Keyword: positron
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MOPAB030 Research and Development Progress of CEPC RF Shield Bellows vacuum, impedance, electron, controls 142
 
  • J.M. Liu, Y.H. Guan, S.M. Liu, B. Tan, P.C. Wang
    DNSC, Dongguan, People’s Republic of China
  • H. Dong, Y. Ma
    IHEP, Beijing, People’s Republic of China
  • H.Y. He, T. Huang
    IHEP CSNS, Guangdong Province, People’s Republic of China
  
  The circular electron positron collider (CEPC) is a candidate for the next-generation electron positron collider, which can be used to accurately measure the Higgs and electroweak bosons. The RF shield bellow is a vacuum component necessary for the construction of CEPC. Therefore, a RF shield bellow model machine with an elliptical cross-section was designed and processed for technical verification. Based on the traditional interdigital structure, a special contact force testing device was also designed to reduce measurement errors. The on-off status of the circuit was used by the device to determine whether the spring finger was pulled up, thus reducing the influences of human factors in the measurement process. It can be known from the measurement results of the model machine that the contact force of the spring finger is between 120g and 130g, which can satisfy the technical requirements.  
poster icon Poster MOPAB030 [1.467 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB030  
About • paper received ※ 19 May 2021       paper accepted ※ 20 May 2021       issue date ※ 13 August 2021  
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MOPAB034 VEPP-4M Collider Operation at High Energy collider, experiment, luminosity, electron 155
 
  • P.A. Piminov, G.N. Baranov, A.V. Bogomyagkov, V.M. Borin, V.L. Dorokhov, S.E. Karnaev, K.Yu. Karyukina, V.A. Kiselev, E.B. Levichev, O.I. Meshkov, S.I. Mishnev, I.A. Morozov, I.N. Okunev, E.A. Simonov, S.V. Sinyatkin, E.V. Starostina, A.N. Zhuravlev
    BINP SB RAS, Novosibirsk, Russia
  
  VEPP-4M is an electron positron collider equipped with the universal KEDR detector for HEP experiments in the beam energy range from 1 GeV to 6 GeV. A unique feature of VEPP-4M is the high precision beam energy calibration by resonant polarization technique which allows conducting of interesting experiments despite the low luminosity of the collider. Recently we have started new luminosity acquisition run above 2 GeV. The hadron cross section was measured from 2.3 GeV to 3.5 GeV has been done. The luminosity run for gamma-gamma physics has been started. The luminosity at ψ(1S)-meson has been obtained. For the beam energy calibration the laser polarimeter is used. The paper discusses recent results from VEPP-4M collider.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB034  
About • paper received ※ 18 May 2021       paper accepted ※ 31 May 2021       issue date ※ 22 August 2021  
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MOPAB133 Recovering the Positron Beam After Muon Production in the Lemma Muon Source target, emittance, linac, injection 470
 
  • I. Drebot
    INFN-Milano, Milano, Italy
  • M.E. Biagini, O.R. Blanco-García, A. Giribono, S. Guiducci, C. Vaccarezza, A. Variola
    INFN/LNF, Frascati, Italy
  • S.M. Liuzzo
    ESRF, Grenoble, France
  
  In the LEMMA muon source proposal* a positron beam at 45 GeV is used to produce muons at threshold by interaction with some targets. In order to release the required intensity on the main positron source, orders of magnitude higher than the state of the art, the possibility to recover the primary positron beam after the interaction with the targets was studied. The particles distribution, with a strongly degraded energy spread after the interac- tion, was injected back into a low emittance, large energy acceptance 45 GeV ring. Studies of injection efficiency were performed. The possibility of compressing the beam in a linac before injection was also studied. As a result, even without compression, about 80% of the disrupted e+ beam can be injected back into the ring.
* D. Alesini et al, "Positron driven muon source for a muon collider", arXiv:1905.05747v2 [physics.acc-ph], May 2019 		 
poster icon Poster MOPAB133 [4.171 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB133  
About • paper received ※ 17 May 2021       paper accepted ※ 24 May 2021       issue date ※ 20 August 2021  
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MOPAB145 Acceleration and Focusing of Positron Bunch by Electron Bunch Wakefield in the Dielectric Waveguide Filled with Plasma plasma, electron, focusing, wakefield 505
 
