IPAC2022 - List of Keywords (polarization)

Paper	Title	Other Keywords	Page
MOPOST008	Simulations of Protons to Extraction at Gγ=7.5 in the AGS Booster	resonance, proton, dipole, booster	62
	K. Hock, H. Huang, F. Méot BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. To prepare for polarized helion collisions at the Electron Ion Collider (EIC), polarization transmission at the injectors for the Hadron Storage Ring must be studied and optimized. To this effect, an AC dipole has been installed in the AGS Booster to maximize polarization transmission of helions through several intrinsic resonances. This installation also allows polarized protons to be extracted at higher energy without polarization loss. By increasing the proton extraction energy from $Gγ$ = 4.5 to $Gγ$ = 7.5, protons will cross the $Gγ$ = 0 + ν_y$ and $Gγ = 12 - ν_y$ depolarizing vertical intrinsic resonances, the $Gγ$ = 5, 6, and 7 imperfection resonances in addition to the $Gγ$ = 3, 4 that are crossed in the present configuration, and be injected into the AGS at a higher rigidity. By simulation, it is determined that there is sufficient strength of the AC dipole to fully flip the spin spin through each of the intrinsic resonances, and there is sufficient corrector current to preserve polarization through the three additional imperfection resonances. The higher injection rigidity facilitates the horizontal and vertical tunes being placed inside the AGS spin-tune gap at injection due to a substantial improvement on the AGS admittance at injection.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST008
About •	Received ※ 06 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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MOPOPT025	Development of an Electro-Optical Longitudinal Bunch Profile Monitor at KARA Towards a Beam Diagnostics Tool for FCC-ee	laser, electron, operation, collider	296
	M. Reißig, M. Brosi, E. Bründermann, S. Funkner, B. Härer, A.-S. Müller, G. Niehues, M.M. Patil, R. Ruprecht, C. Widmann KIT, Karlsruhe, Germany
	Funding: The Future Circular Collider Innovation Study (FCCIS) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 951754. M. R. and M. M. P. acknowledge the support by the Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology". C. W. achnowledges funding by BMBF contract number 05K19VKD. The Karlsruhe Research Accelerator (KARA) at KIT features an electro-optical (EO) near-field diagnostics setup to conduct turn-by-turn longitudinal bunch profile measurements in the storage ring using electro-optical spectral decoding (EOSD). Within the Future Circular Collider Innovation Study (FCCIS) an EO monitor using the same technique is being conceived to measure the longitudinal profile and center-of-charge of the bunches in the future electron-positron collider FCC-ee. This contribution provides an overview of the EO near-field diagnostics at KARA and discusses the development and its challenges towards an effective beam diagnostics concept for the FCC-ee.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT025
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022
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MOPOTK027	Characterization of Various GaN Samples for Photoinjectors	cathode, electron, ECR, brightness	500
	M.B. Andorf, I.V. Bazarov, S.J. Levenson, J.M. Maxson Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J. Encomendero, D. Jena, V.V. Protasenko, H.G. Xing Cornell University, Ithaca, New York, USA
	Funding: DOE-HEP DESC0021002 DOE-NP DE-SC0021425 Photoemission properties (quantum efficiency, spectral response, and lifetime) of various GaN based photocathodes are summarized, including p-doped samples in its hexagonal phase, cubic GaN and a more exotic 2-D hole gas sample. The 2-D hole contains no dopant impurity but achieves high conductivity via polarization fields produced at the heterojunction of GaN and AlN. For efficient electron production, cesium is used to achieve Negative Electron Affinity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK027
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 26 June 2022
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MOPOMS004	Optimizing Activation Recipe with Cs, Te, O for GaAs-Based Photocathodes	cathode, electron, site, vacuum	628
	J. Bae, M.B. Andorf, I.V. Bazarov, A. Galdi, J.M. Maxson Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA L. Cultrera BNL, Upton, New York, USA
	Funding: Department of Energy (DOE) DE-SC0021039. GaAs-based photocathodes are the most popular electron sources for producing highly spin-polarized electron beams in accelerator physics and condensed matter physics. Spin-polarized photoemission requires activation to achieve Negative Electron Affinity (NEA). Conventional NEA surfaces such as CS-O/NF3 are extremely vacuum sensitive, and this results in rapid QE degradation. In this work, we activated GaAs with various recipes using Cs, Te, and oxygen. We demonstrate NEA activation on GaAs surfaces. Among Cs-Te activated samples, the oxidized sample showed the highest QE and longest lifetime at 780 nm.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS004
About •	Received ※ 04 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 24 June 2022
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TUPOPT014	The Status of the SASE3 Variable Polarization Project at the European XFEL	undulator, FEL, vacuum, radiation	1029
	S. Karabekyan, S. Abeghyan, M. Bagha-Shanjani, S. Casalbuoni, U. Englisch, W. Freund, G. Geloni, J. Grünert, S. Hauf, C. Holz, D. La Civita, J. Laksman, D. Mamchyk, M.P. Planas, F. Preisskorn, S. Serkez, H. Sinn, M. Wuenschel, M. Yakopov, C. Youngman EuXFEL, Schenefeld, Germany P. Altmann, A. Block, W. Decking, L. Fröhlich, O. Hensler, T. Ladwig, D. Lenz, D. Lipka, R. Mattusch, N. Mildner, E. Negodin, J. Prenting, F. Saretzki, M. Schlösser, F. Schmidt-Föhre, E. Schneidmiller, M. Scholz, D. Thoden, T. Wamsat, T. Wilksen, T. Wohlenberg, M.V. Yurkov DESY, Hamburg, Germany J. Bahrdt HZB, Berlin, Germany M. Brügger, M. Calvi, S. Danner, R. Ganter, L. Huber, A. Keller, C. Kittel, X. Liang, S. Reiche, M.S. Schmidt, T. Schmidt, K. Zhang PSI, Villigen PSI, Switzerland D.E. Kim PAL, Pohang, Republic of Korea Y. Li IHEP, People’s Republic of China
