IPAC2021 - Table of Session: THPAB (Thursday Poster Session)

Paper	Title	Page
THPAB001	Reaching the Sub Per Mil Level Coupling Corrections in the LHC	3752
	E.J. Høydalsvik, T.H.B. Persson CERN, Geneva, Switzerland
	The High Luminosity LHC (HL-LHC) is requiring sub per mil coupling correction, as defined by the closest tune approach. In this article, the current coupling correction strategy is analyzed in order to understand if it can robustly correct to these very low levels. The impact of realistic errors on the coupling correction is investigated with MAD-X simulations, including the influence of local coupling on the global coupling correction. Through simulations and measurements in the LHC, the effect of BPM noise on the coupling correction is analyzed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB001
About •	paper received ※ 11 May 2021 paper accepted ※ 28 July 2021 issue date ※ 23 August 2021
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THPAB002	Lattice Design for BEPCII Upgrade	3756
	H. Geng, W.B. Liu, J. Qiu, J. Xing, C.H. Yu, Y. Zhangpresenter IHEP, Beijing, People’s Republic of China
	The Beijing Electron Positron Collider II (BEPCII) has achieved a series of achievements in high-energy physics study. Along with the deepening of the research, more important physics is expected in higher energy regions (>2.1 GeV). As the upper limit of BEPCII design energy is 2.1GeV, an urgent upgrade is required for BEPCII. To achieve a higher luminosity at higher energy, the number of RF cavities is expected to be doubled. In this paper, the lattice design for the upgrade of BEPCII is studied. The dynamic aperture tracking result shows that the lattice could meet the injection requirement of the BEPCII beam with a reasonable margin.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB002
About •	paper received ※ 14 May 2021 paper accepted ※ 17 June 2021 issue date ※ 14 August 2021
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THPAB003	Application of Generalized Gaussian Distribution in the Processing the Wire Scanner Data	3759
	H. Geng, C. Meng, F. Yan, Y. Zhangpresenter, Y.L. Zhao IHEP, Beijing, People’s Republic of China
	Wire scanners are widely used for measuring beam emittance in both electron and hadron accelerators. Gaussian fitting is the most commonly used method in processing the wire scanner data. But in hadron machines, beams are normally not gaussian distribution due to the action of nonlinear forces such as space charge effect. Under these circumstances, there would be big deviations if the wire scanner data was still fitted with gaussian distributions. This paper introduces generalized Gaussian distribution in the processing the wire scanner data measured in the ADS injector-I. The results using different fitting method will be compared.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB003
About •	paper received ※ 14 May 2021 paper accepted ※ 18 June 2021 issue date ※ 30 August 2021
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THPAB007	Technology Spinoff and Lessons Learned from the 4-Turn ERL CBETA	3762
	K.E. Deitrick, N. Banerjee, A.C. Bartnik, D.C. Burke, J.A. Crittenden, J. Dobbins, C.M. Gulliford, G.H. Hoffstaetter, Y. Li, W. Lou, P. Quigley, D. Sagan, K.W. Smolenski Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.S. Berg, S.J. Brooks, R.L. Hulsart, G.J. Mahler, F. Méot, R.J. Michnoff, S. Peggs, T. Roser, D. Trbojevic, N. Tsoupas BNL, Upton, New York, USA T. Miyajima KEK, Ibaraki, Japan
	The Cornell-BNL ERL Test Accelerator (CBETA) developed several energy-saving measures: multi-turn energy recovery, low-loss superconducting radiofrequency (SRF) cavities, and permanent magnets. With green technology becoming imperative for new high-power accelerators, the lessons learned will be important for projects like the FCC-ee or new light sources, where spinoffs and lessons learned from CBETA are already considered for modern designs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB007
About •	paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 12 August 2021
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THPAB009	A Hard X-Ray Compton Source at CBETA	3765
	K.E. Deitrick, C. Franck, G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J. Crone, H.L. Owen UMAN, Manchester, United Kingdom G.A. Krafft JLab, Newport News, Virginia, USA G.A. Krafft, B. Terzić ODU, Norfolk, Virginia, USA B.D. Muratori, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom B.D. Muratori, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Inverse Compton scattering (ICS) holds the potential for future high flux, narrow bandwidth x-ray sources driven by high quality, high repetition rate electron beams. CBETA, the Cornell-BNL Energy recovery linac (ERL) Test Accelerator, is the world’s first superconducting radiofrequency multi-turn ERL, with a maximum energy of 150 MeV, capable of ICS production of x-rays above 400 keV. We present an update on the bypass design and anticipated parameters of a compact ICS source at CBETA. X-ray parameters from the CBETA ICS are compared to those of leading synchrotron radiation facilities, demonstrating that, above a few hundred keV, photon beams produced by ICS outperform those produced by undulators in term of flux and brilliance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB009
About •	paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 10 August 2021
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THPAB011	Monte Carlo Driven MDI Optimization at a Muon Collider	3769
	C. Curatolo, D. Lucchesi Univ. degli Studi di Padova, Padova, Italy F. Collamati INFN-Roma1, Rome, Italy C. Curatolo, D. Lucchesi INFN- Sez. di Padova, Padova, Italy A. Mereghetti CERN, Meyrin, Switzerland A. Mereghetti CNAO Foundation, Pavia, Italy N.V. Mokhov Fermilab, Batavia, Illinois, USA M.A. Palmer BNL, Upton, New York, USA P.R. Sala INFN-Milano, Milano, Italy
	A Muon Collider represents a very interesting possibility for a future machine to explore the energy frontier in particle physics. However, to reach the needed luminosity, beam intensities of the order of 10⁹–10¹² muons per bunch are needed. In this context, the Beam-Induced Background must be taken into account for its effects on magnets and detector. Several mitigation strategies can however be conceived. In this view, it is of crucial importance to develop a flexible tool that allows to easily reconstruct the machine geometry in a Monte Carlo code, allowing to simulate in detail the interaction of muon decay products in the machine, while being able to change the machine optics itself to find the best configuration. In this contribution, a possible approach to such a purpose is presented, based on FLUKA for the Monte Carlo simulation and on LineBuilder for the geometry reconstruction. Results based on the 1.5 TeV machine optics developed by the MAP collaboration are discussed, as well as a first approach to possible mitigation strategies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB011
About •	paper received ※ 19 May 2021 paper accepted ※ 13 July 2021 issue date ※ 01 September 2021
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THPAB012	The Magnetic Compensation Scheme of the FCC-ee Detectors	3773
	M. Koratzinos, K. Oide CERN, Meyrin, Switzerland
	A crucial part of the design of an FCC-ee detector is the minimisation of the disruption of the beam due to the presence of a large and powerful detector magnet. Indeed, the emittance blow-up of the few meters around the interaction point (IP) at lower energies is comparable to the emittance introduced by the rest of the 100 km ring. Vertical emittance is the single most important factor in achieving high performance (luminosity, in this case) in a modern e⁺ e⁻ storage ring such as the FCC-ee. The design adopted is the simplest possible arrangement that can nevertheless deliver high performance: two additional coils per IP side. The performance achieved is such that vertical emittance blow-up will not be a limiting performance factor even in the case of a ring with four experiments, and even in the most demanding energy regime, that of the Z running (about 45 GeV beam energy).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB012
About •	paper received ※ 10 May 2021 paper accepted ※ 28 July 2021 issue date ※ 30 August 2021
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THPAB013	Magnetic Measurements at Warm of the First FCC-ee Final Focus Quadrupole Prototype	3777
	M. Koratzinos MIT, Cambridge, Massachusetts, USA G. Kirby, M. Liebsch, C. Petrone CERN, Geneva, Switzerland
	The first FCC-ee final focus quadrupole prototype has been designed, manufactured, assembled and tested at warm. The prototype is a single aperture quadrupole magnet of the CCT type. One edge of the magnet was designed with local multipole cancellation, whereas the other was left with the conventional design. An optimized rotating induction-coil sensor was used. A technique was developed to take into account field distortions due to the environment of the test and distinguish them from magnet effects, demonstrating an excellent field quality for the prototype.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB013
About •	paper received ※ 11 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021
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THPAB014	Matlab Simulations of the Helium Liquefier in the FREIA Laboratory	3781
	E. Waagaard, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden
	We describe simulations that track a state vector with pressure, temperature, and gas flow through the helium liquefier in the FREIA laboratory. Most components, including three-way heat exchangers, are represented by matrices that allow us to track the state through the system. The only non-linear element is the Joule-Thomson valve, which is represented by a non-linear map for the state variables. Realistic properties for the enthalpy and other thermodynamic quantities are taken into account with the help of the Coolprop library. The resulting system of equations is rapidly solved by iteration and shows good agreement with the observed LHe yield with and without nitrogen pre-cooling.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB014
About •	paper received ※ 13 May 2021 paper accepted ※ 14 July 2021 issue date ※ 26 August 2021
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THPAB015	Studies of the Imperfection in Crab Crossing Scheme for Electron-Ion Collider	3784
	Y. Hao, J.S. Berg, D. Holmes, Y. Luo, C. Montag BNL, Upton, New York, USA V.S. Morozov JLab, Newport News, Virginia, USA J. Qiang LBNL, Berkeley, California, USA D. Xu FRIB, East Lansing, Michigan, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. Crab crossing scheme is the essential scheme that accommodates large crossing angle without loss of luminosity in the design of Electron-Ion collider (EIC). The ideal optics and phase advances of the crab cavity pair are set to create a local crabbing bump in the interaction region (IR). However, there are always small errors in the actual lattice of IR. In this article, we will present the simulation and analytical studies on the imperfections in the crab crossing scheme in the EIC design. The tolerance of the imperfection and the possible remedies can be concluded from these studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB015
About •	paper received ※ 17 May 2021 paper accepted ※ 16 July 2021 issue date ※ 12 August 2021
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THPAB016	Revisit of Nonlinear Dynamics in Hénon Map Using Square Matrix Method	3788
	Y. Hao, K.J. Anderson FRIB, East Lansing, Michigan, USA L.H. Yu BNL, Upton, New York, USA
	Funding: Work supported by the Accelerator Stewardship program, award number DE-SC0019403 with the U.S. Department of Energy Hénon map (2D or 4D) represents a thin lens sextupole in an otherwise linear lattice and had been well studied for many decades. We revisit the nonlinear properties of the Hénon map with the aid of the square matrix method and Arnold theorem, including acquiring the resonance structure and amplitude-dependent frequency.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB016
About •	paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 17 August 2021
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THPAB017	The International Muon Collider Collaboration	3792
	D. Schulte CERN, Meyrin, Switzerland
	A muon collider offers a unique opportunity for high-energy, high-luminosity lepton collisions and could push the frontiers of particle physics by providing excellent discovery reach with excellent precision. A scheme has been developed by the MAP collaboration. The updated European Strategy for Particle Physics recommended the development of an Accelerator R&D Roadmap for Europe and CERN Council has charged the LDG to develop it. LDG has initiated panels to provide input including one on the use of muon beams, in particular in view of a high-energy, high luminosity muon collider. A new international collaboration, is forming to develop a muon collider design and address the associated challenges, which are mainly due to the limited muon lifetime. The focus is on two energy ranges, around 3 TeV and above 10 TeV. Ambitious magnets, RF systems, targets and shielding are key for the design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB017
About •	paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 11 August 2021
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THPAB021	Status of VEPP-5 Injection Complex	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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THPAB022	Possibilities for Upgrading to Polarized SuperKEKB	3799
	Z.J. Liptak, M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan J.M. Roney Victoria University, Victoria, B.C., Canada
	The SuperKEKB accelerator is currently in operation in Tsukuba, Japan, with a planned long shutdown in 2026. Among the possible upgrades being considered during this period is the change to a polarized electron beam in the High Energy Ring. Such a change would require modifications in the source generation and transport, geometrical and lattice variations to provide spin rotation, and polarimetry. A Polarized SuperKEKB Working Group has been formed from members of the Belle II experiment and the SuperKEKB accelerator team to investigate the possibilities and challenges of these modifications. This talk lays out the goals of the proposed upgrade, considers the necessary changes to the existing accelerator and their feasibility and lays out the physics motivation behind such an effort.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB022
About •	paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 29 August 2021
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THPAB025	A Proposed Beam-Beam Test Facility COMBINE	3802
	E.A. Nissen, G.A. Krafft JLab, Newport News, Virginia, USA J.R. Delayen ODU, Norfolk, Virginia, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, license to publish or reproduce this manuscript. The COmpact Machine for Beam-beam Interactions in Non-Equilibrium systems (COMBINE) is a proposed, dedicated, beam-beam test facility. The base design would make use of a pair of identical octagonal rings (2.5 meters per side) one rotated 180 degrees from the other, meeting at their common interaction point. These would be fed by an electron gun producing up to 125 keV electrons. The low energy will allow for beam-beam tune shifts commensurate with existing colliders, some linac-ring type systems, and will also allow for an exploration of the predicted effects of gear-changing, which would be performed using a variable pathlength scheme. The low energy, and small size will allow for cost effective research, simulation code benchmarking, as well as training opportunities for students.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB025
About •	paper received ※ 20 May 2021 paper accepted ※ 01 September 2021 issue date ※ 16 August 2021
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THPAB026	Final Booster Complex Design for the Jefferson Lab Electron Ion Collider	3805
	E.A. Nissen JLab, Newport News, Virginia, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. retains a license to publish or reproduce this manuscript for U.S. Government purposes. In this work we show the final iteration of the design for the booster complex of the Jefferson Lab EIC, which would have brought the ions from an energy (proton) of 150 MeV up to 12.1 GeV. This complex would have consisted of two figure-8 rings. The Low Energy Booster (LEB) which would have accelerated its protons from 150 MeV to 8 GeV, and has had its lattice tweaked to increase the effectiveness of chromaticity cancellations. The High Energy Booster (HEB) would have brought the 8 GeV protons up to 12.1 GeV. The HEB would in the tunnel that was designed for the collider rings, sitting on top of them. It has had a bypass around the interaction region added, as well as a cooling solenoid installed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB026
About •	paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 31 August 2021
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THPAB028	Beam-Beam Related Design Parameter Optimization for the Electron-Ion Collider	3808
	Y. Luo, J.S. Berg, M. Blaskiewicz, W. Fischer, X. Gu, H. Lovelace III, C. Montag, R.B. Palmer, S. Peggs, V. Ptitsyn, F.J. Willeke BNL, Upton, New York, USA Y. Hao, D. Xu FRIB, East Lansing, Michigan, USA H. Huang ODU, Norfolk, Virginia, USA E.A. Nissen, T. Satogata JLab, Newport News, Virginia, USA J. Qiang LBNL, Berkeley, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The design luminosity goal for the Electron-Ion Collider (EIC) is 1e34 cm^-2s⁻¹. To achieve such a high luminosity, the EIC design adopts high bunch intensities, flat beams at the interaction point (IP) with a small vertical β^*-function, and a high collision frequency, together with crab cavities to compensate the geometrical luminosity loss due to the large crossing angle of 25mrad. In this article, we present our strategies and approaches to obtain the design luminosity by optimizing some key beam-beam related design parameters. Through our extensive strong-strong and weak-strong beam-beam simulations, we found that beam flatness, electron and proton beam size matching at the IP, electron and proton working points, and synchro-betatron resonances arising from the crossing angle collision play a crucial role in proton beam size growth and luminosity degradation. After optimizing those parameters, we found a set of beam-beam related design parameters to reach the design luminosity with an acceptable beam-beam performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB028
About •	paper received ※ 17 May 2021 paper accepted ※ 28 July 2021 issue date ※ 25 August 2021
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THPAB029	Dynamic Aperture Evaluation for the Hadron Storage Ring in the Electron-Ion Collider	3812
	Y. Luo, J.S. Berg, M. Blaskiewicz, W. Fischer, X. Gu, H. Lovelace III, C. Montag, R.B. Palmer, S. Peggs, V. Ptitsyn, F.J. Willeke, H. Witte BNL, Upton, New York, USA Y. Hao, D. Xu FRIB, East Lansing, Michigan, USA H. Huang ODU, Norfolk, Virginia, USA V.S. Morozov, E.A. Nissen, T. Satogata JLab, Newport News, Virginia, USA J. Qiang LBNL, Berkeley, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The Electron-Ion Collider (EIC) is aiming at a design luminosity of 1e34 cm^-2s⁻¹. To maintain such a high luminosity, both beams in the EIC need an acceptable beam lifetime in the presence of the beam-beam interaction. For this purpose, we carried out weak-strong element-by-element particle tracking to evaluate the long-term dynamic aperture for the hadron ring lattice design. We improved our simulation code SimTrack to treat some new lattice design features, such as radially offset on-momentum orbits, coordinate transformations in the interaction region, etc. In this article, we will present the preliminary dynamic aperture calculation results with β^*- function scan, radial orbit shift, crossing angle collision, and magnetic field errors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB029
About •	paper received ※ 17 May 2021 paper accepted ※ 01 September 2021 issue date ※ 28 August 2021
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THPAB031	Dump Line Layout and Beam Dilution Pattern Optimization of the Future Circular Collider	3815
	B. Facskó, D. Barna Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary A. Lechner, E. Renner CERN, Geneva, Switzerland
	To avoid any damage to the beam dump target in the Future Circular Collider, the beam will be swept over its surface using oscillating kickers in the x/y planes with a 90-degree phase difference, and an amplitude changing in time, creating a spiral pattern. The ideal pattern must have an increasing spiral pitch towards smaller radii to produce an even energy deposition density. We recommend the realization of the optimal pattern using two beating frequencies. This method enables a flat energy deposition density while only using simple independent damped oscillators. In this poster, we also present the study of the beamline optics and hardware that can realize the needed pattern. Two different possible hardware layouts were examined and optimized as well.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB031
About •	paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 18 August 2021
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THPAB035	Study of the Tolerances for Superconducting Undulators at the European XFEL	3819
	B. Marchetti, S. Casalbuoni, V. Grattoni, S. Serkez EuXFEL, Schenefeld, Germany
	European XFEL is investing in the development of superconducting undulators (SCUs) for future upgrade of its beamlines SCUs made of NbTi, working at 2K, with a period length of 15 mm and a vacuum gap of 5 mm allow covering a range between 54 keV and 100 keV for 17.5 GeV electron energy. The effect of mechanical errors in the distribution of K along the undulators is more relevant for working points at lower photon energy, which are obtained using a higher magnetic field in the undulator. In this article we investigate the effect of error distribution in the K-parameter for a working point at 50keV photon energy obtained injecting an electron beam with 16.5 GeV energy from the XFEL linear accelerator in a undulator line composed by SCUs with 1.58 T peak magnetic field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB035
About •	paper received ※ 12 May 2021 paper accepted ※ 05 July 2021 issue date ※ 18 August 2021
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THPAB036	Superconducting Phase Shifter Design for the Afterburner at the European XFEL	3823
	V. Grattoni, J.E. Baader, S. Casalbuoni EuXFEL, Schenefeld, Germany
	At the European XFEL, a superconducting afterburner is under design for the SASE2 hard X-ray beamline. It will consist of 5 undulator modules. One module corresponds to two superconducting undulator (SCU) coils of 2 m length plus one phase shifter. Such an afterburner will enable photon energies above 30 keV. Superconducting (SC) phase shifters will be installed in each undulator module to keep the correct phase delay between the electron beam and photon beam. In this contribution, we present the required SC phase shifter parameters to enable operation in the electron beam energy range 11.5-17.5 GeV. We also analyze different magnetic designs satisfying the calculated specifications.
	Poster THPAB036 [0.991 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB036
About •	paper received ※ 18 May 2021 paper accepted ※ 06 July 2021 issue date ※ 12 August 2021
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THPAB037	Insertion Devices Impact on Solaris Storage Ring Optics	3827
	G.W. Kowalski, R. Panaś, A.I. Wawrzyniak NSRC SOLARIS, Kraków, Poland
	Solaris storage ring is currently operating with three insertion devices. The IDs installed are the APPLE II type elliptically polarised undulators (EPU). The UARPES beamline is operating with the long period length EPU of 120 mm (EPU120) which has a significant impact on the linear optics and tune shift. The linear optics compensation of the EPU120 impact is realised by local adjustment of SQFO quadrupole/sextupole focusing gradient and defocusing gradient in the flanking dipoles. Two additional EPUs with period lengths of 58 and 46.6 mm are recently installed for next beamlines PHELIX and DEMETER, respectively and are under commissioning now. To reduce the impact of all undulators movement the additional correction coils are installed and the correction feedforward tables has been determined experimentally. Additionally to keep the tune at the nominal values the tune feedback is planned to be implemented. Within this presentation the effect of all existing insertion devices on the linear optics based on measurements and simulations to be discussed. Moreover the nonlinear effects, especially the impact on dynamic aperture of Solaris storage ring will be investigated.
	Poster THPAB037 [2.522 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB037
About •	paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 30 August 2021
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THPAB040	A Phase Shifter for Inline Undulators at the Advanced Photon Source Upgrade Project	3830
	E.R. Moog, R.J. Dejus, A.T. Donnelly, Y. Piao, M.F. Qian, 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. Several undulator lines for the Advanced Photon Source Upgrade (APS-U) will consist of two inline undulators. In order to keep the undulators operating with optimal phasing over the full range of gaps, a phase shifter will be included between the undulators. A design has been developed for a phase shifter that will serve for a variety of undulator period lengths and gap ranges. The permanent-magnet phase shifter will use SmCo magnets to reduce the risk of radiation-induced demagnetization. The available space between the undulators is tight, so magnetic shields are placed between the undulators, the phase shifter, and the corrector magnet that is also located in the inter-undulator space. While these shields guard against magnetic cross-talk between the devices as the undulator and phase shifter gaps change, they do have an effect on the end fields of the devices. These end-field effects are examined and relevant tolerances are set and presented.
	Poster THPAB040 [0.429 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB040
About •	paper received ※ 23 May 2021 paper accepted ※ 21 June 2021 issue date ※ 14 August 2021
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THPAB041	Design of Photon Masks for the ILC Positron Source	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	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 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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THPAB043	A Superconducting Undulator for CompactLight: Resistive Wall Wakefield Analysis	3841
	K.B. Marinov STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The CompactLight project is an advanced X-ray FEL light source, with high-frequency, high-gradient linacs and compact undulators. Lower electron energies give higher energy efficiency and a smaller environmental footprint. The extremely short bunch lengths (few fs) and narrow undulator gaps (4 mm) drastically increase the impact of resistive wall wakefields on the lasing process. The longitudinal resistive wall wakefield impedance is calculated in the framework of the surface impedance approach, in accordance with anomalous skin effect (ASE) theory. The dependence of the electron energy loss factor and the correlated energy spread of the bunch on the residual resistivity ratio (RRR) for both copper and aluminum is much higher for long (100 fs) than for ultra-short (6 fs) bunches. This is due to a known property of the longitudinal wakefield impedance - the field acting on a single particle traversing a resistive vessel does not depend on the conductivity of the vessel. The wakefields generated by the ultra-short bunch are already close to that of a single-particle regime and this leads to interesting consequences which are discussed in the present work.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB043
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 21 August 2021
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THPAB045	Design of a Short Period Helical Superconducting Undulator	3844
	A.G. Hinton STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom J. Boehm, L. Cooper, B. Green, T. Hayler, P. Jeffery, C.P. Macwaters STFC/RAL, Chilton, Didcot, Oxon, United Kingdom S. Milward DLS, Oxfordshire, United Kingdom B.J.A. Shepherd STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom B.J.A. Shepherd Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Superconducting technology provides the possibility to develop short period, small bore undulators that can generate much larger magnetic fields than alternative technologies. This may allow an XFEL with optimised superconducting undulators to cover a broader range of wavelengths than traditional undulators. At STFC, we have undertaken work to design and build a prototype helical superconducting undulator (HSCU) module with parameters suitable for use on a future XFEL facility. This work includes the design of a full 2 m long undulator module, including an undulator with 13 mm period and 5 mm inner winding diameter, the supporting cryogenic and vacuum systems required for operation, and quadrupoles, phase shifters and correction magnets for use between undulator sections. We present here the magnetic and mechanical design of the HSCU. The choice of undulator parameters and their influence on the design is discussed. A turnaround scheme to allow continuous winding of the undulator without the need for superconducting joints is also presented. Techniques for winding the undulator are currently being investigated and a short prototype will soon be wound and tested.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB045
About •	paper received ※ 17 May 2021 paper accepted ※ 18 June 2021 issue date ※ 21 August 2021
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THPAB047	Status of Magnetic Measurement Benches for Insertion Device Characterization at MAX IV Laboratory	3848
	M. Ebbeni, M. Gehlot, M. Holz, H. Tarawneh MAX IV Laboratory, Lund University, Lund, Sweden
	Insertion Devices (IDs) are the sole source of radiation used in all beamlines in MAX IV Laboratory with 14 IDs in operation of which 6 were built in-house. This paper shows the current capabilities and performance of the of the ID magnetic measurement systems, and the ongoing development work.
	Poster THPAB047 [1.185 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB047
About •	paper received ※ 11 May 2021 paper accepted ※ 27 July 2021 issue date ※ 28 August 2021
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THPAB048	Design and Fabrication Concepts of a Compact Undulator with Laser-Structured 2G-HTS Tapes	3851
	A. Will, T.A. Arndt, E. Bründermann, N. Glamann, A.W. Grau, B. Krasch, A.-S. Müller, R. Nast, D. Saez de Jauregui KIT, Karlsruhe, Germany D. Astapovych, H. De Gersem, E. Gjonaj TEMF, TU Darmstadt, Darmstadt, Germany
	To produce small-scale high-field undulators for table-top free electron lasers (FELs), compact designs have been proposed using high temperature superconducting (HTS) tapes, which show both large critical current densities and high critical magnetic fields with a total tape thickness of about 50 μm and a width of up to 12 mm. Instead of winding coils, a meander structure can be laser-scribed directly into the superconductor layer, guiding the current path on a quasi-sinusoidal trajectory. Stacking pairs of such scribed tapes allows the generation of the desired sinusoidal magnetic fields above the tape plane, along the tape axis. Two practically feasible designs are presented, which are currently under construction at KIT: A coil concept wound from a single structured tape with a length of 15 m, which is a progression of a design that has been presented already in the past, as well as a novel stacked and soldered design, made from 25 cm long structured tapes, soldered in a zig-zag-pattern. In this contribution the designs are briefly recapped and the experimental progress is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB048
About •	paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 15 August 2021
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THPAB049	Modeling the Magnetic Field of the LCLS-I Undulator for THz@PITZ	3855
	M. Krasilnikov, X. Li, A. Lueangaramwong, F. Mueller, F. Stephan DESY Zeuthen, Zeuthen, Germany A. Brachmann, H.-D. Nuhn SLAC, Menlo Park, California, USA M. Tischer, P. Vagin DESY, Hamburg, Germany
	Funding: This work was supported by the European XFEL research and development program An accelerator-based THz source for pump-probe experiments at the European XFEL is under development at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). For the proof-of-principle experiments an LCLS-I undulator is planned to be installed downstream of the PITZ accelerator. The fields of the undulator module 26 have been re-measured at DESY in Hamburg and the results are consistent with earlier SLAC measurements. A model for 3D field reconstruction based on the undulator magnetic measurements has been developed. It includes also a horizontal gradient of the vertical field. Tracking of the 17 MeV/c beam has revealed that the transverse gradient will lead to a significant off-axis trajectory in the horizontal plane. This offset has to be corrected with a steering coil, the design of which is also presented. The performance of the THz generation with the correction coil is discussed as well.
	Poster THPAB049 [1.409 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB049
About •	paper received ※ 12 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021
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THPAB050	Compact Hybrid Planar Permanent Magnet Undulator Design for the APS Upgrade	3859
	M. Abliz, M. Borland, J.H. Grimmer, J.S. Kerby, M. Ramanathan, A. Xiao ANL, Lemont, Illinois, USA
	We report on the successful design of a compact 28-mm period hybrid planar permanent magnet (HPPM) undulator for the Advanced Photon Source Upgrade (APS-U) project. The design produces a peak field of 9750 G at a gap of 8.5 mm, with a pole width reduced to 35 mm as compared to the planar undulators currently in use at the Advanced Photon Source. The design includes a detailed investigation into the origin of the HPPM undulator demagnetization. We report on a finding of an optimization method that reduces the demagnetization field and increases the field at the gap center of the design. It includes an optimization of the pole edges to increase the field and decrease roll-off in the transverse direction. Further design optimizations include analyses of the mechanical assembly tolerances and comparison with the original design before building the device. Beam physics analyses included kick-map analysis, dynamic acceptance (DA), local momentum acceptance (LMA), and Touschek lifetime of this design were performed with the 42-pm lattice of the APS-U. Detailed magnetic design, effective field, field roll-off, magnetic force, and tracking results are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB050
About •	paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 21 August 2021
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THPAB051	Vertical Septum Magnet Design for the APS Upgrade	3862
	M. Abliz, M. Borland, H. Cease, G. Decker, A.K. Jain, M.S. Jaski, M. Kasa, J.S. Kerby, U. Wienands, A. Xiao ANL, Lemont, Illinois, USA J.W. Amann SLAC, Menlo Park, California, USA D.J. Harding Fermilab, Batavia, Illinois, USA
	The vertical injection scheme proposed for the APS Upgrade (APS-U) Project requires a challenging septum magnet that must meet stringent beam physics, magnetic field leakage, and vacuum requirements. The current iteration of this magnet design includes an enlarged stored-beam chamber aperture of 9 mm x 12 mm and a reduction of the septum thickness to 1.5 mm. The enlarged aperture accommodates a non-evaporable getter (NEG)-coated stored beam chamber to better achieve the required vacuum. A prototype septum magnet has been built and measurements confirm the cancellation of a peak leakage field even though the value is six times larger than the design. The leakage field measured at the upstream (US) end cancels the downstream (DS) end as was expected by design. The measured and simulated leakage field and the stored beam trajectories are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB051
About •	paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 27 August 2021
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THPAB052	Insertion Devices at the MAX IV 3 GeV Ring	3865
	H. Tarawneh, M. Ebbeni, M. Gehlot, M. Holz MAX IV Laboratory, Lund University, Lund, Sweden
	Currently, there are 8 Insertion Devices (ID) installed and in operation and 2 new ones to be installed end of 2021 at the MAX IV 3 GeV storage ring. In this paper, the first commissioning results of the three newly installed IDs in 2020 will be described. The new IDs are one APPLE II for SoftiMAX beamline and two In-vacuum Undulators (IVU) for the DanMAX and CoSAXS beamlines. The mitigation scheme adopted to reduce undulator-like radiation from BALDER in-vacuum wiggler will be discussed. Two new IVUs with a period length of 17 mm and 18 mm for the ForMAX and MicroMAX beamlines will be installed during the winter shutdown of 2021-2022. Both IDs have 3 m lengths and a minimum gap of 4 mm. In this paper, the magnetic measurement results will be presented in terms of the achieved field quality and phase error.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB052
About •	paper received ※ 11 May 2021 paper accepted ※ 02 July 2021 issue date ※ 02 September 2021
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THPAB053	Magnetic Field Calculation of Planar SCUs Using ANSYS Maxwell	3868
	Y. Shiroyanagi, E.A. Anliker, Q.B. Hasse, H. Hu, Y. Ivanyushenkov, M. Kasa, I. Kesgin ANL, Lemont, Illinois, USA
	Funding: This work was supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) Upgrade includes a 4.8-m-long superconducting undulator (SCU) cryostat containing two 1.9-m-long, 16.5-mm-period planar NbTi undulator magnets. The magnetic and mechanical design of this magnet follows the design of the existing 1.1-m-long, 18-mm-period planar SCU that is currently in operation at the APS . Although OPERA is a reliable standard software tool for magnetic field calculations, ANSYS Maxwell 3D has the advantage of calculating a large and complex geometry. In this paper, first, the magnetic field map, including the peak field and end fields, is bench-marked against the magnetic measurement data of the existing planar SCU18-1. Then, corrector current optimization is presented for the 1.5-m-long, 21-mm-period planar SCU. Finally, a magnetic field model of a full-scale, 1.9-m-long planar SCU is presented. Y. Ivanyushenkov et al., Phys. Rev. Accel. Beams 20, 100701 (2017).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB053
About •	paper received ※ 18 May 2021 paper accepted ※ 18 June 2021 issue date ※ 11 August 2021
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THPAB054	Measurement Results of the First Scape Prototype	3872
	M. Kasa, E.A. Anliker, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The SCAPE (SuperConducting Arbitrarily Polarizing Emitter) undulator is under development at the Advanced Photon Source (APS) as a part of the APS upgrade. SCAPE is comprised of four superconducting magnets which are arranged to create an on-axis undulator field that can be planar, elliptical, or circular. As a first step towards developing a full length device, a 0.5-meter long prototype was manufactured and assembled for testing in a liquid helium bath cryostat. A description of the mechanical assembly and subsequent measurement results of the first prototype will be presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB054
About •	paper received ※ 19 May 2021 paper accepted ※ 01 September 2021 issue date ※ 22 August 2021
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THPAB055	Reconstruction of Linear Optics Observables Using Supervised Learning	3875
	E. Fol, H. Garcia, R. Tomás García CERN, Meyrin, Switzerland
	In the LHC, most of the optical functions can be obtained from turn-by-turn beam centroid data. However, the measurement of such observables as β^* and the dispersion function require special dedicated techniques and additional operational time. In this work, we propose an alternative approach to estimate these observables using supervised machine learning, in case the dedicated measurements are not available but turn-by-turn data are. The performance of developed estimators is demonstrated on LHC simulations. Comparison to traditional techniques for the computation of beta-function will be also provided.
	Poster THPAB055 [0.713 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB055
About •	paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 15 August 2021
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THPAB056	Conceptual Design of a Multiple Period Staggered Undulator	3879
	I. Asparuhov, J. Chavanne, G. Le Bec ESRF, Grenoble, France
	In staggered undulators, a ferromagnetic pole structure paired to a solenoid generates a sinusoidal field. Interest of such insertion devices has been studied for application to FEL systems in the end of the previous century. However, the concept has never been used in synchrotron radiation sources due to the undesirable magnetic effect of the solenoid on electron beam parameters in storage rings. Advent of fourth-generation low emittance light sources is foreseen to change this situation. Indeed, consequent electron beam transverse size and divergence reduction for such new storage rings give promise for a beam less sensitive to the presence of a longitudinal solenoidal field. Relating to this, a staggered concept can be an adequate design choice for short-period undulators producing high-energy photon flux. Such undulators would have a low K value a priori limiting their photon energy tunability. Considering integration of separate magnetic arrays of distinct periods in a solenoid to compose a global assembly can help suppress this possible drawback. Magnetic design and radiative performance of such an insertion device are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB056
About •	paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021
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THPAB057	Goubau-Line Set Up for Bench Testing Impedance of In-Vacuum Undulator Components	3883
	P.I. Volz, S. Grimmer, M. Huck, A. Meseck HZB, Berlin, Germany A. Meseck KPH, Mainz, Germany
	The worldwide first in-vacuum elliptical undulator, IVUE32, is being developed at Helmholtz Zentrum Berlin. The 2.5 m long device with a period length of 3.2 cm and a minimum gap of about 7 mm is to be installed in the BESSY II storage ring. It will deliver soft X-radiation to several beamlines. The proximity of the undulator structure to the electron beam makes the device susceptible to wakefield effects which can influence beam stability. A complete understanding of its impedance characteristics is required prior to installation and operation, as unforeseen heating of components could have catastrophic consequences. Since its complex structure makes numerical calculations, such as CST simulations, at high frequency very resource intensive, bench testing the device may proof invaluable. A Goubau-line is a single wire transmission line for high frequency surface waves with a transverse electric field resembling that of a charged particle beam out to a certain radial distance. This can be used to measure the impedance of vacuum chamber components. A concept optimized for bench testing IVUE32-components will be discussed and progress towards the test bench set up will be shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB057
About •	paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 21 August 2021
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THPAB060	Dispersion Controlled Temporal Shaping of Photoinjector Laser Pulses for Electron Emittance Reduction in X-Ray Free Electron Lasers	3886
	R.A. Lemons, S. Carbajo, J.P. Duris, A. Marinelli, N.R. Neveu SLAC, Menlo Park, California, USA C.G. Durfee Colorado School of Mines, Golden, USA
	Funding: Office of Science DE-SC0014664 Temporal shaping of photocathode excitation laser pulses is a long-sought-after challenge to tailor the phase-space of electrons. The temporal profile of lasers, typically up-converted from infrared to ultraviolet, have significant impact on the distribution and time-evolution of the collective electron bunches. Towards this end, we present a method combining efficient nonlinear up-conversion with simultaneous and adaptable temporal profile shaping through dispersion-controlled sum-frequency generation* resulting in temporal profiles with sharp rise-fall times and flat top profiles. Using the LCLS-II photoinjector as a case study, we demonstrate a reduction in generated electron transverse emittance by upwards of 30% over conventionally implemented temporal profiles. Additionally, we discuss the ongoing experimental implementation of this method and preliminary results. * R. Lemons, et al. arXiv:2012.00957 [physics.optics] (2020)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB060
About •	paper received ※ 17 May 2021 paper accepted ※ 08 July 2021 issue date ※ 26 August 2021
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THPAB061	Pulse-Burst CO₂ Laser for High-Brilliance Compton Light Sources	3890
	I. Pogorelsky, M.N. Polyanskiy, T.V. Shaftan BNL, Upton, New York, USA
	Funding: U.S. Department of Energy under contract DE-SC0012704 We propose a novel architecture for a mid-IR, high-repetition, kilowatt-class, CO₂ laser system operating in a pulse-burst regime and its implementation in In-verse Compton Scattering (ICS) sources of x-ray and gamma-ray radiation. Different types of particle accelerators are considered for conversion to such ICS sources, including energy recovery linacs and synchrotron storage rings. The expected ICS performance parameters are compared with earlier proposals where CBETA and DAΦNE accelerators have been paired with near-IR, mode-locked solid-state lasers operating at a multi-megahertz repetition rate. A considerable increase in acting laser energy attainable in our CO₂ laser-based scheme, combined with an order of magnitude higher number of laser photons per Joule of energy allows maintaining a similarly high average flux of produced hard x-rays while the peak flux and brilliance will be raised by three to four orders of magnitude compared to aforementioned schemes based on near-IR lasers.
	Poster THPAB061 [1.082 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB061
About •	paper received ※ 12 May 2021 paper accepted ※ 21 June 2021 issue date ※ 29 August 2021
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THPAB062	Long-Wave IR Terawatt Laser Pulse Compression to Sub-Picoseconds	3893
	I. Pogorelsky, M. Babzien, M.A. Palmer, M.N. Polyanskiy BNL, Upton, New York, USA
	Funding: U.S. Department of Energy under contract DE-SC0012704 We report an experiment and simulations on post-compression of 2 ps, 0.15 TW CO₂ laser pulses to 480 fs, ~0.25 TW by means of a self-phase modulation accompanied by a negative group dispersion in KCl and BaF2 optical slabs. In addition, down to 130 fs fine pulse structure, but at lower conversion efficiency, has been observed through self-compression in a bulk NaCl crystal. The obtained results surpass by far previous achievements in the ultra-fast long-wave IR laser technology
	Poster THPAB062 [2.675 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB062
About •	paper received ※ 12 May 2021 paper accepted ※ 18 June 2021 issue date ※ 24 August 2021
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THPAB063	Laser Transport System of Shanghai Laser Electron Gamma Source (SLEGS)	3897
	H.H. Xu, G.T. Fan SSRF, Shanghai, People’s Republic of China
	Shanghai Laser Electron Gamma Source (SLEGS) , based on laser Compton scattering (LCS), as one of beamlines of Shanghai Synchrotron Radiation Facility (SSRF) in phase II, is under construction now. The technical design of its laser injection system has been implemented and optimized consecutively over the last few years. In order to inject the 10640 nm CO₂ laser into the interaction point from the laser hutch outside the storage ring’s shielding, a laser transport system longer than 20 m using relay-imaging telescopes is designed. There are two operation mode in SLEGS. One is backscattering mode, which will make the laser and electron bunch collide at 180° with flux higher than 10⁷ gamma/s. The other mode is slanting mode, which mainly inherits the design used in the prototype. In this paper, a brief summary of the laser transport system is given. The system contains several modules to perform beam expansion, combining, monitoring and real-time adjustment. The design models, simulation study of the laser quality through the transporta-tion, and the experimental results are presented. Y. Xu, W. Xu, et al., NIM A, 578, 457 (2007). ** H.H. Xu, J.H. Chen, et al., Transaction on Nuclear Science, IEEE, 63, 906 (2016).
	Poster THPAB063 [2.508 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB063
About •	paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 27 August 2021
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THPAB064	LUMOS: A Visible Diagnostic Beamline for the Solaris Storage Ring	3901
	R. Panaś, A. Curcio, A.I. Wawrzyniak NSRC SOLARIS, Kraków, Poland
	LUMOS is a diagnostic beamline which operates in the visible region. It was installed in the Solaris storage ring during summer 2019. The first light was observed at the beginning of December 2019. During 2020 the beamline was commissioned and equipped with a streak camera setup. Currently, LUMOS allows to analyze far-field and near field images of synchrotron light for transverse beam profile measurements. Moreover, using the streak camera setup, it is also possible to investigate the bunch length, the filling pattern and the longitudinal beam profile changes with respect to the different condition (ramping, 3rd harmonic cavities tuning, etc.). During the presentation the optical setup to be presented along with the measurements conducted with it.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB064
About •	paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 01 September 2021
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THPAB065	Experimental Verification of the Source of Excessive Helical SCU Heat Load at APS	3904
	V. Sajaev, J.C. Dooling, K.C. Harkay ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Immediately after the installation of the Helical superconducting undulator (HSCU) in the APS storage ring, higher than expected heating was observed in the cryogenic cooling system. Steering the electron beam orbit in the upstream dipole reduced the amount of synchrotron radiation reaching into the HSCU and allowed the device to properly cool and operate. The simplest explanation of the excessive heat load was higher than expected heat transfer from the vacuum chamber to the magnet coils. However, modeling of the synchrotron radiation interaction with the HSCU vacuum chamber showed that Compton scattering could also result in synchrotron radiation penetrating the vacuum chamber and depositing energy directly into the HSCU coils*. In this paper, we present experimental evidence that the excessive heat load of the HSCU coils is not caused by the heat transfer from the vacuum chamber but resulted from the synchrotron radiation penetrating the vacuum chamber. M. Kasa et. al., Phys. Rev. AB, v. 23 050701 (2020) ** J. Dooling et. al., IPAC 2019 Proc., THPTS093 (2019)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB065
About •	paper received ※ 12 May 2021 paper accepted ※ 02 September 2021 issue date ※ 16 August 2021
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THPAB066	Ground Diffusion Measurement and Its Effect on APS-U Orbit Stability	3907
	V. Sajaev ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Spatial and temporal ground diffusion can be approximately described by the ATL law,. Ground diffusion can have an important effect on the long-term stability of the accelerator alignment. To estimate the possible consequences of the ground diffusion on the APS Upgrade performance, the ground diffusion constant of the existing APS tunnel was measured using historical data of the orbit correction effort and then used to estimate the ground diffusion effect on the orbit stability of the APS Upgrade. In this paper, we will describe the diffusion constant measurement and present the estimations of the expected APS-U alignment and orbit stability. B.A. Baklakov et. al., Technical Physics, v.38(10), pp.894-898(1993) ** V. Shiltsev, Physical Review Letters, 104(23), p.238501 (2010).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB066
About •	paper received ※ 12 May 2021 paper accepted ※ 13 July 2021 issue date ※ 24 August 2021
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THPAB067	Simulation of the APS-U Orbit Motion Due to RF Noise	3911
	V. Sajaev ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. APS Upgrade storage ring will keep the same rf system that is presently used at APS. This rf system has amplitude and phase noise dominated by the lines at 60, 180, and 360 Hz. APS presently operates with synchrotron frequency close to 2 kHz, which is far away from the rf noise frequencies, and still the rf system noise contributes over 2 micrometers rms into the horizontal orbit noise due to beam energy variation. APS-U will operate with a bunch-lengthening cavity, which will lower the synchrotron frequency down to about 200 Hz. This could potentially lead to large orbit noise and other negative consequences due to energy variation caused by the rf system noise. In this paper, we will present simulations of the rf noise-induced orbit motion at APS and APS-U and define the rf amplitude and phase noise requirements that need to be achieved for APS-U operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB067
About •	paper received ※ 12 May 2021 paper accepted ※ 13 July 2021 issue date ※ 23 August 2021
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THPAB068	Denoising of Optics Measurements Using Autoencoder Neural Networks	3915
	E. Fol, R. Tomás García CERN, Meyrin, Switzerland
	Noise artefacts can appear in optics measurements data due to instrumentation imperfections or uncertainties in the applied analysis methods. A special type of semi-supervised neural networks, autoencoders, are widely applied to denoising tasks in image and signal processing as well as to generative modeling. Recently, an autoencoder-based approach for denoising and reconstruction of missing data has been developed to improve the quality of phase measurements obtained from harmonic analysis of LHC turn-by-turn data. We present the results achieved on simulations demonstrating the potential of the new method and discuss the effect of the noise in light of optics corrections computed from the cleaned data.
	Poster THPAB068 [0.881 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB068
About •	paper received ※ 19 May 2021 paper accepted ※ 13 July 2021 issue date ※ 02 September 2021
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THPAB069	Design Concepts for a High-Gradient C-Band Linac	3919
	T.B. Bolin, S.I. Sosa Guitron UNM-ECE, Albuquerque, USA S. Biedron UNM-ME, Albuquerque, New Mexico, USA J.R. Cary Tech-X, Boulder, Colorado, USA M. Dal Forno SLAC, Menlo Park, California, USA
	Funding: This work was performed under Contract No. 89233218CNA000001, supported by the U.S. DOE’s National Nuclear Security Administration, for the operation of Los Alamos National Laboratory (LANL). During the last decade, the production of soft to hard x-rays (up to 25 keV) at XFEL facilities has enabled new developments in a broad range of disciplines. One caveat is that these instruments can require a large amount of real estate. For example, the XFEL driver is typically an electron beam linear accelerator (LINAC) and the need for higher electron beam energies capable of generating higher energy X-rays can require longer linacs; costs quickly become prohibitive, requiring state of art methods. One cost-saving measure is to produce a high accelerating gradient while reducing cavity size. Compact accelerating structures are also high-frequency. Here, we describe design concepts for a high-gradient, cryo-cooled LINAC for XFEL facilities in the C-band regime (~4-8 GHz). We are also exploring C-band for different applications including drivers for security applications. We investigate 2 different traveling wave (TW) geometries optimized for high-gradient operation as modeled with VSim software.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB069
About •	paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021
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THPAB071	Physics Goals of DWA Experiments at FACET-II	3922
	J.B. Rosenzweig, H.S. Ancelin, G. Andonian, A. Fukasawa, C.E. Hansel, G.E. Lawler, W.J. Lynn, N. Majernik, J.I. Mann, P. Manwani, Y. Sakai, O. Williams, M. Yadav UCLA, Los Angeles, California, USA S.V. Baryshev Michigan State University, East Lansing, Michigan, USA S. Baturin Northern Illinois University, DeKalb, Illinois, USA M.J. Hogan, B.D. O’Shea, D.W. Storey, V. Yakimenko SLAC, Menlo Park, California, USA
	Funding: This work supported by DOE HEP Grant DE-SC0009914, The dielectric wakefield acceleration (DWA) program at FACET produced a multitude of new physics results that range from GeV/m acceleration to the discovery of high field-induced conductivity in THz waves, and beyond, to a demonstration of positron-driven wakes. Here we review the rich program now developing in the DWA experiments at FACET-II. With increases in beam quality, a key feature of this program is extended interaction lengths, near 0.5 m, permitting GeV-class acceleration. Detailed physics studies in this context include beam breakup and its control through the exploitation of DWA structure symmetry. The next step in understanding DWA limits requires the exploration of new materials with low loss tangent, large bandgap, and improved thermal characteristics. Advanced structures with photonic features for mode confinement and exclusion of the field from the dielectric, as well as quasi-optical handling of coherent Cerenkov signals is discussed. Use of DWA for laser-based injection and advanced temporal diagnostics is examined.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB071
About •	paper received ※ 25 May 2021 paper accepted ※ 28 July 2021 issue date ※ 22 August 2021
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THPAB073	Study of Seven-Bend-Achromat Lattice Option for Half	3926
	J.H. Xu, Z.H. Bai, Z.L. Ren, J.J. Tan, P.H. Yang USTC/NSRL, Hefei, Anhui, People’s Republic of China Q. Zhang INEST, Hefei, People’s Republic of China
	A seven-bend-achromat (7BA) storage ring lattice design for Hefei Advanced Light Facility (HALF) with a beam energy of 2.2 GeV and a circumference of 388.8 m is presented. The 7BA lattice is designed with the combined function bends and reverse bends which has a natural emittance of about 67 pm·rad. Two lattice candidates with different tunes have been selected. One lattice has better nonlinear dynamic performance for off-axis injection. The other lattice provides lower beta functions at the center of straight sections. The results of these studies are discussed in this paper.
	Poster THPAB073 [1.146 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB073
About •	paper received ※ 15 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021
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THPAB074	ESRF-EBS: Implementation, Performance and Restart of User Operation	3929
	J.-L. Revol, P. Berkvens, J.-F. Bouteille, N. Carmignani, L.R. Carver, J.M. Chaize, J. Chavanne, F. Ewald, A. Franchi, L. Hardy, J. Jacob, L. Jolly, G. Le Bec, I. Leconte, S.M. Liuzzo, D. Martin, J. Pasquaud, T.P. Perron, Q. Qin, P. Raimondi, B. Roche, K.B. Scheidt, R. Versteegen, S.M. White ESRF, Grenoble, France
	The European Synchrotron Radiation Facility - Extremely Brilliant Source (ESRF-EBS) is a facility upgrade allowing its scientific users to take advantage of the first high-energy 4th generation light source. In December 2018, after 30 years of operation, the beam stopped for a 12-month shutdown to dismantle the old storage ring and to install the new X-ray source. In December 2019, the first beam was stored and accumulated in the storage ring, allowing the vacuum conditioning and tuning to be started. The beam was delivered to beamlines in March 2020 for their commissioning. On 25 August, the user programme was restarted with beam parameters very close to nominal values. In this report, the milestones and key aspects of the return to user-mode operation are presented and discussed.
	Poster THPAB074 [2.864 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB074
About •	paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 01 September 2021
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THPAB075	Collective (In)stability Near the Coupling Resonance	3933
	R.R. Lindberg ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We show how to treat transverse collective instabilities when operating in the vicinity of the coupling (or tune difference) resonance. We begin by defining the approximate independent degrees of freedom including both linear coupling and chromatic effects. We then show how the destabilizing force due to wakefields and the stabilizing chromatic effects can be described by a linear combination of the horizontal and vertical motion that depends upon how close one is to the resonance. The theory agrees well with tracking studies, and will be relevant for those next-generation storage rings that plan to operate near the coupling resonance to produce nearly round beams, including the multi-bend achromat upgrade for the Advanced Photon Source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB075
About •	paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 01 September 2021
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THPAB076	Effects of Chromaticity and Synchrotron Emission on Coupled-Bunch Transverse Stability	3937
	R.R. Lindberg ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We present a theory that can compute the transverse coupled-bunch instability growth rates at any chromaticity and for any longitudinal potential provided only that the long-range wakefield varies slowly over the bunch. The theory is expressed in terms of the usual coupled-bunch eigenvalues at zero chromaticity, and when the longitudinal motion is simple harmonic our solution only requires numerical root-finding that is easy to implement and fast to solve; the more general case requires some additional calculations but is still relatively fast. The theory predicts that the coupled-bunch growth rates can be significantly reduced when the chromatic betatron tune spread is larger than the coupled-bunch growth rate at zero chromaticity. Our theoretical results are compared favorably with tracking simulations for the long-range resistive wall instability, and we also indicate how damping and diffusion from synchrotron emission can further reduce or even stabilize the dynamics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB076
About •	paper received ※ 20 May 2021 paper accepted ※ 26 July 2021 issue date ※ 26 August 2021
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THPAB077	Magnetic Shims Studies for APS-U Hybrid Permanent Magnet Undulators	3941
	Y. Piao, R.J. Dejuspresenter, M.F. Qian, 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 For the newly designed and fabricated APS Upgrade (APS-U) hybrid permanent magnet undulators (HPMUs), the development of magnetic shims has been critical to successfully tuning the undulators to meet the tight APS-U physics requirements. Different types of side and surface shims have been developed and applied for this purpose. The side shims are primarily used for trajectory tuning, and the surface shims are for phase and multipole tuning as well as trajectory tuning. Current design, applications, and measurement of the shims for the newly designed and fabricated APS28 (28 mm period) undulators are presented in this paper.
	Poster THPAB077 [0.531 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB077
About •	paper received ※ 20 May 2021 paper accepted ※ 18 June 2021 issue date ※ 27 August 2021
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THPAB078	SOLEIL Update Status	3945
	L.S. Nadolski, G. Abeillé, Y.-M. Abiven, F. Bouvet, P. Brunelle, A. Buteau, N. Béchu, I. Chado, M.-E. Couprie, X. Delétoille, A. Gamelin, C. Herbeaux, N. Hubert, J.-F. Lamarre, V. Leroux, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, A. Nadji, R. Nagaoka, S. Pierre-Joseph Zéphir, F. Ribeiro, G. Schagene, K. Tavakoli, M.-A. Tordeux SOLEIL, Gif-sur-Yvette, France
	SOLEIL is both a synchrotron light source and a research laboratory at the cutting edge of experimental techniques dedicated to matter analysis down to the atomic scale, as well as a service platform open to all scientific and industrial communities. This French 2.75 GeV third generation synchrotron light source provides today extremely stable photon beams to 29 beamlines (BLs) complementary to ESRF. We report facility performance, ongoing projects and recent major achievements. Major R&D areas will also be discussed, and progress towards a lattice baseline for making SOLEIL a diffraction limited storage ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB078
About •	paper received ※ 22 May 2021 paper accepted ※ 12 July 2021 issue date ※ 22 August 2021
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THPAB079	Design Study on Beam Size Measurement System Using SR Interferometry for Low Beam Current	3949
	W. Li, P. Liu, Y.K. Wu, J. Yan FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. To enable reliable measurements of the small vertical size of the electron beam in the Duke storage ring, a measurement system is being developed using synchrotron radiation interferometry (SRI). By relating the transverse beam size to the transverse spatial coherence of synchrotron radiation from a dipole magnet according to the Van Cittert-Zernike theorem, the transverse beam size can be inferred by recording and fitting the interference fringe as a function of the characteristic features of the interference filter used. In this paper, we describe the preliminary design of such a measurement system and present design considerations to make it possible to measure the electron beam vertical size for a wide range of electron beam energies and currents. Especially this system will be optimized to measure the electron beam size for low current operation down to 50 to 100~μA. This beam size measurement system will be used as an important beam diagnostic for the intrabeam scattering research at the Duke storage ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB079
About •	paper received ※ 27 May 2021 paper accepted ※ 12 July 2021 issue date ※ 28 August 2021
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THPAB080	Correcting the Magnetic Field Offsets Inside the Undulators of the EuXFEL Using the K-Monochromator	3953
	F. Brinker DESY, Hamburg, Germany S. Casalbuoni, W. Freund EuXFEL, Schenefeld, Germany
	Hard X-ray free-electron lasers (XFELs) generate intense coherent X-ray beams by passing electrons through undulators, i.e. very long periodic magnet structures, which extend over hundreds of meters. A crucial condition for the lasing process is the spatial overlap of the electrons with the electromagnetic field. Well-established electron beam-based procedures allow finding a straight trajectory for the electrons defined by the beam position monitors (BPM) between the undulators. A bending of the trajectory in between the BPMs cannot be seen by these methods. A general field offset inside the undulators has the effect that the synchrotron radiation is emitted at a different angle at the beginning and the end of the undulator which can result in a degradation of the FEL-gain especially for very short wavelengths. We report on how the spectral and spatial characteristics of the monochromatized radiation of a single undulator can be used to minimize the field offset in situ with the help of correction coils.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB080
About •	paper received ※ 19 May 2021 paper accepted ※ 25 June 2021 issue date ※ 12 August 2021
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THPAB081	High-Power Prototype Canon Coupler for APS-U Booster Cavities	3956
	G.J. Waldschmidt, D.J. Bromberek, D. Horan, G. Trento, U. Wienands ANL, Lemont, Illinois, USA T. Harada, H. Oikawa, H. Takahashi CETD, Tochigi, Japan
	The Advanced Photon Source Upgrade (APS-U) plans to achieve a beam capture efficiency above 90% at 17 nC bunch charge into the Booster. Due to large beam loading at injection, the 352-MHz Booster cavities will be significantly detuned necessitating effective-power handling much greater than the 100kW effective power rating of the present coupler. Canon Electron Tubes & Devices Co., Ltd. (CETD) has designed and built a compact coupler for the APS-U Booster using a high-power ceramic disk window design in addition to accommodating significant space restrictions and additional diagnostics and cooling requirements. The coupler design was modified from an existing 500MHz, 800kW coupler that has been in routine operation at KEKB. The APS-U coupler has been installed and tested in the high-power 352-MHz test stand at the APS. The details of the design and testing of the prototype coupler will be reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB081
About •	paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 15 August 2021
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THPAB082	Recent Operational Experience with Thermionic RF Guns at the APS	3959
	Y. Sun, M. Borland, G.I. Fystro, X. Huang, H. Shang ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 The electron beam at the Argonne Advanced Photon Source (APS) is generated from an S-band thermionic RF gun. There are two locations at the frontend of the linac where thermionic RF guns are installed – RG1 and RG2. Three so-called generation-III guns are available, two are installed at RG1 and RG2, one is a spare. In recent years, these guns are showing signs of aging after over a couple of decades of operations. RF trips started to occur, and we had to reduce the nominal operating rf power to alleviate the problem. In addition, beam generated by RG1 suffers from low transportation efficiency from the gun to the linac, and beam trajectory is unstable which results in charge instabilities. Recently, APS obtained a new type of prototype gun and it was beam commissioned in the linac. In this paper, we report our operational experience with these thermionic rf guns including thermionic-cathode beam extraction, gun front-end optimization for maximum charge transmission through the linac, linac lattice setup to match beam for injection into the Particle Accumulator Ring (PAR) and optimization for maximum PAR injection efficiency.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB082
About •	paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 26 August 2021
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THPAB083	Measurement of the Longitudinal Phase-Space of the APS Photo-Injector Beam	3963
	Y. Sun ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. An S-band photo-cathode RF gun (PCG) exists at the front of the linac. The high-brightness photoinjector beam is accelerated by the linac and and can be used for accelerator technology and beam physics R&D experiments in the Linac Extension Area (LEA). For some applications, the beam needs to be compressed by a magnetic bunch compressor in the middle of the linac. An S-band transverse-mode cavity (Tcav) is available at the end of the linac for beam longitudinal phase-space diagnostics. Beam commissioning experience of the Tcav is reported in this paper. The cavity rf conditioning and calibration was performed. There is a horizontally bending dipole magnet downstream of the Tcav, which kicks beam in the vertical plane. Beam image on a YAG screen downstream of the Tcav and dipole magnet contains the single-shot information of the longitudinal phase-space of the photo-injector beam. The first measurements of the longitudinal phase-space of the compressed and non-compressed photoinjector beam are discussed. Improvements of the measurement resolution are planned.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB083
About •	paper received ※ 25 May 2021 paper accepted ※ 12 July 2021 issue date ※ 21 August 2021
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THPAB085	Status of Insertion Device Tuning for the APS Upgrade	3966
	R.J. Dejus, Y. Piao, M.F. Qian, J.M. TerHAAR, 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 Upgrade (APS-U) project is developing a multi-bend achromat (MBA) lattice at 6.0-GeV beam energy to replace the existing APS storage ring lattice operating at 7.0 GeV. One of the key components of the project is to design, fabricate, and install optimized insertion devices (IDs) for 35 beamlines. A plan was developed to standardize on four new undulator period lengths for 44 new undulators and to reuse 23 existing undulators with four more different period lengths. Early in the Upgrade project we anticipated there would be large challenges in meeting the tight fabrication and tuning schedules so that all undulators would be ready for installation in the upgraded storage ring prior to beam commissioning. With recent developments and techniques used in the magnetic measurement laboratory, we have successfully tuned many of the new and reused undulators to demanding magnetic field requirements. We will report on the tools and techniques used and on results to date.
	Poster THPAB085 [0.890 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB085
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 15 August 2021
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THPAB089	Lattice Design for a Future Plan of UVSOR Synchrotron	3970
	E. Salehi, M. Katoh UVSOR, Okazaki, Japan M. Katoh HSRC, Higashi-Hiroshima, Japan
	UVSOR is a 750 MeV synchrotron light source with a moderately small emittance of about 17nm. We surveyed the periodic solutions by drawing a tie diagram and mapped the emittance and the dynamic aperture on the tune diagram. The aim of this work is to search for a possible low emittance solution without a major change of the lattice. Although, we could not find a solution which has a drastically small emittance, we have found a few solutions which has a significantly smaller emittance than present value. They may be useful for some special low emittance operation modes dedicated to developments on new light sources technologies and their applications.
	Poster THPAB089 [1.592 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB089
About •	paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 16 August 2021
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THPAB090	Progress with the Diamond-II Storage Ring Lattice	3973
	H. Ghasem, I.P.S. Martin, B. Singh DLS, Oxfordshire, United Kingdom
	Building on the CDR proposal for the Diamond-II storage ring, a number of changes have been implemented to improve the performance of the lattice. Firstly, anti-bend magnets have been utilized to provide additional control over the dispersion function, and an improved symmetrization in the phase advance between the sextupoles was found to be beneficial for the dynamic aperture. Furthermore, the longitudinal variable bends have been tailored to reduce the emittance and have had transverse gradient added to improve the optics control in the mid-straights. In the absence of IDs, the current design provides 161 pm electron beam emittance, reducing to 139 pm once all effects are taken into account. The dynamic aperture is large enough to support an off-axis injection scheme using a nonlinear kicker and has a lifetime greater than 4 h. In this paper, the main parameters and magnet specifications for the Diamond-II lattice are provided. The related linear and non-linear beam dynamics issues are discussed, along with the impact of IDs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB090
About •	paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 26 August 2021
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THPAB097	Towards Arbitrary Pulse Shapes in the Terahertz Domain	3977
	C. Mai, B. Büsing, A. Held, S. Khan, D. Krieg DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF (05K19PEC). The TU Dortmund University operates the 1.5-GeV electron storage ring DELTA as a synchrotron light source in user operation and for accererator physics research. At a dedicated beamline, experiments with (sub-)THz radiation are carried out. Here, an interaction of short laser pulses with electron bunches is used to modulate the electron energy which causes the formation of a dip in the longitudinal electron density, giving rise to the coherent emission of radiation between 75 GHz and 6 THz. The standard mode of operation is the generation of broadband radiation. However, more sophisticated energy modulation schemes were implemented using a liquid-crystal phase modulator. Here, a modulation of the spectral phase of the laser is used to control the spectral shape of the THz pulses. The resulting THz spectra have a relative bandwidth of about 2 %. Measurement results from the different THz generation schemes are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB097
About •	paper received ※ 18 May 2021 paper accepted ※ 12 July 2021 issue date ※ 24 August 2021
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THPAB104	Magnetic Error Effects of the Storage Ring for the Southern Advanced Photon Source	3980
	J. Chen, Y. Jiao, X. Liupresenter, S. Wang IHEP, Beijing, People’s Republic of China Y. Zhao IHEP CSNS, Guangdong Province, People’s Republic of China
	There are various magnetic errors in the actual accelerator, which will significantly affect the beam quality and machine performance. The diffraction-limited storage ring (DLSR) of Southern Advanced Photon Source (SAPS) will use a large number of ultra-high gradient quadrupoles and sextupoles, which, in turn, leads to the tight tolerance of beam parameters to magnetic errors. Based on a preliminary designed storage ring lattice of the SAPS, the influence of various magnetic errors on lattice parameters has been evaluated.
	Poster THPAB104 [0.588 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB104
About •	paper received ※ 17 May 2021 paper accepted ※ 23 June 2021 issue date ※ 18 August 2021
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THPAB106	Optimization of a High Bunch Charge ERL Injection Merger for PERLE	3983
	B. Hounsell, M. Klein, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom S.A. Bogacz JLab, Newport News, Virginia, USA C. Bruni, B. Hounsell, W. Kaabi Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France B. Hounsell, B.L. Militsyn, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Delivery of high charge electron bunches into the main loop of an ERL (energy recovery linac) while preserving the emittance is challenging. This is because at the typical injection momentum, space charge forces still have a significant effect on the beam dynamics. In this work we consider the design of the merger for PERLE, an ERL test facility to be based at IJCLab in France. Previous simulations have shown that the baseline DC gun based injector can achieve the required emittance at the booster linac exit. The quality of the 500 pC bunches must then be preserved with space charge through the merger at total beam energy of 7 MeV keeping the emittance below 6 mm mrad. The beam dynamics in the merger were simulated using the code OPAL and optimised using a genetic algorithm. Three possible merger schemes were investigated. The goal of the optimisation was to minimise the emittance growth while also achieving the required Twiss parameters to match onto the spreader at the main linac exit. A three dipole solution is then examined in more detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB106
About •	paper received ※ 19 May 2021 paper accepted ※ 16 July 2021 issue date ※ 12 August 2021
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THPAB113	The Extended Operative Range of the LNF LINAC and BTF Facilities	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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THPAB119	Many-Objective Beam Dynamics Optimization for High-Repetition-Rate XFEL Photoinjector	3991
	Z.H. Zhu, J.W. Yan SINAP, Shanghai, People’s Republic of China D. Gu SARI-CAS, Pudong, Shanghai, People’s Republic of China Q. Gu Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
	SHINE, as the first hard x-ray free-electron-laser (FEL) facility in China, is design to provide high-brightness FEL lasing under high-repetition-rate operation. In order to drive x-ray FEL pulses with high qualities, the photoinjector section is deployed to provide the specified electron beam with low transverse emittance and high brightness. Normally the multi-objective optimization algorithm is employed in the injector beam dynamics design. In this paper, the many-objective optimization algorithm NSGA-III is introduced to the injector physical design for optimizing the 4 detailed beam quality properties using 17 variables for the first time. The results of the optimization are presented and the correlations are analyzed. This approach can provide guidance for further physical research as well as improve the beam dynamics optimization efficiency.
	Poster THPAB119 [0.936 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB119
About •	paper received ※ 17 May 2021 paper accepted ※ 07 July 2021 issue date ※ 22 August 2021
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THPAB120	Beam on Demand for High-Repetition-Rate X-Ray Free-Electron Lasers	3995
	Z. Zhang, Y. Ding, Z. Huang SLAC, Menlo Park, California, USA
	High-repetition-rate (HRR) free-electron lasers (FELs) with multiple undulator beamlines will advance the frontiers of X-ray science significantly from the remarkable success of existing X-ray FEL facilities. The wide-ranging requirements for the photon properties from multiple beamlines are extremely challenging to satisfy by the same electron beam from a single superconducting radio-frequency (SRF) accelerator. To realize the full potential of an HRR FEL facility, a new emerging concept of "beam on demand" is proposed here. The concept is based on advanced beam dynamics and radio-frequency (RF) techniques to provide beam properties tailored to each undulator line at the desired repetition rate. The beam properties that will be pursued in this proposal include, but are not limited to, beam energy, bunch charge, bunch length, beam current, and its profile. The realization of "beam on demand" will allow optimization of photon properties of individual beamlines to maximize their performance and drastically improve the multiplexing capabilities of Linac Coherent Light Source II and its high-energy upgrade.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB120
About •	paper received ※ 17 May 2021 paper accepted ※ 23 July 2021 issue date ※ 27 August 2021
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Paper