  • G.V. Sotnikov, R.R. Kniaziev, P.I. Markov
    NSC/KIPT, Kharkov, Ukraine
  
  Funding: The National Research Foundation of Ukraine, program "Leading and Young Scientists Research Support" (project # 2020.02/0299)
The results of the numerical PIC-simulation of accelerated positron bunch focusing in the plasma dielectric wakefield accelerator unit, filled with radially inhomogeneous plasma that has vacuum channel inside are presented. The Wakefield was created by drive electron bunch in quartz dielectric tube with external and internal diameters of 1.2 mm and 1.0 mm, respectively. The tube was embedded in cylindrical metal waveguide. The internal area of dielectric tube has been filled with different transverse density profiles of plasma: homogeneous density and inhomogeneous density created in capillary discharge. Drive bunch electrons energy was 5 GeV, drive bunch charge was 3 nC. The test positron bunch had the same parameters as the drive bunch except for the charge of 0.05 nC. Results of numerical PIC simulation have shown the possibility of simultaneous acceleration and focusing of test positron bunch in the wakefield excited by drive electron bunch. The dependence of transport and acceleration of positron bunch on size of vacuum channel is studied. 		 
poster icon Poster MOPAB145 [2.003 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB145  
About • paper received ※ 19 May 2021       paper accepted ※ 20 May 2021       issue date ※ 25 August 2021  
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MOPAB163 First Synchronous Measurement of Single-Bunched Electron and Positron Beams with a Wideband Feedthrough-BPM at the Positron Capture Section of the SuperKEKB Injector Linac electron, solenoid, wakefield, linac 557
 
  • M.A. Rehman, F. Miyahara, T. Suwada
    KEK, Ibaraki, Japan
  
  The SuperKEKB is an asymmetric e−/e+ collider with 40 times higher luminosity than the KEKB project, to explore the new physics beyond the standard model. For the SuperKEKB, the positrons are created by striking the accelerated electrons at a tungsten target. The secondary electrons are also produced during the positron creation process and accelerated in the capture section. Because of phase slipping in the capture section, the secondary electron bunch is only  ∼ 180 ps away from the positron. Conventional stripline-type BPM cannot detect such closely spaced and opposite polarity signals due to slow frequency response and high cable losses. Therefore, a new wideband feedthrough-type beam position monitor was developed. It was successfully employed at the positron capture section of the SuperKEKB injector linac for the first synchronous measurement of the electron and positron beams. The cable losses effect also has been de-embedded to reveal correct signal properties. This paper describes the initial results of synchronous measurement of e−/e+ transverse position.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB163  
About • paper received ※ 20 May 2021       paper accepted ※ 27 May 2021       issue date ※ 16 August 2021  
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MOPAB165 Identical Focusing of Train of Relativistic Positron Gaussian Bunches in Plasma plasma, focusing, electron, wakefield 565
 
  • D.S. Bondar
    KhNU, Kharkov, Ukraine
  • V.I. Maslov, I.N. Onishchenko
    NSC/KIPT, Kharkov, Ukraine
  
  Funding: The study is supported by the National Research Fundation of Ukraine under the program "Leading and Young Scientists Research Support" (project # 2020.02/0299).
Focusing of both electron and positron bunches in an electron-positron collider is necessary. The focusing mechanism in the plasma, in which all electron bunches are focused identically, has been proposed earlier*. This mechanism is considered for positron bunches by using simulation with LCODE**. Three types of lenses with different trains of cosine profile positron bunches are considered depending on the bunch length, the distance between bunches, and their charge. It has been shown that all positron bunches are focused identically at special parameters of the first positron bunch, wherein the middle of bunches are focused weaker than their fronts.
* V. I. Maslov et al. PAST. 3(2012) 159.
** K. V. Lotov, Phys. Plas. 5 (1998) 785. 		 
poster icon Poster MOPAB165 [2.272 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB165  
About • paper received ※ 17 May 2021       paper accepted ※ 20 May 2021       issue date ※ 17 August 2021  
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MOPAB254 Measurement of Horizontal Beam Size Using Sextupole Magnets sextupole, quadrupole, storage-ring, dipole 802
 