	The undulator systems at the European XFEL consist of two hard X-ray systems, SASE1 and SASE2, and one soft X-ray system, SASE3. All three systems are equipped with planar undulators using permanent neodymium magnets. These systems allow the generation of linearly polarized radiation in the horizontal plane. In order to generate variable polarization radiation in the soft X-ray range, an afterburner is currently being implemented behind the SASE3 planar undulator system. It consists of four APPLE-X helical undulators. The project, called SASE 3 Variable Polarization, is close to being put into operation. All four helical undulators have been installed in the tunnel during the 2021-2022 winter shutdown. This paper describes the status of the project and the steps toward its commissioning. It also presents lessons learned during the implementation of the project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT014
About •	Received ※ 02 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 05 July 2022
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TUPOPT050	Investigation of Polarization Dependent Thomson Scattering in an Energy-Recovering Linear Accelerator on the Example of Mesa	electron, scattering, photon, HOM	1114
	C.L. Lorey, A. Meseck KPH, Mainz, Germany
	Funding: GRK 2128 AccelencE funded by the DFG At the Johannes Gutenberg University (JGU) in Mainz, a new accelerator is currently under construction in order to deliver electron beams of up to 155 MeV to two experiments. The Mainz Energy-recovering Superconducting Accelerator (MESA) will offer two modes of operation, one of which is an energy-recovering (ER) mode. As an ERL, MESA, with it’s high brightness electron beam, is a promising accelerator for supplying a Thomson back scattering based Gamma source. Furthermore, at MESA, the polarization of the electron beam can be set by the injector. The aim of this work is to provide a concept and comprehensive analysis of the merit and practical feasibility of a Thomson backscattering source at MESA under consideration of beam polarization and transversal effects. In this paper, an overview and results of our semi analytical approach to calculate various Thomson back scattering light source scenarios at MESA will be given. Furthermore we will discuss the benefits of using polarized electrons in combination with a polarized laser beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT050
About •	Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 26 June 2022
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WEIXGD1	EIC Beam Dynamics Challenges	electron, hadron, luminosity, cavity	1576
	D. Xu, E.C. Aschenauer, G. Bassi, J. Beebe-Wang, J.S. Berg, W.F. Bergan, M. Blaskiewicz, J.M. Brennan, S.J. Brooks, K.A. Brown, Z.A. Conway, K.A. Drees, A.V. Fedotov, W. Fischer, C. Folz, D.M. Gassner, X. Gu, R.C. Gupta, Y. Hao, C. Hetzel, D. Holmes, H. Huang, J. Kewisch, Y. Li, C. Liu, H. Lovelace III, G.J. Mahler, D. Marx, F. Méot, M.G. Minty, C. Montag, S.K. Nayak, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, M.P. Sangroula, S. Seletskiy, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, N. Tsoupas, J.E. Tuozzolo, E. Wang, D. Weiss, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman BNL, Upton, New York, USA S.V. Benson, B.R. Gamage, J.M. Grames, T.J. Michalski, E.A. Nissen, J.P. Preble, R.A. Rimmer, T. Satogata, A. Seryi, M. Wiseman, W. Wittmer JLab, Newport News, Virginia, USA A. Blednykh, Y. Luo, B. Podobedov, S. Verdú-Andrés Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA Y. Cai, Y.M. Nosochkov, G. Stupakov, M.K. Sullivan SLAC, Menlo Park, California, USA E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA G.H. Hoffstaetter, D. Sagan, J.E. Unger Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA V.S. Morozov ORNL RAD, Oak Ridge, Tennessee, USA J. Qiang LBNL, Berkeley, California, USA
	The Electron Ion Collider aims to produce luminosities of 10³⁴ cm^-2s^-1 . The machine will operate over a broad range of collision energies with highly polarized beams. The coexistence of highly radiative electrons and nonradiative ions produce a host of unique effects. Strong hadron cooling will be employed for the final factor of 3 luminosity boost.
	Slides WEIXGD1 [3.952 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEIXGD1
About •	Received ※ 06 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 14 June 2022
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WEPOST007	Centre-of-Mass Energy in FCC-ee	collider, radiation, cavity, simulation	1683
	J. Keintzel, R. Tomás García, F. Zimmermann CERN, Meyrin, Switzerland A.P. Blondel DPNC, Genève, Switzerland D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	The Future Circular electron-positron Collider (FCC-ee) is designed for high precision particle physics experiments. This demands a precise knowledge of the beam energies, obtained by resonant depolarization, and from which the center-of-mass energy and possible boosts at all interaction points are then determined. At the highest beam energy mode of 182.5 GeV, the energy loss due to synchrotron radiation is about 10 GeV per revolution. Hence, not only the location of the RF cavities, but also a precise control of the optics and understanding of beam dynamics, are crucial. In the studies presented here, different possible locations of the RF-cavities are considered, when calculating the beam energies over the machine circumference, including energy losses from crossing angles, a non-homogeneous dipole distribution, and an estimate of the beamstrahlung effect at the collision point.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST007
About •	Received ※ 08 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 27 June 2022
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WEPOST020	EIC Hadron Spin Rotators	proton, electron, storage-ring, hadron	1734
	V. Ptitsyn, J.S. Berg BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The Electron-Ion Collider in BNL will collide polarized electrons with polarized protons or polarized 3He ions. Spin rotators will be used to create the longitudinal beam polarization at a location of the EIC experimental detector. Helical spin rotators utilized for polarized proton operation in present RHIC will be reused in the EIC Hadron Storage Ring. However, due to a significant difference of EIC and RHIC interaction region layouts, the EIC spin rotator arrangement has several challenges. Turning on the EIC spin rotators may lead to a significant spin tune shift. To prevent beam depolarization during the spin rotator turn-on, Siberian Snakes have to be tuned simultaneously with rotators. The EIC spin rotators must be able to operate in a wide energy range for polarized protons and polarized 3He ions. The paper presents the challenges of spin rotator usage in the EIC and remedies assuring the successful operation with the rotators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST020
