the cause of the optical spectra, to provide understanding into characteristics and evolution of emission sites.  
poster icon Poster WEPAB380 [1.158 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB380  
About • paper received ※ 11 May 2021       paper accepted ※ 24 June 2021       issue date ※ 31 August 2021  
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WEPAB381 Multipactor Simulations for MYRRHA Spoke Cavity: Comparison Between SPARK3D, MUSICC3D, CST PIC and Measurement 3606
 
  • N. Hu, M. Chabot, J.-L. Coacolo, D. Longuevergne, G. Olry
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • M.B. Belhaj
    ONERA, Toulouse, France
 
  The multipactor effect can lead to thermal breakdown (quench), high field emission and limited accelerating gradient in superconducting accelerator devices. To determine the multipactor breakdown power level, multipactor simulations can be performed. The objective of this study is to compare the results given by different simulation codes with the results of vertical testing of SRF cavities. In this paper, Spark3D, MUSICC3D and CST Studio PIC solver have been used to simulate the multipactor effect in Spoke cavity developed within the framework of MYRRHA project. Then, a benchmark of these three simulation codes has been made. The breakdown power level, the multipactor order and the most prominent location of multipactor are presented. Finally, the simulation results are compared with the measurements done during the vertical tests.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB381  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 30 August 2021  
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WEPAB383 An Evolutionary Algorithm Approach to Multi-Pass ERL Optics Design 3610
 
  • I. Neththikumara, T. Satogata
    ODU, Norfolk, Virginia, USA
  • R.M. Bodenstein, S.A. Bogacz, T. Satogata
    JLab, Newport News, Virginia, USA
  • A. Vandenhoeke
    ULB, Bruxelles, Belgium
 
  Funding: This material is based upon work supported by the U.S. Department of Energy under contract DE-AC05-06OR23177.
An Energy Recovery Experiment at CEBAF (ER@CEBAF) is aimed at demonstrating high energy, low current, multi-pass energy recovery at the existing 12 GeV CEBAF accelerator. The beam break-up instability, limiting the maximum beam current, can be controlled through minimizing beta functions for the lowest energy pass, which gives a preference to strongly focusing optics, e.g. a semi-periodic FODO lattice. On the other hand, one needs to limit beta function excursions, caused by under focusing, at the higher energy passes, which in turn favors weakly focusing linac optics. Balancing both effects is the main objective of proposed multi-pass linac optics optimization. Here, we discuss an optics design process for ER@CEBAF transverse optics using a genetic algorithm.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB383  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 30 August 2021  
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WEPAB384 Design and Beam Dynamics of the Electron Lens for Space Charge Compensation in SIS18 3614
 
  • S. Artikova, D. Ondreka, K. Schulte-Urlichs, P.J. Spiller
    GSI, Darmstadt, Germany
 
  An electron lens for space charge compensation is being developed at GSI to increase the ion beam intensities in SIS18 for the FAIR project. It uses an electron beam of 10A maximum current at 30keV. The maximum magnetic field on-axis is 0.6T, considerably higher than the field of the existing electron cooler. The magnetic system of the lens consists of solenoids and toroids. The toroids’ vertical field component creates a significant horizontal orbit deflection in the circulating low rigidity ion beam. To correct this deflection, four correction dipoles have been introduced. As common for electron lenses, the high-power electron beam is not dumped at ground potential, but rather in a collector with a small bias potential with respect to the cathode. The present design foresees a collector at -27kV, leading to a power dissipation of 30kW, distributed over a large surface area by placing the collector in an appropriately shaped magnetic field of a pre-collector solenoid. This contribution reports on the design of the lens and presents the results of beam transport simulations for the electron beam (with space charge) and a representative ion beam, performed using the 3D CST STUDIO.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB384  
About • paper received ※ 20 May 2021       paper accepted ※ 05 July 2021       issue date ※ 15 August 2021  
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WEPAB385 Beam Dynamic Analysis of RF Modulated Electron Beam Produced by Gridded Thermionic Guns 3618
 