  • J.A. Crittenden, K.E. Deitrick, H.X. Duan, G.H. Hoffstaetter, V. Khachatryan, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: This work is supported by National Science Foundation award number DMR-1829070.
The quadratic dependence of sextupole fields on position results in a beam-size-dependent kick on a beam traversing a sextupole magnet. A change in sextupole strength changes the closed orbit and the tune of the beam in a storage ring. Measuring both therefore allows conclusions about the beam size in the sextupole. Here we derive the pertinent formula and discuss the applicability to storage rings. In particular we investigate the measurement accuracy that can be achieved at the Cornell High Energy Synchrotron Source. The Cornell Electron-positron Storage Ring underwent a major upgrade in 2018 with the goal of reducing the emittance by a factor of four. A variety of beam size measurement methods have been developed to monitor the positron beam size, including visible synchrotron light and interferometry. We investigate the sensitivity of the sextupole method and compare to other measurement techniques. The design horizontal emittance of the 6-GeV positron beam is about 30 nm-rad with typical beam sizes of about 1 mm, setting the scale for the required accuracy in the beam-size measurement. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB254  
About • paper received ※ 19 May 2021       paper accepted ※ 22 June 2021       issue date ※ 01 September 2021  
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MOPAB272 Consideration the Prospects of Beam Diagnostic System Upgrade in the Transport Channels of Injection Complex VEPP-5 electron, injection, diagnostics, operation 860
 
  • K.V. Astrelina, F.A. Emanov
    BINP SB RAS, Novosibirsk, Russia
  • F.A. Emanov
    NSU, Novosibirsk, Russia
  
  Transport electron and positron channels from linear accelerator to storage ring of Injection Complex VEPP-5 (BINP, Novosibirsk) have complicated 3D configuration and equipped only with luminophore screens as a beam test. For the regular machine operations the non-destructive beam diagnostic system is required to adjust the electron and positron beam trajectories and minimize the beam losses. The proposal of new beam position monitors (BPM) assembling is considered. Newly added BPMs allow one to control the beam trajectory during operations. Collecting beam position data in several points makes it possible to calculate and correct the beamline parameters: Twiss parameters, dispersion, beam energy variations. The possible configuration of the new BPMs placing is suggested and the rate of beam loss reducing due the additional diagnostics is estimated.  
poster icon Poster MOPAB272 [1.164 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB272  
About • paper received ※ 20 May 2021       paper accepted ※ 02 June 2021       issue date ※ 02 September 2021  
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TUPAB001 DAΦNE Commissioning for SIDDHARTA-2 Experiment luminosity, optics, collider, feedback 1322
 
  • C. Milardi, D. Alesini, O.R. Blanco-García, M. Boscolo, B. Buonomo, S. Cantarella, A. D’Uffizi, A. De Santis, C. Di Giulio, G. Di Pirro, A. Drago, L.G. Foggetta, G. Franzini, A. Gallo, S. Incremona, A. Michelotti, L. Pellegrino, L. Piersanti, R. Ricci, U. Rotundo, L. Sabbatini, A. Stecchi, A. Stella, A. Vannozzi, M. Zobov
    INFN/LNF, Frascati, Italy
  • J. Chavanne, G. Le Bec, P. Raimondi
    ESRF, Grenoble, France
  
  DAΦNE, the Frascati lepton collider, has completed the preparatory phase in order to deliver luminosity to the SIDDHARTA-2 detector. DAΦNE colliding rings rely on a new interaction region, which implements the well-established Crab-Waist collision scheme, and includes a low-beta section equipped with newly designed permanent magnet quadrupoles, and vacuum components. Diagnostics tools have been improved, especially the ones used to keep under control the beam-beam interaction. The horizontal feedback in the positron ring has been potentiated in order to achieve a higher positron current. Luminosity diagnostics have been also updated so to be compatible with the new detector design. The commissioning was initially focused on recovering the optimal dynamical vacuum conditions, outlining alignment errors, and optimizing ring optics. For this reason, a detuned optics, featured by relaxed low-b condition at the interaction point and Crab-Waist Sestupoles off, has been applied. In a second stage a low-b optics has been implemented to test collisions with a preliminary setup of the experiment detector. Machine preparation and the first luminosity results are presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB001  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 10 August 2021  
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TUPAB003 Final Focus Solenoids Beam-Based Positioning Tests solenoid, alignment, collider, lattice 1330
 