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022
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WEPOST031	RHIC Polarized Proton Operation in Run 22	operation, proton, luminosity, dipole	1765
	V. Schoefer, E.C. Aschenauer, D. Bruno, K.A. Drees, W. Fischer, C.J. Gardner, K. Hock, H. Huang, R.L. Hulsart, C. Liu, Y. Luo, I. Marneris, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, J. Morris, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, J. Sandberg, W.B. Schmidke, F. Severino, T.C. Shrey, P. Thieberger, J.E. Tuozzolo, M. Valette, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno BNL, Upton, New York, USA
	The Relativistic Heavy Ion Collider (RHIC) Run 22 physics program consisted of collisions with vertically po- larized proton beams at a single collision point (the STAR detector). During initial startup of the collider, power out- ages damaged two of the coils in one of the RHIC helical dipole snake magnets used for polarization preservation in the Blue ring. That snake was reconfigured for use as a partial snake. We will outline some of the remediating mea- sures taken to maximize polarization transmission in this configuration. These measures included changing the col- liding beam energy from 255 GeV to 254.2 GeV to adjust the spin closed orbit at store and adjustment of the field in the other helical dipole in the Blue ring to improve injection spin matching. Later in the run, the primary motor gener- ator for the AGS (the injector to RHIC) failed and a lower voltage backup had to be used, resulting in a period of lower polarization. Other efforts include detailed measurement of the stable spin direction at store and the commissioning of a machine protection relay system to prevent spurious firing of the RHIC abort kickers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST031
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 04 July 2022
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WEPOPT006	Investigation of Spin-Decoherence in the NICA Storage Ring for the Future EDM-Measurement Experiment	experiment, storage-ring, dipole, GUI	1835
	A.E. Aksentyev, A.A. Melnikov, Y. Senichev RAS/INR, Moscow, Russia A.E. Aksentyev MEPhI, Moscow, Russia V. Ladygin, E. Syresin JINR, Dubna, Moscow Region, Russia
	Funding: We acknowledge support by the joint Deutsche ForschungsGemeinschaft (DFG) and Russian Science Foundation (RSF) grant 22-42-04419 A new experiment to measure electric dipole moments (EDMs) of elementary particles, based on the Frequency Domain method, has been proposed for implementation at the NICA facility (JINR, Russia). EDM experiments in general, being measurement-of-polarization experiments, require long spin-coherence times at around 1,000 seconds. The FD method involves a further complication (well paid off in orders of precision) of switching the polarity of the guiding field as part of its CW-CCW injection procedure. This latter procedure necessitates a calibration process, during which the beam polarization axis changes its orientation from the radial (used for the measurement) to the vertical (used for the calibration) direction. If this change occurs adiabatically, the beam particles’ spin-vectors follow the direction of the polarization axis, which undermines the calibration technique; however, concerns were raised as to whether violation of adiabaticity could damage spin-coherence.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT006
About •	Received ※ 16 May 2022 — Accepted ※ 15 June 2022 — Issue date ※ 22 June 2022
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WEPOPT019	RHIC Blue Snake Blues	closed-orbit, operation, optics, simulation	1881
	F. Méot, E.C. Aschenauer, H. Huang, A. Marusic, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, V. Schoefer BNL, Upton, New York, USA
	Funding: Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Two helical full snakes are used in both Blue and Yellow rings of RHIC collider, in order to preserve beam polarization during acceleration to collision energy and polarization lifetime at store. A snake in RHIC is comprised of four 2.4m long modules, powered by pair. During the startup of RHIC Run 22 in December 2021, two successive power dips have caused the 9 o’clock RHIC BlBrookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.ue ring snake to loose two of its four modules. In spite of this regrettable loss, it has been possible to maintain near 180deg snake precession, by proper powering of the remaining two modules, as well as, by re-tuning the 3 o’clock sister snake, vertical spin precession axis around the ring and spin tune 1/2. Determining these new settings, in order to salvage polarization with the handicapped Blue snake pair, has required series of numerical simulations, a brief overview is given here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT019
About •	Received ※ 03 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 07 July 2022
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WEPOPT026	Possibilities for Upgrading to Polarized a SuperKEKB	electron, experiment, lattice, cathode	1901
	Z.J. Liptak HU/AdSM, Higashi-Hiroshima, Japan
	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 presentation lays out the goals and motivations of polarizing the electron beam, considers the necessary changes to the existing accelerator and their feasibility and reports progress in investigations to this point.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT026
About •	Received ※ 12 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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WEPOTK040	Spin-Tracking Simulations in a COSY Model Using Bmad	simulation, resonance, dipole, experiment	2158
	M. Vitz FZJ, Jülich, Germany
	The matter-antimatter asymmetry might be understood by investigating the EDM (Electric Dipole Moment) of elementary charged particles. A permanent EDM of a subatomic particle violates time reversal and parity symmetry at the same time and would be, with the currently achievable experimental accuracy, an indication for further CP violation than established in the Standard Model. The JEDI-Collaboration (Jülich Electric Dipole moment Investigations) in Jülich has performed a direct EDM measurement for deuterons with the so called precurser experiments at the storage ring COSY (COoler SYnchrotron). In order to understand the measured data and to disentangle an EDM signal from systematic effects, spin tracking simulations in an accurate simulation model of COSY are needed. Therefore a model of COSY was implemented using the software library Bmad. Systematic effects were considered by including element misalignments, effective dipole shortening and steerer kicks. These effects rotate the invariant spin axis additional to the EDM and have to be analyzed and understood. The most recent spin tracking results as well as the methods to find the invariant spin axis will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK040