  • G. Adam
    University of Strathclyde, Glasgow, United Kingdom
  • A.W. Cross, L. Zhang
    USTRAT/SUPA, Glasgow, United Kingdom
  • B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • B.L. Militsyn
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: Science and Technology Facilities Council (STFC) U.K training grant, industrial case with TMD Ltd, UK ST/R002141/1 "Accelerators for Security, healthcare and Environmental applications ".
A thermionic cathode gridded electron gun used in injectors for different types of circular and linear particle accelerators and for energy recovery configurations was studied. Both theory and numerical simulation were used to explore the relationship between the bunch charge and bunch length. The electron gun is based on a Pierce-type geometry. It was initially designed using Vaughan synthesis followed by optimization using a 2D electron trajectory solver TRAK. After optimization, the grid in front of the cathode was inserted and the RF field was introduced through a coaxial waveguide structure. The complete gun was simulated using the PIC code MAGIC. High duty cycle operations at frequencies 1.5 GHz and 3.0 GHz, were investigated using different combinations of both the bias and the RF voltage applied between the cathode and the grid. The beam dynamics results from the PIC showed that a minimum bunch length of 106 ps could be achieved with a bunch charge of 33 pC when the driving RF frequency was 1.5 GHz. Operating at the higher RF frequency of 3GHz did not significantly reduce the bunch length. The normalized emittance of about 5.6 mm-mrad was demonstrated in PIC simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB385  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 24 August 2021  
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WEPAB387 Study of Failure Modes in Electron Linac-Based X-Ray Sources for Industrial Applications 3622
 
  • K.P. Dixit, G. Vinod
    BARC, Mumbai, India
 
  Electron linac-based X-ray sources (XRS) have an increased demand in industrial applications, mainly for their advantages of compactness and ease of use. In order to achieve reliable operation, it is necessary to have rugged components in the linac system. Hence, this study focusses on achieving high reliability design; also in formulating a preventive maintenance programme to optimise the availability and prognostic methods for performance monitoring of components. This paper investigates the failure modes in the important sub-systems of a 6 MeV electron linac, including electron gun, RF power source, vacuum system, x-ray target, control system, etc. Electron guns suffer from problems related to the filament heater damage and high voltage insulation failure. In the RF source, major components (line-type pulsed modulators, magnetrons, circulator and RF window) are studied to assess their life. Fault tree analysis of the individual sub-systems and the effect of individual failures on the linac down-time are studied. A few mitigation techniques used in practical systems are also discussed here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB387  
About • paper received ※ 18 May 2021       paper accepted ※ 23 July 2021       issue date ※ 13 August 2021  
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WEPAB390 High-Quality, Conformal Bellows Coatings Using Ultra-Fast HiPIMS with Precision Ion Energy Control 3626
 
  • T.J. Houlahan, I. Haehnlein, W.M. Huber, B.E. Jurczyk, I.A. Shchelkanov, R.A. Stubbers
    Starfire Industries LLC, Champaign, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy under Award Number DE-SC0020481.
In this paper we demonstrate a replacement for traditional ’wet’ chemical deposition processes using a vacuum, ionized physical vapor deposition (iPVD) process that results in a conformal metal film, capable of coating complex, convoluted parts that are common in modern particle accelerators (e.g., bellows, RF cavities). Results are presented for a process utilizing the combined deposition and etching that are achieved using ultra-fast high-power impulse magnetron sputtering (HiPIMS) coupled with precision control of the ion energy using a positive voltage reversal. This process results in a conformal film and has been used to coat both test coupons and full bellows assemblies. The resulting Cu films, which are 5-10 µm in thickness, exhibit excellent adhesion. Further, they have been shown to tolerate temperature extremes ranging from 77 K to a 400 C vacuum bakeout as well as extreme plastic deformation of the substrate without any buckling, cracking, or delamination.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB390  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 26 August 2021  
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WEPAB394 Development of a New Interlock and Data Acquisition for the RF System at High Energy Photon Source 3630
 