Title

Page

Reaching the Sub Per Mil Level Coupling Corrections in the LHC

3752

E.J. Høydalsvik, T.H.B. Persson
CERN, Geneva, Switzerland

The High Luminosity LHC (HL-LHC) is requiring sub per mil coupling correction, as defined by the closest tune approach. In this article, the current coupling correction strategy is analyzed in order to understand if it can robustly correct to these very low levels. The impact of realistic errors on the coupling correction is investigated with MAD-X simulations, including the influence of local coupling on the global coupling correction. Through simulations and measurements in the LHC, the effect of BPM noise on the coupling correction is analyzed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB001

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paper received ※ 11 May 2021 paper accepted ※ 28 July 2021 issue date ※ 23 August 2021

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THPAB002

Lattice Design for BEPCII Upgrade

3756

H. Geng, W.B. Liu, J. Qiu, J. Xing, C.H. Yu, Y. Zhangpresenter
IHEP, Beijing, People’s Republic of China

The Beijing Electron Positron Collider II (BEPCII) has achieved a series of achievements in high-energy physics study. Along with the deepening of the research, more important physics is expected in higher energy regions (>2.1 GeV). As the upper limit of BEPCII design energy is 2.1GeV, an urgent upgrade is required for BEPCII. To achieve a higher luminosity at higher energy, the number of RF cavities is expected to be doubled. In this paper, the lattice design for the upgrade of BEPCII is studied. The dynamic aperture tracking result shows that the lattice could meet the injection requirement of the BEPCII beam with a reasonable margin.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB002

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paper received ※ 14 May 2021 paper accepted ※ 17 June 2021 issue date ※ 14 August 2021

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THPAB003

Application of Generalized Gaussian Distribution in the Processing the Wire Scanner Data

3759

H. Geng, C. Meng, F. Yan, Y. Zhangpresenter, Y.L. Zhao
IHEP, Beijing, People’s Republic of China

Wire scanners are widely used for measuring beam emittance in both electron and hadron accelerators. Gaussian fitting is the most commonly used method in processing the wire scanner data. But in hadron machines, beams are normally not gaussian distribution due to the action of nonlinear forces such as space charge effect. Under these circumstances, there would be big deviations if the wire scanner data was still fitted with gaussian distributions. This paper introduces generalized Gaussian distribution in the processing the wire scanner data measured in the ADS injector-I. The results using different fitting method will be compared.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB003

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paper received ※ 14 May 2021 paper accepted ※ 18 June 2021 issue date ※ 30 August 2021

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THPAB007

Technology Spinoff and Lessons Learned from the 4-Turn ERL CBETA

3762

K.E. Deitrick, N. Banerjee, A.C. Bartnik, D.C. Burke, J.A. Crittenden, J. Dobbins, C.M. Gulliford, G.H. Hoffstaetter, Y. Li, W. Lou, P. Quigley, D. Sagan, K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.S. Berg, S.J. Brooks, R.L. Hulsart, G.J. Mahler, F. Méot, R.J. Michnoff, S. Peggs, T. Roser, D. Trbojevic, N. Tsoupas
BNL, Upton, New York, USA
T. Miyajima
KEK, Ibaraki, Japan

The Cornell-BNL ERL Test Accelerator (CBETA) developed several energy-saving measures: multi-turn energy recovery, low-loss superconducting radiofrequency (SRF) cavities, and permanent magnets. With green technology becoming imperative for new high-power accelerators, the lessons learned will be important for projects like the FCC-ee or new light sources, where spinoffs and lessons learned from CBETA are already considered for modern designs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB007

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paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 12 August 2021

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THPAB009

A Hard X-Ray Compton Source at CBETA

3765

K.E. Deitrick, C. Franck, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J. Crone, H.L. Owen
UMAN, Manchester, United Kingdom
G.A. Krafft
JLab, Newport News, Virginia, USA
G.A. Krafft, B. Terzić
ODU, Norfolk, Virginia, USA
B.D. Muratori, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
B.D. Muratori, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Inverse Compton scattering (ICS) holds the potential for future high flux, narrow bandwidth x-ray sources driven by high quality, high repetition rate electron beams. CBETA, the Cornell-BNL Energy recovery linac (ERL) Test Accelerator, is the world’s first superconducting radiofrequency multi-turn ERL, with a maximum energy of 150 MeV, capable of ICS production of x-rays above 400 keV. We present an update on the bypass design and anticipated parameters of a compact ICS source at CBETA. X-ray parameters from the CBETA ICS are compared to those of leading synchrotron radiation facilities, demonstrating that, above a few hundred keV, photon beams produced by ICS outperform those produced by undulators in term of flux and brilliance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB009