About •	Received ※ 02 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 05 July 2022
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WEPOMS051	Spin Matching for the EIC’s Electrons	emittance, electron, lattice, storage-ring	2369
	M.G. Signorelli Cornell University, Ithaca, New York, USA J.A. Crittenden, G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J. Kewisch BNL, Upton, New York, USA
	The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will provide spin-polarized collisions of electron and protons or light ion beams. In order to maximize the electron polarization and require less frequent beam re-injections to restore the polarization level, the stochastic depolarizing effects of synchrotron radiation must be minimized via spin matching. In this study, Bmad was used to perform first order spin matching in the Electron Storage Ring (ESR) of the EIC. Spin matches were obtained for the rotator systems and for a vertical chicane, inserted as a vertical emittance creator. Monte Carlo spin tracking with radiation was then performed to analyze the effects of the spin matching on the polarization.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS051
About •	Received ※ 31 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 05 July 2022
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WEPOMS056	Spin Matching and Monte-Carlo Simulation of Radiative Spin Depolarization in e⁺e⁻ Storage Rings with Bmad	resonance, storage-ring, electron, lattice	2383
	O. Beznosov, J.A. Ellison, K.A. Heinemann UNM-MATH, Albuquerque, New Mexico, USA D.P. Barber DESY, Hamburg, Germany J.A. Crittenden, G.H. Hoffstaetter, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award Numbers DE-SC0018008 and DE-SC0018370. The Bmad/Tao software toolkit has been extended to estimate the rate of radiative spin depolarization in e⁺/e⁻ storage rings. First estimates are made using the SLIM algorithm of linearized spin-orbit motion. The extension implements the effects on s-o motion of stochastic photon emission using a Monte-Carlo tracking algorithm. Spins are tracked in 3-D along particle trajectories with the aid of Taylor expansions of quaternions provided by PTC. The efficiency of long-term tracking is guarantied by the use of a sectioning technique that was exploited in previous-generation software. Sectioning is the construction of the deterministic s-o maps for sections between the dipoles during the initialization phase. Maps can be reused during the tracking. In a simulation for a realistic storage ring, the computational cost of initial map construction is amortized by the multi-turn tracking computational cost. The use of 1st-order terms in the quaternion expansions to construct the s-o coupling matrices in the matrices of the SLIM algorithm. These matrices are then available for an extension of the optimization facilities in Bmad to minimize depolarizing effects by spin matching. SLICKTRACK and SITROS ** Polymorphic Tracking Code by Etienne Forest
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS056
About •	Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 08 July 2022
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THPOST004	EIC’s Rapid Cycling Synchrotron Spin Tracking Update	emittance, lattice, resonance, electron	2439
	V.H. Ranjbar, H. Lovelace III, F. Méot BNL, Upton, New York, USA F. Lin ORNL RAD, Oak Ridge, Tennessee, 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) to be built will collide polarized electrons and ions up to 140 GeV center of mass with a time averaged polarization of 70% and luminosity up to 10³⁴ cm^-2 s^-1. The EIC’s Rapid Cycling Synchrotron (RCS) will accelerate 2 polarized electrons bunches from 400 MeV to energies of 5, 10 and 18 GeV and inject them into the EIC’s Electron Storage Ring. The design of the RCS has progressed to accommodate a larger magnet free section for the detectors and to meet the space requirements of the RHIC tunnel. We present progress on full 6D spin tracking studies of the RCS with the updated lattice using the Zgoubi code to include magnet misalignments, field errors and corrections as well as radiative effects.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST004
About •	Received ※ 07 June 2022 — Revised ※ 22 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 29 June 2022
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THPOPT052	The Status of the In-Vacuum-APPLE II Undulator IVUE32 at HZB / BESSY II	undulator, vacuum, shielding, photon	2716
	J. Bahrdt, J. Bakos, S. Gaebel, S. Gottschlich, S. Grimmer, S. Knaack, C. Kuhn, F. Laube, A. Meseck, C. Rethfeldt, E.C.M. Rial, A. Rogosch-Opolka, M. Scheer, P.I. Volz HZB, Berlin, Germany
	At BESSY II, two new beamlines for RIXS and for X-Ray-microscopy demand a short period variably polarizing undulator. For this purpose, the first in-vacuum APPLE undulator worldwide is under construction. The parameters are as follows: period length=32mm, magnetic length=2500mm, minimum gap=7mm. The design incorporates a force compensation scheme as proposed by two of the authors at the SRI2018. All precision parts of the drive chain are located in air. New transverse slides for the transversal slit adjustment have been developed and tested. Optical micrometers measure the gap and shift positions, similar to the system of the CPMU17 at BESSY II. They provide the signals for motor feedback loops. A new UHV-compatible soldering technique, as developed with industry, relaxes fabrication tolerances of magnets and magnet holders and simplifies the magnet assembly. A 10-period prototype has been setup for lifetime tests of the new magnetic keeper design. The paper describes first results of the prototype and other key-components and summarizes the status of the full-scale undulator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT052
About •	Received ※ 19 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 22 June 2022
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Paper