  • Z.W. Deng, J.P. Dai, H.Y. Lin, Q.Y. Wang, P. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Funding: This work was supported by High Energy Photon Source, a major national science and technology infrastructure in China.
A new interlock and data acquisition (DAQ) system is being developed for the RF system at High Energy Photon Source (HEPS) to protect essential devices as well as to locate the fault. Various signals collected and pre-processed by the DAQ system and individual interlock signals from solid-state power amplifiers, low-level RFs, arc detectors, etc. are sent to the interlock system for logic decision to control the RF switch. Programmable logic controllers (PLC) are used to collect slow signals like temperature, water flowrate, etc., while fast acquisition for RF signals is realized by dedicated boards with down-conversion frontend and digital signal processing boards. In order to improve the response time, field programmable gate array (FPGA) has been used for interlock logic implementation with an embedded experimental physics and industrial control system (EPICS). Data storage is managed by using EPICS Archiver Appliance and an operator interface is developed by using Control System Studio (CSS) running on a standalone computer. This paper presents the design and the first test of the new interlock and DAQ for HEPS RF system.
 
poster icon Poster WEPAB394 [2.140 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB394  
About • paper received ※ 16 May 2021       paper accepted ※ 14 July 2021       issue date ※ 31 August 2021  
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WEPAB396 First Measurements on Multipactor Study 3633
 
  • Y. Gómez Martínez, J. Angot, M.A. Baylac, T. Cabanel, P.-O. Dumont, N. Emeriaud, O. Zimmermann
    LPSC, Grenoble Cedex, France
  • D. Longuevergne
    FLUO, Orsay, France
  • G. Sattonnay
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
 
  Multipactor (MP) is an undesired phenomenon of resonant electron build up encountered on particle accelerators. It can induce anomalous thermal losses, higher than the Joule losses, inducing a decrease of the superconducting cavities quality factor, it can even lead to a cavity quench. On couplers, it can produce irreversible damages or generate a breakdown of their vacuum window. Multipactor may lead to Electron Cloud build up as well. The accelerator group at LPSC has developed a test bench dedicated to the multipactor studies. This paper presents the experimental set-up and its first measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB396  
About • paper received ※ 18 May 2021       paper accepted ※ 14 July 2021       issue date ※ 30 August 2021  
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WEPAB397 Design of the Two-Layer Girder for Accelerating Tube 3636
 
  • X.J. Nie, H.Y. He, L. Kang
    IHEP, Beijing, People’s Republic of China
  • J.X. Chenpresenter, L. Liu, R.H. Liu, C.J. Ning, A.X. Wang, G.Y. Wang, Y.J. Yu, J.S. Zhang, D.H. Zhu
    IHEP CSNS, Guangdong Province, People’s Republic of China
  • J.B. Yu
    DNSC, Dongguan, People’s Republic of China
 
  An accelerating tube is one kind of important acceleration equipment of a linear accelerator. It is often made up of oxygen-free copper with a long tubular structure. It’s easy to suffer from deformation. Based on support requirements, the reasonable structure of the girder was obtained. Four supporting blocks were installed on the top surface of aluminum profile with the uniform distribution along the beam direction. The support strength with static condition and different working conditions were checked by ANSYS simulation calculation to ensure the stable operation of the girder. The two-layer girder can be used as a reference for other similar slender part for its simple structure and reliable support.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB397  
About • paper received ※ 14 May 2021       paper accepted ※ 13 August 2021       issue date ※ 01 September 2021  
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WEPAB398 A C-Band RF Mode Launcher with Quadrupole Field Components Cancellation for High Brightness Applications 3638
 
  • G. Pedrocchi
    SBAI, Roma, Italy
  • D. Alesini, F. Cardelli, A. Gallo, A. Giribono, B. Spataro
    INFN/LNF, Frascati, Italy
  • G. Castorina
    AVO-ADAM, Meyrin, Switzerland
  • L. Ficcadenti
    INFN-Roma, Roma, Italy
  • M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
 