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paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 10 August 2021

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THPAB011

Monte Carlo Driven MDI Optimization at a Muon Collider

3769

C. Curatolo, D. Lucchesi
Univ. degli Studi di Padova, Padova, Italy
F. Collamati
INFN-Roma1, Rome, Italy
C. Curatolo, D. Lucchesi
INFN- Sez. di Padova, Padova, Italy
A. Mereghetti
CERN, Meyrin, Switzerland
A. Mereghetti
CNAO Foundation, Pavia, Italy
N.V. Mokhov
Fermilab, Batavia, Illinois, USA
M.A. Palmer
BNL, Upton, New York, USA
P.R. Sala
INFN-Milano, Milano, Italy

A Muon Collider represents a very interesting possibility for a future machine to explore the energy frontier in particle physics. However, to reach the needed luminosity, beam intensities of the order of 10⁹–10¹² muons per bunch are needed. In this context, the Beam-Induced Background must be taken into account for its effects on magnets and detector. Several mitigation strategies can however be conceived. In this view, it is of crucial importance to develop a flexible tool that allows to easily reconstruct the machine geometry in a Monte Carlo code, allowing to simulate in detail the interaction of muon decay products in the machine, while being able to change the machine optics itself to find the best configuration. In this contribution, a possible approach to such a purpose is presented, based on FLUKA for the Monte Carlo simulation and on LineBuilder for the geometry reconstruction. Results based on the 1.5 TeV machine optics developed by the MAP collaboration are discussed, as well as a first approach to possible mitigation strategies.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB011

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paper received ※ 19 May 2021 paper accepted ※ 13 July 2021 issue date ※ 01 September 2021

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THPAB012

The Magnetic Compensation Scheme of the FCC-ee Detectors

3773

M. Koratzinos, K. Oide
CERN, Meyrin, Switzerland

A crucial part of the design of an FCC-ee detector is the minimisation of the disruption of the beam due to the presence of a large and powerful detector magnet. Indeed, the emittance blow-up of the few meters around the interaction point (IP) at lower energies is comparable to the emittance introduced by the rest of the 100 km ring. Vertical emittance is the single most important factor in achieving high performance (luminosity, in this case) in a modern e⁺ e⁻ storage ring such as the FCC-ee. The design adopted is the simplest possible arrangement that can nevertheless deliver high performance: two additional coils per IP side. The performance achieved is such that vertical emittance blow-up will not be a limiting performance factor even in the case of a ring with four experiments, and even in the most demanding energy regime, that of the Z running (about 45 GeV beam energy).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB012

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paper received ※ 10 May 2021 paper accepted ※ 28 July 2021 issue date ※ 30 August 2021

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THPAB013

Magnetic Measurements at Warm of the First FCC-ee Final Focus Quadrupole Prototype

3777

M. Koratzinos
MIT, Cambridge, Massachusetts, USA
G. Kirby, M. Liebsch, C. Petrone
CERN, Geneva, Switzerland

The first FCC-ee final focus quadrupole prototype has been designed, manufactured, assembled and tested at warm. The prototype is a single aperture quadrupole magnet of the CCT type. One edge of the magnet was designed with local multipole cancellation, whereas the other was left with the conventional design. An optimized rotating induction-coil sensor was used. A technique was developed to take into account field distortions due to the environment of the test and distinguish them from magnet effects, demonstrating an excellent field quality for the prototype.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB013

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paper received ※ 11 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021

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THPAB014

Matlab Simulations of the Helium Liquefier in the FREIA Laboratory

3781

E. Waagaard, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden

We describe simulations that track a state vector with pressure, temperature, and gas flow through the helium liquefier in the FREIA laboratory. Most components, including three-way heat exchangers, are represented by matrices that allow us to track the state through the system. The only non-linear element is the Joule-Thomson valve, which is represented by a non-linear map for the state variables. Realistic properties for the enthalpy and other thermodynamic quantities are taken into account with the help of the Coolprop library. The resulting system of equations is rapidly solved by iteration and shows good agreement with the observed LHe yield with and without nitrogen pre-cooling.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB014

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paper received ※ 13 May 2021 paper accepted ※ 14 July 2021 issue date ※ 26 August 2021

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THPAB015

Studies of the Imperfection in Crab Crossing Scheme for Electron-Ion Collider

3784

Y. Hao, J.S. Berg, D. Holmes, Y. Luo, C. Montag
BNL, Upton, New York, USA
V.S. Morozov
JLab, Newport News, Virginia, USA
J. Qiang
LBNL, Berkeley, California, USA
D. Xu
FRIB, East Lansing, Michigan, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Crab crossing scheme is the essential scheme that accommodates large crossing angle without loss of luminosity in the design of Electron-Ion collider (EIC). The ideal optics and phase advances of the crab cavity pair are set to create a local crabbing bump in the interaction region (IR). However, there are always small errors in the actual lattice of IR. In this article, we will present the simulation and analytical studies on the imperfections in the crab crossing scheme in the EIC design. The tolerance of the imperfection and the possible remedies can be concluded from these studies.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB015

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paper received ※ 17 May 2021 paper accepted ※ 16 July 2021 issue date ※ 12 August 2021

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THPAB016

Revisit of Nonlinear Dynamics in Hénon Map Using Square Matrix Method

3788

Y. Hao, K.J. Anderson
FRIB, East Lansing, Michigan, USA
L.H. Yu
BNL, Upton, New York, USA

Funding: Work supported by the Accelerator Stewardship program, award number DE-SC0019403 with the U.S. Department of Energy
Hénon map (2D or 4D) represents a thin lens sextupole in an otherwise linear lattice and had been well studied for many decades. We revisit the nonlinear properties of the Hénon map with the aid of the square matrix method and Arnold theorem, including acquiring the resonance structure and amplitude-dependent frequency.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB016

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paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 17 August 2021

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THPAB017

The International Muon Collider Collaboration

3792

D. Schulte
CERN, Meyrin, Switzerland

A muon collider offers a unique opportunity for high-energy, high-luminosity lepton collisions and could push the frontiers of particle physics by providing excellent discovery reach with excellent precision. A scheme has been developed by the MAP collaboration. The updated European Strategy for Particle Physics recommended the development of an Accelerator R&D Roadmap for Europe and CERN Council has charged the LDG to develop it. LDG has initiated panels to provide input including one on the use of muon beams, in particular in view of a high-energy, high luminosity muon collider. A new international collaboration, is forming to develop a muon collider design and address the associated challenges, which are mainly due to the limited muon lifetime. The focus is on two energy ranges, around 3 TeV and above 10 TeV. Ambitious magnets, RF systems, targets and shielding are key for the design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB017

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 11 August 2021

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THPAB021

Status of VEPP-5 Injection Complex

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB021

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paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 27 August 2021

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THPAB022

Possibilities for Upgrading to Polarized SuperKEKB

3799

Z.J. Liptak, M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
J.M. Roney
Victoria University, Victoria, B.C., Canada

The SuperKEKB accelerator is currently in operation in Tsukuba, Japan, with a planned long shutdown in 2026. Among the possible upgrades being considered during this period is the change to a polarized electron beam in the High Energy Ring. Such a change would require modifications in the source generation and transport, geometrical and lattice variations to provide spin rotation, and polarimetry. A Polarized SuperKEKB Working Group has been formed from members of the Belle II experiment and the SuperKEKB accelerator team to investigate the possibilities and challenges of these modifications. This talk lays out the goals of the proposed upgrade, considers the necessary changes to the existing accelerator and their feasibility and lays out the physics motivation behind such an effort.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB022

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paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 29 August 2021

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THPAB025

A Proposed Beam-Beam Test Facility COMBINE

3802

E.A. Nissen, G.A. Krafft
JLab, Newport News, Virginia, USA
J.R. Delayen
ODU, Norfolk, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, license to publish or reproduce this manuscript.
The COmpact Machine for Beam-beam Interactions in Non-Equilibrium systems (COMBINE) is a proposed, dedicated, beam-beam test facility. The base design would make use of a pair of identical octagonal rings (2.5 meters per side) one rotated 180 degrees from the other, meeting at their common interaction point. These would be fed by an electron gun producing up to 125 keV electrons. The low energy will allow for beam-beam tune shifts commensurate with existing colliders, some linac-ring type systems, and will also allow for an exploration of the predicted effects of gear-changing, which would be performed using a variable pathlength scheme. The low energy, and small size will allow for cost effective research, simulation code benchmarking, as well as training opportunities for students.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB025

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paper received ※ 20 May 2021 paper accepted ※ 01 September 2021 issue date ※ 16 August 2021

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THPAB026

Final Booster Complex Design for the Jefferson Lab Electron Ion Collider

3805

E.A. Nissen
JLab, Newport News, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. retains a license to publish or reproduce this manuscript for U.S. Government purposes.
In this work we show the final iteration of the design for the booster complex of the Jefferson Lab EIC, which would have brought the ions from an energy (proton) of 150 MeV up to 12.1 GeV. This complex would have consisted of two figure-8 rings. The Low Energy Booster (LEB) which would have accelerated its protons from 150 MeV to 8 GeV, and has had its lattice tweaked to increase the effectiveness of chromaticity cancellations. The High Energy Booster (HEB) would have brought the 8 GeV protons up to 12.1 GeV. The HEB would in the tunnel that was designed for the collider rings, sitting on top of them. It has had a bypass around the interaction region added, as well as a cooling solenoid installed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB026

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paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 31 August 2021

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THPAB028

Beam-Beam Related Design Parameter Optimization for the Electron-Ion Collider

3808

Y. Luo, J.S. Berg, M. Blaskiewicz, W. Fischer, X. Gu, H. Lovelace III, C. Montag, R.B. Palmer, S. Peggs, V. Ptitsyn, F.J. Willeke
BNL, Upton, New York, USA
Y. Hao, D. Xu
FRIB, East Lansing, Michigan, USA
H. Huang
ODU, Norfolk, Virginia, USA
E.A. Nissen, T. Satogata
JLab, Newport News, Virginia, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The design luminosity goal for the Electron-Ion Collider (EIC) is 1e34 cm^-2s⁻¹. To achieve such a high luminosity, the EIC design adopts high bunch intensities, flat beams at the interaction point (IP) with a small vertical β^*-function, and a high collision frequency, together with crab cavities to compensate the geometrical luminosity loss due to the large crossing angle of 25mrad. In this article, we present our strategies and approaches to obtain the design luminosity by optimizing some key beam-beam related design parameters. Through our extensive strong-strong and weak-strong beam-beam simulations, we found that beam flatness, electron and proton beam size matching at the IP, electron and proton working points, and synchro-betatron resonances arising from the crossing angle collision play a crucial role in proton beam size growth and luminosity degradation. After optimizing those parameters, we found a set of beam-beam related design parameters to reach the design luminosity with an acceptable beam-beam performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB028

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paper received ※ 17 May 2021 paper accepted ※ 28 July 2021 issue date ※ 25 August 2021

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THPAB029

Dynamic Aperture Evaluation for the Hadron Storage Ring in the Electron-Ion Collider

3812

Y. Luo, J.S. Berg, M. Blaskiewicz, W. Fischer, X. Gu, H. Lovelace III, C. Montag, R.B. Palmer, S. Peggs, V. Ptitsyn, F.J. Willeke, H. Witte
BNL, Upton, New York, USA
Y. Hao, D. Xu
FRIB, East Lansing, Michigan, USA
H. Huang
ODU, Norfolk, Virginia, USA
V.S. Morozov, E.A. Nissen, T. Satogata
JLab, Newport News, Virginia, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Electron-Ion Collider (EIC) is aiming at a design luminosity of 1e34 cm^-2s⁻¹. To maintain such a high luminosity, both beams in the EIC need an acceptable beam lifetime in the presence of the beam-beam interaction. For this purpose, we carried out weak-strong element-by-element particle tracking to evaluate the long-term dynamic aperture for the hadron ring lattice design. We improved our simulation code SimTrack to treat some new lattice design features, such as radially offset on-momentum orbits, coordinate transformations in the interaction region, etc. In this article, we will present the preliminary dynamic aperture calculation results with β^*- function scan, radial orbit shift, crossing angle collision, and magnetic field errors.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB029

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paper received ※ 17 May 2021 paper accepted ※ 01 September 2021 issue date ※ 28 August 2021

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THPAB031

Dump Line Layout and Beam Dilution Pattern Optimization of the Future Circular Collider

3815

B. Facskó, D. Barna
Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
A. Lechner, E. Renner
CERN, Geneva, Switzerland

To avoid any damage to the beam dump target in the Future Circular Collider, the beam will be swept over its surface using oscillating kickers in the x/y planes with a 90-degree phase difference, and an amplitude changing in time, creating a spiral pattern. The ideal pattern must have an increasing spiral pitch towards smaller radii to produce an even energy deposition density. We recommend the realization of the optimal pattern using two beating frequencies. This method enables a flat energy deposition density while only using simple independent damped oscillators. In this poster, we also present the study of the beamline optics and hardware that can realize the needed pattern. Two different possible hardware layouts were examined and optimized as well.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB031

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paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 18 August 2021

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THPAB035

Study of the Tolerances for Superconducting Undulators at the European XFEL

3819

B. Marchetti, S. Casalbuoni, V. Grattoni, S. Serkez
EuXFEL, Schenefeld, Germany

European XFEL is investing in the development of superconducting undulators (SCUs) for future upgrade of its beamlines SCUs made of NbTi, working at 2K, with a period length of 15 mm and a vacuum gap of 5 mm allow covering a range between 54 keV and 100 keV for 17.5 GeV electron energy. The effect of mechanical errors in the distribution of K along the undulators is more relevant for working points at lower photon energy, which are obtained using a higher magnetic field in the undulator. In this article we investigate the effect of error distribution in the K-parameter for a working point at 50keV photon energy obtained injecting an electron beam with 16.5 GeV energy from the XFEL linear accelerator in a undulator line composed by SCUs with 1.58 T peak magnetic field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB035

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paper received ※ 12 May 2021 paper accepted ※ 05 July 2021 issue date ※ 18 August 2021

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THPAB036

Superconducting Phase Shifter Design for the Afterburner at the European XFEL

3823

V. Grattoni, J.E. Baader, S. Casalbuoni
EuXFEL, Schenefeld, Germany

At the European XFEL, a superconducting afterburner is under design for the SASE2 hard X-ray beamline. It will consist of 5 undulator modules. One module corresponds to two superconducting undulator (SCU) coils of 2 m length plus one phase shifter. Such an afterburner will enable photon energies above 30 keV. Superconducting (SC) phase shifters will be installed in each undulator module to keep the correct phase delay between the electron beam and photon beam. In this contribution, we present the required SC phase shifter parameters to enable operation in the electron beam energy range 11.5-17.5 GeV. We also analyze different magnetic designs satisfying the calculated specifications.

Poster THPAB036 [0.991 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB036

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paper received ※ 18 May 2021 paper accepted ※ 06 July 2021 issue date ※ 12 August 2021

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THPAB037

Insertion Devices Impact on Solaris Storage Ring Optics

3827

G.W. Kowalski, R. Panaś, A.I. Wawrzyniak
NSRC SOLARIS, Kraków, Poland

Solaris storage ring is currently operating with three insertion devices. The IDs installed are the APPLE II type elliptically polarised undulators (EPU). The UARPES beamline is operating with the long period length EPU of 120 mm (EPU120) which has a significant impact on the linear optics and tune shift. The linear optics compensation of the EPU120 impact is realised by local adjustment of SQFO quadrupole/sextupole focusing gradient and defocusing gradient in the flanking dipoles. Two additional EPUs with period lengths of 58 and 46.6 mm are recently installed for next beamlines PHELIX and DEMETER, respectively and are under commissioning now. To reduce the impact of all undulators movement the additional correction coils are installed and the correction feedforward tables has been determined experimentally. Additionally to keep the tune at the nominal values the tune feedback is planned to be implemented. Within this presentation the effect of all existing insertion devices on the linear optics based on measurements and simulations to be discussed. Moreover the nonlinear effects, especially the impact on dynamic aperture of Solaris storage ring will be investigated.

Poster THPAB037 [2.522 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB037

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paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 30 August 2021

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THPAB040

A Phase Shifter for Inline Undulators at the Advanced Photon Source Upgrade Project

3830

E.R. Moog, R.J. Dejus, A.T. Donnelly, Y. Piao, M.F. Qian, 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.
Several undulator lines for the Advanced Photon Source Upgrade (APS-U) will consist of two inline undulators. In order to keep the undulators operating with optimal phasing over the full range of gaps, a phase shifter will be included between the undulators. A design has been developed for a phase shifter that will serve for a variety of undulator period lengths and gap ranges. The permanent-magnet phase shifter will use SmCo magnets to reduce the risk of radiation-induced demagnetization. The available space between the undulators is tight, so magnetic shields are placed between the undulators, the phase shifter, and the corrector magnet that is also located in the inter-undulator space. While these shields guard against magnetic cross-talk between the devices as the undulator and phase shifter gaps change, they do have an effect on the end fields of the devices. These end-field effects are examined and relevant tolerances are set and presented.

Poster THPAB040 [0.429 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB040

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paper received ※ 23 May 2021 paper accepted ※ 21 June 2021 issue date ※ 14 August 2021

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THPAB041

Design of Photon Masks for the ILC Positron Source

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB041

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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

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 THPAB042 [1.871 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB042

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paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 25 August 2021

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THPAB043

A Superconducting Undulator for CompactLight: Resistive Wall Wakefield Analysis

3841

K.B. Marinov
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The CompactLight project is an advanced X-ray FEL light source, with high-frequency, high-gradient linacs and compact undulators. Lower electron energies give higher energy efficiency and a smaller environmental footprint. The extremely short bunch lengths (few fs) and narrow undulator gaps (4 mm) drastically increase the impact of resistive wall wakefields on the lasing process. The longitudinal resistive wall wakefield impedance is calculated in the framework of the surface impedance approach, in accordance with anomalous skin effect (ASE) theory. The dependence of the electron energy loss factor and the correlated energy spread of the bunch on the residual resistivity ratio (RRR) for both copper and aluminum is much higher for long (100 fs) than for ultra-short (6 fs) bunches. This is due to a known property of the longitudinal wakefield impedance - the field acting on a single particle traversing a resistive vessel does not depend on the conductivity of the vessel. The wakefields generated by the ultra-short bunch are already close to that of a single-particle regime and this leads to interesting consequences which are discussed in the present work.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB043

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 21 August 2021

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THPAB045

Design of a Short Period Helical Superconducting Undulator

3844

A.G. Hinton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
J. Boehm, L. Cooper, B. Green, T. Hayler, P. Jeffery, C.P. Macwaters
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
S. Milward
DLS, Oxfordshire, United Kingdom
B.J.A. Shepherd
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
B.J.A. Shepherd
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Superconducting technology provides the possibility to develop short period, small bore undulators that can generate much larger magnetic fields than alternative technologies. This may allow an XFEL with optimised superconducting undulators to cover a broader range of wavelengths than traditional undulators. At STFC, we have undertaken work to design and build a prototype helical superconducting undulator (HSCU) module with parameters suitable for use on a future XFEL facility. This work includes the design of a full 2 m long undulator module, including an undulator with 13 mm period and 5 mm inner winding diameter, the supporting cryogenic and vacuum systems required for operation, and quadrupoles, phase shifters and correction magnets for use between undulator sections. We present here the magnetic and mechanical design of the HSCU. The choice of undulator parameters and their influence on the design is discussed. A turnaround scheme to allow continuous winding of the undulator without the need for superconducting joints is also presented. Techniques for winding the undulator are currently being investigated and a short prototype will soon be wound and tested.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB045

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paper received ※ 17 May 2021 paper accepted ※ 18 June 2021 issue date ※ 21 August 2021

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THPAB047

Status of Magnetic Measurement Benches for Insertion Device Characterization at MAX IV Laboratory

3848

M. Ebbeni, M. Gehlot, M. Holz, H. Tarawneh
MAX IV Laboratory, Lund University, Lund, Sweden

Insertion Devices (IDs) are the sole source of radiation used in all beamlines in MAX IV Laboratory with 14 IDs in operation of which 6 were built in-house. This paper shows the current capabilities and performance of the of the ID magnetic measurement systems, and the ongoing development work.

Poster THPAB047 [1.185 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB047

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paper received ※ 11 May 2021 paper accepted ※ 27 July 2021 issue date ※ 28 August 2021

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THPAB048

Design and Fabrication Concepts of a Compact Undulator with Laser-Structured 2G-HTS Tapes

3851

A. Will, T.A. Arndt, E. Bründermann, N. Glamann, A.W. Grau, B. Krasch, A.-S. Müller, R. Nast, D. Saez de Jauregui
KIT, Karlsruhe, Germany
D. Astapovych, H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany

To produce small-scale high-field undulators for table-top free electron lasers (FELs), compact designs have been proposed using high temperature superconducting (HTS) tapes, which show both large critical current densities and high critical magnetic fields with a total tape thickness of about 50 μm and a width of up to 12 mm. Instead of winding coils, a meander structure can be laser-scribed directly into the superconductor layer, guiding the current path on a quasi-sinusoidal trajectory. Stacking pairs of such scribed tapes allows the generation of the desired sinusoidal magnetic fields above the tape plane, along the tape axis. Two practically feasible designs are presented, which are currently under construction at KIT: A coil concept wound from a single structured tape with a length of 15 m, which is a progression of a design that has been presented already in the past, as well as a novel stacked and soldered design, made from 25 cm long structured tapes, soldered in a zig-zag-pattern. In this contribution the designs are briefly recapped and the experimental progress is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB048

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 15 August 2021

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THPAB049

Modeling the Magnetic Field of the LCLS-I Undulator for THz@PITZ

3855

M. Krasilnikov, X. Li, A. Lueangaramwong, F. Mueller, F. Stephan
DESY Zeuthen, Zeuthen, Germany
A. Brachmann, H.-D. Nuhn
SLAC, Menlo Park, California, USA
M. Tischer, P. Vagin
DESY, Hamburg, Germany

Funding: This work was supported by the European XFEL research and development program
An accelerator-based THz source for pump-probe experiments at the European XFEL is under development at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). For the proof-of-principle experiments an LCLS-I undulator is planned to be installed downstream of the PITZ accelerator. The fields of the undulator module 26 have been re-measured at DESY in Hamburg and the results are consistent with earlier SLAC measurements. A model for 3D field reconstruction based on the undulator magnetic measurements has been developed. It includes also a horizontal gradient of the vertical field. Tracking of the 17 MeV/c beam has revealed that the transverse gradient will lead to a significant off-axis trajectory in the horizontal plane. This offset has to be corrected with a steering coil, the design of which is also presented. The performance of the THz generation with the correction coil is discussed as well.

Poster THPAB049 [1.409 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB049

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paper received ※ 12 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

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THPAB050

Compact Hybrid Planar Permanent Magnet Undulator Design for the APS Upgrade

3859

M. Abliz, M. Borland, J.H. Grimmer, J.S. Kerby, M. Ramanathan, A. Xiao
ANL, Lemont, Illinois, USA

We report on the successful design of a compact 28-mm period hybrid planar permanent magnet (HPPM) undulator for the Advanced Photon Source Upgrade (APS-U) project. The design produces a peak field of 9750 G at a gap of 8.5 mm, with a pole width reduced to 35 mm as compared to the planar undulators currently in use at the Advanced Photon Source. The design includes a detailed investigation into the origin of the HPPM undulator demagnetization. We report on a finding of an optimization method that reduces the demagnetization field and increases the field at the gap center of the design. It includes an optimization of the pole edges to increase the field and decrease roll-off in the transverse direction. Further design optimizations include analyses of the mechanical assembly tolerances and comparison with the original design before building the device. Beam physics analyses included kick-map analysis, dynamic acceptance (DA), local momentum acceptance (LMA), and Touschek lifetime of this design were performed with the 42-pm lattice of the APS-U. Detailed magnetic design, effective field, field roll-off, magnetic force, and tracking results are reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB050

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paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 21 August 2021

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THPAB051

Vertical Septum Magnet Design for the APS Upgrade

3862

M. Abliz, M. Borland, H. Cease, G. Decker, A.K. Jain, M.S. Jaski, M. Kasa, J.S. Kerby, U. Wienands, A. Xiao
ANL, Lemont, Illinois, USA
J.W. Amann
SLAC, Menlo Park, California, USA
D.J. Harding
Fermilab, Batavia, Illinois, USA

The vertical injection scheme proposed for the APS Upgrade (APS-U) Project requires a challenging septum magnet that must meet stringent beam physics, magnetic field leakage, and vacuum requirements. The current iteration of this magnet design includes an enlarged stored-beam chamber aperture of 9 mm x 12 mm and a reduction of the septum thickness to 1.5 mm. The enlarged aperture accommodates a non-evaporable getter (NEG)-coated stored beam chamber to better achieve the required vacuum. A prototype septum magnet has been built and measurements confirm the cancellation of a peak leakage field even though the value is six times larger than the design. The leakage field measured at the upstream (US) end cancels the downstream (DS) end as was expected by design. The measured and simulated leakage field and the stored beam trajectories are reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB051

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paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 27 August 2021

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THPAB052

Insertion Devices at the MAX IV 3 GeV Ring

3865

H. Tarawneh, M. Ebbeni, M. Gehlot, M. Holz
MAX IV Laboratory, Lund University, Lund, Sweden

Currently, there are 8 Insertion Devices (ID) installed and in operation and 2 new ones to be installed end of 2021 at the MAX IV 3 GeV storage ring. In this paper, the first commissioning results of the three newly installed IDs in 2020 will be described. The new IDs are one APPLE II for SoftiMAX beamline and two In-vacuum Undulators (IVU) for the DanMAX and CoSAXS beamlines. The mitigation scheme adopted to reduce undulator-like radiation from BALDER in-vacuum wiggler will be discussed. Two new IVUs with a period length of 17 mm and 18 mm for the ForMAX and MicroMAX beamlines will be installed during the winter shutdown of 2021-2022. Both IDs have 3 m lengths and a minimum gap of 4 mm. In this paper, the magnetic measurement results will be presented in terms of the achieved field quality and phase error.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB052

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paper received ※ 11 May 2021 paper accepted ※ 02 July 2021 issue date ※ 02 September 2021

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THPAB053

Magnetic Field Calculation of Planar SCUs Using ANSYS Maxwell

3868

Y. Shiroyanagi, E.A. Anliker, Q.B. Hasse, H. Hu, Y. Ivanyushenkov, M. Kasa, I. Kesgin
ANL, Lemont, Illinois, USA

Funding: This work was supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) Upgrade includes a 4.8-m-long superconducting undulator (SCU) cryostat containing two 1.9-m-long, 16.5-mm-period planar NbTi undulator magnets. The magnetic and mechanical design of this magnet follows the design of the existing 1.1-m-long, 18-mm-period planar SCU that is currently in operation at the APS *. Although OPERA is a reliable standard software tool for magnetic field calculations, ANSYS Maxwell 3D has the advantage of calculating a large and complex geometry. In this paper, first, the magnetic field map, including the peak field and end fields, is bench-marked against the magnetic measurement data of the existing planar SCU18-1. Then, corrector current optimization is presented for the 1.5-m-long, 21-mm-period planar SCU. Finally, a magnetic field model of a full-scale, 1.9-m-long planar SCU is presented.
* Y. Ivanyushenkov et al., Phys. Rev. Accel. Beams 20, 100701 (2017).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB053

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paper received ※ 18 May 2021 paper accepted ※ 18 June 2021 issue date ※ 11 August 2021

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THPAB054

Measurement Results of the First Scape Prototype

3872

M. Kasa, E.A. Anliker, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The SCAPE (SuperConducting Arbitrarily Polarizing Emitter) undulator is under development at the Advanced Photon Source (APS) as a part of the APS upgrade. SCAPE is comprised of four superconducting magnets which are arranged to create an on-axis undulator field that can be planar, elliptical, or circular. As a first step towards developing a full length device, a 0.5-meter long prototype was manufactured and assembled for testing in a liquid helium bath cryostat. A description of the mechanical assembly and subsequent measurement results of the first prototype will be presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB054

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paper received ※ 19 May 2021 paper accepted ※ 01 September 2021 issue date ※ 22 August 2021

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THPAB055

Reconstruction of Linear Optics Observables Using Supervised Learning

3875

E. Fol, H. Garcia, R. Tomás García
CERN, Meyrin, Switzerland

In the LHC, most of the optical functions can be obtained from turn-by-turn beam centroid data. However, the measurement of such observables as β^* and the dispersion function require special dedicated techniques and additional operational time. In this work, we propose an alternative approach to estimate these observables using supervised machine learning, in case the dedicated measurements are not available but turn-by-turn data are. The performance of developed estimators is demonstrated on LHC simulations. Comparison to traditional techniques for the computation of beta-function will be also provided.

Poster THPAB055 [0.713 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB055

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paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 15 August 2021

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THPAB056

Conceptual Design of a Multiple Period Staggered Undulator

3879

I. Asparuhov, J. Chavanne, G. Le Bec
ESRF, Grenoble, France

In staggered undulators, a ferromagnetic pole structure paired to a solenoid generates a sinusoidal field. Interest of such insertion devices has been studied for application to FEL systems in the end of the previous century. However, the concept has never been used in synchrotron radiation sources due to the undesirable magnetic effect of the solenoid on electron beam parameters in storage rings. Advent of fourth-generation low emittance light sources is foreseen to change this situation. Indeed, consequent electron beam transverse size and divergence reduction for such new storage rings give promise for a beam less sensitive to the presence of a longitudinal solenoidal field. Relating to this, a staggered concept can be an adequate design choice for short-period undulators producing high-energy photon flux. Such undulators would have a low K value a priori limiting their photon energy tunability. Considering integration of separate magnetic arrays of distinct periods in a solenoid to compose a global assembly can help suppress this possible drawback. Magnetic design and radiative performance of such an insertion device are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB056

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

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THPAB057

Goubau-Line Set Up for Bench Testing Impedance of In-Vacuum Undulator Components

3883

P.I. Volz, S. Grimmer, M. Huck, A. Meseck
HZB, Berlin, Germany
A. Meseck
KPH, Mainz, Germany

The worldwide first in-vacuum elliptical undulator, IVUE32, is being developed at Helmholtz Zentrum Berlin. The 2.5 m long device with a period length of 3.2 cm and a minimum gap of about 7 mm is to be installed in the BESSY II storage ring. It will deliver soft X-radiation to several beamlines. The proximity of the undulator structure to the electron beam makes the device susceptible to wakefield effects which can influence beam stability. A complete understanding of its impedance characteristics is required prior to installation and operation, as unforeseen heating of components could have catastrophic consequences. Since its complex structure makes numerical calculations, such as CST simulations, at high frequency very resource intensive, bench testing the device may proof invaluable. A Goubau-line is a single wire transmission line for high frequency surface waves with a transverse electric field resembling that of a charged particle beam out to a certain radial distance. This can be used to measure the impedance of vacuum chamber components. A concept optimized for bench testing IVUE32-components will be discussed and progress towards the test bench set up will be shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB057

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paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 21 August 2021

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THPAB060

Dispersion Controlled Temporal Shaping of Photoinjector Laser Pulses for Electron Emittance Reduction in X-Ray Free Electron Lasers

3886

R.A. Lemons, S. Carbajo, J.P. Duris, A. Marinelli, N.R. Neveu
SLAC, Menlo Park, California, USA
C.G. Durfee
Colorado School of Mines, Golden, USA

Funding: Office of Science DE-SC0014664
Temporal shaping of photocathode excitation laser pulses is a long-sought-after challenge to tailor the phase-space of electrons. The temporal profile of lasers, typically up-converted from infrared to ultraviolet, have significant impact on the distribution and time-evolution of the collective electron bunches. Towards this end, we present a method combining efficient nonlinear up-conversion with simultaneous and adaptable temporal profile shaping through dispersion-controlled sum-frequency generation* resulting in temporal profiles with sharp rise-fall times and flat top profiles. Using the LCLS-II photoinjector as a case study, we demonstrate a reduction in generated electron transverse emittance by upwards of 30% over conventionally implemented temporal profiles. Additionally, we discuss the ongoing experimental implementation of this method and preliminary results.
* R. Lemons, et al. arXiv:2012.00957 [physics.optics] (2020)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB060

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paper received ※ 17 May 2021 paper accepted ※ 08 July 2021 issue date ※ 26 August 2021

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THPAB061

Pulse-Burst CO₂ Laser for High-Brilliance Compton Light Sources

3890

I. Pogorelsky, M.N. Polyanskiy, T.V. Shaftan
BNL, Upton, New York, USA

Funding: U.S. Department of Energy under contract DE-SC0012704
We propose a novel architecture for a mid-IR, high-repetition, kilowatt-class, CO₂ laser system operating in a pulse-burst regime and its implementation in In-verse Compton Scattering (ICS) sources of x-ray and gamma-ray radiation. Different types of particle accelerators are considered for conversion to such ICS sources, including energy recovery linacs and synchrotron storage rings. The expected ICS performance parameters are compared with earlier proposals where CBETA and DAΦNE accelerators have been paired with near-IR, mode-locked solid-state lasers operating at a multi-megahertz repetition rate. A considerable increase in acting laser energy attainable in our CO₂ laser-based scheme, combined with an order of magnitude higher number of laser photons per Joule of energy allows maintaining a similarly high average flux of produced hard x-rays while the peak flux and brilliance will be raised by three to four orders of magnitude compared to aforementioned schemes based on near-IR lasers.

Poster THPAB061 [1.082 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB061

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paper received ※ 12 May 2021 paper accepted ※ 21 June 2021 issue date ※ 29 August 2021

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THPAB062

Long-Wave IR Terawatt Laser Pulse Compression to Sub-Picoseconds

3893

I. Pogorelsky, M. Babzien, M.A. Palmer, M.N. Polyanskiy
BNL, Upton, New York, USA

Funding: U.S. Department of Energy under contract DE-SC0012704
We report an experiment and simulations on post-compression of 2 ps, 0.15 TW CO₂ laser pulses to 480 fs, ~0.25 TW by means of a self-phase modulation accompanied by a negative group dispersion in KCl and BaF2 optical slabs. In addition, down to 130 fs fine pulse structure, but at lower conversion efficiency, has been observed through self-compression in a bulk NaCl crystal. The obtained results surpass by far previous achievements in the ultra-fast long-wave IR laser technology

Poster THPAB062 [2.675 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB062

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paper received ※ 12 May 2021 paper accepted ※ 18 June 2021 issue date ※ 24 August 2021

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THPAB063

Laser Transport System of Shanghai Laser Electron Gamma Source (SLEGS)

3897

H.H. Xu, G.T. Fan
SSRF, Shanghai, People’s Republic of China

Shanghai Laser Electron Gamma Source (SLEGS) *, based on laser Compton scattering (LCS), as one of beamlines of Shanghai Synchrotron Radiation Facility (SSRF) in phase II, is under construction now. The technical design of its laser injection system has been implemented and optimized consecutively over the last few years. In order to inject the 10640 nm CO₂ laser into the interaction point from the laser hutch outside the storage ring’s shielding, a laser transport system longer than 20 m using relay-imaging telescopes is designed. There are two operation mode in SLEGS. One is backscattering mode, which will make the laser and electron bunch collide at 180° with flux higher than 10⁷ gamma/s. The other mode is slanting mode, which mainly inherits the design used in the prototype**. In this paper, a brief summary of the laser transport system is given. The system contains several modules to perform beam expansion, combining, monitoring and real-time adjustment. The design models, simulation study of the laser quality through the transporta-tion, and the experimental results are presented.
* Y. Xu, W. Xu, et al., NIM A, 578, 457 (2007).
** H.H. Xu, J.H. Chen, et al., Transaction on Nuclear Science, IEEE, 63, 906 (2016).