  • D.B. Shwartz
    BINP SB RAS, Novosibirsk, Russia
  • D.B. Shwartz
    NSU, Novosibirsk, Russia
  
  The final focusing at the VEPP-2000 electron-positron collider is done by 13 T superconducting solenoids. The misalignment of solenoids not only provides closed orbit distortions but also harmful for dynamic aperture reduction due to strong nonlinear fringe fields. The final beam-based alignment of solenoids was foreseen but turned out to be not a trivial procedure. Here we present the test study of solenoids positioning reconstruction procedure based on circulating beam orbit responses.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB003  
About • paper received ※ 22 May 2021       paper accepted ※ 02 June 2021       issue date ※ 28 August 2021  
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TUPAB009 SuperKEKB Optics Measurements Using Turn-by-Turn Beam Position Data optics, closed-orbit, damping, collider 1352
 
  • J. Keintzel, R. Tomás García
    CERN, Geneva, Switzerland
  • H. Koiso, G. Mitsuka, A. Morita, K. Ohmi, Y. Ohnishi, H. Sugimoto, M. Tobiyama, R.J. Yang
    KEK, Ibaraki, Japan
  
  SuperKEKB, an asymmetric electron-positron collider, has recently achieved the world record instantaneous luminosity of 2.8 × 1034 \si{cm-2s-1} using crab-waist collision scheme. In order to reach the design value of 6×1035 \si{cm-2s-1} a vertical beta function at the interaction point of §I{0.3}{mm} is required, demanding unprecedented optics control. Turn-by-turn beam position data could enable fast optics measurements for rapid identification of unexpected error sources. Experiments exploring various data acquisition techniques at different squeezing steps during commissioning are presented and compared to results obtained from closed orbit distortion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB009  
About • paper received ※ 18 May 2021       paper accepted ※ 10 June 2021       issue date ※ 24 August 2021  
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TUPAB015 Beam Loading Compensation of APS Cavity with Off-Crest Acceleration in ILC e-Driven Positron Source beam-loading, linac, electron, target 1368
 
  • M. Kuriki, S. Konno, H. Nagoshi
    HU/AdSM, Higashi-Hiroshima, Japan
  • T. Omori, J. Urakawa, K. Yokoya
    KEK, Ibaraki, Japan
  • T. Takahashi
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
  
  In E-Driven positron source of ILC, the generated positron is captured by RF accelerator by APS cavity. The positron is initially placed at the deceleration phase and gradually slipped down to acceleration phase. Because the beam-loading is expected to be more than 1A with a multi-bunch format, the compensation is essential to obtain uniform intensity over the pulse. A conventional method for the compensation is controlling the timing, but it doesn’t work in off-crest case. In this manuscript, we discuss the compensation with the phase and amplitude modulation on the input RF.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB015  
About • paper received ※ 19 May 2021       paper accepted ※ 27 July 2021       issue date ※ 26 August 2021  
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TUPAB026 Application of Plasma Lenses as Optical Matching Device for Positron Sources at Linear Colliders plasma, simulation, target, optical-matching 1394
 
  • M. Formela, N. Hamann, G.A. Moortgat-Pick
    University of Hamburg, Hamburg, Germany
  • K. Flöttmann, G.A. Moortgat-Pick
    DESY, Hamburg, Germany
  • S. Riemann
    DESY Zeuthen, Zeuthen, Germany
  
  Funding: Quantum Universe
In the baseline design of the International Linear Collider (ILC) an undulator-based positron source is foreseen. The proposed luminosity of the recently chosen first energy stage with √{s}=250 GeV requires an improvement by a factor of 2500 to the world’s first linear collider, the past SLC experiment. This ambitious luminosity goal can only be achieved, if all technological boundaries are being pushed. One such area is the captured positron number, which is primarily determined in the capture section within the positron source and specifically by its optical matching device. It is responsible for transforming the phase-space of the outgoing particles produced in the target for the succeeding accelerator sections. The plasma lens is a new candidate for this task. It being an especially adequate method due its magnetic field being azimuthal. Optimizing an idealised tapered active plasma lens for the ILC led us to a design with improved captured positron yield, outperforming ILC’s currently proposed quarter wave transformer by approximately 50%. The captured yield also proved to be stable within ±1.5% for deviations in design parameters of ±10%. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB026  
About • paper received ※ 20 May 2021       paper accepted ※ 24 June 2021       issue date ※ 24 August 2021  
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TUPAB156 Optimal Field Shape, Accelerating Positron Bunch in Plasma Wakefield plasma, wakefield, electron, acceleration 1747
 