  The R&D of high gradient radiofrequency devices is aimed to develop innovative and compact accelerating stuctures based on new manufactoring techniques and materials in order to produce devices operating with the highest accelerating gradient. Recent studies have shown a large increase in the maximum sustained RF surface electric fields in copper structure operating at cryogenic temperature. These novel approaches allow significant performance improvements of RF photoinjectors. Indeed the operation at high surface fields results in considerable increase of electron brilliance. This requires high field quality in the RF photoinjector and specifically in its poweer coupler. In this work we present a novel power coupler for the RF photoinjector. The coupler is a compact C-band TM01 mode launcher with a fourfold symmetry which minimized both the dipole and the quadrupole RF field components.  
poster icon Poster WEPAB398 [1.799 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB398  
About • paper received ※ 13 May 2021       paper accepted ※ 06 July 2021       issue date ※ 29 August 2021  
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WEPAB399 Applications of the Local Observable in Future Optics Measurements in HL-LHC and PETRA III 3642
 
  • A. Wegscheider, R. Tomás García
    CERN, Meyrin, Switzerland
 
  Phase advances among four nearby beam position monitors in a circular accelerator can be used to calculate a local observable of quadrupolar lattice imperfections. This work explores the applicability of this local observable to two different circular accelerators: PETRA III, a synchrotron light source, and the LHC, a hadron collider as well as its upgrade project HL-LHC. MADX simulations for important optics settings are performed, showing that the local observable can detect strong error sources. This is of particular interest in important regions of the accelerators like the LHC’s interaction regions and PETRA III’s experimental hall.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB399  
About • paper received ※ 19 May 2021       paper accepted ※ 23 July 2021       issue date ※ 13 August 2021  
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WEPAB400 Forced Coupling Resonance Driving Terms 3646
 
  • A. Wegscheider, R. Tomás García
    CERN, Meyrin, Switzerland
 
  At the LHC, coupling is routinely measured using forced oscillations of the beam through excitation with an AC-dipole. The driving of the particle motion has an impact on the measurement of resonance driving terms. Recent findings suggest that the current models describing the forced motion are neglecting a local effect of the AC-dipole, creating a jump of the amplitude of the resonance driving terms. This work presents a study of the improvement of coupling measurements for typical LHC optics as well as its upgrade project HL-LHC, by using the new model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB400  
About • paper received ※ 19 May 2021       paper accepted ※ 02 August 2021       issue date ※ 30 August 2021  
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WEPAB401 Study for Alternative Cavity Wall and Inductive Insert Material 3650
 
  • C.E. Taylor, C.-F. Chen, T.W. Hall, E. Henestroza, J.T.M. Lyles, J. Upadhyay
    LANL, Los Alamos, New Mexico, USA
  • S. Biedron, M.A. Fazio, S.I. Salvador, T.J. Schaub
    UNM-ECE, Albuquerque, USA
 
  Funding: Contract No. 89233218CNA000001, supported by the U.S. Department of Energy’s National Nuclear Security Administration (NNSA), for the management and operation of Los Alamos National Laboratory (LANL).
The goal of this work was to develop a solution to the problem of longitudinal beam instability. Beam instability has been a significant problem with storage rings’ performance for many decades. The proton storage ring (PSR) at the Los Alamos Neutron Science Center (LANCE) is no exception. To mitigate the instability, it was found that ferrite inductive inserts can be used to bunch the protons that are diverging due to the electron background. The PSR was the first storage ring to successfully use inductive inserts to mitigate the longitudinal instability with normal production beams. However, years later new machine upgrades facilitate shorter, more intense beams to meet the needs of researchers. The ferrite inserts used to reduce the transverse instabilities induce a microwave instability with the shorter more intense proton beam. This study investigates alternative magnetic materials for inductive inserts in particle beam storage rings, including the necessary engineering for maintaining the ideal temperature during operation.
’ tjschaub@unm.edu
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB401  
About • paper received ※ 29 May 2021       paper accepted ※ 02 July 2021       issue date ※ 10 August 2021  
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WEPAB402 Status and Progress of the High-Power RF System for High Energy Photon Source 3653
 
  • T.M. Huang, J. Li, H.Y. Lin, Y.L. Luo, Q. Ma, W.M. Pan, P. Zhangpresenter, F.C. Zhao
    IHEP, Beijing, People’s Republic of China
 