Poster THPAB063 [2.508 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB063

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paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 27 August 2021

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THPAB064

LUMOS: A Visible Diagnostic Beamline for the Solaris Storage Ring

3901

R. Panaś, A. Curcio, A.I. Wawrzyniak
NSRC SOLARIS, Kraków, Poland

LUMOS is a diagnostic beamline which operates in the visible region. It was installed in the Solaris storage ring during summer 2019. The first light was observed at the beginning of December 2019. During 2020 the beamline was commissioned and equipped with a streak camera setup. Currently, LUMOS allows to analyze far-field and near field images of synchrotron light for transverse beam profile measurements. Moreover, using the streak camera setup, it is also possible to investigate the bunch length, the filling pattern and the longitudinal beam profile changes with respect to the different condition (ramping, 3rd harmonic cavities tuning, etc.). During the presentation the optical setup to be presented along with the measurements conducted with it.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB064

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paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 01 September 2021

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THPAB065

Experimental Verification of the Source of Excessive Helical SCU Heat Load at APS

3904

V. Sajaev, J.C. Dooling, K.C. Harkay
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Immediately after the installation of the Helical superconducting undulator (HSCU) in the APS storage ring, higher than expected heating was observed in the cryogenic cooling system. Steering the electron beam orbit in the upstream dipole reduced the amount of synchrotron radiation reaching into the HSCU and allowed the device to properly cool and operate. The simplest explanation of the excessive heat load was higher than expected heat transfer from the vacuum chamber to the magnet coils. However, modeling of the synchrotron radiation interaction with the HSCU vacuum chamber showed that Compton scattering could also result in synchrotron radiation penetrating the vacuum chamber and depositing energy directly into the HSCU coils**. In this paper, we present experimental evidence that the excessive heat load of the HSCU coils is not caused by the heat transfer from the vacuum chamber but resulted from the synchrotron radiation penetrating the vacuum chamber.
* M. Kasa et. al., Phys. Rev. AB, v. 23 050701 (2020)
** J. Dooling et. al., IPAC 2019 Proc., THPTS093 (2019)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB065

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paper received ※ 12 May 2021 paper accepted ※ 02 September 2021 issue date ※ 16 August 2021

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THPAB066

Ground Diffusion Measurement and Its Effect on APS-U Orbit Stability

3907

V. Sajaev
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Spatial and temporal ground diffusion can be approximately described by the ATL law*,**. Ground diffusion can have an important effect on the long-term stability of the accelerator alignment. To estimate the possible consequences of the ground diffusion on the APS Upgrade performance, the ground diffusion constant of the existing APS tunnel was measured using historical data of the orbit correction effort and then used to estimate the ground diffusion effect on the orbit stability of the APS Upgrade. In this paper, we will describe the diffusion constant measurement and present the estimations of the expected APS-U alignment and orbit stability.
* B.A. Baklakov et. al., Technical Physics, v.38(10), pp.894-898(1993)
** V. Shiltsev, Physical Review Letters, 104(23), p.238501 (2010).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB066

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paper received ※ 12 May 2021 paper accepted ※ 13 July 2021 issue date ※ 24 August 2021

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THPAB067

Simulation of the APS-U Orbit Motion Due to RF Noise

3911

V. Sajaev
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
APS Upgrade storage ring will keep the same rf system that is presently used at APS. This rf system has amplitude and phase noise dominated by the lines at 60, 180, and 360 Hz. APS presently operates with synchrotron frequency close to 2 kHz, which is far away from the rf noise frequencies, and still the rf system noise contributes over 2 micrometers rms into the horizontal orbit noise due to beam energy variation. APS-U will operate with a bunch-lengthening cavity, which will lower the synchrotron frequency down to about 200 Hz. This could potentially lead to large orbit noise and other negative consequences due to energy variation caused by the rf system noise. In this paper, we will present simulations of the rf noise-induced orbit motion at APS and APS-U and define the rf amplitude and phase noise requirements that need to be achieved for APS-U operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB067

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paper received ※ 12 May 2021 paper accepted ※ 13 July 2021 issue date ※ 23 August 2021

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THPAB068

Denoising of Optics Measurements Using Autoencoder Neural Networks

3915

E. Fol, R. Tomás García
CERN, Meyrin, Switzerland

Noise artefacts can appear in optics measurements data due to instrumentation imperfections or uncertainties in the applied analysis methods. A special type of semi-supervised neural networks, autoencoders, are widely applied to denoising tasks in image and signal processing as well as to generative modeling. Recently, an autoencoder-based approach for denoising and reconstruction of missing data has been developed to improve the quality of phase measurements obtained from harmonic analysis of LHC turn-by-turn data. We present the results achieved on simulations demonstrating the potential of the new method and discuss the effect of the noise in light of optics corrections computed from the cleaned data.

Poster THPAB068 [0.881 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB068

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paper received ※ 19 May 2021 paper accepted ※ 13 July 2021 issue date ※ 02 September 2021

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THPAB069

Design Concepts for a High-Gradient C-Band Linac

3919

T.B. Bolin, S.I. Sosa Guitron
UNM-ECE, Albuquerque, USA
S. Biedron
UNM-ME, Albuquerque, New Mexico, USA
J.R. Cary
Tech-X, Boulder, Colorado, USA
M. Dal Forno
SLAC, Menlo Park, California, USA

Funding: This work was performed under Contract No. 89233218CNA000001, supported by the U.S. DOE’s National Nuclear Security Administration, for the operation of Los Alamos National Laboratory (LANL).
During the last decade, the production of soft to hard x-rays (up to 25 keV) at XFEL facilities has enabled new developments in a broad range of disciplines. One caveat is that these instruments can require a large amount of real estate. For example, the XFEL driver is typically an electron beam linear accelerator (LINAC) and the need for higher electron beam energies capable of generating higher energy X-rays can require longer linacs; costs quickly become prohibitive, requiring state of art methods. One cost-saving measure is to produce a high accelerating gradient while reducing cavity size. Compact accelerating structures are also high-frequency. Here, we describe design concepts for a high-gradient, cryo-cooled LINAC for XFEL facilities in the C-band regime (~4-8 GHz). We are also exploring C-band for different applications including drivers for security applications. We investigate 2 different traveling wave (TW) geometries optimized for high-gradient operation as modeled with VSim software.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB069

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paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021

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THPAB071

Physics Goals of DWA Experiments at FACET-II

3922

J.B. Rosenzweig, H.S. Ancelin, G. Andonian, A. Fukasawa, C.E. Hansel, G.E. Lawler, W.J. Lynn, N. Majernik, J.I. Mann, P. Manwani, Y. Sakai, O. Williams, M. Yadav
UCLA, Los Angeles, California, USA
S.V. Baryshev
Michigan State University, East Lansing, Michigan, USA
S. Baturin
Northern Illinois University, DeKalb, Illinois, USA
M.J. Hogan, B.D. O’Shea, D.W. Storey, V. Yakimenko
SLAC, Menlo Park, California, USA

Funding: This work supported by DOE HEP Grant DE-SC0009914,
The dielectric wakefield acceleration (DWA) program at FACET produced a multitude of new physics results that range from GeV/m acceleration to the discovery of high field-induced conductivity in THz waves, and beyond, to a demonstration of positron-driven wakes. Here we review the rich program now developing in the DWA experiments at FACET-II. With increases in beam quality, a key feature of this program is extended interaction lengths, near 0.5 m, permitting GeV-class acceleration. Detailed physics studies in this context include beam breakup and its control through the exploitation of DWA structure symmetry. The next step in understanding DWA limits requires the exploration of new materials with low loss tangent, large bandgap, and improved thermal characteristics. Advanced structures with photonic features for mode confinement and exclusion of the field from the dielectric, as well as quasi-optical handling of coherent Cerenkov signals is discussed. Use of DWA for laser-based injection and advanced temporal diagnostics is examined.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB071

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paper received ※ 25 May 2021 paper accepted ※ 28 July 2021 issue date ※ 22 August 2021

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THPAB073

Study of Seven-Bend-Achromat Lattice Option for Half

3926

J.H. Xu, Z.H. Bai, Z.L. Ren, J.J. Tan, P.H. Yang
USTC/NSRL, Hefei, Anhui, People’s Republic of China
Q. Zhang
INEST, Hefei, People’s Republic of China

A seven-bend-achromat (7BA) storage ring lattice design for Hefei Advanced Light Facility (HALF) with a beam energy of 2.2 GeV and a circumference of 388.8 m is presented. The 7BA lattice is designed with the combined function bends and reverse bends which has a natural emittance of about 67 pm·rad. Two lattice candidates with different tunes have been selected. One lattice has better nonlinear dynamic performance for off-axis injection. The other lattice provides lower beta functions at the center of straight sections. The results of these studies are discussed in this paper.

Poster THPAB073 [1.146 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB073

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paper received ※ 15 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021

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THPAB074

ESRF-EBS: Implementation, Performance and Restart of User Operation

3929

J.-L. Revol, P. Berkvens, J.-F. Bouteille, N. Carmignani, L.R. Carver, J.M. Chaize, J. Chavanne, F. Ewald, A. Franchi, L. Hardy, J. Jacob, L. Jolly, G. Le Bec, I. Leconte, S.M. Liuzzo, D. Martin, J. Pasquaud, T.P. Perron, Q. Qin, P. Raimondi, B. Roche, K.B. Scheidt, R. Versteegen, S.M. White
ESRF, Grenoble, France

The European Synchrotron Radiation Facility - Extremely Brilliant Source (ESRF-EBS) is a facility upgrade allowing its scientific users to take advantage of the first high-energy 4th generation light source. In December 2018, after 30 years of operation, the beam stopped for a 12-month shutdown to dismantle the old storage ring and to install the new X-ray source. In December 2019, the first beam was stored and accumulated in the storage ring, allowing the vacuum conditioning and tuning to be started. The beam was delivered to beamlines in March 2020 for their commissioning. On 25 August, the user programme was restarted with beam parameters very close to nominal values. In this report, the milestones and key aspects of the return to user-mode operation are presented and discussed.

Poster THPAB074 [2.864 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB074

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 01 September 2021

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THPAB075

Collective (In)stability Near the Coupling Resonance

3933

R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
We show how to treat transverse collective instabilities when operating in the vicinity of the coupling (or tune difference) resonance. We begin by defining the approximate independent degrees of freedom including both linear coupling and chromatic effects. We then show how the destabilizing force due to wakefields and the stabilizing chromatic effects can be described by a linear combination of the horizontal and vertical motion that depends upon how close one is to the resonance. The theory agrees well with tracking studies, and will be relevant for those next-generation storage rings that plan to operate near the coupling resonance to produce nearly round beams, including the multi-bend achromat upgrade for the Advanced Photon Source.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB075

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paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 01 September 2021

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THPAB076

Effects of Chromaticity and Synchrotron Emission on Coupled-Bunch Transverse Stability

3937

R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
We present a theory that can compute the transverse coupled-bunch instability growth rates at any chromaticity and for any longitudinal potential provided only that the long-range wakefield varies slowly over the bunch. The theory is expressed in terms of the usual coupled-bunch eigenvalues at zero chromaticity, and when the longitudinal motion is simple harmonic our solution only requires numerical root-finding that is easy to implement and fast to solve; the more general case requires some additional calculations but is still relatively fast. The theory predicts that the coupled-bunch growth rates can be significantly reduced when the chromatic betatron tune spread is larger than the coupled-bunch growth rate at zero chromaticity. Our theoretical results are compared favorably with tracking simulations for the long-range resistive wall instability, and we also indicate how damping and diffusion from synchrotron emission can further reduce or even stabilize the dynamics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB076

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paper received ※ 20 May 2021 paper accepted ※ 26 July 2021 issue date ※ 26 August 2021

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THPAB077

Magnetic Shims Studies for APS-U Hybrid Permanent Magnet Undulators

3941

Y. Piao, R.J. Dejuspresenter, M.F. Qian, 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
For the newly designed and fabricated APS Upgrade (APS-U) hybrid permanent magnet undulators (HPMUs), the development of magnetic shims has been critical to successfully tuning the undulators to meet the tight APS-U physics requirements. Different types of side and surface shims have been developed and applied for this purpose. The side shims are primarily used for trajectory tuning, and the surface shims are for phase and multipole tuning as well as trajectory tuning. Current design, applications, and measurement of the shims for the newly designed and fabricated APS28 (28 mm period) undulators are presented in this paper.

Poster THPAB077 [0.531 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB077

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paper received ※ 20 May 2021 paper accepted ※ 18 June 2021 issue date ※ 27 August 2021

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THPAB078

SOLEIL Update Status

3945

L.S. Nadolski, G. Abeillé, Y.-M. Abiven, F. Bouvet, P. Brunelle, A. Buteau, N. Béchu, I. Chado, M.-E. Couprie, X. Delétoille, A. Gamelin, C. Herbeaux, N. Hubert, J.-F. Lamarre, V. Leroux, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, A. Nadji, R. Nagaoka, S. Pierre-Joseph Zéphir, F. Ribeiro, G. Schagene, K. Tavakoli, M.-A. Tordeux
SOLEIL, Gif-sur-Yvette, France

SOLEIL is both a synchrotron light source and a research laboratory at the cutting edge of experimental techniques dedicated to matter analysis down to the atomic scale, as well as a service platform open to all scientific and industrial communities. This French 2.75 GeV third generation synchrotron light source provides today extremely stable photon beams to 29 beamlines (BLs) complementary to ESRF. We report facility performance, ongoing projects and recent major achievements. Major R&D areas will also be discussed, and progress towards a lattice baseline for making SOLEIL a diffraction limited storage ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB078

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paper received ※ 22 May 2021 paper accepted ※ 12 July 2021 issue date ※ 22 August 2021

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THPAB079

Design Study on Beam Size Measurement System Using SR Interferometry for Low Beam Current

3949

W. Li, P. Liu, Y.K. Wu, J. Yan
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
To enable reliable measurements of the small vertical size of the electron beam in the Duke storage ring, a measurement system is being developed using synchrotron radiation interferometry (SRI). By relating the transverse beam size to the transverse spatial coherence of synchrotron radiation from a dipole magnet according to the Van Cittert-Zernike theorem, the transverse beam size can be inferred by recording and fitting the interference fringe as a function of the characteristic features of the interference filter used. In this paper, we describe the preliminary design of such a measurement system and present design considerations to make it possible to measure the electron beam vertical size for a wide range of electron beam energies and currents. Especially this system will be optimized to measure the electron beam size for low current operation down to 50 to 100~μA. This beam size measurement system will be used as an important beam diagnostic for the intrabeam scattering research at the Duke storage ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB079

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paper received ※ 27 May 2021 paper accepted ※ 12 July 2021 issue date ※ 28 August 2021

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THPAB080

Correcting the Magnetic Field Offsets Inside the Undulators of the EuXFEL Using the K-Monochromator

3953

F. Brinker
DESY, Hamburg, Germany
S. Casalbuoni, W. Freund
EuXFEL, Schenefeld, Germany

Hard X-ray free-electron lasers (XFELs) generate intense coherent X-ray beams by passing electrons through undulators, i.e. very long periodic magnet structures, which extend over hundreds of meters. A crucial condition for the lasing process is the spatial overlap of the electrons with the electromagnetic field. Well-established electron beam-based procedures allow finding a straight trajectory for the electrons defined by the beam position monitors (BPM) between the undulators. A bending of the trajectory in between the BPMs cannot be seen by these methods. A general field offset inside the undulators has the effect that the synchrotron radiation is emitted at a different angle at the beginning and the end of the undulator which can result in a degradation of the FEL-gain especially for very short wavelengths. We report on how the spectral and spatial characteristics of the monochromatized radiation of a single undulator can be used to minimize the field offset in situ with the help of correction coils.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB080

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paper received ※ 19 May 2021 paper accepted ※ 25 June 2021 issue date ※ 12 August 2021

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THPAB081

High-Power Prototype Canon Coupler for APS-U Booster Cavities

3956

G.J. Waldschmidt, D.J. Bromberek, D. Horan, G. Trento, U. Wienands
ANL, Lemont, Illinois, USA
T. Harada, H. Oikawa, H. Takahashi
CETD, Tochigi, Japan

The Advanced Photon Source Upgrade (APS-U) plans to achieve a beam capture efficiency above 90% at 17 nC bunch charge into the Booster. Due to large beam loading at injection, the 352-MHz Booster cavities will be significantly detuned necessitating effective-power handling much greater than the 100kW effective power rating of the present coupler. Canon Electron Tubes & Devices Co., Ltd. (CETD) has designed and built a compact coupler for the APS-U Booster using a high-power ceramic disk window design in addition to accommodating significant space restrictions and additional diagnostics and cooling requirements. The coupler design was modified from an existing 500MHz, 800kW coupler that has been in routine operation at KEKB. The APS-U coupler has been installed and tested in the high-power 352-MHz test stand at the APS. The details of the design and testing of the prototype coupler will be reported in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB081

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paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 15 August 2021

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THPAB082

Recent Operational Experience with Thermionic RF Guns at the APS

3959

Y. Sun, M. Borland, G.I. Fystro, X. Huang, H. Shang
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
The electron beam at the Argonne Advanced Photon Source (APS) is generated from an S-band thermionic RF gun. There are two locations at the frontend of the linac where thermionic RF guns are installed – RG1 and RG2. Three so-called generation-III guns are available, two are installed at RG1 and RG2, one is a spare. In recent years, these guns are showing signs of aging after over a couple of decades of operations. RF trips started to occur, and we had to reduce the nominal operating rf power to alleviate the problem. In addition, beam generated by RG1 suffers from low transportation efficiency from the gun to the linac, and beam trajectory is unstable which results in charge instabilities. Recently, APS obtained a new type of prototype gun and it was beam commissioned in the linac. In this paper, we report our operational experience with these thermionic rf guns including thermionic-cathode beam extraction, gun front-end optimization for maximum charge transmission through the linac, linac lattice setup to match beam for injection into the Particle Accumulator Ring (PAR) and optimization for maximum PAR injection efficiency.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB082

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paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 26 August 2021

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THPAB083

Measurement of the Longitudinal Phase-Space of the APS Photo-Injector Beam

3963

Y. Sun
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An S-band photo-cathode RF gun (PCG) exists at the front of the linac. The high-brightness photoinjector beam is accelerated by the linac and and can be used for accelerator technology and beam physics R&D experiments in the Linac Extension Area (LEA). For some applications, the beam needs to be compressed by a magnetic bunch compressor in the middle of the linac. An S-band transverse-mode cavity (Tcav) is available at the end of the linac for beam longitudinal phase-space diagnostics. Beam commissioning experience of the Tcav is reported in this paper. The cavity rf conditioning and calibration was performed. There is a horizontally bending dipole magnet downstream of the Tcav, which kicks beam in the vertical plane. Beam image on a YAG screen downstream of the Tcav and dipole magnet contains the single-shot information of the longitudinal phase-space of the photo-injector beam. The first measurements of the longitudinal phase-space of the compressed and non-compressed photoinjector beam are discussed. Improvements of the measurement resolution are planned.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB083

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paper received ※ 25 May 2021 paper accepted ※ 12 July 2021 issue date ※ 21 August 2021

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THPAB085

Status of Insertion Device Tuning for the APS Upgrade

3966

R.J. Dejus, Y. Piao, M.F. Qian, J.M. TerHAAR, 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 Upgrade (APS-U) project is developing a multi-bend achromat (MBA) lattice at 6.0-GeV beam energy to replace the existing APS storage ring lattice operating at 7.0 GeV. One of the key components of the project is to design, fabricate, and install optimized insertion devices (IDs) for 35 beamlines. A plan was developed to standardize on four new undulator period lengths for 44 new undulators and to reuse 23 existing undulators with four more different period lengths. Early in the Upgrade project we anticipated there would be large challenges in meeting the tight fabrication and tuning schedules so that all undulators would be ready for installation in the upgraded storage ring prior to beam commissioning. With recent developments and techniques used in the magnetic measurement laboratory, we have successfully tuned many of the new and reused undulators to demanding magnetic field requirements. We will report on the tools and techniques used and on results to date.

Poster THPAB085 [0.890 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB085

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 15 August 2021

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THPAB089

Lattice Design for a Future Plan of UVSOR Synchrotron

3970

E. Salehi, M. Katoh
UVSOR, Okazaki, Japan
M. Katoh
HSRC, Higashi-Hiroshima, Japan

UVSOR is a 750 MeV synchrotron light source with a moderately small emittance of about 17nm. We surveyed the periodic solutions by drawing a tie diagram and mapped the emittance and the dynamic aperture on the tune diagram. The aim of this work is to search for a possible low emittance solution without a major change of the lattice. Although, we could not find a solution which has a drastically small emittance, we have found a few solutions which has a significantly smaller emittance than present value. They may be useful for some special low emittance operation modes dedicated to developments on new light sources technologies and their applications.

Poster THPAB089 [1.592 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB089

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 16 August 2021

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THPAB090

Progress with the Diamond-II Storage Ring Lattice

3973

H. Ghasem, I.P.S. Martin, B. Singh
DLS, Oxfordshire, United Kingdom

Building on the CDR proposal for the Diamond-II storage ring, a number of changes have been implemented to improve the performance of the lattice. Firstly, anti-bend magnets have been utilized to provide additional control over the dispersion function, and an improved symmetrization in the phase advance between the sextupoles was found to be beneficial for the dynamic aperture. Furthermore, the longitudinal variable bends have been tailored to reduce the emittance and have had transverse gradient added to improve the optics control in the mid-straights. In the absence of IDs, the current design provides 161 pm electron beam emittance, reducing to 139 pm once all effects are taken into account. The dynamic aperture is large enough to support an off-axis injection scheme using a nonlinear kicker and has a lifetime greater than 4 h. In this paper, the main parameters and magnet specifications for the Diamond-II lattice are provided. The related linear and non-linear beam dynamics issues are discussed, along with the impact of IDs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB090

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paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 26 August 2021

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THPAB097

Towards Arbitrary Pulse Shapes in the Terahertz Domain

3977

C. Mai, B. Büsing, A. Held, S. Khan, D. Krieg
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF (05K19PEC).
The TU Dortmund University operates the 1.5-GeV electron storage ring DELTA as a synchrotron light source in user operation and for accererator physics research. At a dedicated beamline, experiments with (sub-)THz radiation are carried out. Here, an interaction of short laser pulses with electron bunches is used to modulate the electron energy which causes the formation of a dip in the longitudinal electron density, giving rise to the coherent emission of radiation between 75 GHz and 6 THz. The standard mode of operation is the generation of broadband radiation. However, more sophisticated energy modulation schemes were implemented using a liquid-crystal phase modulator. Here, a modulation of the spectral phase of the laser is used to control the spectral shape of the THz pulses. The resulting THz spectra have a relative bandwidth of about 2 %. Measurement results from the different THz generation schemes are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB097

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paper received ※ 18 May 2021 paper accepted ※ 12 July 2021 issue date ※ 24 August 2021

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THPAB104

Magnetic Error Effects of the Storage Ring for the Southern Advanced Photon Source

3980

J. Chen, Y. Jiao, X. Liupresenter, S. Wang
IHEP, Beijing, People’s Republic of China
Y. Zhao
IHEP CSNS, Guangdong Province, People’s Republic of China

There are various magnetic errors in the actual accelerator, which will significantly affect the beam quality and machine performance. The diffraction-limited storage ring (DLSR) of Southern Advanced Photon Source (SAPS) will use a large number of ultra-high gradient quadrupoles and sextupoles, which, in turn, leads to the tight tolerance of beam parameters to magnetic errors. Based on a preliminary designed storage ring lattice of the SAPS, the influence of various magnetic errors on lattice parameters has been evaluated.

Poster THPAB104 [0.588 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB104

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paper received ※ 17 May 2021 paper accepted ※ 23 June 2021 issue date ※ 18 August 2021

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THPAB106

Optimization of a High Bunch Charge ERL Injection Merger for PERLE

3983

B. Hounsell, M. Klein, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
S.A. Bogacz
JLab, Newport News, Virginia, USA
C. Bruni, B. Hounsell, W. Kaabi
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
B. Hounsell, B.L. Militsyn, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Delivery of high charge electron bunches into the main loop of an ERL (energy recovery linac) while preserving the emittance is challenging. This is because at the typical injection momentum, space charge forces still have a significant effect on the beam dynamics. In this work we consider the design of the merger for PERLE, an ERL test facility to be based at IJCLab in France. Previous simulations have shown that the baseline DC gun based injector can achieve the required emittance at the booster linac exit. The quality of the 500 pC bunches must then be preserved with space charge through the merger at total beam energy of 7 MeV keeping the emittance below 6 mm mrad. The beam dynamics in the merger were simulated using the code OPAL and optimised using a genetic algorithm. Three possible merger schemes were investigated. The goal of the optimisation was to minimise the emittance growth while also achieving the required Twiss parameters to match onto the spreader at the main linac exit. A three dipole solution is then examined in more detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB106

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paper received ※ 19 May 2021 paper accepted ※ 16 July 2021 issue date ※ 12 August 2021

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THPAB113

The Extended Operative Range of the LNF LINAC and BTF Facilities

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB113

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 27 August 2021

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THPAB119

Many-Objective Beam Dynamics Optimization for High-Repetition-Rate XFEL Photoinjector

3991

Z.H. Zhu, J.W. Yan
SINAP, Shanghai, People’s Republic of China
D. Gu
SARI-CAS, Pudong, Shanghai, People’s Republic of China
Q. Gu
Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China

SHINE, as the first hard x-ray free-electron-laser (FEL) facility in China, is design to provide high-brightness FEL lasing under high-repetition-rate operation. In order to drive x-ray FEL pulses with high qualities, the photoinjector section is deployed to provide the specified electron beam with low transverse emittance and high brightness. Normally the multi-objective optimization algorithm is employed in the injector beam dynamics design. In this paper, the many-objective optimization algorithm NSGA-III is introduced to the injector physical design for optimizing the 4 detailed beam quality properties using 17 variables for the first time. The results of the optimization are presented and the correlations are analyzed. This approach can provide guidance for further physical research as well as improve the beam dynamics optimization efficiency.

Poster THPAB119 [0.936 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB119

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paper received ※ 17 May 2021 paper accepted ※ 07 July 2021 issue date ※ 22 August 2021

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THPAB120

Beam on Demand for High-Repetition-Rate X-Ray Free-Electron Lasers

3995

Z. Zhang, Y. Ding, Z. Huang
SLAC, Menlo Park, California, USA

High-repetition-rate (HRR) free-electron lasers (FELs) with multiple undulator beamlines will advance the frontiers of X-ray science significantly from the remarkable success of existing X-ray FEL facilities. The wide-ranging requirements for the photon properties from multiple beamlines are extremely challenging to satisfy by the same electron beam from a single superconducting radio-frequency (SRF) accelerator. To realize the full potential of an HRR FEL facility, a new emerging concept of "beam on demand" is proposed here. The concept is based on advanced beam dynamics and radio-frequency (RF) techniques to provide beam properties tailored to each undulator line at the desired repetition rate. The beam properties that will be pursued in this proposal include, but are not limited to, beam energy, bunch charge, bunch length, beam current, and its profile. The realization of "beam on demand" will allow optimization of photon properties of individual beamlines to maximize their performance and drastically improve the multiplexing capabilities of Linac Coherent Light Source II and its high-energy upgrade.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB120

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paper received ※ 17 May 2021 paper accepted ※ 23 July 2021 issue date ※ 27 August 2021

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THPAB121

Plasma Muon Beam Cooling for HEP

3999

M.A. Cummings, R.J. Abrams, R.P. Johnson, S.A. Kahn, T.J. Roberts
Muons, Inc, Illinois, USA
V.S. Morozov, A.V. Sy
JLab, Newport News, Virginia, USA
K. Yonehara
Fermilab, Batavia, Illinois, USA

Ionization cooling has the potential to shrink the phase space of a muon beam by a factor of 10⁶ within the muons’ short lifetime (2.2 µs) because the collision frequency in a cooling medium is extremely high compared to conventional beam cooling methods. It has been realized that ionization cooling inherently produces a plasma of free electrons inside the absorber material, and this plasma can have an important effect on the muon beam. In particular, under the right circumstances, it can both improve the rate of cooling and reduce the equilibrium emittance of the beam. This has the potential to improve the performance of muon facilities based on muon cooling; in particular a future muon collider. We describe how this project will integrate Plasma muon beam cooling into both the basic Helical Cooling Channel (HCC) and extreme Parametric-resonance Ionization Cooling (PIC) techniques. This potentially whole new approach to muon cooling has exciting prospects for significantly reduced muon beam emittance.

Poster THPAB121 [1.214 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB121

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021

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THPAB123

Pytomic: A Python Tool for Polarized Atomic Beam Tracking

4002

J.L. Martinez Marin, W. Armstrong, B.M. Mustapha
ANL, Lemont, Illinois, USA

Funding: This work was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357 through ANL’s LDRD program.
Pytomic is a new tool for the simulation and analysis of atomic beams through magnetic systems. It is written in Python and based on the same fundamentals as other particle tracking codes but for atomic beams instead of charged beams. In this case, the manipulation and control of neutral atomic beams is via a force due to the spin interacting with a magnetic field gradient. An object-oriented tool was developed to aid in the design of a beamline through the manipulation of modular elements. The Python language allowed for a smooth implementation and kept the code clear and simple. The primary purpose of developing this code was to have a tool to design, simulate, and optimize a Breit-Rabi Polarimeter to measure the polarization of an atomic beam. Therefore, different set-ups with different magnets need to be simulated and optimized for direct comparison. In addition to simulation and tracking modules, a new data analysis module was developed to be able to quickly analyze simulation results, gaining insight from each iteration of the simulation, leading to an efficient and rapid design process. Example applications to design polarimeters for atomic beams will be presented.

Poster THPAB123 [7.765 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB123

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paper received ※ 20 May 2021 paper accepted ※ 21 June 2021 issue date ※ 27 August 2021

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THPAB124

Application of the FFA Concept to a Muon Collider Complex

4006

S. Machida, J.-B. Lagrange
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
M.E. Topp-Mugglestone
JAI, Oxford, United Kingdom

Muon collider complex is one of the places where the concept of fixed field alternating gradient (FFA) optics can be applied with great benefits. Vertical excursion FFA (vFFA) provides the isochronous condition for the ultra-relativistic muon beams after pre-acceleration. Together with the fixed transverse tune, it will be an ideal accelerator of short-lived muon beams with no time variation of magnetic fields and RF frequency. Novel collider ring optics is a design based on skew quadrupole after extracting essential functions from vFFA. That enables control of the momentum compaction factor. Neutrinos from the continuing decay of muons are spread out with orbit wiggling in the vertical direction as well as horizontal. The paper discusses the underline principle and describes some design examples.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB124

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paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 28 August 2021

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THPAB126

Operational Experience and Characterization of a Superconducting Transverse Gradient Undulator for Compact Laser Wakefield Accelerator-Driven FEL

4009

K. Damminsek, A. Bernhard, J. Gethmann, A.W. Grau, A.-S. Müller, Y. Nie, M.S. Ning, S.C. Richter, R. Rossmanith
KIT, Karlsruhe, Germany

A 40-period superconducting transverse gradient undulator (TGU) has been designed and fabricated at Karlsruhe Institute of Technology (KIT). Combining a TGU with a Laser Wakefield Accelerator (LWFA) is a potential key for realizing an extremely compact Free Electron Laser (FEL) radiation source. The TGU scheme is a viable option to compensate the challenging properties of the LWFA electron beam in terms of beam divergence and energy spread. In this contribution, we report on the operational experience of this TGU inside its own cryostat and show the current status of the TGU and the further plan for experiments. This work is supported by the BMBF project 05K19VKA PlasmaFEL (Federal Ministry of Education and Research).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB126

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paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 02 September 2021

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THPAB129

Beam Dynamics Simulations in a High-Gradient X-Band Photoinjector

4013

W.H. Tan, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
G. Chen, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
G. Chen
IIT, Chicago, Illinois, USA
G. Ha, C.-J. Jing
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid Beamlabs, Bolingbrook, USA

A high-gradient X-band (11.7-GHz) photoinjector was recently developed by Euclid Techlabs and is in its commissioning phase at the Argonne Wakefield Accelerator (AWA). This contribution discuss the beam-dynamics modeling of the photoinjector system comprising an RF gun and linac section. We especially discuss beam-dynamics optimization of setup for an integrated proof-of-principle experiments. We also discuss the use of such a photoinjector as a witness-bunch source for a future high-gradient collinear-wakefield accelerator experiments at the AWA.
* S. V. Kuzikov, et al. these proceedings.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB129

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paper received ※ 20 May 2021 paper accepted ※ 14 July 2021 issue date ※ 31 August 2021

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THPAB130

Design of a Very Low Energy Beamline for NA61/SHINE

4017

C.A. Mussolini, N. Charitonidis
CERN, Geneva, Switzerland
P. Burrows
JAI, Oxford, United Kingdom
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
Y. Nagai
Colorado University at Boulder, Boulder, Colorado, USA
Y. Nagai
ELTE, Budapest, Hungary
E.D. Zimmerman
CIPS, Boulder, Colorado, USA

A new, low-energy beamline branch is currently under consideration for the H₂ beamline at the CERN North Area. This new branch would extend the capabilities of the current infrastructure enabling the study of particles in the very low, 1-13 GeV/c, momentum range. The design of this new beamline involves various stages. Firstly, a study of the secondary targets to maximise the yield of secondary hadrons. Secondly, the development of high acceptance transverse optics with high momentum resolution on the order of a few %. Finally, we discuss the first considerations on instrumentation to enable particle identification and background rejection. The first experiment to profit from this new line could be NA61/SHINE, but other possible future fixed target experiments or test-beams installed in the downstream zones could also use the low-energy particles provided. The aim is to arrive at a complete design of this branch by the end of 2021, which, pending the approval of the CERN scientific committees, could be envisaged for construction after 2024. This timescale is compatible with requests for measurements by various large international collaborations, in the next 10-year horizon.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB130

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paper received ※ 15 May 2021 paper accepted ※ 27 July 2021 issue date ※ 27 August 2021

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THPAB131

Spatio-Temporal Measurements of THz Pulses

4021

G.A. Hine
ORNL, Oak Ridge, Tennessee, USA

Funding: This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory under Contract No. DEAC05-00OR22725.
The 3D characterization of single-cycle Terahertz (THz) pulses in its transverse and temporal dimensions is presented. The high fields and short wavelengths of THz pulses make them an intriguing prospect for novel accelerator technologies. Effective application for free-space THz pulses requires high beam quality and concomitant measuring techniques. The combination of conventional electro-optic sampling to measure the temporal profile and detectors like microbolometer focal plane arrays to measure the transverse profile does not capture the correlations that can arise in single-cycle THz pulses. To capture these correlations, a modified version electro-optic sampling using a CCD is implemented. THz pulses generated by optical rectification in organic crystals are measured using this technique and their spatiotemporal correlations characterized.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB131

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 17 August 2021

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THPAB134

Development and Analysis of Software for the Numerical Simulation of Field Emission Electron Sources

4024

N.S. Kakorin, K.A. Nikiforov
Saint Petersburg State University, Saint Petersburg, Russia
N.V. Egorov
St. Petersburg State University, St. Petersburg, Russia

Funding: The reported study was funded by RFBR, project number 20-07-01086.
The open-source DAISI C++ package (Design of Accelerators, optImizations and SImulations) is extended with the ability to simulate the operation of electron sources in the field emission mode, with the user-defined initial distribution of emitted electrons velocities, as a model parameter, and with the automated calculation of current-voltage characteristics. Particles injection scheme is suggested. Computational experiments are performed for silicon carbide field emission electron source nanostructure with bimodal energy spectrum, revealed from experimental study, and comparative analysis with Maxwell distribution is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB134

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paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 17 August 2021

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THPAB138

FEbreak: A Comprehensive Diagnostic and Automated Conditioning Interface for Analysis of Breakdown and Dark Current Effects

4027

M.E. Schneider, S.V. Baryshev
Michigan State University, East Lansing, Michigan, USA
R.L. Fleming, D. Gorelov, J.W. Lewellen, E.I. Simakov
LANL, Los Alamos, New Mexico, USA
E. Jevarjian
MSU, East Lansing, Michigan, USA

Funding: DE-AC02-06CH11357, No. DE-SC0018362, DE-NA-0003525, DE-AC52-06NA25396, LA-UR-21-20613
As the next generation of accelerator technology pushes towards being able to achieve higher and higher gradients there is a need to develop high-frequency structures that can support these fields *. The conditioning process of the structures and waveguides to high gradient is a labor-intensive process, its length increases as the maximum gradient is increased. This results in the need to automate the conditioning process. This automation must allow for high accuracy calculations of the breakdown probabilities associated with the conditioning process which can be used to instruct the conditioning procedure without the need for human intervention. To automate the conditioning process at LANL’s high gradient C-band accelerator test stand we developed FEbreak that is a breakout probability and conditioning automation software that is a part of the FEmaster series **, ***, ****. FEbreak directly interfaces with the rest of FEmaster to automate the data collection and data processing to not only analyze the breakdown probability but also the dark current effects associated with these high gradient structures.
* E. I. Simakov Nuc. Inst. and Meth, in Phy. Research Section A: Acc. Spec, 907 221 (2019)
** E. Jevarjian arXiv:2009.13046
*** T. Y. Posos arXiv:2012.03578
**** M. Schneider arXiv:2012.10804

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB138

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paper received ※ 18 May 2021 paper accepted ※ 02 July 2021 issue date ※ 16 August 2021

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THPAB140

Modelling Seeded Self Modulation of Long Elliptical Bunches in Plasma

4030

A. Perera, O. Apsimon, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J. Resta-López
IFIC, Valencia, Spain

Funding: This work was supported by STFC Centre for Doctoral Training in Data-Intensive Science (LIV. DAT) under grant ST/P006752/1 and the STFC Scientific Computing Department’s SCARF cluster.
The stability of particle bunches undergoing seeded self-modulation (SSM) over tens or hundreds of meters is crucial to the generation of GV/m wakefields that can accelerate electron beams as proposed for use in several high energy plasma-based linear colliders. Here, 3D particle-in-cell simulations using QuickPIC are compared to an analytical model of seeded self-modulation (SSM) of elliptical beam envelopes using linear wakefield theory. It is found that there is quantitative agreement between simulations and analytical predictions for the envelope in the early growth of the SSM. A scaling law is derived for the reduction of the maximum overall modulation growth rate with aspect ratio and is found to match well with simulation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB140

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paper received ※ 19 May 2021 paper accepted ※ 22 July 2021 issue date ※ 31 August 2021

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THPAB141

Novel Design of a HVDC Magnetized Electron Source

4034

O.H. Rahman, J. Skaritka, E. Wang
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 hadron beam in EIC is flat with a transverse size ratio of about 1:3. The cooling rate of the hadron beam can be maximized if the electron beam from the strong hadron cooler fully overlaps with the hadron beam. Therefore, generating a flat electron beam is essential. The most efficient way to generate a flat electron beam is to produce a magnetized beam first, and then convert it to flat to the desired transverse size ratio. Using a Magnetized electron beam is a promising way to cool high-energy hadrons. One of the major challenges in producing magnetized beams is fine-tuning the longitudinal magnetic field on the cathode surface and maintaining the desired field uniformity over the emission area. In this paper, we discuss the design of a novel high voltage DC gun capable of fine-tuning the B field on the cathode. This is achieved by installing a permanent magnet inside the cathode puck, with a solenoid field at the front of the cathode. We show magnetostatic simulation to prove the feasibility of this idea. We also show preliminary beam dynamics simulations showing emittance from the gun as the permanent magnet and solenoidal fields are tuned for minimum emittance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB141

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paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 17 August 2021

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THPAB142

Optical and Surface Characterization of Alkali-Antimonide Photocathodes

4037

P. Saha, O. Chubenko, G.S. Gevorkyan, A.H. Kachwala, S.S. Karkare, C.J. Knill
Arizona State University, Tempe, USA
E.J. Montgomery, S. Poddar
Euclid Beamlabs, Bolingbrook, USA
H.A. Padmore
LBNL, Berkeley, California, USA

Alkali-antimonides, characterized by high quantum efficiency and low mean transverse energy in visible light, are excellent electron sources to drive x-ray free electron lasers, electron cooling and ultrafast electron diffraction applications etc. Existing studies of alkali-antimonides have focused on quantum efficiency and emittance, but information is lacking on the fundamental aspects of the electronic structure, such as the energy gap of the semiconductor and the density of defects as well as the overall nano-structure of the materials. We are, therefore, conducting photoconductivity measurements to measure fundamental semiconductor properties as well as using atomic force microscope (AFM) and kelvin probe force microscope (KPFM) to measure the nanostructure variations in structure and surface potential.