  • R.T. Ovsiannikov
    KhNU, Kharkov, Ukraine
  • I.P. Levchuk (Yarovaya), V.I. Maslov, I.N. Onishchenko
    NSC/KIPT, Kharkov, Ukraine
  
  Funding: This work is supported by National Research Fundation of Ukraine "Leading and Young Scientists Research Support", grant agreement # 2020.02/0299.
The quality of the electron or positron beam, accelerated in plasma accelerators, is still insufficient for applications. Accurate control over the properties of the electron or positron beam is a key issue for wakefield plasma accelerators. The effect of the presence of a witness-beam (the effect of the spatial charge distribution of the witness beam) (see [*, **]) to compensate the energy spread of the positron beam in plasma wakefield accelerators has been studied. This paper presents the results of a numerical simulation on the optimization of the parameters of the driver-bunch and witness-bunch for the formation of a self-consistent longitudinal distribution of the accelerating plateau-type field, which leads to the same values of the wakefield for the whole bunch of accelerated particles and minimizing bunch degradation during acceleration by means of an ion-driver-bunch with external injection into the plasma wake accelerator. The dependence of the longitudinal distribution of the accelerating wakefield on the density and shape of the accelerated bunch in the blowout regime was investigated. Plateau formation and energy spread compensation were observed.
* Romeo S., Ferrario M., Rossi A.R. Phys. Rev. Accel. Beams. 23 (2020) 071301.
** Katsouleas T. et al. Particle Accelerators. 22 (1987) 81. 		 
poster icon Poster TUPAB156 [1.200 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB156  
About • paper received ※ 18 May 2021       paper accepted ※ 16 June 2021       issue date ※ 25 August 2021  
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TUPAB362 Physical Design of Electrostatic Deflector in CSNS Muon Source simulation, high-voltage, emittance, operation 2360
 
  • Y.W. Wu, S. Li, J.Y. Tang, X. Wu
    IHEP, Beijing, People’s Republic of China
  • C.D. Deng, Y. Hong
    DNSC, Dongguan, People’s Republic of China
  • Y.Q. Liu
    IHEP CSNS, Guangdong Province, People’s Republic of China
  
  CSNS will build a muon source at the end of the RTBT. In the current design, the muon source propose two schemes, namely the baseline scheme and the baby scheme. High voltage electrostatic deflectors (ESD) are used to deflect the beam in the two schemes. A three-channel ESD with 400 kV HV is employed in the baseline scheme and a 210 kV dual-channel ESD in the simplified scheme. According to physical requirements, the electric field concentration factor is introduced, and the electrode of ESD is theoretically designed. 2D and 3D simulations are carried out to analyze the characteristics of electric field distribution by OPERA. The geometry of the electrodes also met the requirements of electric field uniformity, high voltage resistance and mechanical strength at the same time. In the baseline scheme and the baby scheme, the ESD electric field concentration factors are 1.36 and 1.53, and the maximum electric field is 6.78MV/m and 4.6MV/m, respectively. The design meets the requirements and is reasonably feasible.  
poster icon Poster TUPAB362 [2.214 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB362  
About • paper received ※ 13 May 2021       paper accepted ※ 09 June 2021       issue date ※ 22 August 2021  
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WEPAB013 A New Algorithm for Positron Source Parameter Optimisation target, electron, simulation, linac 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 ※ 17 August 2021  
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WEPAB014 Optimisation of the CLIC Positron Source target, simulation, linac, electron 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 ※ 25 August 2021  
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WEPAB015 Comparison of Different Matching Device Field Profiles for the FCC-ee Positron Source target, linac, electron, simulation 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 ※ 30 August 2021  
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WEPAB075 Xenos: X-Ray Monte Carlo Code Suite electron, simulation, photon, operation 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 ※ 25 August 2021  
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WEPAB144 A New Flux Concentrator Made of Cu Alloy for the SuperKEKB Positron Source operation, vacuum, target, GUI 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 ※ 26 August 2021  
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WEPAB358 Development of Low-Z Collimator for SuperKEKB impedance, cavity, electron, operation 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 ※ 10 August 2021  
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WEPAB359 Report on Collimator Damaged Event in SuperKEKB electron, detector, MMI, operation 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 ※ 20 August 2021  
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THPAB021 Status of VEPP-5 Injection Complex injection, damping, electron, linac 3796
 