  Funding: Work was supported in part by High Energy Photon Source, a major national science and technology infrastructure in China, and in part by the National Natural Science Foundation of China(12075263).
High Energy Photon Source is a 6-GeV diffraction-limited synchrotron light source currently under construction in Beijing. Three types of high-power RF systems are used to drive the booster and the storage ring. For the booster ring, a total of 600-kW continuous-wave (CW) RF power is generated by six 500-MHz solid-state power amplifiers (SSA) and fed into six normal-conducting copper cavities. Concerning the storage ring, five CW 260-kW SSAs at 166 MHz and two CW 260-kW SSAs at 500-MHz are used to drive five fundamental and two third-harmonic superconducting cavities respectively. The RF power distributions are realized by 9-3/16" rigid coaxial line for the 166-MHz system and EIA standard WR1800 waveguide for the 500-MHz one. High-power circulators and loads are installed at the outputs of all SSAs to further protect the power transmitters from damages due to reflected power although each amplifier module is equipped with individual isolators. The overall system layout and the progress of the main components are presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB402  
About • paper received ※ 18 May 2021       paper accepted ※ 02 July 2021       issue date ※ 29 August 2021  
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WEPAB405 Supercontinuum Generation for the Improvement of Pulse Radiolysis System 3657
 
  • M. Sato, Y. Kaneko, Y. Koshiba, M. Washio
    RISE, Tokyo, Japan
  • K. Sakaue
    The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan
 
  Pulse radiolysis is one of the absorption measurement methods for investigating the fundamental, ultrafast process of radiation chemical reactions. Analytical light is transmitted simultaneously with the timing of electron beam irradiation, and its absorption by reactive species is detected. Since the target reactions arise in pico second time scale or even shorter, analytical light is required to have such duration. Besides, so as not to be buried in noise of the radiation source, the optical power of the analytical light must be high enough. Furthermore, it is desirable that the analytical light covers visible region because important absorptions caused by irradiation products such as hydrated electron, hydroxyl radical, or so exist in the region. We considered that the supercontinuum light generated from an ultrashort pulse laser is suitable as an analytical light because it has all these characteristics. In this study, we generate the second harmonic (775 nm) of an erbium fiber laser (1550 nm) as a seed laser for supercontinuum generation. In this presentation, we report the current situation of our laser system and prospects.  
poster icon Poster WEPAB405 [0.734 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB405  
About • paper received ※ 18 May 2021       paper accepted ※ 24 August 2021       issue date ※ 01 September 2021  
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WEPAB407 An Innovative Eco-System for Accelerator Science and Technology 3660
 
  • C. Darve, J.B. Andersen, S. Salman
    ESS, Lund, Sweden
  • B. Nicquevert, S. Petit
    CERN, Geneva, Switzerland
  • M. Stankovski
    LINXS, Lund, Sweden
 
  The emergence of new technologies and innovative communication tools permits us to transcend societal challenges. While particle accelerators are essential instruments to improve our quality of life through science and technology, an adequate ecosystem is essential to activate and maximize this potential. Research Infrastructure (RI) and industries supported by enlightened organizations and education, can generate a sustainable environment to serve this purpose. In this paper, we will discuss state-of-the-art infrastructures taking the lead to reach this impact, thus contributing to economic and social transformation.  
poster icon Poster WEPAB407 [61.076 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB407  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 25 August 2021  
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WEPAB410 Finite Element Analyses of Synchrotron Radiation Induced Stress in Beryllium Synch-Light Mirrors 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 ※ 01 September 2021  
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WEPAB411 Ion Coulomb Crystals in Storage Rings for Quantum Information Science 3667
 