Poster THPAB142 [1.211 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB142

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paper received ※ 16 May 2021 paper accepted ※ 14 July 2021 issue date ※ 13 August 2021

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THPAB143

M2 Experimental Beamline Optics Studies for Next Generation Muon Beam Experiments at CERN

4041

D. Banerjee, J. Bernhard, M. Brugger, N. Charitonidis, G.L. D’Alessandro, A. Gerbershagen, E. Montbarbon, C.A. Mussolini, E.G. Parozzi, B. Rae, B.M. Veit
CERN, Geneva, Switzerland
L. Gatignon
Lancaster University, Lancaster, United Kingdom

In the context of the Physics Beyond Colliders Project, various new experiments have been proposed for the M2 beamline at the CERN North Area fixed target experimental facility. The experiments include MUonE, NA64µ, and the successor to the COMPASS experiment, tentatively named AMBER/NA66. The AMBER/NA66 collaboration proposes to build a QCD facility requiring conventional muon and hadron beams for runs up to 2024 in the first phase of the experiment. MUonE aims to measure the hadronic contribution to the vacuum polarization in the context of the (gµ-2) anomaly with a setup longer than 40 m and a 160 GeV/c high intensity, low divergence muon beam. NA64µ is a muon beam program for dark sector physics requiring a 100 - 160 GeV/c muon beam with a 15-25 m long setup. All three experiments request similar beam times up to 2024 with compelling physics programs, which required launching extensive studies for integration, installation, beam optics, and background estimations. The experiments will be presented along with details of the studies performed to check their feasibility and compatibility with an emphasis on the updated optics for these next-generation muon beam experiments.

Poster THPAB143 [14.259 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB143

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paper received ※ 17 May 2021 paper accepted ※ 20 July 2021 issue date ※ 25 August 2021

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THPAB145

Cold Test of a Novel S-Band 1.6 Cell Photocathode RF Gun

4045

Zh.X. Tang, S.X. Dong, Y.J. Pei, B.F. Wei
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China(Grant No. 11805199 and U1832135) and Fundamental Research Funds for the Central Universities (Grant No. WK2310000072)
The photocathode RF gun is one of the most critical components for high quality electron beam sources. The asymmetric multi-pole field contributes to the transverse emittance growth and degrades the beam quality. In order to overcome the problem, we propose a novel rotationally symmetric 1.6 cell RF gun to construct the symmetric field in this paper. The concrete proposal is that a coaxial cell cavity with a symmetrical distribution of four grooves is concatenated to the photocathode end of the traditional 0.6 cell cavity to form the novel 0.6 cell cavity. Through the detailed design study, the profile of the RF gun is optimized to improve the shunt impedance and mode separation and make the surface peak electric field at the photocathode end. Considering the filling time, a coupling slot is designed to couple input power into the RF gun. The RF cavity is machined by numerical control machine tool, and the tuning and low power RF measurement are carried out. The experimental results are consistent with the simulation results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB145

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paper received ※ 09 May 2021 paper accepted ※ 02 September 2021 issue date ※ 29 August 2021

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THPAB146

Preliminary Study of Femtosecond Electron Source Based on THz Acceleration and Field Emission

4048

Zh.X. Tang, G. Feng, B.F. Wei
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China (Grant No. U1832135 and 11805199) and Fundamental Research Funds for the Central Universities (Grant No. WK2310000072)
In this paper, we propose a novel electron gun based on THz acceleration and field emission to generate femtosecond electron bunches. The field emission cathode is placed in the center of the cavity, and the standing wave field is established in the cavity to achieve the field emission conditions and extract the electron beam. Because the period of THz band is about picosecond, the femtosecond bunch is formed by controlling the field strength and the pulse width of the extracted beam. We analyzed the feasibility of field emission and the length of the pulse beam. The surface peak field intensity of the structure of the cavity with different emitters are simulated by CST software.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB146

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paper received ※ 09 May 2021 paper accepted ※ 02 September 2021 issue date ※ 01 September 2021

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THPAB147

Preliminary Study of 500 MHz HOM-Free RF Cavity

4050

Zh.X. Tang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China(Grant No. U1832135 and 11805199)}
In this paper, we study the microwave characteristics of 500 MHz RF cavity, including the optimization of cavity structure, the simulation design of high-order mode (HOM) absorption structure and the design of coupler. The cavity structure is simulated by CST. The absorption waveguide is designed and optimized. The coupler is designed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB147

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paper received ※ 09 May 2021 paper accepted ※ 16 July 2021 issue date ※ 02 September 2021

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THPAB151

The Advantage of Cold Electron Source in Electron Diffraction

4053

J. Liu, H. Luo
SWUST, Mianyang City, Sichuan Province, People’s Republic of China

In this paper, a model for discussing the influence of transverse coherence of electron beams on electron diffraction is established. With reference to Fedele’s thermal-wave model, the transverse coherence length is introduced into this model to characterize the transverse coherence of electron beams. The simulation results show that the transverse coherence of electron beams has a significant influence on electron diffraction, and the cold electron source with high transverse coherence has an obvious advantage in electron diffraction.

Poster THPAB151 [0.647 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB151

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paper received ※ 15 May 2021 paper accepted ※ 21 June 2021 issue date ※ 25 August 2021

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THPAB153

Design, Construction and Tests of the Cooling System with a Cryocooler for Cavity Testing

4056

P. Pizzol, J.W. Lewellen, E.R. Olivas, E.I. Simakov, T. Tajima
LANL, Los Alamos, New Mexico, USA

Cryogenically cooled normal-conducting cavities have shown higher gradients than those operated at room temperature. We are constructing a compact cooling system with a cryocooler to test C-band normal-conducting cavities and 1.3 GHz superconducting cavities. This paper describes the design, construction, and cooling test results as well as some low-power cavity Q measurement results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB153

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paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 12 August 2021

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THPAB155

Strong Quadrupole Wakefield Based Focusing in Dielectric Wakefield Accelerators

4059

W.J. Lynn, G. Andonian, N. Majernik, J.B. Rosenzweig
UCLA, Los Angeles, California, USA

Funding: Grant number: DOE HEP Grants DE-SC0017648, DE-SC0009914, and National Science Foundation Grant No. PHY-1549132.
We propose here to exploit the quadrupole wakefields in an alternating symmetry slab-based dielectric wakefield accelerator (DWA) to produce second-order focusing. The resultant focusing is found to be strongly dependent on longitudinal position in the bunch. We analyze this effect with analytical estimates and electromagnetic PIC simulations. We examine the use of this scenario to induce beam stability in very high gradient DWA, with positive implications for applications in linear colliders and free-electron lasers.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB155

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paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 19 August 2021

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THPAB156

Built-in Thermionic Electron Source for an SRF Linacs

4062

I.V. Gonin, S. Kazakov, R.D. Kephart, T.N. Khabiboulline, T.H. Nicol, N. Solyak, J.C.T. Thangaraj, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

The design of a thermionic electron source connected directly to a superconducting cavity, the key part of an SRF gun, is described. The results of beam dynamics optimization are presented which allow lack of beam current intercepting in the superconducting cavity. The electron source concept is presented including the cathode-grid assembly, thermal insulation of the cathode from the cavity, and the gun resonator design. The cavity thermal load caused by the gun is analyzed including the static heat load, black body radiation, backward electron heating, etc.

Poster THPAB156 [0.670 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB156

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 27 August 2021

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THPAB157

Studying X-Ray Spectra of the SIS18 Electrostatic Septa to Measure Their Electric Field

4065

B. Gålander, E. Kozlova, D. Ondreka, A. Sokolov, P.J. Spiller, J. Stadlmann
GSI, Darmstadt, Germany

The synchrotron SIS18 at GSI uses resonant extraction for slow beam extraction on the order of seconds. For some time, there has been an unexplained discrepancy of the slow extraction with a lower extraction efficiency than expected at the highest beam energies. Recent machine studies have indicated that the deflection by the electrostatic septum might be less than the nominal 2.5 mrad, leading to increased losses at the magnetic septum. In this paper, we pursue an idea to directly measure the voltage of the electrode gap by utilizing the fact that dark current electrons accelerated in the gap of the electrostatic extraction septum generate Bremsstrahlung X-rays when hitting the anode. The high-energy cut-off of the X-ray spectra then corresponds to the voltage of the electrode gap. Measurements of the X-ray spectra at the extraction septum of SIS18 have been performed using a solid-state CdTe detector. This technique provides an in-situ measurement of the voltage applied to the electrostatic extraction channel and has proven to be a useful diagnostics tool.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB157

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paper received ※ 19 May 2021 paper accepted ※ 02 September 2021 issue date ※ 19 August 2021

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THPAB158

BEAM COLLIMATION IN THE PIP-II LINAC TO BOOSTER TRANSFER LINE

4068

D.E. Johnson, V.V. Kapin, J.-F. Ostiguy, V.I. Sidorov, M. Xiao
Fermilab, Batavia, Illinois, USA
D.G. Georgobiani
FRIB, East Lansing, Michigan, 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 new PIP-II superconducting linac will deliver a 2 mA average H^- beam to the existing Booster synchrotron. The injected beam is accumulated by charge exchange over approximately 300 turns; phase space painting is used to mitigate space charge effects. To limit the power load on the internal waste beam absorber from the transverse tails of the H⁻ distribution missing the foil, the beam will be collimated in both planes in the linac to Booster transfer line using compact collimators of a novel design. Both the number of parasitic hits and the fraction of the beam missing the foil are sensitive functions of the H⁻ beam centroid position with respect to the edge of the foil. The positioning of the collimation is constrained by the availability of suitable space in the transfer line lattice, by specifics of the collimator design, by the phase space orientation at the collimator, and by the betatron phase advance to the foil needed to achieve proper orientation of the spatial distribution at the injection point. In this contribution, we describe the procedure by which collimator positions were optimized. We then discuss the expected performance of the overall system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB158

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paper received ※ 04 June 2021 paper accepted ※ 02 July 2021 issue date ※ 26 August 2021

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THPAB165

5 MW Beam Power in the ESSnuSB Accumulator: A Way to Manage Foil Stripping Injection at 14 Hz Linac Pulse Rate

4072

H. Schönauer
CERN, Geneva, Switzerland
Y. Zoupresenter
Uppsala University, Uppsala, Sweden

Funding: This work is supported by the European Union’s Horizon 2020 research and innovation program under grant agreement No 777419.
In the past, the scenario for foil stripping consisted of splitting a linac pulse into 4 rings, or 3 or 4 intermediate pulses, and one ring. At present, the scenario, in view of laser stripping, consists of one ring, one pulse, split into four batches. Conventional stripping geometry would lead to foil evaporation under this beam load. One way out appears to be replacing the standard corner foil by a single-edge foil rotated to about 45deg. The tilted foil allows moving the injection point together with the painting bumps along the foil edge, distributing the deposited beam power over a larger foil area. Simulation results obtained with the same tools as in the past scenarios are presented. They show peak foil temperatures, which compare with the best results obtained from the past scenarios.

Poster THPAB165 [2.205 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB165

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paper received ※ 11 May 2021 paper accepted ※ 21 June 2021 issue date ※ 18 August 2021

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THPAB167

Technical Design of an RFQ Injector for the IsoDAR Cyclotron

4075

H. Höltermann, D. Koser, B. Koubek, H. Podlech, U. Ratzinger, M. Schuett, M. Syha
BEVATECH, Frankfurt, Germany
J.M. Conrad, J. Smolsky, L.H. Waites, D. Winklehner
MIT, Cambridge, Massachusetts, USA

For the IsoDAR (Isotope Decay-At-Rest) experiment, a high intensity (10 mA CW) primary proton beam is needed. To generate this beam, H²⁺ is accelerated in a cyclotron and stripped into protons after extraction. An RFQ, partially embedded in the cyclotron yoke, will be used to bunch and axially inject H²⁺ ions into the main accelerator. The strong RFQ bunching capabilities will be used to optimize the overall injection efficiency. To keep the setup compact the distance between the ion source and RFQ can be kept very short as well. In this paper, we describe the technical design of the RFQ. We focus on two critical aspects: 1. The use of a split-coaxial structure, necessitated by the low frequency of 32.8 MHz (matching the cyclotron RF) and the desired small tank diameter; 2. The high current, CW operation, requiring a good cooling concept for the RFQ tank and vanes.

Poster THPAB167 [2.162 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB167

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paper received ※ 14 May 2021 paper accepted ※ 27 July 2021 issue date ※ 21 August 2021

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THPAB168

Optics Measurement by Excitation of Betatron Oscillations in the CERN PSB

4078

E.H. Maclean, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, J. Keintzel, M. Le Garrec, T.E. Levens, L. Malina, T.H.B. Persson, T. Prebibaj, E. Renner, P.K. Skowroński, F. Soubelet, R. Tomás García, A. Wegscheider, L. van Riesen-Haupt
CERN, Geneva, Switzerland

Optics measurement from analysis of turn-by-turn BPM data of betatron oscillations excited with a kicker magnet has been employed very successfully in many machines but faces particular challenges in the CERN PSB where BPM to BPM phase advances are sub-optimal for optics reconstruction. Experience using turn-by-turn oscillation data for linear optics measurements during PSB commissioning in2021 is presented, with implications for the prospect of such techniques in the PSB more generally.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB168

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021

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THPAB169

A Mechanism for Emittance Growth Based on Non-Linear Islands in LHC

4082

E.H. Maclean, M. Giovannozzi, T.H.B. Persson, R. Tomás García
CERN, Geneva, Switzerland

Landau octupoles are used in the LHC to prevent coherent instabilities of the circulating beam. The reduction of their strength occurring during the energy ramp can transport particles in nonlinear islands to larger amplitude. This has the potential to lead to emittance growth and to beam-losses. Beam-based studies and simulations of emittance growth during Landau octupole ramps performed in the LHC are presented to explore this mechanism in more detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB169

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paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 14 August 2021

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THPAB170

RF Deflector Design for Rapid Proton Therapy

4086

E.J.C. Snively, G.B. Bowden, V.A. Dolgashev, Z. Li, E.A. Nanni, D.T. Palmer, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work is supported by US Department of Energy Contract No. DE-AC02-76SF00515.
Pencil beam scanning of charged particle beams is a key technology enabling high dose rate cancer therapy. The potential benefits of high-speed dose delivery include not only a reduction in total treatment time and improvements to motion management during treatment but also the possibility of enhanced healthy tissue sparing through the FLASH effect, a promising new treatment modality. We present here the design of an RF deflector operating at 2.856 GHz for the rapid steering of 150 MeV proton beams. The design utilizes a TE11-like mode supported by two posts protruding into a pillbox geometry to form an RF dipole. This configuration provides a significant enhancement to the efficiency of the structure, characterized by a transverse shunt impedance of 68 MOhm/m, as compared to a conventional TM11 deflector. We discuss simulations of the structure performance for several operating configurations including the addition of a permanent magnet quadrupole to amplify the RF-driven deflection. In addition to simulation studies, we will present preliminary results from a 3-cell prototype fabricated using four copper slabs to accommodate the non-axially symmetric cell geometry.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB170

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021

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THPAB171

mm-Wave Linac Design for Next Generation VHEE Cancer Therapy Systems

4090

E.J.C. Snively, K.C. Deering, E.A. Nanni
SLAC, Menlo Park, California, USA

Direct electron therapy offers an attractive method for providing the high dose rates necessary for FLASH radiation therapy, a new treatment modality with the potential for enhanced healthy tissue sparing. Direct electron therapy has been limited by the low beam energies, up to 20 MeV, provided by today’s medical linacs, restricting the achievable dose depth to superficial tumors. Very High Energy Electron (VHEE) therapy could reach deep-seated tumors throughout the body. A clinically viable VHEE system must provide electron energies of around 100 MeV in a compact footprint, roughly 1 to 2 meters, with modest power requirements. We investigate the development of mm-wave linacs to provide the necessary beam energies on the sub-meter scale, taking advantage of the favorable scaling of high-frequency operation to support gradients well above 100 MeV/m. We discuss the design parameters necessary for high-efficiency structures, with shunt impedance on the order of 1 GOhm/m, producing high gradients with only a few megawatts of power. We present simulations of cavity performance in the mm-wave operating regime, with an emphasis on compatibility with the requirements of VHEE therapy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB171

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 15 August 2021

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THPAB172

Bunch Luminosity Variations in LHC Run 2

4094

I. Efthymiopoulos, S.D. Fartoukh, G. Iadarola, N. Karastathis, S. Papadopoulou, Y. Papaphilippou
CERN, Geneva, Switzerland

The LHC is designed to collide intense bunches of protons with tightly defined conditions, aimed to maximize the delivered recorded integrated luminosity to the experiments. One of these conditions is the maximum level of bunch-to-bunch fluctuation in the luminosity, in particular when levelling at maximum acceptable event rate at the experiments. Analysis results of the bunch-to-bunch luminosity variations in LHC Run 2 are presented here. In particular, the observed correlations with the LHC filling pattern that can enhance the effects introducing bunch-dependent losses or emittance blow-up from injection to collisions are discussed. In Run 2 conditions, bunch-by-bunch luminosity fluctuations reached 10% at the start of collisions and gradually increased with time, without affecting the experiments as the luminosity was not levelled. Projections for Run 3 and HL-LHC operation are discussed along with envisaged mitigation measures.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB172

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paper received ※ 18 May 2021 paper accepted ※ 19 July 2021 issue date ※ 23 August 2021

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THPAB173

Fundamental Study on Electromagnetic Characteristics of Half-Wave Resonator for 200 MeV Energy Upgrade of KOMAC Proton Linac

4098

J.J. Dang, Y.-S. Cho, H.S. Kim, H.-J. Kwon, S. Lee
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work has been supported through KOMAC operation fund of KAERI by the Korea government (MSIT).
A superconducting linac has been developed at KOrea Multi-purpose Accelerator Complex (KOMAC). A goal of the SRF linac is to increase proton beam energy from 100 MeV to 200 MeV. 350 MHz medium beta half-wave resonator (HWR) should provide 3.6 MV accelerating voltage to achieve the energy upgrade. An electromagnetic (EM) analysis on the parametrically designed HWR cavity was conducted. The cavity design was optimized to reduce a peak electric field and a peak magnetic field while satisfying the required acerating voltage. In addition, a mechanical-EM coupled simulation was conducted to estimate a helium pressure sensitivity. Also, Lorentz force detuning was simulated. The design is being optimized to minimize the frequency detuning due to the helium pressure and Lorentz force.

Poster THPAB173 [0.800 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB173

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 23 August 2021

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THPAB174

T-BMT Spin Resonance Tracker Code for He3 with Six Snakes

4101

V.H. Ranjbar, H. Huang, Y. Luo, F. Méot, V. Ptitsyn
BNL, Upton, New York, USA
G.H. Hoffstaetter, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
F. Lin, V.S. Morozov
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy .
Polarization lifetime for He3 using two and six snakes are studied using the T-BMT Spin Resonance Tracker code. This code integrates a reduced spinor form of the T-BMT equation including only several spin resonances and the kinematics of synchrotron motion. It was previously benchmarked against RHIC polarization lifetime under the two snake system *.
* Phys. Rev.Accel. Beams 22 (2019) 9, 091001

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB174

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paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 28 August 2021

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THPAB175

nuSTORM Accelerator Challenges and Opportunities

4104

C.T. Rogers, J.-B. Lagrange
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
N. Gall
CERN, Meyrin, Switzerland
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The nuSTORM facility uses a stored muon beam to generate a neutrino source. Muons are captured and stored in a storage ring using stochastic injection. The facility will aim to measure neutrino-nucleus scattering cross-sections with uniquely well-characterized neutrino beams; to facilitate the search for sterile neutrino and other Beyond Standard Model processes with exquisite sensitivity, and to provide a muon source that makes an excellent technology test-bed required for the development of muon beams capable of serving as a multi-TeV collider. In this paper, we describe the latest status of the development of nuSTORM, the R&D needs, and the potential for nuSTORM as a Muon Collider test facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB175

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paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 31 August 2021

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THPAB176

Studies on Beam Collimation System for the ESSnuSB Accumulator

4107

Y. Zou, M. Olvegård
Uppsala University, Uppsala, Sweden

Funding: This work is supported by the European Union Horizon 2020 research and innovation program under grant agreement No 777419.
The ESSnuSB, a neutrino facility based on the European Spallation Source, aims at measuring, with precision, the charge-parity (CP) violating lepton phase at the 2nd oscillation maximum. The ESS linac will have to be upgraded to provide an additional 5 MW beam for the ESSnuSB to produce an unprecedented high-intensity neutrino beam. An accumulator ring is employed to compress the 2.86 ms long pulse from the linac to around 1.5 µs in order to satisfy the target requirements and improve the physics performance. In the operation of a high-intensity proton accumulator, the most important issue is to minimize the uncontrolled beam loss to reduce component activation to make hands-on maintenance possible. For this purpose, a two-stage collimation system is designed, which consists of a thin scraper to scatter halo particles and secondary collimators to absorb those scattered particles. Phase advances between scraper and secondary collimators, together with the material, the thickness of collimators, have been detailed studied and numerical simulations have been performed to evaluate the performance of the collimation system. This paper presents the design of the collimation system.

Poster THPAB176 [5.022 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB176

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paper received ※ 11 May 2021 paper accepted ※ 21 June 2021 issue date ※ 01 September 2021

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THPAB177

Simulation Model Improvements at the Cooler Synchrotron COSY Using the LOCO Algorithm

4111

V. Poncza, A. Lehrachpresenter
FZJ, Jülich, Germany
A. Lehrachpresenter, V. Poncza
RWTH, Aachen, Germany

Funding: ERC Advanced Grant (srEDM #694340) of the European Union
The JEDI (Jülich Electric Dipole moment Investigations) collaboration is searching for Electric Dipol Moments (EDMs) of charged particles in storage rings. In a stepwise approach, a first direct deuteron EDM measurement was performed at the Cooler Synchrotron COSY and design studies for a dedicated proton EDM storage ring are underway. In an experiment with a polarized beam in a storage ring, an EDM leads to a vertical polarization buildup. However, the vertical polarization component is also induced by systematic effects such as magnet misalignments. To investigate systematic effects individually and to support data analysis, a realistic simulation model of the storage ring is needed. In this paper, the development of such a model based on the Bmad software library is presented. Furthermore, various systematic effects and their impact on the spin motion in COSY are investigated and quantified by means of beam and spin tracking simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB177

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 12 August 2021

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THPAB178

The SIS100 Extraction and Emergency Kicker Magnet System

4115

J.H. Hottenbacher, K. Dunkel, M. Eisengruber, M. Osemann, A. Padvi, C. Piel
RI Research Instruments GmbH, Bergisch Gladbach, Germany
S. Heberer, I.J. Petzenhauser
GSI, Darmstadt, Germany

The extraction and emergency kicker system for SIS100 is a bipolar kicker system that allows for an in-situ choice between two directions: extraction to the experiments or to the beam dump. For that, both magnet ends are connected to a PFN each which are being charged simultaneously up to 80kV continuously. Due to the static HV operation, different to usually in other pulsed kicker systems, not only displacement current is flowing in the ferrite material. After less than 1s, the ferrite material is nearly field-free and the E-field is concentrated in the surrounding ceramic magnet clamp mechanism. As the field is further concentrated in gaps between ceramic and metallic parts, the HV layout of the magnet is a critical design task. As a magnetic field homogeneity of ±1% is required, special shaping of the coil is required as found during iterative 3D field simulations. The kicker chamber is designed to operate at a pressure level of 3·10^-11 mBar. As one 3 meter-chamber contains 3.5 m² ferrite surface, careful vacuum heat treatment of the ferrite is required to reach this pressure level. The paper will describe design principles for HV and UHV and effects found by 3D modeling.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB178

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paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 26 August 2021

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THPAB180

Simulation of 4D Emittance Measurement at the Spallation Neutron Source

4119

A.M. Hoover
UTK, Knoxville, Tennessee, USA
N.J. Evans
ORNL RAD, Oak Ridge, Tennessee, USA

Similar to the KV distribution, the Danilov distribution has an elliptical shape and uniform density in the transverse plane and maintains these properties under any linear transport. Efforts are underway at the Spallation Neutron Source (SNS) to paint a Danilov distribution in the accumulator ring. After the beam has been painted, the level to which it approximates an ideal Danilov distribution must be quantified. One way to do this is to measure the four-dimensional emittance, which is ideally zero due to linear relationships between the phase space variables. To measure this emittance, we will utilize a standard method of reconstructing the covariance matrix using various optics settings in conjunction with beam profile measurements. We present the results of preliminary simulations which aim to optimize this measurement scheme for the SNS Ring to Target Beam Transport (RTBT) line.

Poster THPAB180 [2.525 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB180

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 25 August 2021

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THPAB181

AI-ML Developments for the ATLAS Ion Linac Facility

4122

B.M. Mustapha, B.R. Blomberg, C. Dickerson, J.L. Martinez Marinpresenter, C.E. Peters
ANL, Lemont, Illinois, USA

Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-AC02-06CH11357. This research used the ATLAS facility, which is a DOE Office of Nuclear Physics User Facility.
ATLAS is a DOE/NP User Facility for the study of low-energy nuclear physics with heavy ions. It operates ~6000 hours per year. In addition to delivering any stable beam from proton to uranium, the facility also provides radioactive beams from the CARIBU source or via the in-flight radioactive ion separator, RAISOR. The facility uses 3 ion sources and services 6 target areas at energies from ~1-15 MeV/u. To accommodate the large number and variety of approved experiments, ATLAS reconfigures once or twice per week over 40 weeks of operation per year. The startup time varies from ~12-48 hours depending on the complexity of the tuning, which will increase with the upcoming Multi-User Upgrade to deliver beam to two experimental stations simultaneously. DOE/NP has recently approved a project to use AI/ML to support ATLAS operations. The project aim is to significantly reduce the accelerator tuning time and improve machine performance by developing and deploying artificial intelligence methods. These improvements will increase the scientific throughput of the facility and the quality of the data collected. Our recent developments and future plans will be presented and discussed.

Poster THPAB181 [1.034 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB181

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paper received ※ 06 June 2021 paper accepted ※ 28 July 2021 issue date ※ 12 August 2021

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THPAB182

DC-280 Cyclotron for Factory of Super Heavy Elements, Experimental Results

4126

V.A. Semin, S.L. Bogomolov, K. Gikal, G.G. Gulbekyan, I.A. Ivanenko, I.V. Kalagin, N.Yu. Kazarinov, V.I. Mironov
JINR, Dubna, Moscow Region, Russia
L.A. Pavlov
JINR/FLNR, Moscow region, Russia

The DC280 is the high current cyclotron with design beam intensities up to 10 pµA for ions with energy from 4 to 8 MeV/nucleon. It was developed and created at the FLNR JINR. The first was extracted from the cyclotron on January 17, 2019. Experiments on acceleration of 12C, 40Ar, 48Ca, 48Ti, 52Cr and 84Kr beams production were carried out. The following intensities of accelerated beam have been achieved: 10 pµA for 12C+2; 9,2 pµA for 40Ar+7; 7,1 pµA for 48Ca+10; 1,0 pµA for 48Ti+10; 2,4 pµA for 52Cr+10 and 1.43 pµA for 84Kr+14;. The accelerator has worked more than 9000 hours. The work of accelerator was stable and high efficiency. The total acceleration efficiency from ion source to transport channel was about 46%.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB182

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paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 21 August 2021

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THPAB183

New Longitudinal Beam Production Methods in the CERN Proton Synchrotron Booster

4130

S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, E. Renner
CERN, Meyrin, Switzerland
E. Renner
TU Vienna, Wien, Austria

As part of the LHC Injectors Upgrade (LIU) project, significant improvements were made to the CERN Proton Synchrotron Booster (PSB) during the 2019/2020 long shutdown, including a new Finemet-based wideband RF system, renovated longitudinal beam control, and a new magnetic cycle. To meet the requirements of the diverse experimental program, the PSB provides beams with intensities spanning three orders of magnitude and a large range of longitudinal emittances. To maximize the brightness, in particular for the LHC beams, the voltages at low energy are designed to reduce the impact of transverse space charge using a second RF harmonic in bunch lengthening mode. At high energies, the risk of longitudinal microwave instability is avoided by optimizing the longitudinal distribution to raise the instability threshold. RF phase noise is applied to provide controlled longitudinal emittance blow-up and to shape the longitudinal distribution. This paper discusses the design of the RF functions used to meet the beam specifications, whilst ensuring longitudinal stability.

Poster THPAB183 [6.692 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB183

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paper received ※ 18 May 2021 paper accepted ※ 22 July 2021 issue date ※ 20 August 2021

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THPAB185

Solution to Beam Transmission Decline in the CSNS Linac Operation Using Measurements and Simulations

4134

J. Peng, M.T. Li, X.H. Lu, X.B. Luo
IHEP CSNS, Guangdong Province, People’s Republic of China
Y.W. An, S. Fu, L. Huang, M.Y. Huang, Y. Li, Z.P. Li, S. Wang, S.Y. Xu, Y. Yuan
IHEP, Beijing, People’s Republic of China

The CSNS linac operation at its design average power currently. However, the beam transmission is declining and the beam loss is increasing during the operation. With simulations and experiments, we found there is a long longitudinal tail exist in the beam bunch output from the RFQ. And this tail caused the beam loss in the following linac. After inhibition of the longitudinal tail in the beam bunch, the beam transmission in operation can keep stable.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB185

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 02 September 2021

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THPAB186

Review of Proton Linac Beam Dynamic Simulation Code

4137

X.Y. Feng, J. Pengpresenter
IHEP CSNS, Guangdong Province, People’s Republic of China

CSNS-II project design a linac accelerates 40 mA H⁻ beam from 3.8 MeV to 300 MeV, which should not only overcome the space-charge effect at low energy but also have high efficiency at high energy. Therefore, lots of simulation studies should be done on a variety of codes. Each of them has its own characteristics. For example, MAD can easily match quadrupole fast while it couldn’t do the multiparticle calculation. This paper will introduce some common and efficient code used to design linac and study beam dynamic performance.