Title

Other Keywords

Page

MOPOST008

Simulations of Protons to Extraction at Gγ=7.5 in the AGS Booster

resonance, proton, dipole, booster

62

K. Hock, H. Huang, F. Méot
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
To prepare for polarized helion collisions at the Electron Ion Collider (EIC), polarization transmission at the injectors for the Hadron Storage Ring must be studied and optimized. To this effect, an AC dipole has been installed in the AGS Booster to maximize polarization transmission of helions through several intrinsic resonances. This installation also allows polarized protons to be extracted at higher energy without polarization loss. By increasing the proton extraction energy from $Gγ$ = 4.5 to $Gγ$ = 7.5, protons will cross the $Gγ$ = 0 + ν_y$ and $Gγ = 12 - ν_y$ depolarizing vertical intrinsic resonances, the $Gγ$ = 5, 6, and 7 imperfection resonances in addition to the $Gγ$ = 3, 4 that are crossed in the present configuration, and be injected into the AGS at a higher rigidity. By simulation, it is determined that there is sufficient strength of the AC dipole to fully flip the spin spin through each of the intrinsic resonances, and there is sufficient corrector current to preserve polarization through the three additional imperfection resonances. The higher injection rigidity facilitates the horizontal and vertical tunes being placed inside the AGS spin-tune gap at injection due to a substantial improvement on the AGS admittance at injection.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST008