  • K.A. Brown, G.J. Mahler, T. Roser, T.V. Shaftan, Z. Zhao
    BNL, Upton, New York, USA
  • A. Aslam, S. Biedron, T.B. Bolin, C. Gonzalez-Zacarias, S.I. Sosa Guitron
    UNM-ECE, Albuquerque, USA
  • R. Chen, T.G. Robertazzi
    Stony Brook University, Stony Brook, New York, USA
  • B. Huang
    SBU, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We discuss the possible use of crystalline beams in storage rings for applications in quantum information science (QIS). Crystalline beams have been created in ion trap systems and proven to be useful as a computational basis for QIS applications. The same structures can be created in a storage ring, but the ions necessarily have a constant velocity and are rotating in a circular trap. The basic structures that are needed are ultracold crystalline beams, called ion Coulomb crystals (ICC’s). We will describe different applications of ICC’s for QIS, how QIS information is obtained and can be used for quantum computing, and some of the challenges that need to be resolved to realize practical QIS applications in storage rings.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB411  
About • paper received ※ 19 May 2021       paper accepted ※ 20 July 2021       issue date ※ 24 August 2021  
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WEPAB412 Use of a Noise IoT Detection System to Measure the Environmental Noise in Taiwan Light Source 3671
 
  • P.J. Wen, S.P. Kao, S.Y. Lin, Y.C. Lin
    NSRRC, Hsinchu, Taiwan
 
  In the past, the method of general noise monitoring altered little; noise was still measured with a human hand-held mobile device, or the measurement at fixed sites was made using traditional analogue data-storage equipment. In recent years, with the rapidly improved network transmission capabilities, the development of a small noise-detection IoT system allows the detection data to be transmitted wirelessly without need for human strength measurements, and records noise information. The statistics of subsequent noise data become a basis for analysis and improvement. Taiwan Light Source (TLS) beamlines have many vacuum pumps, cooling pumps, liquid-nitrogen pressure-relief systems, computer servers etc. that generate much noise. This study is expected to prepare for installation of noise detection. The system uses a noise-detection box to detect, to disclose louder locations, to collect noise data, to determine the source and type of noise source, and to provide information to reduce the noise of the working environment. The TLS noise-detection results find that the inner-ring area has less noise and are more stable than the outer ring area.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB412  
About • paper received ※ 14 May 2021       paper accepted ※ 24 June 2021       issue date ※ 10 August 2021  
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WEPAB416 Industrialization Study of the Accelerating Structures for a 380 GeV Compact Linear Collider 3674
 
  • A. Magazinik
    Tampere University, Tampere, Finland
  • N. Catalán Lasheras
    CERN, Meyrin, Switzerland
  • S. Mäkinen
    Tampere University of Technology, Tampere, Finland
  • J. Sauza-Bedolla
    Lancaster University, Lancaster, United Kingdom
 
  The LHC at CERN will continue its operation for approximately 20 years. In parallel, diverse studies are conducted for the design of a future large-scale accelerator. One of the options is the Compact Linear Collider (CLIC) who aims to provide a very high accelerating gradient (100 MV/m) achieved by using normal conducting radiofrequency (RF) cavities operating in the X-band range (12 GHz). Each accelerating structure is a challenging component involving ultra-precise machining and diffusion bonding techniques. The first stage of CLIC operates at a collision energy of 380 GeV with an accelerator length of 11 km, consisting of 21630 accelerating structures. Even though the prototypes have shown a mature and ready to build concept, the present number of qualified suppliers is limited. Therefore, an industrialization study was done through a technical survey with hi-tech companies. The aim is to evaluate current capabilities, to ensure the necessary manufacturing yield, schedule, and cost for mass production. This paper presents the results of the industrialization study for 12 GHz accelerating structures for CLIC 380 GeV, highlighting the principal challenges towards mass production.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB416  
About • paper received ※ 19 May 2021       paper accepted ※ 22 June 2021       issue date ※ 28 August 2021  
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WEPAB418 The Power Supply System for 10 MeV & 20 kW Industry Irradiation Facility 3678
 
  • F.L. Shang, L. Shang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: Work supported by National Key R&D Program of China 2018YFF0109204
The 10 MeV and 20 kW industry irradiation facility (IIF) has been designed by National Synchrotron Radiation Laboratory (NSRL) for years. Modular design power supplies are employed for the latest version, depend on the performance of these power supplies with high precision and high stability, the operating reliability of the IIF has been greatly improved.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB418  
About • paper received ※ 15 May 2021       paper accepted ※ 23 June 2021       issue date ※ 29 August 2021  
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