Poster THPAB186 [0.880 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB186

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paper received ※ 17 May 2021 paper accepted ※ 08 July 2021 issue date ※ 11 August 2021

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THPAB187

Determination of Required Tolerances and Stop Band Width for Cells Manufacturing and Tuning in Compensated High Energy Accelerating Structures

4139

I.V. Rybakov, V.V. Paramonov
RAS/INR, Moscow, Russia

The required value of the spread for accelerating field distribution comes from the beam dynamics conditions and for cavities in high energy hadron linacs is ~1%. The standard deviation of the accelerating field distribution depends on the spread in frequencies of accelerating and coupling cells, stop bandwidth and deviations in coupling coefficients. The deviations in frequencies for accelerating, coupling cells, coupling coefficients, are directly related to tolerances manufacturing tolerances for cells. The stop bandwidth should be adjusted with cell tuning. Relations between the standard deviation of field distribution and deviations in cells parameters* are known. Together with the relation between deviations in cells dimensions and cells parameters** recommendations for cells manufacturing tolerances could be obtained. In relation to the coupling coefficient of compensated accelerating structures (ACS, SCS, CDS, DAW) for high-energy parts of linacs some recommendations for the determination of optimal manufacturing tolerances and acceptable stopband are presented.
* V.F. Vikulov and V.E. Kalyuzhny // Tech. Phys., v. 50, 1980, pp. 773-779
** I.V. Rybakov, V.V. Paramonov, A.K. Skassyrskaya // Proc. RuPAC 2016, pp. 291-293

Poster THPAB187 [0.649 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB187

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paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 24 August 2021

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THPAB189

New Techniques to Compute the Linear Tune

4142

G. Russo, M. Giovannozzi
CERN, Geneva, Switzerland
G. Franchetti
GSI, Darmstadt, Germany

Tune determination in numerical simulations is an essential aspect of nonlinear beam dynamics studies. In particular, because it allows probing whether an initial condition is close to resonance, and it enables assessment of the stability of the orbit, i.e. whether the motion is regular or chaotic. In this paper, results of recently developed techniques to obtain accurate tune computation from numerical simulation data are presented and discussed in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB189

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paper received ※ 18 May 2021 paper accepted ※ 26 July 2021 issue date ※ 19 August 2021

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THPAB190

Optimising and Extending a Single-Particle Tracking Library for High Parallel Performance

4146

M. Schwinzerl, H. Bartosik, R. De Maria, G. Iadarola, K. Paraschou
CERN, Geneva, Switzerland
A. Oeftiger
GSI, Darmstadt, Germany
M. Schwinzerl
KFUG/IMSC, Graz, Austria

SixTrackLib is a library for performing beam-dynamics simulations on highly parallel computing devices such as shared memory multi-core processors or graphical processing units (GPUs). Its single-particle approach fits very well with parallel implementations with reasonable baseline performance, making such a library an interesting building block for various use cases, including simulations covering collective effects. We describe optimizations to improve their performance on SixTrackLib’s main target platforms and the associated performance gains. Finally, we outline the implemented technical interfaces and extensions that allow SixTrackLib to be used in a wider range of applications and studies.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB190

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paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 16 August 2021

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THPAB191

Physics-Enhanced Reinforcement Learning for Optimal Control

4150

A.N. Ivanov, I.V. Agapov, A. Eichler, S. Tomin
DESY, Hamburg, Germany

We propose an approach for incorporating accelerator physics models into reinforcement learning agents. The proposed approach is based on the Taylor mapping technique for simulation of the particle dynamics. The resulting computational graph is represented as a polynomial neural network and embedded into the traditional reinforcement learning agents. The application of the model is demonstrated in a nonlinear simulation model of beam transmission. The comparison of the approach with the traditional numerical optimization as well as neural networks based agents demonstrates better convergence of the proposed technique.

Poster THPAB191 [0.846 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB191

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paper received ※ 11 May 2021 paper accepted ※ 29 July 2021 issue date ※ 24 August 2021

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THPAB192

Continuous Beam Dynamics Simulation in COMSOL Multiphysics

4153

D. Popov, O. Karamyshev, I.D. Lyapin, V. Malinin
JINR/DLNP, Dubna, Moscow region, Russia

The classic way of beam dynamics simulation in a cyclotron is to separate it into many different stages from the ion source to the extraction (or even further), this was absolutely necessary to fit the calculations into any reasonable time in a cost of influence of some operation devices from one stage, on beam dynamics of another (next or previous mostly) stage. We’ve managed to perform beam dynamics from ion source through a solenoid to the center region in a single model in COMSOL, using several fields simultaneously: external magnetic (the magnet), calculated magnetic (the solenoid) and alternating and stationary electric fields in the center region.

Poster THPAB192 [1.233 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB192

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paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 17 August 2021

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THPAB197

Enhancing Efficiency of Multi-Objective Neural-Network-Assisted Nonlinear Dynamics Lattice Optimization via 1-D Aperture Objectives & Objective Focusing

4156

Y. Hidaka, D.A. Hidas, F. Plassard, T.V. Shaftan, G.M. Wang
BNL, Upton, New York, USA

Funding: This work is supported by U.S. DOE under Contract No. DE-SC0012704.
Mutli-objective optimizers such as multi-objective genetic algorithm (MOGA) have been quite popular in discovering desirable lattice solutions for accelerators. However, even these successful algorithms can become ineffective as the dimension and range of the search space increase due to exponential growth in the amount of exploration required to find global optima. This difficulty is even more exacerbated by the resource-intensive and time-consuming tendency for the evaluations of nonlinear beam dynamics. Lately the use of surrogate models based on neural network has been drawing attention to alleviate this problem. Following this trend, to further enhance the efficiency of nonlinear lattice optimization for storage rings, we propose to replace typically used objectives with those that are less time-consuming and to focus on a single objective constructed from multiple objectives, which can maximize utilization of the trained models through local optimization and objective gradient extraction. We demonstrate these enhancements using a NSLS-II upgrade lattice candidate as an example.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB197

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paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 10 August 2021

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THPAB198

Commissioning of Current Strips for Elliptically Polarizing Undulators at NSLS-II

4160

Y. Hidaka, O.V. Chubar, T. Tanabe
BNL, Upton, New York, USA
C.A. Kitégi
SOLEIL, Gif-sur-Yvette, France

Funding: This work is supported by U.S. DOE under Contract No. DE-SC0012704.
Most of the Elliptically Polarizing Undulators (EPUs) at NSLS-II are equipped with current strips (or flat wires), attached to their vacuum chambers. These strips compensate the dynamic field integrals of the EPU to minimize undesirable nonlinear beam dynamics effect that can lead to reduction in injection efficiency and beam lifetime. For each EPU, we measured the field integrals of the insertion device alone, the current strips alone, and both, while creating horizontal bumps of different amplitudes at the straight section to assess the effectiveness of the compensation provided by the design current values for the strips. The commissioning results of these current strips are reported in this article.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB198

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paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 28 August 2021

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THPAB199

Studies of Longitudinal Beam Losses at LHC Injection

4164

L.E. Medina Medrano, T. Argyropoulos, R. Calaga, H. Timko
CERN, Geneva, Switzerland

Funding: Research supported by the HL-LHC project.
Due to higher beam intensities, the required rf power in the High-Luminosity LHC (HL-LHC) era is expected to be at the limit of the available rf power. To mitigate potential limitations of the rf system, the injection voltage can be reduced at the expense of beam losses. In this paper, the average and bunch-by-bunch losses are estimated from Run 2 beam intensity measurements in the SPS before extraction and in the LHC after injection. Macro-particle simulations are performed with CERN’s Beam Longitudinal Dynamics code to reproduce the observed SPS-to-LHC capture and LHC flat-bottom losses. First estimates of injection losses for the HL-LHC at different injection voltages and injection energy errors are discussed.

Poster THPAB199 [2.428 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB199

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paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 14 August 2021

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THPAB200

Cavity Control Modelling for SPS-to-LHC Beam Transfer Studies

4168

L.E. Medina Medrano, T. Argyropoulos, P. Baudrenghien, H. Timko
CERN, Geneva, Switzerland

Funding: Research supported by the HL-LHC project.
To accurately simulate injection losses in the LHC and the High-Luminosity LHC era, a realistic beam distribution model at SPS extraction is needed. To achieve this, the beam-loading compensation by the SPS cavity controller has to be included, as it modulates the bunch positions with respect to the rf buckets. This dynamic cavity control model also allows generating a more realistic beam halo, from which the LHC injection losses will mainly originate. In this paper, the implementation of the present SPS cavity controller in CERN’s Beam Longitudinal Dynamics particle tracking code is described. Just like in the machine, the feedback and feedforward controls are included in the simulation model, as well as the generator-beam-cavity interaction. Benchmarking against measurements of the generated beam distributions at SPS extraction are presented.

Poster THPAB200 [4.164 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB200

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paper received ※ 18 May 2021 paper accepted ※ 27 July 2021 issue date ※ 26 August 2021

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THPAB201

A Machine Learning Technique for Dynamic Aperture Computation

4172

B. Dalena, M. Ben Ghali
CEA-IRFU, Gif-sur-Yvette, France

Currently, dynamic aperture calculations of high-energy hadron colliders are performed through computer simulations, which are both a resource-heavy and time-costly processes. The aim of this study is to use a reservoir computing machine learning model in order to achieve a faster extrapolation of dynamic aperture values. A recurrent echo-state network (ESN) architecture is used as a basis for this work. Recurrent networks are better fitted to extrapolation tasks while the reservoir echo-state structure is computationally effective. Model training and validation is conducted on a set of "seeds" corresponding to the simulation results of different machine configurations. Adjustments in the model architecture, manual metric and data selection, hyper-parameters tuning and the introduction of new parameters enabled the model to reliably achieve good performance on examining testing sets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB201

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paper received ※ 14 May 2021 paper accepted ※ 22 July 2021 issue date ※ 02 September 2021

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THPAB202

Problem and Solution with the Longitudinal Tracking of the ORBIT Code

4176

L.H. Zhang, J.Y. Tang
IHEP, Beijing, People’s Republic of China
Y.K. Chen
IHEP CSNS, Guangdong Province, People’s Republic of China
L.H. Zhang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

The ORBIT code has been widely used for beam dynamics simulations including injection and acceleration in high-intensity hadron synchrotrons. When the ORBIT’s 1D longitudinal tracking was employed for the acceleration process in CSNS/RCS, the longitudinal emittance in eV-s was found decreasing substantially during acceleration, though the adiabatic condition is still met during this process. This is against the Liouville theorem that predicts the preservation of the emittance during acceleration. The recent machine study in the accelerator and the simulations with a self-made code demonstrate that the longitudinal emittance is almost invariant, which further indicates that the ORBIT longitudinal tracking might be incorrect. A detailed check-over in the ORBIT code source finds that the longitudinal finite difference equation used in the code is erroneous when applied to an acceleration process. The new code format PyORBIT has the same problem. After the small secondary factor is included in the code, ORBIT can produce results keeping the longitudinal emittance invariant. This paper presents some details about the study.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB202

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paper received ※ 14 May 2021 paper accepted ※ 01 July 2021 issue date ※ 21 August 2021

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THPAB203

Update of the Tracking Code RF-Track

4180

A. Latina
CERN, Geneva, Switzerland

During the last couple of years, the RF-Track particle tracking code has seen a tremendous increase in the number of its applications: medical linacs, compact injector electron guns, and positron sources are among the main ones. Following a work of consolidation of its internal structure, new simulation capabilities have been introduced, together with several new effects: arbitrary orientation of elements in space, full element overlap, short- and long-range wakefields, and laser-beam interaction through Compton scattering are the most significant ones. In this paper, some of these new features are presented and discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB203

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paper received ※ 14 May 2021 paper accepted ※ 02 August 2021 issue date ※ 01 September 2021

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THPAB204

End-to-End RMS Envelope Model of the ISAC-I Linac

4183

O. Shelbaya, R.A. Baartman, O.K. Kester
TRIUMF, Vancouver, Canada

A full end-to-end simulation of the ISAC-I linear accelerator has been built in the first order envelope code TRANSOPTR. This enables the fast tracking of rms sizes and correlations for a 6-dimensional hyperellipsoidal beam distribution defined around a Frenet-Serret reference particle frame, for which the equations guiding envelope evolution are numerically solved through a model of the machine’s electromagnetic potentials. Further, the adopted formalism enables the direct integration of energy gain via time-dependent accelerating potentials, without resorting to transit-time factors.

Poster THPAB204 [0.627 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB204

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paper received ※ 18 May 2021 paper accepted ※ 08 July 2021 issue date ※ 31 August 2021

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THPAB205

On-Line Retuning of ISAC Linac Beam with Quadrupole Scan Tomography

4187

O. Shelbaya, R.A. Baartman, P.M. Jung, O.K. Kester, S. Kiy, T. Planche, Y.-N. Rao, S.D. Rädel
TRIUMF, Vancouver, Canada

The method of tomographic reconstruction has been in use at TRIUMF and elsewhere for several years, allowing for the beam diagnostic extraction of elements of the beam matrix on-line. One of the more recent applications of the technique at ISAC consists of using the measured density distribution as the input parameters for a real-time tune re-computation. This technique is advantageous since it does not require installation of dedicated emittance meters, but can instead be carried out with existing position monitors. Instead of requiring an operator to manually re-tune quadrupoles in a matching section, which can be time consuming, the technique allows for a fast and reproducible means to precisely control the beam and can be proceduralized for use by operators tuning the machine.

Poster THPAB205 [0.468 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB205

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paper received ※ 18 May 2021 paper accepted ※ 08 July 2021 issue date ※ 10 August 2021

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THPAB206

Validating pyORBIT for Modeling Beam Dynamics in the IOTA Ring

4190

R. Li
UW-Madison/PD, Madison, Wisconsin, USA
J.-F. Ostiguy, T. Sen
Fermilab, Batavia, Illinois, USA

Funding: Supported 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 Integrable Optics Test Accelerator (IOTA) ring is a new Fermilab facility dedicated to beam physics experiments, currently operating with 150 MeV electrons. Space charge effects are expected to be significant when it operates with 2.5 MeV protons. In this contribution, we present results of a suite of validation tests of PyORBIT, a PICstyle space charge code. Single particle dynamics of quasiintegrable optics using an octupole string in IOTA is compared with MADX, and shown to be in good agreement. Requirements for the convergence of space charge computations are systematically established and when possible, tests involving space charge are compared with theoretical predictions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB206

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paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 12 August 2021

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THPAB207

Beam Dynamics Simulation about the Dual Harmonic System by PyORBIT

4194

H.Y. Liu, X.Y. Feng, L. Huang, M.T. Li, X.H. Lu
IHEP CSNS, Guangdong Province, People’s Republic of China
S. Wang, S.Y. Xu
IHEP, Beijing, People’s Republic of China

The space charge effect is a strong limitation in high-intensity accelerators, especially for low- and medium-energy proton synchrotrons. And for CSNS-II, the number of particles in the RCS is 3.9·10¹³ ppp, which is five times of CSNS. To mitigate the effects of the strong space charge effect, CSNS-II/RCS (Rapid Cycling Synchrotron) will use a dual harmonic system to increase the bunching factor during the injection and the initial acceleration phase. For studying the beam dynamics involved in a dual harmonic RF system, PyORBIT is used as the major simulation code, which is developed at SNS to simulate beam dynamics in accumulation rings and synchrotrons. We modified parts of the code to make it applicable to the beam dynamic in RCS. This paper includes the major code modification of the Dual Harmonic RF system and some benchmark results. The preliminary simulation results of the dual-harmonic system in CSNS-II/RCS simulated by the particle tracking code PyORBIT will also be discussed.

Poster THPAB207 [0.354 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB207

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paper received ※ 16 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021

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THPAB209

Tracking Complex Re-Circulating Machines with PLACET2

4197

R.A.J. Costa, A. Latina
CERN, Geneva, Switzerland

We present the latest version of the multi-particle tracking package PLACET2. This software was designed to track multiple electron bunches through re-circulating machines with complex topologies, such as the recombination complex of the Compact Linear Collider (CLIC), energy-recovery linacs such as the Large Hadron-Electron Collider (LHeC), racetracks and others. This update also expands the capabilities of PLACET2 to track heavier particles such as muons. In addition to simulation, PLACET2 was also developed to allow beamline optimization scans, evaluating beam properties and tuning the beamline parameters at runtime either standalone or accessing the optimization tools present in the Octave and Python packages, with which it interfaces. This paper presents and benchmarks PLACET2’s latest features, such as coherent and incoherent synchrotron radiation, long and short wakefields and power extraction.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB209

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paper received ※ 18 May 2021 paper accepted ※ 13 July 2021 issue date ※ 27 August 2021

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THPAB210

Extrapolated Range for Low Energy Electrons (< 1 keV)

4201

C. Inguimbert, M.B. Belhaj, Q. Gibaru
ONERA, Toulouse, France
Q. Gibaru, D. Lambert, M. Raine
CEA, Arpajon, France
Q. Gibaru
CNES, PARIS, France

Funding: ONERA- DPHY, 2 avenue E. Belin, 31055 Toulouse, France CEA, DAM, DIF, 91297 Arpajon, France CNES, 18 av. E. Belin, 31055 Toulouse, France
The Secondary Electron Emission (SEE) process plays an important role in the performance of various devices. Mitigating the multipactor phenomenon that may occur in radio-frequency components is a concern in many fields such as space technologies or electron microscopy. SEE is also a concern in the accelerator physics community, where the beam lines stability can strongly be affected by this phenomenon*,**. In that scope, the escaped depth and thus the range of emitted electrons is of great interest. Our goal, by means of simulations is to provide a better knowledge of SEE. We have developed a Monte Carlo electron transport code for low energy electrons [~eV, ~10keV], that is part of the Dec. 2020 release of GEANT4***. It has been used to study the practical range of low energy electrons. Our goal is to formulate, below ~10 keV, an analytic range vs. energy expression, and to relate it to fundamental physcial parameters such as the mean free paths of electrons in matter. The goal is to provide simple practical extrapolated range formula that can help to understand SEE phenomenon.
* M. Mostajeran et al. J. of Instr. 5 (2010)
** C. Y. Vallgren et al. Phys. Rev. Accel. Beam 14 (2011)
*** Q. Gibaru et al. Nuc. Inst. And Met. 487 (2021)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB210

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paper received ※ 10 May 2021 paper accepted ※ 23 June 2021 issue date ※ 27 August 2021

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THPAB211

Monte Carlo Simulation of 3D Surface Morphologies for Secondary Electron Emission Reduction

4204

Q. Gibaru, M.B. Belhaj, C. Inguimbert
ONERA, Toulouse, France
Q. Gibaru, D. Lambert, M. Raine
CEA, Arpajon, France
Q. Gibaru
CNES, PARIS, France

Low energy electrons of few tens of eV may cause Multipactor breakdowns in waveguides driven by the Secondary Electron Emission Yield (SEY) of the walls. This risk is lowered by using low emissive surfaces and this topic has been studied experimentally and with numerical simulations. The dependence of the SEY on surface properties is well known*. Surface morphology has been widely used to reduce the SEY by forming roughness patterns on the surface**. All patterns do not have the same efficiency so their analysis in terms of SEY is relevant. Monte-Carlo simulation codes can be used to study the processes behind the SEY. The MicroElec module of GEANT4 has recently been extended with more materials and processes and validated with experimental data for SEY calculations**. In this work, simulation results are shown for a bulk sample capped with different roughness patterns. The effects of the shape parameters on the SEY are studied for typical dimensions between 20 µm and 100 µm. The results are checked with experimental SEY measurements on samples with similar roughness patterns.
*:T Gineste et al, Appl Surf Sci 359 (2015) 398-404
**:J Pierron et al, J Appl Phys 124 (2018) 095101
***:Q. Gibaru, C. Inguimbert, P. Caron, M. Raine, D. Lambert, J. Puech, NIM B. 487 (2021) 66-77

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB211

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paper received ※ 12 May 2021 paper accepted ※ 23 June 2021 issue date ※ 17 August 2021

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THPAB214

Recent BDSIM Related Developments and Modeling of Accelerators

4208

L.J. Nevay, A. Abramov, S.E. Alden, S.T. Boogert, G. D’Alessandro, S.M. Gibson, H. Lefebvre, W. Shields, S.D. Walker
JAI, Egham, Surrey, United Kingdom
A. Abramov, G. D’Alessandro, C. Hernalsteens
CERN, Meyrin, Switzerland
E. Gnacadja, C. Hernalsteens, E. Ramoisiaux, R. Tesse
ULB, Bruxelles, Belgium
S. Liu
DESY, Hamburg, Germany

Funding: This work is supported by the STFC (UK) grants: JAI ST/P00203X/1, HL-LHC-UK1 ST/N001583/1, HL-LHC-UK2 ST/T001925/1, and ST/P003028/1.
Beam Delivery Simulation (BDSIM) is a program based on Geant4 that creates 3D radiation transport models of accelerators from a simple optical description in a vastly reduced time frame with great flexibility. It also uses ROOT and CLHEP to create a single simulation model that can accurately track all particle species in an accelerator to predict and understand beam losses, secondary radiation, dosimetric quantities and their origin. BDSIM provides a library of scalable generic geometry for a variety of applications. Our Python package, Pyg4ometry, allows rapid preparation and conversion of geometries for BDSIM and other radiation transport simulations including FLUKA. We present a broad overview of BDSIM developments related to a variety of experiments at several facilities. We present a model of the forward experiment FASER at the LHC, CERN where the geometry is composited from multiple sources using Pyg4ometry. The analysis of particle history is presented as well as production mechanisms. We also present the application of recently introduced laser interactions in Geant4 to Compton photons from a laserwire diagnostic at the ATF2.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB214

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paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 22 August 2021

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THPAB217

Lightsource Unified Modeling Environment (LUME), a Start-to-End Simulation Ecosystem

4212

C.E. Mayes, A.L. Edelen, P. Fuoss, J.R. Garrahan, A. Halavanau, F. Ji, J. Krzywiński, W. Lou, N.R. Neveu, H.H. Slepicka
SLAC, Menlo Park, California, USA
J.C. E, C. Fortmann-Grote
EuXFEL, Schenefeld, Germany
C.M. Gulliford, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
L. Gupta
University of Chicago, Chicago, Illinois, USA
A. Huebl, R. Lehé
LBNL, Berkeley, USA

SLAC is developing the Lightsource Unified Modeling Environment (LUME) for efficient modeling of X-ray free electron laser (XFEL) performance. This project takes a holistic approach starting with the simulation of the electron beams, to the production of the photon pulses, to their transport through the optical components of the beamline, to their interaction with the samples and the simulation of the detectors, and finally followed by the analysis of simulated data. LUME leverages existing, well-established simulation codes, and provides standard interfaces to these codes via open-source Python packages. Data are exchanged in standard formats based on openPMD and its extensions. The platform is built with an open, well-documented architecture so that science groups around the world can contribute specific experimental designs and software modules, advancing both their scientific interests and a broader knowledge of the opportunities provided by the exceptional capabilities of X-ray FELs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB217

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paper received ※ 20 May 2021 paper accepted ※ 20 July 2021 issue date ※ 19 August 2021

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THPAB219

Beam Dynamics in Coherent Electron Cooling Accelerator

4216

Y.C. Jing, V. Litvinenko, I. Petrushina, I. Pinayev, K. Shih, Y.H. Wu
BNL, Upton, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
I. Petrushina, Y.H. Wu
SUNY SB, Stony Brook, New York, USA
K. Shih
SBU, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron Cooling (CeC) has the potential to substantially reduce the cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. Recent development in CeC cooling theory requires the accelerator to deliver high-quality electron bunches with low beam noise. In this paper, we present our design of the CeC accelerator to achieve the electron beam requirements and compare our findings with the experimental observations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB219

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paper received ※ 27 May 2021 paper accepted ※ 27 July 2021 issue date ※ 11 August 2021

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THPAB220

Multibunch Studies for LCLS-II High Energy Upgrade

4219

R.J. England, K.L.F. Bane, Z. Li, T.O. Raubenheimer, M.D. Woodley
SLAC, Menlo Park, California, USA
M. Borland
ANL, Lemont, Illinois, USA
A. Lunin
Fermilab, Batavia, Illinois, USA

Funding: The work is supported in part by DOE Contract No. DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) X-ray free-electron laser at SLAC is being upgraded to LCLS-II with a superconducting linac and 1 MHz bunch repetition rate. The proposed high-energy upgrade (LCLS-II-HE) will increase the beam energy from 4 to 8 GeV, extending the reach of accessible X-ray photon energies. With the increased repetition rate and longer linac of LCLS-II-HE, multi-bunch effects are of greater concern. We use recently introduced capabilities in the beam transport code ELEGANT to study dipole and monopole beam breakup effects for LCLS-II HE beam parameters. The results indicate that resonant dipole kicks have steady-state settle times on the order of 500 bunches or less and appear manageable. We also consider a statistical variation of the cavity frequencies and transverse offsets of cavities and quadrupoles. Resonant emittance growth driven by monopole kicks is found to be disrupted by frequency variation between cavities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB220

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paper received ※ 19 May 2021 paper accepted ※ 15 July 2021 issue date ※ 21 August 2021

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THPAB221

Multi-Objective Optimization with ACE3P and IMPACT

4223

D.A. Bizzozero, J. Qiang
LBNL, Berkeley, California, USA
L. Ge, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA

Funding: This work is supported by the Director of the Office of Science of the US Department of Energy under contracts DE-AC02-05-CH11231 and DE-AC02-76-SF00515.
Photo injector design is an important consideration in the construction of next-generation accelerators. In current injector optimization, components (e.g. RF cavities) are individually shape-optimized for performance subject to requirements such as peak surface field, shunt impedance, and resonant frequency. Once these component shapes are determined, beam dynamics simulations optimize the injector lattice by adjusting parameters such as the amplitude and phase of the driving fields. However, this form of beam dynamics optimization is restricted by the fixed geometry and field profile of the components. To optimize accelerator design more generally, a coupled optimization of the cavity shape and beam parameters is required. For this coupled optimization problem, we have created an integrated ACE3P-IMPACT workflow. Within this workflow, component geometries are adjusted, field modes are computed with Omega3P (a module in the ACE3P suite), and beam dynamics are simulated with IMPACT-T. This workflow is encapsulated into a multi-objective optimization algorithm using the DEAP* and libEnsemble** Python libraries to yield a Pareto-optimal set of solutions for a simple injector model.
* F.-A. Fortin et al, DEAP: Evolutionary Algorithms Made Easy, J Mach Learn Res, 13, 2171-2175, July 2012
** S. Hudson et al, libEnsemble User Manual, Argonne National Laboratory, Rev 0.7.1, 2020

Poster THPAB221 [1.842 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB221

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paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 14 August 2021

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THPAB222

Transverse Impedance Coaxial Wire Measurement in an Extended Frequency Range

4227

E.E. Ergenlik, C. Bruni, D. Le Guidec, P. Lepercq
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
A. Gamelin
SOLEIL, Gif-sur-Yvette, France

The low energy accelerators are tend to have some instabilities especially the beam coupling impedances which comes from the interaction between the beam and accelerator components. As long as the longitudinal impedance are important, transverse impedance determination is crucial for determine the instabilities which will affect the working efficiency of the accelerators. However due to their small amplitudes and measurement setup configuration they are hardly measurable especially in wide frequency ranges. We developed a specific setup for small diameter pieces (28-40mm) for moving and two wire transverse impedance measurements. The dipolar and quadrupolar impedance measurement even with a few Ω level up to 6 GHz for the bellows of ThomX will be presented. Also the comparison with electromagnetic simulations have been performed and can be seen for dipolar impedance measurements.

Poster THPAB222 [1.578 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB222

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 23 August 2021

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THPAB223

Energy Compression System Radio Frequency Design at the Canadian Light Source

4231

E.J. Ericson, D. Bertwistle, M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada

The Canadian Light Source (CLS), Canada’s only synchrotron light source, is considering a linear accelerator (LINAC) upgrade. As a result, the radio frequency (RF) structure in the downstream Energy Compression System (ECS) needs to be redesigned. In this paper, we describe the design process followed to determine the geometry of the RF structure cells and coupler.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB223

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paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 28 August 2021

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THPAB224

The Correction of Time-Dependent Tune Shift by Harmonic Injection

4234

X.H. Lu
IHEP CSNS, Guangdong Province, People’s Republic of China
J. Chen, S. Wang, S.Y. Xupresenter
IHEP, Beijing, People’s Republic of China

In the Rapid Cycling Synchrotron(RCS) of China Spallation Neutron Source(CSNS), transverse painting injection is employed to suppress the space-charge effects. The beta-beating caused by edge focusing of the injection bump magnets leads to tune shift. A new method based on the harmonic injection is firstly introduced to correct the time-dependent tune shift caused by the edge focusing effect of the chicane bump magnets in RCS. The simulation study was done on the application of the new method to the CSNS/RCS, and the results show the validity and effectiveness of the method.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB224

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paper received ※ 19 May 2021 paper accepted ※ 16 July 2021 issue date ※ 10 August 2021

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THPAB227

MACH-B: Fast Multipole Method Approaches in Particle Accelerator Simulations for the Computational and Intensity Frontiers

4237

M.H. Langston, R. Lethin, P.D. Letourneau, J. Wei
Reservoir Labs, New York, USA
M.J. Morse
Courant Institute of Mathematical Sciences, New York University, New York, USA

Funding: U.S. Department of Energy DOE SBIR Phase I Project DE-SC0020934
The MACH-B (Multipole Accelerator Codes for Hadron Beams) project is developing a Fast Multipole Method (FMM**)-based tool for higher fidelity modeling of particle accelerators for high-energy physics within the next generation of Fermilab’s Synergia* simulation package. MACH-B incorporates (1) highly-scalable, high-performance and generally-applicable FMM-based algorithms to accurately model space-charge effects in high-intensity hadron beams and (2) boundary integral approaches to handle singular effects near the beam pipe using advanced quadratures. MACH-B will allow for more complex beam dynamics simulations that more accurately capture bunch effects and predict beam loss. Further, by introducing an abstraction layer to hide FMM implementation and parallelization complexities, MACH-B removes one of the key impediments to the adoption of FMMs by the accelerator physics community.
* J. Amundson et al. "Synergia: An accelerator modeling tool with 3-D space charge". J.C.P. 211.1 (2006) 229-248.
** L. Greengard. "Fast algorithms for classical physics". Science (Aug 1994) 909-914.

Poster THPAB227 [0.984 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB227

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021

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THPAB228

Study on Laser Modulator for Electron Beam Density Modulation

4241

K. Kan, M. Gohdo, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

Ultrashort electron beams are essential for light sources and time-resolved measurements. Laser modulation using an undulator and pulsed near infrared light is expected for attosecond density modulation of electron beam. In this study, simulation of laser modulation using undulator with period length of 6.6 mm and optical pulse with a wavelength of 800 nm was performed by ELEGANT* code. Simulation results of laser modulation for electron beam with an energy of 32.5 MeV will be presented from a view point of the density modulation.
* M. Borland, elegant: A Flexible SDDS-Compliant Code for Accelerator Simulation, Advanced Photon Source LS-287, September 2000.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB228

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paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021

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THPAB229

Energy-Binning Fast Multipole Method for Electron Injector Simulations

4244

S.A. Schmid, H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany

In a high brilliance electron injector, small beam energy and large charge density give rise to strong space charge effects. Furthermore, a large relative energy spread during the beam generation modifies the space charge interaction between different regions of the particle bunch. Therefore, modeling the phase space evolution in an electron injector requires a numerically efficient particle tracking code that can handle space charge interactions of spatially and energetically strongly inhomogeneous particle distributions. We implemented an energy-binning scheme for a meshless fast multipole method (FMM). The energy-binning approximates the momentum distribution of the beam by assigning particles to adaptive tree structures defined at different Lorentz frames. Based on the tree structures, the FMM computes a hierarchical approximation for the space charge interaction of the particle bunch. We use the energy-binning FMM to simulate the beam generation in the photoinjector of the European XFEL developed at DESY-PITZ. Furthermore, we present numerical convergence and performance studies and compare the simulation results to direct particle-particle methods.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB229

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 25 August 2021

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THPAB230

Design of Split Permanent Magnet Quadrupoles for Small Aperture Implementation

4247

I.I. Gadjev, G. Andonian, T.J. Campese, M. Ruelas
RadiaBeam, Santa Monica, California, USA
C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA

Permanent magnet quadrupoles are ideal for strong focusing in compact footprints. Recent research in the use of permanent magnet based quadrupole magnets has enabled very high-gradient uses approaching 800T/m in final focus systems. However, in order to achieve high quality field profiles with strong fields, small diameter bore magnets must be used necessitating in vacuum operation, or very small beampipes. For small beampipe geometry, we have developed a hybrid-permanent magnet quadrupole, with steel and permanent magnet wedges, that is able to maintain high quality fields but also readily machinable in a separable design. The split design allows for accurate and reproducible reconfiguration on a beam pipe. In this paper, we will discuss the design, engineering, fabrication and first measurements of the split permanent magnet quadrupole.

Poster THPAB230 [1.605 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB230

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paper received ※ 15 May 2021 paper accepted ※ 08 July 2021 issue date ※ 30 August 2021

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THPAB232

Study of Nonlinear Properties of ESR via Tune Scans

4250

G. Franchetti
GSI, Darmstadt, Germany

The ESR storage ring at GSI is a key accelerator for the FAIR phase zero. This phase requires several highly specialized beam manipulations, which range from beam storage to deceleration of several ion species with the ultimate goal to provide intense highly charge ions to CRYRING. This plan will bring the ESR storage ring into a unique unexplored regime of accelerator operations where nonlinear dynamics, IBS, cooling, and high intensity will all become strongly interdependent. It is, therefore, necessary to acquire the best knowledge of the machine starting from its nonlinear dynamics properties. In this work, we present the development of a strategy to be used in the ESR, in which tune scans are used to explore the nonlinear properties of the accelerator. This approach is discussed with the help of simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB232

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paper received ※ 13 May 2021 paper accepted ※ 13 July 2021 issue date ※ 25 August 2021

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THPAB233

Could "Flakes" of Neutral Paramagnetic or Dipolar Molecules Explain Beam Losses in the LHC?