  • F.A. Emanov, A.V. Andrianov, K.V. Astrelina, V.V. Balakin, A.M. Barnyakov, A.M. Batrakov, O.V. Belikov, D.E. Berkaev, Y.M. Boimelshtain, D. Bolkhovityanov, A. Butakov, A.R. Frolov, G.V. Karpov, A.S. Kasaev, A.A. Kondakov, N.Kh. Kot, E.S. Kotov, G.Y. Kurkin, R.M. Lapik, N.N. Lebedev, A.E. Levichev, Yu.I. Maltseva, P.V. Martyshkin, S.V. Motygin, A.A. Murasev, V. Muslivets, D.A. Nikiforov, A.V. Pavlenko, A.M. Pilan, Yu.A. Rogovsky, S.L. Samoylov, A.G. Tribendis, S. Vasiliev, V.D. Yudin
    BINP SB RAS, Novosibirsk, Russia
  
  VEPP-5 injection complex is being put into operation as beam source of VEPP-2000 and VEPP-4 colliders at the end of 2016. Since then injection complex demonstrated maximum positron storage rate 1.7·1010 e+/s and stable operation at the energy of 430 MeV. Latest operation results and prospects are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB021  
About • paper received ※ 20 May 2021       paper accepted ※ 27 July 2021       issue date ※ 27 August 2021  
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THPAB041 Design of Photon Masks for the ILC Positron Source photon, undulator, site, target 3834
 
  • K.S. Alharbi, G.A. Moortgat-Pick, A. Ushakov
    University of Hamburg, Hamburg, Germany
  • K.S. Alharbi, S. Riemann
    DESY Zeuthen, Zeuthen, Germany
  • K.S. Alharbi, A.O. Alrashdi
    King Abdulaziz City for Science and Technology (KACST), The National Center for Accelerator Technology, Riyadh, Kingdom of Saudi Arabia
  • G.A. Moortgat-Pick
    DESY, Hamburg, Germany
  • P. Sievers
    CERN, Geneva, Switzerland
  
  A long superconducting helical undulator is planned as baseline to produce polarized positrons at the International Linear Collider (ILC). To protect the undulator walls from synchrotron radiation, masks must be inserted along the undulator line. The power distribution deposited at these masks is studied in order to design the photon masks.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB041  
About • paper received ※ 19 May 2021       paper accepted ※ 07 July 2021       issue date ※ 12 August 2021  
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THPAB042 Bending Radius Limits of Different Coated REBCO Conductor Tapes - An Experimental Investigation with Regard to HTS Undulators undulator, experiment, collider, wiggler 3837
 
  • S.C. Richter, A. Bernhard, A. Drechsler, A.-S. Müller, B. Ringsdorf, S.I. Schlachter
    KIT, Karlsruhe, Germany
  • S.C. Richter, D. Schoerling
    CERN, Geneva, Switzerland
  
  Funding: This work has been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Research (grant no. 05E18CHA).
Compact FELs require short-period, high-field undulators in combination with compact accelerator structures to produce coherent light up to X-rays. Likewise, for the production of low emittance positron beams for future lepton colliders, like CLIC or FCC-ee, high-field damping wigglers are required. Applying high-temperature superconductors in form of coated REBCO tape conductors allows reaching higher magnetic fields and larger operating margins as compared to low-temperature superconductors like Nb-Ti or Nb3Sn. However, short undulator periods like 13 mm may require bending radii of the conductor smaller than 5 mm inducing significant bending strain on the superconducting layer and may harm its conducting properties. In this paper, we present our designed bending rig and experimental results for REBCO tape conductors from various manufacturers and with different properties. Investigated bending radii reach from 20 mm down to 1 mm and optionally include half of a helical twist. To represent magnet winding procedures, the samples were bent at room temperature and then cooled down to T = 77 K in the bent state to test for potential degradation of the superconducting properties. 		 
poster icon Poster THPAB042 [1.871 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB042  
About • paper received ※ 19 May 2021       paper accepted ※ 18 June 2021       issue date ※ 25 August 2021  
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THPAB113 The Extended Operative Range of the LNF LINAC and BTF Facilities linac, experiment, target, klystron 3987
 