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Received ※ 06 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022

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MOPOPT025

Development of an Electro-Optical Longitudinal Bunch Profile Monitor at KARA Towards a Beam Diagnostics Tool for FCC-ee

laser, electron, operation, collider

296

M. Reißig, M. Brosi, E. Bründermann, S. Funkner, B. Härer, A.-S. Müller, G. Niehues, M.M. Patil, R. Ruprecht, C. Widmann
KIT, Karlsruhe, Germany

Funding: The Future Circular Collider Innovation Study (FCCIS) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 951754. M. R. and M. M. P. acknowledge the support by the Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology". C. W. achnowledges funding by BMBF contract number 05K19VKD.
The Karlsruhe Research Accelerator (KARA) at KIT features an electro-optical (EO) near-field diagnostics setup to conduct turn-by-turn longitudinal bunch profile measurements in the storage ring using electro-optical spectral decoding (EOSD). Within the Future Circular Collider Innovation Study (FCCIS) an EO monitor using the same technique is being conceived to measure the longitudinal profile and center-of-charge of the bunches in the future electron-positron collider FCC-ee. This contribution provides an overview of the EO near-field diagnostics at KARA and discusses the development and its challenges towards an effective beam diagnostics concept for the FCC-ee.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT025

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Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022

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MOPOTK027

Characterization of Various GaN Samples for Photoinjectors

cathode, electron, ECR, brightness

500

M.B. Andorf, I.V. Bazarov, S.J. Levenson, J.M. Maxson
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J. Encomendero, D. Jena, V.V. Protasenko, H.G. Xing
Cornell University, Ithaca, New York, USA

Funding: DOE-HEP DESC0021002 DOE-NP DE-SC0021425
Photoemission properties (quantum efficiency, spectral response, and lifetime) of various GaN based photocathodes are summarized, including p-doped samples in its hexagonal phase, cubic GaN and a more exotic 2-D hole gas sample. The 2-D hole contains no dopant impurity but achieves high conductivity via polarization fields produced at the heterojunction of GaN and AlN. For efficient electron production, cesium is used to achieve Negative Electron Affinity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK027

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 26 June 2022

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MOPOMS004

Optimizing Activation Recipe with Cs, Te, O for GaAs-Based Photocathodes

cathode, electron, site, vacuum

628

J. Bae, M.B. Andorf, I.V. Bazarov, A. Galdi, J.M. Maxson
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
L. Cultrera
BNL, Upton, New York, USA

Funding: Department of Energy (DOE) DE-SC0021039.
GaAs-based photocathodes are the most popular electron sources for producing highly spin-polarized electron beams in accelerator physics and condensed matter physics. Spin-polarized photoemission requires activation to achieve Negative Electron Affinity (NEA). Conventional NEA surfaces such as CS-O/NF3 are extremely vacuum sensitive, and this results in rapid QE degradation. In this work, we activated GaAs with various recipes using Cs, Te, and oxygen. We demonstrate NEA activation on GaAs surfaces. Among Cs-Te activated samples, the oxidized sample showed the highest QE and longest lifetime at 780 nm.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS004

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Received ※ 04 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 24 June 2022

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TUPOPT014

The Status of the SASE3 Variable Polarization Project at the European XFEL

undulator, FEL, vacuum, radiation

1029

S. Karabekyan, S. Abeghyan, M. Bagha-Shanjani, S. Casalbuoni, U. Englisch, W. Freund, G. Geloni, J. Grünert, S. Hauf, C. Holz, D. La Civita, J. Laksman, D. Mamchyk, M.P. Planas, F. Preisskorn, S. Serkez, H. Sinn, M. Wuenschel, M. Yakopov, C. Youngman
EuXFEL, Schenefeld, Germany
P. Altmann, A. Block, W. Decking, L. Fröhlich, O. Hensler, T. Ladwig, D. Lenz, D. Lipka, R. Mattusch, N. Mildner, E. Negodin, J. Prenting, F. Saretzki, M. Schlösser, F. Schmidt-Föhre, E. Schneidmiller, M. Scholz, D. Thoden, T. Wamsat, T. Wilksen, T. Wohlenberg, M.V. Yurkov
DESY, Hamburg, Germany
J. Bahrdt
HZB, Berlin, Germany
M. Brügger, M. Calvi, S. Danner, R. Ganter, L. Huber, A. Keller, C. Kittel, X. Liang, S. Reiche, M.S. Schmidt, T. Schmidt, K. Zhang
PSI, Villigen PSI, Switzerland
D.E. Kim
PAL, Pohang, Republic of Korea
Y. Li
IHEP, People’s Republic of China