4254

G. Franchetti
GSI, Darmstadt, Germany
F. Zimmermann
CERN, Meyrin, Switzerland

"Flakes" of neutral water or oxygen molecules carrying an electric or magnetic dipole moment can be attracted and trapped by the electromagnetic field of the circulating LHC proton beam. The possible presence of such flakes in the vacuum system could explain beam losses and beam instabilities encountered during the 2017 and 2018 LHC runs, and the observed effect of an external magnetic field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB233

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paper received ※ 09 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

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THPAB235

Detailed Electromagnetic Characterisation of HL-LHC Low Impedance Collimators

4258

A. Kurtulus, C. Accentura, N. Biancacci, F. Carra, F. Caspers, N. Chitnis, F. Giordano, R. Illan Fiastre, S. Joly, I. Lamas Garcia, L. Mourier, E. Métral, S. Redaelli, B. Salvant, W. Vollenberg, C. Vollinger, C. Zannini
CERN, Geneva, Switzerland

The High Luminosity Large Hadron Collider (HL-LHC) project will upgrade the LHC machine to allow operation with increased luminosity for the experiments. In order to achieve this goal, different operational parameters of the machine need to be pushed beyond the present design values, including the stored beam energy. One of the main challenges related to the achievement of the upgraded performance is the beam collimation system and its contribution to the overall machine impedance budget. In this perspective, new low impedance collimators have been designed, fabricated, and installed in the LHC. In this study, we will present their detailed electromagnetic (EM) characterization by means of radio frequency (RF) measurements and EM simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB235

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paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 10 August 2021

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THPAB236

First Order Analytic Approaches to Modelling the Vertical Excursion Fixed Field Alternating Gradient Accelerator

4262

M.E. Topp-Mugglestone, S.L. Sheehy
JAI, Oxford, United Kingdom
J.-B. Lagrange, S. Machida
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Whilst the Vertical Excursion Fixed Field Alternating Gradient Accelerator (VFFA) remains a promising solution to a number of problems at the frontiers of accelerator physics, the optics of this type of machine are still poorly understood. Current designers are forced to rely on brute-force numerical tracking codes, with optimisation dependent on time-consuming parameter scans. With an aim to both improve understanding of this machine, as well as to develop tools for rapid design and optimisation of VFFA lattices, first steps towards an analytic approach based on a linearised Hamiltonian formalism have been developed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB236

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paper received ※ 13 May 2021 paper accepted ※ 14 July 2021 issue date ※ 10 August 2021

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THPAB238

An Overview of the Collective Effects and Impedance Calculation for the EIC

4266

A. Blednykh, D.M. Gassner, B. Podobedov, S. Verdú-Andrés
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
M. Blaskiewicz, C. Hetzel, B. Lepore, V.H. Ranjbar, M.P. Sangroula, P. Thieberger, G. Wang, Q. Wu
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A new high-luminosity Electron-Ion Collider (EIC) is being designed at Brookhaven National Laboratory (BNL). Stable operation of the electron beam at an average current of 2.5A within 1100 bunches with a 7mm bunch length is one of the challenging tasks in achieving an electron-proton luminosity of 1033-1034 cm^-2 ses⁻¹ range. Beam induced heating, short-range and long-range wakefield analysis is discussed for some of the vacuum components of the electron storage ring (ESR), the hadron storage ring (HSR), and the rapid cycling synchrotron (RCS) and as well as the impact of the collective effects on the beam stability.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB238

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paper received ※ 15 May 2021 paper accepted ※ 24 June 2021 issue date ※ 29 August 2021

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THPAB239

Impedance Optimization of the EIC Interaction Region Vacuum Chamber

4270

A. Blednykh
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
E.C. Aschenauer, M. Blaskiewicz, C. Hetzel, M.P. Sangroula, G. Wang, H. Witte
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 interaction region chamber has a complex geometry at the crossing location of electron and proton beam pipes. In the direction of the electron beam, the pipe is designed in a way to avoid joints with cavity characteristics. The horizontal slot on the upstream side and the tapered transition on the downstream side are applied to minimize the IR chamber contribution to the total impedance of the electron ring and to avoid generating Higher Order Modes and heating-related issues. The synchrotron radiation mask is included to protect the IR chamber from synchrotron radiation without significant aperture reduction. In the direction of the proton beam, the main area for optimization is the transition area right after the detector.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB239

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paper received ※ 15 May 2021 paper accepted ※ 24 June 2021 issue date ※ 24 August 2021

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THPAB240

Combined Effect of IBS and Impedance on the Longitudinal Beam Dynamics

4274

A. Blednykh
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
B. Bacha, G. Bassi, T.V. Shaftan, V.V. Smaluk
BNL, Upton, New York, USA
M. Borland, R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The horizontal/vertical emittances, the bunch length, and the energy spread increase have been studied in the NSLS-II as a function of a single bunch current. The monotonic growth of the horizontal emittance dependence and the energy spread dependence on the single bunch current below the microwave instability threshold can be explained by the Intrabeam Scattering Effect (IBS). The IBS effect results in an increase in the bunch length and the microwave instability thresholds. It was observed experimentally by varying the vertical emittance. To compare with experimental data, particle tracking simulations have been performed with the ELEGANT code including both IBS and the total longitudinal wakefield calculated from the 3D electromagnetic code GdfidL. The same particle tracking simulations have also been applied for the APS-U project, where IBS is predicted to produce only a marginal effect.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB240

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paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021

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THPAB241

Examination of Semi-Analytic Model for Mode Coupling Instabilities

4278

M.A. Balcewicz, Y. Hao
FRIB, East Lansing, Michigan, USA
M. Blaskiewicz
BNL, Upton, New York, USA

Funding: Work supported by by Brookhaven Science Associates, LLC under contract number 364776.
A semianalytic model for studying beams at high SC tune shift is shown. It is a generalization of SWM ** /ABS ** for an arbitrary number of longitudinal phase space cycles, yielding more realistic longitudinal physics. The consequences of this generalization are explored; model is benchmarked against TRANFT *** and analytical methods.
* Blaskiewicz, Michael. Phys. Rev. ST Accel. Beams, vol. 1, p. 044201, 1998.
** Burov, Alexey. Phys. Rev. Accel. Beams, vol. 22, p. 034202, 2019.
*** M. Blaskiewicz, in Proc. PAC07, Albuquerque,

Poster THPAB241 [0.894 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB241

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 14 August 2021

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THPAB243

Optimizing Mu2e Spill Regulation System Algorithms

4281

A. Narayanan
Northern Illinois University, DeKalb, Illinois, USA
K.J. Hazelwood, M.A. Ibrahim, V.P. Nagaslaev, D.J. Nicklaus, P.S. Prieto, B.A. Schupbach, K. Seiya, R.M. Thurman-Keup, N.V. Tran
Fermilab, Batavia, Illinois, USA
H. Liu, S. Memik, R. Shi, M. Thieme
Northwestern University, Evanston, Illinois, USA

Funding: The work has been performed at Fermilab. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359.
A slow extraction system is being developed for the Fermilab’s Delivery Ring to deliver protons to the Mu2e experiment. During the extraction, the beam on target experiences small intensity variations owing to many factors. Various adaptive learning algorithms will be employed for beam regulation to achieve the required spill quality. We discuss here preliminary results of the slow and fast regulation algorithms validation through the computer simulations before their implementation in the FPGA. Particle tracking with sextupole resonance was used to determine the fine shape of the spill profile. Fast semi-analytical simulation schemes and Machine Learning models were used to optimize the fast regulation loop.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB243

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paper received ※ 20 May 2021 paper accepted ※ 28 July 2021 issue date ※ 20 August 2021

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THPAB244

Design of Interdigital H-Mode Re-Buncher at KoBRA Beamline

4285

Y. Lee, E.-S. Kim
KUS, Sejong, Republic of Korea

KOrea Broad acceptance Recoil spectrometer & Apparatus (KOBRA) is an experimental facility for low energy nuclear physics in the heavy ion accelerator complex RAON. Two re-buncher systems at KOBRA beamline are required to longitudinally focus the 40Ar⁹⁺ with 27MeV/u. The normal conducting IH resonator with seven-gap as the re-buncher structure was chosen because of the reduction in the risk of particulate contamination and total power consumption. In this paper, the detailed design results of the 162.5 MHz IH re-buncher cavity will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB244

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 24 August 2021

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THPAB245

A Simulation Study of Beam Pipe Eddy Current Effects on Beam Optics

4288

T. Asami, T. Koseki
The University of Tokyo, Graduate School of Science, Tokyo, Japan
S. Igarashi, T. Koseki, Y. Kurimoto, Y. Sato
KEK, Ibaraki, Japan

In synchrotrons, fast changes of magnetic field induce eddy currents at the wall of beam pipes. The eddy currents cause a phase delay between excitation currents of the magnets and the magnetic field. The undesired magnetic field affected by eddy currents might be a serious obstacle in controlling beam optics precisely. In fact, in the operation of a high-intensity proton synchrotron J-PARC MR, the largest beam loss is observed at the beginning of acceleration when the magnetic field starts to vary in time. Therefore, it is important to estimate and understand the effects of eddy currents on beam optics. In this study, we have calculated the effect of eddy currents on magnetic field for some magnets in J-PARC MR, using electromagnetic simulation software. In this paper, we would like to report the details and results of the simulation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB245

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 17 August 2021

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THPAB249

X-Ray Beam Position Monitor (XBPM) Calibration at NSRC Solaris

4292

M. Waniczek, A. Curcio, G.W. Kowalski, R. Panaś, A.I. Wawrzyniak
NSRC SOLARIS, Kraków, Poland

During the installation of Front-ends in sections 4th (XMCD beamline frontend) and 6th (PHELIX beamline frontend) at National Synchrotron Radiation Centre Solaris (NSRC Solaris), two units (one for each front end) of X-ray Beam Position Monitors (XBPM) have been installed as a diagnostic tool enabling for measurement of photon beam position. Hardware units of XBPM were manufactured, delivered, and eventually installed in Solaris by FMB Berlin. In order to get readouts of beam position from XBPM units, Libera Photon 2016 controller has been used as a complementary electronic device. Since XBPM units are supposed to be used along with the insertion device, an on-site Libera calibration was necessary. Libera’s calibration required few iterations of scans involving gap and phase movement of insertion devices at the 4th and 6th sections of the Solaris ring. The main focus was put on the derivation of Kx, and Ky coefficients. The content of this document describes step by step the procedure of Libera’s Kx, Ky coefficients value derivation at NSRC Solaris.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB249

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paper received ※ 19 May 2021 paper accepted ※ 17 July 2021 issue date ※ 13 August 2021

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THPAB250

Fire Detection System Reliability Analysis: An Operational Data-Based Framework

4296

M.M.C. Averna, G. Gai
CERN, Meyrin, Switzerland

This paper describes a framework developed at CERN, conducting reliability analysis of Safety-Critical Systems (Fire detection and Alarms) based on operational data. It applies Fault-Tree Analysis on maintenance-related data, categorized based on the component on failure. This framework, a tool implemented in Python, accounts for Fire Detection components installed in tunnels and surface buildings (control panels, detectors, etc) and safety functions triggered upon detection (evacuation, alarms to the CERN Fire Brigade, compartmentalization, electrical isolation, etc). The usefulness of the results of this type of analysis is twofold. Firstly, the results are a supporting tool for estimating the yearly availability of Fire Detection Systems in critical facilities, crucial in Capital and Operational Expenditure identification. Additionally, this approach refines the frequency analysis as part of quantitative fire risk assessments performed in the context of the FIRIA (Fire-Induced Radiological Integrated Assessment) Project, launched by CERN in 2018 and aiming at assessing the risk of fire events in experimental facilities with potential radiologic consequences to the public.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB250

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paper received ※ 18 May 2021 paper accepted ※ 19 July 2021 issue date ※ 22 August 2021

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THPAB251

Efficient Terahertz Generation by Tilted-Pulse-Front Pumping in Lithium Niobate for the Split-Ring Resonator Experiment at FLUTE

4299

M. Nabinger, E. Bründermann, S. Funkner, B. Härer, A.-S. Müller, M.J. Nasse, G. Niehues, R. Ruprecht, J. Schäfer, T. Schmelzer, N.J. Smale
KIT, Karlsruhe, Germany
M.M. Dehler, R. Ischebeck, M. Moser, V. Schlott
PSI, Villigen PSI, Switzerland
T. Feurer, M. Hayati, Z. Ollmann
Universität Bern, Institute of Applied Physics, Bern, Switzerland

Funding: This work is co-funded via the European Union’s H₂020 research and innovation program, GA No 730871, ARIES.
A compact, longitudinal diagnostics for fs-scale electron bunches using a THz electric-field transient in a split-ring resonator (SRR) for streaking will be tested at the Ferninfrarot Linac- Und Test- Experiment (FLUTE). For this new streaking technique, intensive THz pulses are required, which will be generated by laser-based optical rectification. We present a setup for generating THz pulses using tilted-pulse-front pumping in lithium niobate at room temperature. Excited by an 800 nm Ti:Sa pump laser with 35 fs bandwidth-limited pulse length, conversion efficiencies up to 0.027% were achieved. Furthermore, the status of the SRR experiment is shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB251

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 19 August 2021

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THPAB252

Machine Learning for Improved Availability of the SNS Klystron High Voltage Converter Modulators

4303

G.C. Pappas
ORNL RAD, Oak Ridge, Tennessee, USA
D. Lu
ORNL, Oak Ridge, Tennessee, USA
M. Schram
JLab, Newport News, Virginia, USA
D.L. Vrabie
PNNL, Richland, Washington, USA

Funding: SNS/ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
Beam availability has increased at the SNS, however, the targeted availability is greater than 95 %, while the SNS has failed to meet lower targets in the past. The HVCM used to power the linac klystrons have been one source of lost beam time and was chosen to explore using AI/ML techniques to improve reliability. Among the possibilities being explored are automating the tuning of HVCMs and predicting component failures such as capacitor aging, rectifier assemblies containing hundreds of diodes, and insulating oil degradation. The methodology pursued includes data cleaning, de-noising, post-analysis data labeling, and machine learning model development. We explore using Long Short-Term Memory and autoencoders for anomaly detection and prognostication used to schedule maintenance. We evaluate the use of model regularizers and constraints to improve the performance of the model and investigate methods to estimate the uncertainty of the models to provide a robust prediction with statistical interoperability. This paper describes the operational experience and known failures of the HVCMs and the proposed ML methodology and the preliminary results of training the AI/ML algorithms.
* G. Dodson, Approach to Reliable Operations, 26-Dodson_Approach to Reliable Operation-r1.pdf, Feb., 2010.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB252

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paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 29 August 2021

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THPAB257

Fast Orbit Corrector Power Supply in MTCA.4 Form Factor for Sirius Light Source

4307

A.F. Giachero, G.B.M. Bruno, L.M. Russo, D.O. Tavares
LNLS, Campinas, Brazil

A new fast orbit feedback (FOFB) hardware architecture has been pursued at Sirius. The fast corrector magnets’ are fed by power supply modules which are placed in the same MicroTCA.4 crates where the BPM digitizers and FOFB controllers are located. Each channel is made of a 3-Watt linear amplifier whose output currents are digitally controlled by the same FPGA where the distributed orbit feedback controller is processed. The amplifier is specified to reach up to 10 kHz small-signal bandwidth on a 3.5 mH inductance magnet and ±1 A full scale, which translates to 30 urad deflection on Sirius’ 3 GeV beam. Such a high level of integration aims at minimizing the overall latency of the FOFB loop while leveraging the crate infrastructure, namely electronics enclosure, DC power, cooling, and hardware management support already provided by the MTCA.4 crates. The fast corrector power supply channels are placed on Rear Transition Modules (RTMs) which are attached to the front AMC FPGA module where the FOFB controller is implemented. This paper will describe the main design concepts and report on the experimental results of the first prototypes.

Poster THPAB257 [48.881 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB257

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paper received ※ 22 May 2021 paper accepted ※ 27 July 2021 issue date ※ 20 August 2021

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THPAB258

Status of Time-Domain Simulation for the Fast Orbit Feedback System at the HEPS

4311

Y. Wei, Z. Duan, X.Y. Huang, Y. Jiaopresenter
IHEP, Beijing, People’s Republic of China

High Energy Photon Source (HEPS) is a complex designed at ultra-low emittance. A fast orbit feedback system is proposed to meet the requirement of beam orbit stability at the sub-micron level. In this paper, we present our work on setting up an orbit feedback process combined with noise model, system modeling, and particle tracking in the time domain. RF phase parameter is adjusted together with fast correctors to mitigate the orbit fluctuation due to energy vibration. The preliminary results are shown here. By the following optimization, we hope to provide an effective tool to specify and configure the FOFB system with the simulation.

Poster THPAB258 [1.334 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB258

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 31 August 2021

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THPAB259

High Level Applications for Sirius Accelerators Control

4314

A.C.S. Oliveira, M.B. Alves, L. Liu, X.R. Resende, F.H. de Sá
LNLS, Campinas, Brazil

Sirius is a 4th generation 3 GeV synchrotron light source that has just finalised the first commissioning phase at the Brazilian Center for Research in Energy and Materials (CNPEM) campus in Campinas, Brazil. The large number of process variables and large complexity of the subsystems in this type of machine requires the development of tools to simplify the commissioning and operation of the accelerators. This paper describes some of the high level control tools developed for the accelerators commissioning and future operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB259

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paper received ※ 19 May 2021 paper accepted ※ 13 July 2021 issue date ※ 21 August 2021

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THPAB260

Detection and Classification of Collective Beam Behaviour in the LHC

4318

L. Coyle, F. Blanc, T. Pieloni, M. Schenk
EPFL, Lausanne, Switzerland
X. Buffat, M. Solfaroli Camillocci, J. Wenninger
CERN, Meyrin, Switzerland
E. Krymova, G. Obozinski
SDSC, Lausanne, Switzerland

Collective instabilities can lead to a severe deterioration of beam quality, in terms of reduced beam intensity and increased beam emittance, and consequently a reduction of the collider’s luminosity. It is therefore crucial for the operation of the CERN’s Large Hadron Collider to understand the conditions in which they appear in order to find appropriate mitigation measures. Using bunch-by-bunch and turn-by-turn beam amplitude data, courtesy of the transverse damper’s observation box (ObsBox), a novel machine learning based approach is developed to both detect and classify these instabilities. By training an autoencoder neural network on the ObsBox amplitude data and using the model’s reconstruction error, instabilities and other phenomena are separated from nominal beam behaviour. Additionally, the latent space encoding of this autoencoder offers a unique image like representation of the beam amplitude signal. Leveraging this latent space representation allows us to cluster the various types of anomalous signals.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB260

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paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 27 August 2021

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THPAB264

FOFB System Upgrade to ZynqMP FPGA with Fast ORM Measurement

4322

Y.E. Tan, S. Chenpresenter, R.B. Hogan, A. Michalczyk
AS - ANSTO, Clayton, Australia

The FOFB processor has been ported from a Vertex 6 FPGA to a ZynqMP SoC (System on Chip) to provide additional resources to include the enhanced orbit diagnostics (EOD) system that has been designed to inject sinusoidal and pink noise through the feedback loop. The amplitude, duration, phase and frequency of sinusoidal, amplitude and duration of pink noise is user programmable.

Poster THPAB264 [1.601 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB264

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paper received ※ 04 June 2021 paper accepted ※ 26 July 2021 issue date ※ 15 August 2021

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THPAB265

New RF BPM Electronics for the 560 Beam Position Monitors of the APS-U Storage Ring

4325

P. Leban, L. Bogataj, M. Cargnelutti, U. Dragonja, P. Paglovec
I-Tech, Solkan, Slovenia
A.R. Brill, J. Carwardine, W.X. Cheng, N. Sereno
ANL, Lemont, Illinois, USA

Within the upgrade of the APS storage ring to a multi-bend achromat lattice, 560 RF Beam Position Monitors will be required. The projected beam sizes are below 10 microns in both horizontal and vertical planes, putting stringent requirements on the BPM electronics resolution, long-term stability, beam current dependency, and instrument reproducibility. For the APS-U project, the Libera Brilliance⁺ instrument has been upgraded in technology and capabilities, including the independent multi-bunch turn-by-turn processing and an improved algorithm to further reduce the crossbar-switch artifacts. More than 140 instruments, equipped with 4 BPM electronics each, are being delivered to Argonne National Laboratory, consisting of the largest scale production for Instrumentation Technologies. In this contribution, the extensive test conditions to which the instruments were exposed and their results will be presented, as well as the beam-based long-term drift measurements with different fill patterns.

Poster THPAB265 [9.272 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB265

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paper received ※ 16 May 2021 paper accepted ※ 22 June 2021 issue date ※ 21 August 2021

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THPAB268

Hierarchical Intelligent Real-Time Optimal Control for LLRF Using Time Series Machine Learning Methods and Transfer Learning

4329

R. Pirayesh, S. Biedron
UNM-ME, Albuquerque, New Mexico, USA
S. Biedron, J.A. Diaz Cruz, M. Martínez-Ramón
UNM-ECE, Albuquerque, USA
J.A. Diaz Cruz
SLAC, Menlo Park, California, USA

Funding: supported by DOE, Office of Science, Office of High Energy Physics, under award number DE-SC0019468, Contract No. DE-AC02-76SF00515, also supported Office of Basic Energy Sciences. ALCF, Element Aero
Machine learning (ML) has recently been applied to Low-level RF (LLRF) control systems to keep the voltage and phase of Superconducting Radiofrequency (SRF) cavities stable within 0.01 degree in phase and 0.01% amplitude as constraints. Model predictive control (MPC) uses an optimization algorithm offline to minimize a cost function with constraints on the states and control input. The surrogate model optimally controls the cavities online. Time series deep ML structures including recurrent neural network (RNN) and long short-term memory (LSTM) can model the control input of MPC and dynamics of LLRF as a surrogate model. When the predicted states diverge from the measured states more than a threshold at each time step, the states’ measurements from the cavity fine-tune the surrogate model with transfer learning. MPC does the optimization offline again with the updated surrogate model, and, next, transfer learning fine-tunes the surrogate model with the new data from the optimal control inputs. The surrogate model provides us with a computationally faster and accurate modeling of MPC and LLRF, which in turn results in a more stable control system.
Machine learning, Surrogate model, control, LLRF, MPC, Transfer learning

Poster THPAB268 [0.377 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB268

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paper received ※ 16 May 2021 paper accepted ※ 13 July 2021 issue date ※ 18 August 2021

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THPAB269

Compton Spectrometer for FACET-II

4332

B. Naranjo, G. Andonian, A. Fukasawa, W.J. Lynn, N. Majernik, J.B. Rosenzweig, Y. Sakai, O. Williams, M. Yadav, Y. Zhuang
UCLA, Los Angeles, California, USA

Funding: DARPA GRIT Contract 20204571, DOE HEP Grant DE-SC0009914
We present the design of a Compton spectrometer for use at FACET-II. A sextupole is used for magnetic spectral analysis, giving a broad dynamic range (180 keV through 28 MeV) and the capability to capture an energy-angular double-differential spectrum in a single shot. At low gamma energies, below 1 MeV, Compton spectroscopy becomes increasingly challenging as the scattering cross-section becomes more isotropic. To extend the range of the spectrometer down to around 180 keV, we use a 3D-printed tungsten collimator at the detector plane to preferentially select forward-scattered electrons at the Compton edge.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB269

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paper received ※ 20 May 2021 paper accepted ※ 22 July 2021 issue date ※ 19 August 2021

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THPAB270

Pair Spectrometer for FACET-II

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB270

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paper received ※ 20 May 2021 paper accepted ※ 28 July 2021 issue date ※ 18 August 2021

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THPAB271

JLAB LLRF 3.0 Development and Tests

4340

T.E. Plawski, R. Bachimanchi, S. Higgins, C. Hovater, J. Latshaw, C.I. Mounts, D.J. Seidman, J. Yan
JLab, Newport News, Virginia, USA

The Jefferson Lab LLRF 3.0 system is being developed to replace legacy LLRF systems in the CEBAF accelerator. The new design builds upon 25 years of design and operational RF control experience, and our recent collaboration in the design of the LCLSII LLRF system. The new cavity control algorithm is a fully functional phase and amplitude locked Self Exciting Loop (SEL). This paper discusses the progress of the LLRF 3.0 hardware design, FPGA firmware development, User Datagram Protocol (UDP) operation, and recent LLRF 3.0 system tests on the CEBAF Booster cryomodule in the Upgrade Injector Test Facility (UITF).

Poster THPAB271 [1.940 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB271

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paper received ※ 14 May 2021 paper accepted ※ 06 July 2021 issue date ※ 20 August 2021

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THPAB272

Validation of Two Re-Buncher Cavities under High Beam Loading for LIPAc

4343

D. Gavela, I. Podadera, F. Toral
CIEMAT, Madrid, Spain
I. Moya
Fusion for Energy, Garching, Germany
F. Scantamburlo
IFMIF/EVEDA, Rokkasho, Japan

Funding: Work partially supported by the Spanish Ministry of Science and Innovation under project AIC-A-2011-0654 and FIS2013-40860-R
Two re-buncher cavities were installed at the Medium Energy Beam Transport line of the LIPAc accelerator, presently being commissioned at Rokkasho (Japan). They are IH-type cavities with five gaps providing an effective voltage of 350 kV at 175 MHz for a nominal operation of 125 mA CW deuterons at 5 MeV. After full conditioning and beamline integration in Europe, the cavities were installed in the accelerator with special care given to the alignment with respect to the rest of the components. The RF line, cooling circuits, and instrumentation were also mounted. The cavities were operated with an FPGA-based LLRF system. A re-conditioning of the cavities was performed in the first place, followed by tests with a pulsed beam with increasing currents. A maximum pulsed beam current of 100 mA was reached while operating the buncher cavities, under which they reached voltages up to 340 kV and 260 kV respectively. As expected, the beam loading was significant, leading to a series of difficulties and required strategies for a good operation that are discussed in this paper. The effect on the beam dynamics, measured by beam position monitors downstream of the bunchers is also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB272

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paper received ※ 19 May 2021 paper accepted ※ 02 September 2021 issue date ※ 18 August 2021

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THPAB273

Spectral Reconstruction for FACET-II Compton Spectrometer

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB273

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paper received ※ 20 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021

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THPAB276

X-Ray Double Slit Interferometer Progress at CLS

4349

N.A. Simonson, Y. Yousefi Sigari
University of Saskatchewan, Saskatoon, Canada
M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada

The Canadian Light Source (CLS) is a 3rd generation synchrotron that is used to produce extremely bright synchrotron light that can be used for research. The light at the CLS is produced by an electron storage ring that has an emittance of 20 nm. A 4th generation synchrotron (CLS2) is planned which will reduce the emittance to less than 1 nm and thus reduce the transverse beam size significantly, making it very challenging to measure. A double slit interferometer can be used to measure small transverse beam sizes, as first described by Mitsuhashi. An x-ray double slit interferometer will be designed and tested at the current CLS with the goal of using this setup at CLS2.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB276

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paper received ※ 20 May 2021 paper accepted ※ 23 July 2021 issue date ※ 01 September 2021

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THPAB282

Optimization Design of Four-Point Vibration Isolation Support for Spallation Neutron Source Vibration Magnet

4352

J.S. Zhang, J.X. Chenpresenter, H.Y. He, L. Liu, R.H. Liu, C.J. Ning, G.Y. Wang, A.X. Wang, J.B. Yu, Y.J. Yu, D.H. Zhu
IHEP CSNS, Guangdong Province, People’s Republic of China
L. Kang
IHEP, Beijing, People’s Republic of China

Chinese spallation neutron source (CSNS) RCS of the dipole magnets by 25 Hz sinusoidal alternating current (AC) with dc bias field, because the magnet will produce eddy current effect caused by the vibration, this safe and reliable operation of the long-term impact of magnets, so need to CSNS/RCS dipole magnets, a support system for dynamic characteristic research and the performance of vibration isolation design. The mechanical model of ac dipole magnet and support system is first established, and ANSYS theoretical modal analysis and experimental modal verification are carried out. On this basis, vibration isolation parameters of the four-point support system are studied. The theoretical analysis and the experimental results of modal parameters are consistent, which shows that the ANSYS analysis model is correct and reliable. The dynamic system parameter design method established in this paper can be applied to various equipment of AC power accelerator. The final experimental verification shows that the total displacement amplitude of the isolator to the Y direction of the magnet on the magnetic support decreases by 62.3%.

Poster THPAB282 [0.426 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB282

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paper received ※ 16 May 2021 paper accepted ※ 02 September 2021 issue date ※ 27 August 2021

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THPAB284

Analytical and Numerical Characterization of Cherenkov Diffraction Radiation as a Longitudinal Electron Bunch Profile Monitor for AWAKE Run 2

4355

C. Davut, G.X. Xia
UMAN, Manchester, United Kingdom
O. Apsimon
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon
Cockcroft Institute, Warrington, Cheshire, United Kingdom
P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
P. Karataev
JAI, Egham, Surrey, United Kingdom
T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland

In this paper, CST simulations of the coherent Cherenkov Diffraction Radiation with a range of parameters for different dielectric target materials and geometries are discussed and compared with the theoretical investigation of the Polarization Current Approach to design a prototype of a radiator for the bunch length/profile monitor for AWAKE Run 2. It was found that the result of PCA theory and CST simulation are consistent with each other regarding the shape of the emitted ChDR cone.
* Karlovets, D. V. (2011). JETP, 113(1), 27-45.
** Shevelev, M. V., & Konkov, A. S. (2014). JETP, 118(4), 501-511.
*** Curcio, A., et al.(2020). PRAB, 23(2), 022802.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB284

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paper received ※ 16 May 2021 paper accepted ※ 14 July 2021 issue date ※ 10 August 2021

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THPAB286

Quadrupole Focusing Lenses for Heavy Ion Linac

4359

V. Skachkov, A.V. Kozlov, G. Kropachev, T. Kulevoypresenter, D.A. Liakin, O.S. Sergeeva, V.S. Skachkov, Yu. Stasevich
ITEP, Moscow, Russia

Simulation results of pulsed current electromagnet quadrupoles with integral of the magnetic field gradient up to 7 T are presented. Magnets for the DTL and MEBT focusing channels are designing for the heavy-ion linac in Institute for Theoretical and Experimental Physics (ITEP - NRC "Kurchatov Institute"). Appropriate conditions which promise getting the magnetic lens parameters required at restrictions on the overall length <130 mm as well as on the beam aperture >45 mm are defined. It is shown that the channel acceptance to beam emittance ratio desired not less than 3 can be provided by conventional low-carbon steel up to a magnetic aperture of 50 mm in diameter while beyond this size permendur is out of competition. Some aspects of the pulsed power supply system are considered and main parameters of the pulse current generator (PCG) are given.

Poster THPAB286 [0.701 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB286

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paper received ※ 14 May 2021 paper accepted ※ 30 June 2021 issue date ※ 02 September 2021

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THPAB287

Providing Computing Power for High Level Controllers in MicroTCA-based LLRF Systems via PCI Express Extension

4363

P. Nonn, A. Eichler, S. Pfeiffer, H. Schlarb, J.H.K. Timm
DESY, Hamburg, Germany

It is possible to connect the PCIe bus of a high performance computer to a MicroTCA crate. This allows the software on the computer to communicate with the modules in the crate, as if they were peripherals of the computer. This article will discuss the use of this feature in respect to accelerator control with a focus on High Level Controllers.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB287

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 16 August 2021

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THPAB289

Design and Manufacture of Solenoid Center Deviation Measurement Device

4366

X. Wu, C.D. Deng, W. Kang, L. Li, S. Li, Y.Q. Liu, Y.W. Wu, J.X. Zhou
IHEP, Beijing, People’s Republic of China

The solenoids are widely used both in conventional magnets and superconducting magnets in particle accelerators. The longitudinal fields along the longitudinal direction of the solenoids are usually measured with the Hall probe measurement system. However, in some cases, the deviation between the magnetic center and mechanical center of the solenoid is another important parameter and has to be measured accurately. In this paper, a device is designed and developed to measure the center deviation of the solenoid, which can be both used in conventional magnets and superconducting magnets. After the device is finished, some tests are made in the solenoid to check whether the data is correct. For the numerical simulation and analysis of the magnetic field inside the solenoid, the TOSCA code was chosen right from start. The results of the analysis are compared to the result of the tests.

Poster THPAB289 [1.001 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB289

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paper received ※ 14 May 2021 paper accepted ※ 27 July 2021 issue date ※ 22 August 2021

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THPAB290

Evolution of the LHC Beam Screen Surface Conditioning Upon Electron Irradiation

4370

S. Bilgen, S. Della-Negra, D. Jacquet, B. Mercier, I. Ribaud, G. Sattonnay
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
V. Baglin
CERN, Meyrin, Switzerland

For the vacuum scientists and the accelerator community, finding solutions to mitigate pressure rises induced by electron, photon, and ion desorption, and also beam instabilities induced by ion and electron clouds is a major issue. Moreover, it is worth noting that the OFE copper beam screen of the LHC is initially cleaned with standard industrial processes, leading to residual chemical contamination. Along the time, changes in the surface chemistry of vacuum chambers are observed during beam operations, leading to modifications of outgassing rates, stimulated desorption processes, and secondary emission yields (SEY). The impact of ions on molecule desorption and electron production was investigated to identify their influence on the global pressure rises and to quantify the ion conditioning effect on copper surfaces: (i) SEY evolution was measured to understand the changes of surface conditioning upon particle irradiation; (ii) surface chemistry evolution after electron irradiation was investigated by both XPS and TOF-SIMS analyses using the ANDROMEDE facility at IJCLab. Finally, the relationship between surface chemistry and the conditioning phenomenon will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB290

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 10 August 2021

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THPAB291

DYVACS (DYnamic VACuum Simulation) Code: Gas Density Profiles in Presence of Electron Cloud in the LHC

4373

S. Bilgen, B. Mercier, G. Sattonnay
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
V. Baglin
CERN, Meyrin, Switzerland

The computation of residual gas density profiles in particle accelerators is an essential task to optimize beam pipes and vacuum system design. In a hadron collider such as the LHC, the beam induces dynamic effects due to ion, electron, and photon-stimulated gas desorption. The well-known VASCO* code developed at CERN in 2004 is already used to estimate vacuum stability and density profiles in steady-state conditions. Nevertheless, some phenomena are not taken into account such as the ionization of residual gas by the electron clouds and the evolution of the electronic density related to the electron cloud build-up. Therefore, we propose an upgrade of this code by introducing electron cloud maps** to estimate the electron density and the ionization of gas by electrons leading to an increase of induced desorption. The pressure evolution computed with DYVACS reproduces with good accuracy the experimental pressure recorded in the VPS beam pipes sector*** of the LHC from the proton beam injection to the stable beam period. Additionally, DYVACS can also be used as a predictive tool to compute the pressure evolution in the beam pipes for Future Circular Colliders (FCC-hh or -ee).
* A. Rossi, Tech. Report, LHC Project Note 341
** T. Demma et al Phys. Rev. Acceler. and Beams 10, 114401 (2007)
*** B. Henrist et al, Proc. IPAC2014, Dresden

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB291

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paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 31 August 2021

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THPAB292

Dynamic Pressure in the LHC: Detection of Ions Induced by Ionization of Residual Gas by the Proton Beam and by the Electron-Cloud

4377

S. Bilgen, B. Mercier, G. Sattonnay
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
V. Baglin
CERN, Meyrin, Switzerland

Ultra-High Vacuum is an essential requirement to achieve design performances and high luminosities in high-energy particle colliders. Consequently, the understanding of the dynamic pressure evolution during accelerator operation is fundamental to provide solutions to mitigate pressure rises induced by multiple effects leading to beam instabilities. For the LHC, the appearance of instabilities may be due to the succession of several phenomena: (i) the induced desorption of gases adsorbed on the surfaces leading to pressure rises; (ii) the creation of secondary particles (ions, electrons); (iii) the production of the so-called Electron Cloud build-up by multipacting effect. This work aims to investigate some fundamental phenomena which drive the dynamic pressure in the LHC, namely the effects induced by electrons and ions interacting with the copper surface of the beam screens. Electron and ion currents, as well as pressure, were recorded in situ in the Vacuum Pilot Sector (VPS*) located on the LHC ring during the RUN II. By analyzing the results, more ions than expected were detected and the interplay between electrons, ions, and pressure changes was investigated.
* The LHC Vacuum Pilot-Sector Project, B. Henrist, V. Baglin, G. Bregliozzi, and P. Chiggiato, CERN, Geneva, Switzerland, Proceedings of IPAC2014, Dresden, Germany

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB292

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 27 August 2021

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THPAB295

Application of CMM Technology in Accelerator Magnet Detection

4381

S. Li, F.S. Chen, C.D. Deng, W. Kang, Y.Q. Liu, X. Wu, Y.W. Wupresenter
IHEP, Beijing, People’s Republic of China

Accelerator magnet is one of the most difficult equipment in accelerator hardware system. With the improvement of physical requirements, more and more high technical requirements are put forward for magnets. This paper mainly introduces the new application of three coordinate measurement technology in the detection of accelerator magnet, and introduces the working process of CMM in the detection of accelerator magnet polar profile.

Poster THPAB295 [0.677 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB295

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paper received ※ 14 May 2021 paper accepted ※ 02 September 2021 issue date ※ 29 August 2021

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THPAB296

The Spallation Neutron Source Normal Conducting Linac RF System Design for the Proton Power Upgrade Project

4383

J.S. Moss, M.T. Crofford, S.W. Lee, G.D. Toby
ORNL, Oak Ridge, Tennessee, USA
M.E. Middendorf
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 at the Spallation Neutron Source will double the available proton beam power from 1.4 to 2.8 MW by increasing the beam energy from 1.0 to 1.3 GeV and the beam current from 26 to 38 mA. The increase in beam current resulted in the need to redesign the existing normal conducting linac (NCL) RF Systems. High-power testing of the existing NCL RF Systems configured to accelerate PPU-level beam provided the data used to make the final design decisions. This paper describes the development and execution of those in-situ tests and the subsequent results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB296

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paper received ※ 17 May 2021 paper accepted ※ 22 July 2021 issue date ※ 20 August 2021

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THPAB300

Structure Design and Motion Analysis of 6-DOF Sample Positioning Platform

4387

G.Y. Wang, J.X. Chen, L. Liu, R.H. Liu, C.J. Ning, A.X. Wang, J.B. Yupresenter, Y.J. Yu, J.S. Zhang
IHEP CSNS, Guangdong Province, People’s Republic of China
L. Kang
IHEP, Beijing, People’s Republic of China

with the development of synchrotron radiation (SR) light source technology, in order to meet the requirements of sample positioning platform of some beamline stations, such as adjusting resolution at the nanometer level and having larger sample scanning distance, a six degree of freedom positioning platform based on spacefab structure was developed. The key technologies such as coordinate parameter transformation, kinematics analysis, and adjustment decoupling algorithm of 6-DOF pose adjustment system of SpaceFAB positioning platform are mainly studied. A 6-DOF platform driven by a stepping motor is designed and manufactured. The control system of the 6-DOF Platform Based on bus control is developed, and the adjustment accuracy is tested. The repeated positioning accuracy of the platform in three directions is 0.019 mm, and that of rotation is 0.011 ° in three directions. The test results verify the correctness of the theoretical analysis of SpaceFAB structure and the rationality of mechanism design. The research on the platform motion algorithm and control system has important reference value for the follow-up research of large stroke nano-6-dof positioning platform.