  • L.G. Foggetta, M. Belli, B. Buonomo, F. Cardelli, R. Ceccarelli, A. Cecchinelli, R. Clementi, D. Di Giovenale, C. Di Giulio, G. Piermarini, L.A. Rossi, S. Strabioli, R. Zarlenga
    INFN/LNF, Frascati, Italy
  
  Funding: These activities has been partially supported by AIDA-2020 Grant Agreement 654168 and ERAD projects.
In 2020 the INFN-LNF LINAC and BTF have performed long-term runs for test beams and fixed-target experiments. The scientific needs of these items have been leading our groups to continuous improvements of the LINAC operative range both in pulse time at maximum energy and on the minimum transported energy, until the reset to DAΦNE injections at the beginning of 2021. We will also show the BTF recent developments in the transported beams and the second line installation. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB113  
About • paper received ※ 19 May 2021       paper accepted ※ 27 July 2021       issue date ※ 27 August 2021  
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THPAB270 Pair Spectrometer for FACET-II electron, scattering, detector, photon 4336
 
  • B. Naranjo, G. Andonian, A. Fukasawa, N. Majernik, M.H. Oruganti, J.B. Rosenzweig, Y. Sakai, O. Williams, M. Yadav
    UCLA, Los Angeles, California, USA
  • N. Cavanagh, G. Sarri
    Queen’s University of Belfast, Belfast, Northern Ireland, United Kingdom
  • A. Di Piazza, C.H. Keitel
    MPI-K, Heidelberg, Germany
  • E. Gerstmayr, S. Meuren, D.A. Reis, D.W. Storey, V. Yakimenko
    SLAC, Menlo Park, California, USA
  • R. Holtzapple
    CalPoly, San Luis Obispo, California, USA
  • C. Nielsen
    AU, Aarhus, Denmark
  
  Funding: DARPA GRIT Contract 20204571, DOE HEP Grant DE-SC0009914
We present the design of a pair spectrometer for use at FACET-II, where there is a need for spectroscopy of photons having energies up to 10 GeV. Incoming gammas are converted to high-energy positron-electron pairs, which are then subsequently analyzed in a dipole magnet. These charged particles are then recorded in arrays of acrylic Cherenkov counters, which are significantly less sensitive to background x-rays than scintillator counters in this case. To reconstruct energies of single high-energy photons, the spectrometer has a sensitivity to single positron-electron pairs. Even in this single-photon limit, there is always some low-energy continuum present, so spectral deconvolution is not trivial, for which we demonstrate a maximum likelihood reconstruction. Finally, end-to-end simulations of experimental scenarios, together with anticipated backgrounds, are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB270  
About • paper received ※ 20 May 2021       paper accepted ※ 28 July 2021       issue date ※ 18 August 2021  
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THPAB273 Spectral Reconstruction for FACET-II Compton Spectrometer photon, network, electron, site 4346
 
  • Y. Zhuang, B. Naranjo, J.B. Rosenzweig, M. Yadav
    UCLA, Los Angeles, USA
  
  Funding: This work was supported by DOE Contract DE-SC0009914, NSF Grant No. PHY-1549132, and DARPA GRIT Contract 20204571.
The Compton spectrometer under development at UCLA for FACET-II is a versatile tool to analyze gamma-ray spectra in a single shot, in which the energy and angular position of the incoming photons are recorded by observing the momenta and position of Compton scattered electrons. We present methods to reconstruct the primary spectrum from these data via machine learning and the EM Algorithm. A multi-layer fully connected neural network is used to perform the regression task of reconstructing both the double-differential spectrum and the photon energy spectrum incident with zero angular offset. We present the expected performance of these techniques, concentrating on the achievable energy resolution. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB273  
About • paper received ※ 20 May 2021       paper accepted ※ 28 July 2021       issue date ※ 16 August 2021  
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