The undulator systems at the European XFEL consist of two hard X-ray systems, SASE1 and SASE2, and one soft X-ray system, SASE3. All three systems are equipped with planar undulators using permanent neodymium magnets. These systems allow the generation of linearly polarized radiation in the horizontal plane. In order to generate variable polarization radiation in the soft X-ray range, an afterburner is currently being implemented behind the SASE3 planar undulator system. It consists of four APPLE-X helical undulators. The project, called SASE 3 Variable Polarization, is close to being put into operation. All four helical undulators have been installed in the tunnel during the 2021-2022 winter shutdown. This paper describes the status of the project and the steps toward its commissioning. It also presents lessons learned during the implementation of the project.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT014

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Received ※ 02 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 05 July 2022

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TUPOPT050

Investigation of Polarization Dependent Thomson Scattering in an Energy-Recovering Linear Accelerator on the Example of Mesa

electron, scattering, photon, HOM

1114

C.L. Lorey, A. Meseck
KPH, Mainz, Germany

Funding: GRK 2128 AccelencE funded by the DFG
At the Johannes Gutenberg University (JGU) in Mainz, a new accelerator is currently under construction in order to deliver electron beams of up to 155 MeV to two experiments. The Mainz Energy-recovering Superconducting Accelerator (MESA) will offer two modes of operation, one of which is an energy-recovering (ER) mode. As an ERL, MESA, with it’s high brightness electron beam, is a promising accelerator for supplying a Thomson back scattering based Gamma source. Furthermore, at MESA, the polarization of the electron beam can be set by the injector. The aim of this work is to provide a concept and comprehensive analysis of the merit and practical feasibility of a Thomson backscattering source at MESA under consideration of beam polarization and transversal effects. In this paper, an overview and results of our semi analytical approach to calculate various Thomson back scattering light source scenarios at MESA will be given. Furthermore we will discuss the benefits of using polarized electrons in combination with a polarized laser beam.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT050

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Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 26 June 2022

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WEIXGD1

EIC Beam Dynamics Challenges

electron, hadron, luminosity, cavity

1576

D. Xu, E.C. Aschenauer, G. Bassi, J. Beebe-Wang, J.S. Berg, W.F. Bergan, M. Blaskiewicz, J.M. Brennan, S.J. Brooks, K.A. Brown, Z.A. Conway, K.A. Drees, A.V. Fedotov, W. Fischer, C. Folz, D.M. Gassner, X. Gu, R.C. Gupta, Y. Hao, C. Hetzel, D. Holmes, H. Huang, J. Kewisch, Y. Li, C. Liu, H. Lovelace III, G.J. Mahler, D. Marx, F. Méot, M.G. Minty, C. Montag, S.K. Nayak, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, M.P. Sangroula, S. Seletskiy, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, N. Tsoupas, J.E. Tuozzolo, E. Wang, D. Weiss, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman
BNL, Upton, New York, USA
S.V. Benson, B.R. Gamage, J.M. Grames, T.J. Michalski, E.A. Nissen, J.P. Preble, R.A. Rimmer, T. Satogata, A. Seryi, M. Wiseman, W. Wittmer
JLab, Newport News, Virginia, USA
A. Blednykh, Y. Luo, B. Podobedov, S. Verdú-Andrés
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
Y. Cai, Y.M. Nosochkov, G. Stupakov, M.K. Sullivan
SLAC, Menlo Park, California, USA
E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
G.H. Hoffstaetter, D. Sagan, J.E. Unger
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V.S. Morozov
ORNL RAD, Oak Ridge, Tennessee, USA
J. Qiang
LBNL, Berkeley, California, USA

The Electron Ion Collider aims to produce luminosities of 10³⁴ cm^-2s^-1 . The machine will operate over a broad range of collision energies with highly polarized beams. The coexistence of highly radiative electrons and nonradiative ions produce a host of unique effects. Strong hadron cooling will be employed for the final factor of 3 luminosity boost.