Poster THPAB300 [1.517 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB300

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paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 02 September 2021

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THPAB307

Behaviour of Ironless Inductive Position Sensors in Close Proximity to Each Other

4390

N.J. Sammut, A. Grima
University of Malta, Information and Communication Technology, Msida, Malta
M. Di Castro, A. Masi
CERN, Meyrin, Switzerland

Funding: CERN - The European Organisation for Nuclear Research UM - The University of Malta
Safety critical systems like the collimators of the Large Hadron Collider require transducers which are immune to interference from their surroundings. The ironless inductive position sensor is used to measure the position of collimator jaws with respect to the beam and is designed to be immune to external DC or slowly changing magnetic fields. In this paper we investigate whether frequency separation is required when multiple ironless inductive position sensors are used and whether two or more sensors at the same frequency results in cross-talk. Numerical simulations and experiments are conducted to study the magnetic field behaviour of the sensors, their interference with each other and the impact of this interference on the position reading. Finally, this paper defines guidelines on safe operation of the ironless inductive position sensor in the aforementioned conditions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB307

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paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 22 August 2021

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THPAB309

New Working Tune Feedback System for TLS

4394

S.J. Huang, Y.K. Lin, Y.C. Lin
NSRRC, Hsinchu, Taiwan

TLS storage ring has two sets of working tuning feedback systems: one is used to correct the working tune deviation caused by insertion device U90; another system uses a local trim coil to correct the working tune deviation caused by all insertion devices. This article describes a new working tune feedback system in TLS that can correct the working tune effectively back to the required conditions for operation; the two existing feedback systems do not cause problems. We can both avoid increasing the local radiation dose and decreasing the injection efficiency.

Poster THPAB309 [0.831 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB309

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paper received ※ 15 May 2021 paper accepted ※ 02 July 2021 issue date ※ 23 August 2021

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THPAB310

Automatic Correction System for the TLS Booster Linac Klystron Modulator

4396

S.J. Huang, Y.K. Lin
NSRRC, Hsinchu, Taiwan

The aim of this article is to analyse the performance output of the klystron modulator, which is based on the observation of the output voltage and current performance of the linear-accelerator klystron modulator; we modify the operating-point parameters based on those results or assess whether the klystron needs to be replaced. For this purpose, we collect the observation data of the klystron performance; we then develop a program to adjust automatically the high-voltage setting of the klystron to ensure that the storage current maintains beam current 360 mA in the top-up mode operation.

Poster THPAB310 [0.785 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB310

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paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 13 August 2021

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THPAB311

Using Linear Regression to Model the Parameters of the Flat Wires in TLS-EPU56

4399

S.J. Huang, Y.H. Chang, T.Y. Chung
NSRRC, Hsinchu, Taiwan
Y.W. Chen
Academia Sinica, Taipei, Taiwan

Although a theoretical calculation might predict the set currents of the flat wires, which are used to compensate the deviation in the Betatron tune caused by the elliptically polarized undulator (EPU), those set currents must still be tuned in reality. To approach this reality, a strategy of Machine Learning was adopted, which included collecting real-condition data and using a linear-regression model to adjust the parameters of the flat wires. After training the model, the predictions in variables tune x, tune y and beam size x were compared with the required amount of correction of the EPU at various gaps and phases. To prove the feasibility of this method, a test was performed under the real conditions of accelerator Taiwan Light Source (TLS).

Poster THPAB311 [1.226 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB311

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paper received ※ 13 May 2021 paper accepted ※ 28 June 2021 issue date ※ 30 August 2021

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THPAB313

Drive Laser System for Shanghai Soft X-Ray Free Electron Laser

4403

L. Feng, C.L. Li, B. Liu, J.G. Wang
SARI-CAS, Pudong, Shanghai, People’s Republic of China
X. Lu
ANL, Lemont, Illinois, USA
X.T. Wang, W.Y. Zhang
Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China

In this paper, we introduce the design and layout of the drive laser of Shanghai Soft X-ray Free Electron Laser (SXFEL). It is known that the temporal and spatial distribution of the drive laser is crucial for high-quality electron beams. The drive laser provides the laser pulse of 266nm wavelength and 8ps pulse duration for the photocathode, as well as 400nm wavelength, 2-20ps tunable pulse duration for the laser heater. For this purpose, there are mainly four parts in such system, including a third-harmonic generation device, pulse stretcher, image transmitted system, and laser optical module for laser heater. Finally, the measured results of the electron beam under this drive laser system are presented and discussed.

Poster THPAB313 [0.691 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB313

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paper received ※ 20 May 2021 paper accepted ※ 15 July 2021 issue date ※ 24 August 2021

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THPAB314

Development of the Femtosecond Timing Distribution System for the Shanghai Soft X-Ray Free Electron Laser

4406

L. Feng, C.L. Li, B. Liu, J.G. Wang
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

High accuracy timing and synchronization system on femtosecond timescale play an important role for free-electron laser projects such as Shanghai Soft X-ray free-electron laser facility (SXFEL), and future Shanghai high repetition rate XFEL and Extreme light facility (SHINE). To meet the high precision synchronization requirements for both facilities, an optical-based timing distribution system is absolutely necessary. Such a system distributes the laser pulse train from a locked optical master oscillator through the fiber links, which stabilized by a balance optical cross-correlator based on a periodical-poled KTiOPO4 crystal. In this paper, the recent progress and experimental results of SXFEL and SHINE timing distribution system will be reported.

Poster THPAB314 [0.351 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB314

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paper received ※ 20 May 2021 paper accepted ※ 15 July 2021 issue date ※ 22 August 2021

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THPAB317

Experiment and Simulation Study on the Capture and Acceleration Process of XiPAF Synchrotron

4409

Y. Li, X. Guan, X.Y. Liu, M.W. Wang, X.W. Wang, Q.Z. Xing, Y. Yang, H.J. Yao, W.B. Ye, S.X. Zheng
TUB, Beijing, People’s Republic of China
W.L. Liu, D. Wang, Z.M. Wang, Y. Yang, M.T. Zhao
NINT, Shannxi, People’s Republic of China

The beam commissioning of the capture and acceleration process on the XiPAF (Xi’an 200MeV Proton Application Facility) synchrotron has been carried out. The efficiency of the experiment results has been compared with the simulation results. At present, the efficiency of the capture process with single-harmonic is about 73%, and the acceleration efficiency is about 82%, and the simulation results are 77% and 96% without space charge effect, respectively. In order to improve efficiency, dual-harmonic was used during the capture and acceleration process. During the experiment, the capture efficiency was increased by 5%, and the acceleration efficiency was increased by 4%. The capture efficiency decreases with the increase of the maximum RF voltages. We analyzed the reasons for the decrease in capture efficiency. In the next step, further verification will be carried out through experiments under different conditions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB317

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paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 23 August 2021

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THPAB318

Uniformization of the Transverse Beam Profile with Nonlinear Magnet

4413

Y. Li, X. Guan, X.Y. Liu, X.W. Wang, Q.Z. Xing, Y. Yang, H.J. Yao, W.B. Ye, S.X. Zheng
TUB, Beijing, People’s Republic of China
Y. Yang
NINT, Shannxi, People’s Republic of China

The beam generated after slow extraction of the synchrotron is always not uniform and asymmetrical in transverse distribution. In practice, radiation therapy or radiation irradiation requires a high degree of uniformity of beam spot. Therefore, it is necessary to adjust the beam distribution with a nonlinear magnet and other elements on the transport line from synchrotron ring to beam target station. Nonlinear magnet has high requirements on beam quality. Before passing through the nonlinear magnet field, the beam center can be adjusted by taking advantage of the gradient change distribution of the nonlinear magnet’s transverse field map to achieve uniform distribution at the target station. As an example, we use the parameters of heavy ions of XiPAF (Xi’an 200MeV Proton Application Facility) to simulate the beam transport from synchrotron ring to beam target station.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB318

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paper received ※ 20 May 2021 paper accepted ※ 08 July 2021 issue date ※ 21 August 2021

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THPAB319

RF Power Generating System for the Linear Ion Accelerator

4417

V.G. Kuzmichev, T. Kulevoypresenter, D.A. Liakin, D.N. Selesnev, A. Sitnikov
ITEP, Moscow, Russia
M.L. Smetanin, A.V. Telnov, N.V. Zavyalov
VNIIEF, Sarov, Russia

An RF power supply system based on solid-state amplifiers has been developed for the linear accelerator of heavy ions. The report contains information on the characteristics and composition of the system, presents the LLRF structure for RFQ and DTL sections.

Poster THPAB319 [0.275 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB319

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paper received ※ 16 May 2021 paper accepted ※ 16 August 2021 issue date ※ 19 August 2021

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THPAB320

ALD-Based NbTiN Studies for SIS R&D

4420

I. González Díaz-Palacio, R.H. Blick, R. Zierold
University of Hamburg, Hamburg, Germany
W. Hillert, M. Wenskat
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Superconductor-Insulator-Superconductor multilayers improve the performance of SRF cavities providing magnetic screening of the bulk cavity and lower surface resistance. In this framework NbTiN mixtures stand as a potential material of interest. Atomic layer deposition (ALD) allows for uniform coating of complex geometries and enables tuning of the stoichiometry and precise thickness control in sub-nm range. In this talk, we report about NbTiN thin films deposited by plasma-enhanced ALD on insulating AlN buffer layer. The deposition process has been optimized by studying the superconducting electrical properties of the films. Post-deposition thermal annealing studies with varying temperatures, annealing times, and gas atmospheres have been performed to further improve the thin film quality and the superconducting properties. Our experimental studies show an increase in Tc by 87.5% after thermal annealing and a maximum Tc of 13.9 K has been achieved for NbTiN of 23 nm thickness. Future steps include lattice characterization, using XRR/XRD/EBSD/PALS, and SRF measurements to obtain Hc1 and the superconducting gap.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB320

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paper received ※ 24 May 2021 paper accepted ※ 23 July 2021 issue date ※ 18 August 2021

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THPAB322

Transient Beam Loading in the CBETA Multi-Turn ERL

4422

N. Banerjee
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by NSF Grant No. DMR0807731, DOE Award No. DE-SC0012704, and NYSERDA Agreement No. 102192.
The Cornell-BNL ERL Test Accelerator (CBETA) is the first superconducting multi-turn ERL that has been commissioned at Cornell University in a low current mode. In this paper, we first discuss a new model of beam loading which is valid for the low injection energies used in CBETA. Using this model, we explore the effect of bunch patterns, beam turn-on, and turn-off transients on the fundamental mode of the 7-cell SRF cavities used in the main linac. In particular, we examine the operational constraints on the rf system at the design current of 40 mA.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB322

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paper received ※ 20 May 2021 paper accepted ※ 29 July 2021 issue date ※ 16 August 2021

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THPAB324

PIP-II 800 MeV Proton Linac Beam Pattern Generator

4426

H. Maniar, B.E. Chase
Fermilab, Batavia, Illinois, USA
J.E. Dusatko
SLAC, Menlo Park, California, USA
S. Khole
BARC, Trombay, Mumbai, India
D. Sharma
RRCAT, Indore (M.P.), India

The PIP2 IT Beam Pattern Generator is the system that synchronizes beam injection and the RF systems between the PIP2 LINAC to the Booster. The RF frequencies of these two accelerator systems are not harmonically related. Synchronization is accomplished by controlling two MEBT Beam Choppers, which select 162.5MHz beam bunches from the LEBT and RFQ to produce an appropriate reduced beam bunch pattern that enables bucket-to-bucket transfer to the Booster RF at 46.46MHz (84th harmonic). This chopping pattern also reduces the beam current to an average of 2mA over the Booster injection, matching the Linac nominal beam current. The BPG also generates the RF frequency/phase reference which the Booster will phase lock to during injection. The BPG is fully programmable, allowing for arbitrary beam patterns with adjustable timing parameters, having a fine adjustment resolution of 38ps. The latter is accomplished using digital signal processing techniques. This paper discusses the design of the BPG, its construction, test results, and operational experience after being integrated into the PIP2 IT test accelerator and concludes with a discussion of the system’s performance and future plans.

Poster THPAB324 [0.676 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB324

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paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 13 August 2021

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THPAB328

Tapered Modular Quadrupole Magnet to Reduce Higher-Order Optical Aberrations

4429

Y.Z. Shao, G.E. Lawler, B. Naranjo, J.B. Rosenzweig
UCLA, Los Angeles, USA

Funding: US Department of Energy under the contract Nos. DE-SC0017648, DE-SC0009914 and National Science Foundation Grant No. PHY-1549132m
At UCLA’s SAMURAI Laboratory, there will be a need for beam optics to accommodate operation over a range of beam energies. We present a modular quadrupole design that, in addition to satisfying this requirement, incorporates interchangeable tapered end-pieces for mitigation of higher-order aberrations *. The design progresses in an iterative fashion, whereby the tapered shapes, generated algorithmically, are fed into a field solver, and then the aberrations of the resulting particle trajectories are calculated and minimized.
* R. Baartman, Quadrupole shapes, Phys. Rev. ST Accel. Beams 15, 074002 (2012).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB328

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 20 August 2021

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THPAB331

High-Power Test of a Highly Over-Coupled X-Band RF Gun Driven by Short RF Pulses

4432

J.H. Shao, D.S. Doran, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
X. Lu, P. Piot, W.H. Tan
Northern Illinois University, DeKalb, Illinois, USA

Beam brightness, a key figure of merit of RF photocathode guns, can be improved by increasing the cathode surface field which suppresses emittance growth from space charge. The surface field in normal-conducting structures is mainly limited by RF breakdown and it has been experimentally discovered that RF breakdown rate exponentially depends on RF pulse length. A highly over-coupled 1.5-cell X-band photocathode gun has been developed to be powered by 9 ns RF pulses with 3 ns rising time, 3 ns flat-top, and 3 ns falling time generated by an X-band metallic power extractor. In the recent experiment at Argonne Wakefield Accelerator facility, cathode surface field up to ~350 MV/m with a low breakdown rate has been obtained under ~250 MW input power. Strong beam loading from dark current was observed during RF conditioning and quickly recovered to a negligible level after the gun reached the maximum gradient. Detailed high-power test results and data analysis will be reported in this manuscript.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB331

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paper received ※ 25 May 2021 paper accepted ※ 14 July 2021 issue date ※ 23 August 2021

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THPAB332

Development of a Pair of 182 GHz Two-Half Power Extractor and Accelerator for Short Pulse RF Breakdown Study

4435

J.H. Shao, J.G. Power
ANL, Lemont, Illinois, USA
R.B. Agustsson, S.V. Kutsaev, A.Yu. Smirnov
RadiaBeam, Santa Monica, California, USA

High-frequency structures are favorable in structure wakefield acceleration for their strong beam-structure interaction. Recent progress of advanced fabrication technologies, such as high-precision two-half milling and additive machining, has enabled experimental research of mm-wave/THz structures. In this work, we have designed a pair of 182 GHz two-half copper power extractor and accelerator for short pulse RF breakdown study. When driven by a 182 GHz 4-bunch train with 4 nC total charge and 0.3 mm rms bunch length, the power extractor will generate 0.4 ns ~8 MW RF pulses and the corresponding gradient in the single-cell accelerator will reach ~460 MV/m. RF and mechanical design of the proof-of-concept structures will be reported in this manuscript.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB332

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paper received ※ 26 May 2021 paper accepted ※ 19 July 2021 issue date ※ 26 August 2021

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THPAB335

Optical Phase Space Mapping Using a Digital Micro-Mirror Device

4439

M. Vujanovic, R.B. Fiorito, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom
A.L. Kippax
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This project has received funding from European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559.
Optical transition radiation (OTR) is routinely used to measure transverse beam size, divergence , and emittance of charged particle beams. Presented here is an experimental method, which uses micro-mirror device (DMD) to conduct optical phase space mapping (OPSM). OPSM will be a next step and significant enhancement of the measurements capabilities of an adaptive optics-based beam characterization system. For this measurements, a DMD will be used to generate a reflective mask that replicates the double slit. Since the DMD makes it possible to easily change the size, shape and position of the mask, the use of the DMD will greatly simplify OPSM and make it more flexible, faster and more useful for diagnostics applications. The process can be automated and integrated into a control system that can be used to optimize the beam transport.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB335

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paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 28 August 2021

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THPAB336

Novel Magnetron Operation and Control Methods for Superconducting RF Accelerators

4442

G.M. Kazakevich, R.P. Johnson
Muons, Inc, Illinois, USA
T.N. Khabiboulline, G.V. Romanov, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

High power magnetrons designed and optimized for industrial heating, being injection-locked, have been suggested to power superconducting RF cavities for accelerators due to lower cost and higher efficiency. However, standard operation methods do not provide high efficiency with wideband control suppressing microphonics. We have developed and experimentally verified novel methods of operating and controlling the magnetron that provide stable RF generation with higher efficiency and lower noise than other RF sources. By our method the magnetrons operate with the anode voltage notably lower than the self-excitation threshold improving its performance. This is also a promising way to increase tube reliability and longevity. A magnetron operating with the anode voltage lower than the self-excitation threshold, in so-called stimulated coherent generation mode has special advantage for pulse operation with a gated injection-locking signal. This eliminates the need for expensive pulsed HV modulators and additionally increases the magnetron RF source efficiency due to absence of losses in HV modulators.

Poster THPAB336 [0.960 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB336

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paper received ※ 15 May 2021 paper accepted ※ 08 July 2021 issue date ※ 22 August 2021

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THPAB337

Resonance Control System for the PIP-II IT HWR Cryomodule

4446

P. Varghese, B.E. Chase, P.M. Hanlet, H. Maniar, D.J. Nicklaus, S. Sankar Raman
Fermilab, Batavia, Illinois, USA
L.R. Doolittle, S. Paiagua, C. Serrano
LBNL, Berkeley, California, USA

The HWR (half-wave-resonator) cryomodule is the first one in the superconducting section of the PIP-II LINAC project at Fermilab. PIP-II IT is a test facility for the project where the injector, warm front-end, and the first two superconducting cryomodules are being tested. The HWR cryomodule comprises 8 cavities operating at a frequency of 162.5 MHz and accelerating beam up to 10 MeV. Resonance control of the cavities is performed with a pneumatically operated slow tuner which compresses the cavity at the beam ports. Helium gas pressure in a bellows mounted to an end wall of the cavity is controlled by two solenoid valves, one on the pressure side and one on the vacuum side. The resonant frequency of the cavity can be controlled in one of two modes. A pressure feedback control loop can hold the cavity tuner pressure at a fixed value for the desired resonant frequency. Alternately, the feedback loop can regulate the cavity tuner pressure to bring the RF detuning error to zero. The resonance controller is integrated into the LLRF control system for the cryomodule. The control system design and performance of the resonance control system are described in this paper.

Poster THPAB337 [4.426 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB337

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paper received ※ 12 May 2021 paper accepted ※ 26 July 2021 issue date ※ 27 August 2021

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THPAB338

Performance of the LLRF System for the Fermilab PIP-II Injector Test

4450

P. Varghese, B.E. Chase, P.M. Hanlet, H. Maniar, D.J. Nicklaus
Fermilab, Batavia, Illinois, USA
L.R. Doolittle, C. Serrano
LBNL, Berkeley, California, USA

PIP-II IT is a test facility for the PIP-II project where the injector, warm front-end, and the first two superconducting cryomodules are being tested. The 8-cavity half-wave-resonator (HWR) cryomodule operating at 162.5 MHz is followed by the 8-cavity single-spoke resonator(SSR1) cryomodule operating at 325 MHz. The LLRF systems for both cryomodules are based on a common SOC FPGA-based hardware platform. The resonance control systems for the two cryomodules are quite different, the first being a pneumatic system based on helium pressure and the latter a piezo/stepper motor type control. The data acquisition and control system can support both CW and Pulsed mode operations. Beam loading compensation is available which can be used for both manual/automatic control in the LLRF system. The user interfaces include EPICS, Labview, and ACNET. Testing of the RF system has progressed to the point of being ready for a 2 mA beam to be accelerated to 25 MeV. The design and performance of the field control and resonance control system operation with beam are presented in this paper.

Poster THPAB338 [5.482 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB338

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paper received ※ 13 May 2021 paper accepted ※ 27 July 2021 issue date ※ 24 August 2021

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THPAB340

Sub-Nanosecond Switching of HV SiC MOS Transistors for Impact Ionisation Triggering

4454

V. Senaj, T. Kramer, A.A. del Barrio Montañés
CERN, Geneva 23, Switzerland
M. Sack
KIT, Karlsruhe, Germany

Pulse generators with multi kV/kA pulses are necessary for the particle accelerator environment for beam transfer magnets. Traditionally these generators are using thyratrons - until recently the only switches capable of switching such pulses within tens of ns. There is a strong demand to replace thyratrons with semiconductor switches to avoid their future obsolescence. Very promising candidates are components from the family of fast ionization dynistors triggered by impact ionization. Their sub-nanosecond switching time and extreme current densities can provide performances superior to that of thyratrons. Recent investigations showed that impact ionization triggering is feasible also in cheap industrial thyristors. The main issue is the generation of triggering pulses with slew rates in the multi kV/ns region and with the required output current for charging the parasitic capacitance of the thyristor. We present an approach of generating > 1 kV/ns pulses by ultra-boosted gate driving of HV SiC MOS transistors. We found that the MOS lifetime under these extreme triggering conditions can still reach more than 10⁸ pulses, enough for kicker generator applications.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB340

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paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 27 August 2021

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THPAB341

TiN Metalizing and Coating for Multi-Megawatt RF Vacuum Windows

4457

M.L. Neubauer, A. Dudas, R.P. Johnson
Muons, Inc, Illinois, USA

Coatings on microwave windows and high-voltage ceramics are required to eliminate secondary electron emission (SEE), which initiates multipactoring discharge causing local heating and ceramic failures due to cracking and loss of vacuum. The region surrounding the triple junction (ceramic+metal+vacuum) is the primary source of free electrons and in microwave windows and high-voltage ceramics. This region is located at the metalizing and braze joint of the ceramic support structure making the vacuum seal. On very large microwave windows typically at low frequencies, this critical region is difficult to coat by the traditional techniques of sputter coating anti-multipactoring titanium nitride or other materials. The novel processes proposed here include a means for applying and controlling the thickness of titanium nitride both in the metallizing (controlling the source) and on the surface of the window, eliminating SEE and the multipactoring discharge.

Poster THPAB341 [0.845 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB341

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paper received ※ 23 May 2021 paper accepted ※ 21 July 2021 issue date ※ 01 September 2021

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THPAB343

Test Results of the Prototype SSR1 Cryomodule for PIP-II at Fermilab

4461

D. Passarelli, J. Bernardini, C. Boffo, B.M. Hanna, S. Kazakov, T.N. Khabiboulline, A. Lunin, J.P. Ozelis, M. Parise, Y.M. Pischalnikov, V. Roger, B. Squires, A.I. Sukhanov, G. Wu, V.P. Yakovlev, S. Zorzetti
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, Michigan, USA

Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy
A prototype cryomodule containing eight Single Spoke Resonators type-1 (SSR1) operating at 325 MHz and four superconducting focusing lenses has been successfully assembled and cold tested in the framework of PIP-II project at Fermilab. The performance of cavities and focusing lenses along with test results of other cryomodule’s key parameters are presented in this contribution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB343

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paper received ※ 20 May 2021 paper accepted ※ 08 August 2021 issue date ※ 28 August 2021

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THPAB344

Magneto-Optical Trap Cathode for High Brightness Applications

4466

V.S. Yu, C.E. Hansel, G.E. Lawler, M. Mills, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
J.I. Mann
PBPL, Los Angeles, USA

Funding: This work was performed with support of the US Department of Energy under Contract No. DE-SC0020409 and the National Science Foundation under Grant No. PHY-1549132
Electron bunches extracted from magneto-optical traps (MOTs) via femtosecond photo-ionization and electrostatic acceleration can have significantly lower transverse emittance than emissions from traditional metal cathodes. Such MOT cathodes, however, have two drawbacks: the need for multiple trapping lasers and the limit to ~MV/m fields. Designs exist for MOTs which only require one trapping laser. Our RF simulations in High-Frequency Structure Simulator (HFSS) indicate that the cone MOT is the only one compatible with high gradient RF cavities. We present the combination of the two, an RF cavity with a cone-MOT as part of its geometry. It only requires one trapping laser and can use much higher fields. The geometry of the chamber is compatible with a wide range of MOT species, which allows the search for one which is compatible with copper cavities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB344

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paper received ※ 19 May 2021 paper accepted ※ 29 July 2021 issue date ※ 12 August 2021

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THPAB347

Status of Sirius Storage Ring RF System

4470

A.P.B. Lima, D. Daminelli, R.H.A. Farias, F.K.G. Hoshino, F.S. Oliveira, R.R.C. Santos, M.H. Wallner
LNLS, Campinas, Brazil

The design configuration of the Sirius Light Source RF System is based on two superconducting RF cavities and eight 60 kW solid state amplifiers operating at 500 MHz. The current configuration, based on a 7-cell room temperature cavity, was initially planned for commissioning and initial tests of the beamlines. However, it will have to remain in operation longer than planned. Sirius has been operating in decay mode for beamline tests with an initial current of 70 mA. We present an overview of the first-year operation of the RF system and the preparations for the installation of the two superconducting cavities, which is expected to take place in 2023.

Poster THPAB347 [1.322 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB347

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paper received ※ 16 May 2021 paper accepted ※ 23 July 2021 issue date ※ 26 August 2021

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THPAB348

INFN-LASA for the PIP-II LB650 Linac

4474

R. Paparella, M. Bertucci, M. Bonezzi, A. Bosotti, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, D. Sertore
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

INFN joined the international effort for the PIP-II project at Fermilab and it’s going to contribute to the low-beta section of the PIP-II proton linac. In particular, INFN-LASA is finalizing its commitment to deliver in kind the full set of the LB650 cavities, namely 36 plus spares 5-cell cavities at 650 MHz and geometrical beta 0.61. All cavities, designed by INFN-LASA, will be produced and surface treated in industry, qualified through vertical cold test, and delivered as ready for string installation. This paper reports the status of INFN’s contribution to PIP-II and of ongoing activities toward the experimental qualifications of infrastructures and prototypes.

Poster THPAB348 [4.076 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB348

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paper received ※ 16 May 2021 paper accepted ※ 01 July 2021 issue date ※ 12 August 2021

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THPAB349

Feed-Forward Neural Network Based Modelling of an Ultrafast Laser for Enhanced Control

4478

A. Aslam, M. Martínez-Ramón, S.D. Scott
UNM-ECE, Albuquerque, USA
S. Biedron
Argonne National Laboratory, Office of Naval Research Project, Argonne, Illinois, USA
S. Biedron
Element Aero, Chicago, USA
S. Biedron
UNM-ME, Albuquerque, New Mexico, USA
M. Burger, J. Murphy
NERS-UM, Ann Arbor, Michigan, USA
K.M. Krushelnick, J. Nees, A.G.R. Thomas
University of Michigan, Ann Arbor, Michigan, USA
Y. Ma
IHEP, Beijing, People’s Republic of China
Y. Ma
Michigan University, Ann Arbor, Michigan, USA

Funding: Acknowledgements: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under award number DE-SC0019468.
The applications of machine learning in today’s world encompass all fields of life and physical sciences. In this paper, we implement a machine learning based algorithm in the context of laser physics and particle accelerators. Specifically, a neural network-based optimisation algorithm has been developed that offers enhanced control over an ultrafast femtosecond laser in comparison to the traditional Proportional Integral and derivative (PID) controls. This research opens a new potential of utilising machine learning and even deep learning techniques to improve the performance of several different lasers and accelerators systems.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB349

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paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 17 August 2021

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THPAB351

INFN-LASA Experimental Activities on PIP-II Low-Beta Cavity Prototypes

4481

M. Bertucci, A. Bosotti, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, C. Pagani, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
A. Gresele, A. Torri
Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
M. Rizzi
Ettore Zanon S.p.A., Schio, Italy

This paper reports on the first results obtained by INFN-LASA on PIP-II low-beta cavity prototypes. The goal of this activity was to validate the reference surface treatment based on Electropolishing as a bulk removal step. The cavity treatment procedures are here presented together with the strategy used for their optimization. The experimental results of cavity cold tests for a single cell prototype are presented and discussed. Having this cavity achieved the requested performance, the baseline procedure is considered as validated and a plan for a future high-Q cavity surface treatment is proposed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB351

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paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 29 August 2021

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THPAB352

Computer Vision Techniques Used to Monitor the Alignment of Cavities and Solenoids in the PIP-II Prototype SSR1 Cryomodule

4485

S. Zorzetti, J. Bernardinipresenter, D. Passarelli
Fermilab, Batavia, Illinois, USA

The alignment of the SRF PIP-II string components is studied as the acceptable beam deflection, offset and defocusing, which may otherwise cause beam loss. Simulations and measurements established that the maximum deviation of the beam pipe from the reference orbit should not exceed a small fraction of the beam aperture. To observe the translations and rotations of each single component within the cryomodule, optical instruments (H-BCAM) surveying highly reflective targets, installed in the internal assembly of the module were used. The alignment monitoring concept for the PIP II SSR1 prototype cryomodule, along with relevant measurements of the components’ position monitoring during coldmass cooldown is presented in this contribution. This development paves the way to new computer vision applications in the field of cryomodule assemblies in cleanroom environment, in which robotically-assisted operations have the potential to dramatically reduce the risk of chemical and particulate contamination.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB352

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paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 31 August 2021

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THPAB354

Deployment and Commissioning of the CERN PS Injection Kicker System for Operation with 2 GeV Beams in Short Circuit Mode

4489

T. Kramer, N. Ayala, J.C.C.M. Borburgh, P.A.H. Burkel, E. Carlier, L. Ducimetière, L.M.C. Feliciano, A. Ferrero Colomo, M.A. Fraser, L.A. Govertsen, R. Noulibos, S. Pavis, L. Sermeus
CERN, Geneva, Switzerland

Within the framework of the LHC Injector Upgrade (LIU) project, the feasibility and design of an upgrade of the existing CERN PS proton injection kicker system have been outlined in previous publications already. This paper describes the adjustments of final design choices, testing, and deployment as well as the validation and commissioning of the new 2 GeV injection kicker system. The upgrade pays particular attention to the reduction of pulse reflections unavoidably induced by a magnet in short circuit mode configuration whilst keeping a fast 10⁴ ns rise and fall time. An adapted thyratron triggering system to reduce jitter and enhance thyratron lifetime is outlined. Additionally, improvements to the magnet entry box and the elimination of SF6 gas in the magnet connection box and the associated pulse transmission lines are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB354

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 10 August 2021

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THPAB356

Progress and Status on Civil Construction of the SIS100 Accelerator Building

4493

M. Draisbach, N. Pyka, P.J. Spiller
GSI, Darmstadt, Germany
J. Blaurock, M. Ossendorf
FAIR, Darmstadt, Germany

Besides the accelerator machine itself, civil construction of the accelerator ring tunnel building in the northern area of the FAIR campus is a core activity of the rapidly progressing FAIR project. It will facilitate and supply the future SIS100 accelerator at 17m underground level and has been growing continuously and according to schedule since groundbreaking in 2017. This contribution presents the current status of the civil construction progress and gives an optimistic forecast for the preparation of machine installation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB356

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paper received ※ 20 May 2021 paper accepted ※ 06 July 2021 issue date ※ 15 August 2021

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THPAB359

Simulations of the Stage 2 FFA Injection Line of LhARA for Evaluating Beam Transport Performance

4495

W. Shields
JAI, Egham, Surrey, United Kingdom
A. Kurup, H.T. Lau, K.R. Long, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

A new, novel facility for radiobiological research, the Laser-hybrid Accelerator for Radiobiological Applications (LhARA), has recently been proposed. LhARA will be a two-stage facility with the first stage employing laser-target acceleration to produce intense proton bunches of energies up to 15 MeV. The second stage will accelerate the beam in an FFA ring up to 127 MeV. Optimal performance of stage 2, however, will require an emittance reduction of the stage 1 beam due to the FFA’s nominal dynamical acceptance. Here, we demonstrate a new optical configuration of LhARA’s stage 1 lattice that will provide this reduced emittance. The profile of the laser-target generated beam is far from an ideal Gaussian, therefore two start-to-end Monte Carlo particle tracking codes have been used to model beam transport performance from the laser-target source through to the end of the stage 2 FFA injection line. The Geant4-based Beam Delivery Simulation (BDSIM) was used to model beam losses and the collimation that is crucial to LhARA’s energy selection system, and General Particle Tracer (GPT) was used to model the space-charge effects that may impact performance given the emittance reduction.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB359

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paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 18 August 2021

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THPAB364

Mu*STAR: A System to Consume Spent Nuclear Fuel While Economically Generating Nuclear Power

4499

R.P. Johnson, R.J. Abrams, M.A. Cummingspresenter, S.A. Kahn, J.D. Lobo, T.J. Roberts
Muons, Inc, Illinois, USA

Mu*STAR is a superconducting-accelerator driven, subcritical, molten-salt reactor designed to consume the spent nuclear fuel (SNF) from today’s commercial fleet of light water reactors. In the process of doing so it will: 1. generate electricity in a cost-competitive manner, 2. significantly reduce the waste-stream volume per Gigawatt-hour generated, 3. greatly reduce the radio-toxic lifetime of the waste stream. As many states and countries now prohibit licensing of new nuclear plants until a national strategy has been established for the long-term disposal of their nuclear waste, Mu*STAR can be an important enabler for new nuclear facilities. This is especially important in the light of climate change, as nuclear energy is the only carbon-free technology for a base-load generation that is readily expandable.

Poster THPAB364 [0.497 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB364

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paper received ※ 20 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

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THPAB369

Research and Design of an X-Band 100-MeV Compact Electron Accelerator for Very High Energy Electron Therapy in Tsinghua University

4502

X. Lin, H.B. Chen, J. Shi, C.-X. Tang, H. Zha, L.Y. Zhou
TUB, Beijing, People’s Republic of China

A 100-MeV Compact Electron Accelerator scheme based on the Tsinghua X-band (11.424 GHz) High Power Test stand (TPot-X) was proposed for Very High Energy Electron (VHEE) radiotherapy. A pulse compressor with correction cavity chain was designed to compress the 50 MW, 1500 ns microwave pulse from the X-band klystron to 120 MW, 300 ns. The acceleration system consists of 3 parts, a buncher which bunches and boosts the electron from a thermionic cathode gun to 8 MeV, and two accelerating structure which further boost the electron energy to 100MeV. The detailed design and consideration are presented in this article.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB369

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 14 August 2021

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THPAB372

SABINA: A Research Infrastructure at LNF

4505

L. Sabbatini, D. Alesini, M.P. Anania, M. Bellaveglia, A. Biagioni, B. Buonomo, S. Cantarella, F. Cardelli, E. Chiadroni, G. Costa, G. Di Pirro, F. Dipace, A. Esposito, M. Ferrario, M. Galletti, A. Gallo, A. Ghigo, L. Giannessi, A. Giribono, S. Incremona, L. Pellegrino, L. Piersanti, R. Pompili, R. Ricci, J. Scifo, A. Stecchi, A. Stella, C. Vaccarezza, A. Vannozzi, S. Vescovi, F. Villa
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
A. Cianchi
INFN-Roma II, Roma, Italy
A. Doria, A. Petralia
ENEA C.R. Frascati, Frascati (Roma), Italy
L. Giannessi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
S. Lupi
Sapienza University of Rome, Roma, Italy
S. Macis
La Sapienza University of Rome, Rome, Italy
V. Petrillo
Universita’ degli Studi di Milano, Milano, Italy
V. Petrillo
INFN-Milano, Milano, Italy

Funding: SABINA is a project co-funded by Regione Lazio within POR-FESR 2014-2020 program.
SABINA (Source of Advanced Beam Imaging for Novel Applications) is a project aimed at the enhancement of the SPARC_LAB research facility. This enhancement is carried out through the following actions: first, the increase of the uptime through the consolidation of technological systems and the replacement of some critical equipment in order to limit the number and extent of faults; then, the improvement of the accelerator performances, by replacing some devices with updated ones. The effect will be greater reliability of the accelerator, which will allow it to be opened as a facility for external users, both industrial and scientific, with the goal of increasing the competitiveness of industries in a broad range of technological areas and enhancing collaborations with research institutions. The two user lines that will be implemented are a power laser target area and a THz radiation line, by using a dedicated undulator. The undulator and the THz line are also described in other contributions to this conference. A brief description of the project and potential exploitations are reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB372

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paper received ※ 24 May 2021 paper accepted ※ 01 July 2021 issue date ※ 20 August 2021

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