Slides WEIXGD1 [3.952 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEIXGD1

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Received ※ 06 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 14 June 2022

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WEPOST007

Centre-of-Mass Energy in FCC-ee

collider, radiation, cavity, simulation

1683

J. Keintzel, R. Tomás García, F. Zimmermann
CERN, Meyrin, Switzerland
A.P. Blondel
DPNC, Genève, Switzerland
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

The Future Circular electron-positron Collider (FCC-ee) is designed for high precision particle physics experiments. This demands a precise knowledge of the beam energies, obtained by resonant depolarization, and from which the center-of-mass energy and possible boosts at all interaction points are then determined. At the highest beam energy mode of 182.5 GeV, the energy loss due to synchrotron radiation is about 10 GeV per revolution. Hence, not only the location of the RF cavities, but also a precise control of the optics and understanding of beam dynamics, are crucial. In the studies presented here, different possible locations of the RF-cavities are considered, when calculating the beam energies over the machine circumference, including energy losses from crossing angles, a non-homogeneous dipole distribution, and an estimate of the beamstrahlung effect at the collision point.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST007

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Received ※ 08 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 27 June 2022

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WEPOST020

EIC Hadron Spin Rotators

proton, electron, storage-ring, hadron

1734

V. Ptitsyn, J.S. Berg
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Electron-Ion Collider in BNL will collide polarized electrons with polarized protons or polarized 3He ions. Spin rotators will be used to create the longitudinal beam polarization at a location of the EIC experimental detector. Helical spin rotators utilized for polarized proton operation in present RHIC will be reused in the EIC Hadron Storage Ring. However, due to a significant difference of EIC and RHIC interaction region layouts, the EIC spin rotator arrangement has several challenges. Turning on the EIC spin rotators may lead to a significant spin tune shift. To prevent beam depolarization during the spin rotator turn-on, Siberian Snakes have to be tuned simultaneously with rotators. The EIC spin rotators must be able to operate in a wide energy range for polarized protons and polarized 3He ions. The paper presents the challenges of spin rotator usage in the EIC and remedies assuring the successful operation with the rotators.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST020

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022

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WEPOST031

RHIC Polarized Proton Operation in Run 22

operation, proton, luminosity, dipole

1765

V. Schoefer, E.C. Aschenauer, D. Bruno, K.A. Drees, W. Fischer, C.J. Gardner, K. Hock, H. Huang, R.L. Hulsart, C. Liu, Y. Luo, I. Marneris, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, J. Morris, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, J. Sandberg, W.B. Schmidke, F. Severino, T.C. Shrey, P. Thieberger, J.E. Tuozzolo, M. Valette, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno
BNL, Upton, New York, USA

The Relativistic Heavy Ion Collider (RHIC) Run 22 physics program consisted of collisions with vertically po- larized proton beams at a single collision point (the STAR detector). During initial startup of the collider, power out- ages damaged two of the coils in one of the RHIC helical dipole snake magnets used for polarization preservation in the Blue ring. That snake was reconfigured for use as a partial snake. We will outline some of the remediating mea- sures taken to maximize polarization transmission in this configuration. These measures included changing the col- liding beam energy from 255 GeV to 254.2 GeV to adjust the spin closed orbit at store and adjustment of the field in the other helical dipole in the Blue ring to improve injection spin matching. Later in the run, the primary motor gener- ator for the AGS (the injector to RHIC) failed and a lower voltage backup had to be used, resulting in a period of lower polarization. Other efforts include detailed measurement of the stable spin direction at store and the commissioning of a machine protection relay system to prevent spurious firing of the RHIC abort kickers.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST031

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 04 July 2022

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WEPOPT006

Investigation of Spin-Decoherence in the NICA Storage Ring for the Future EDM-Measurement Experiment

experiment, storage-ring, dipole, GUI

1835

A.E. Aksentyev, A.A. Melnikov, Y. Senichev
RAS/INR, Moscow, Russia
A.E. Aksentyev
MEPhI, Moscow, Russia
V. Ladygin, E. Syresin
JINR, Dubna, Moscow Region, Russia

Funding: We acknowledge support by the joint Deutsche ForschungsGemeinschaft (DFG) and Russian Science Foundation (RSF) grant 22-42-04419
A new experiment to measure electric dipole moments (EDMs) of elementary particles, based on the Frequency Domain method, has been proposed for implementation at the NICA facility (JINR, Russia). EDM experiments in general, being measurement-of-polarization experiments, require long spin-coherence times at around 1,000 seconds. The FD method involves a further complication (well paid off in orders of precision) of switching the polarity of the guiding field as part of its CW-CCW injection procedure. This latter procedure necessitates a calibration process, during which the beam polarization axis changes its orientation from the radial (used for the measurement) to the vertical (used for the calibration) direction. If this change occurs adiabatically, the beam particles’ spin-vectors follow the direction of the polarization axis, which undermines the calibration technique; however, concerns were raised as to whether violation of adiabaticity could damage spin-coherence.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT006

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Received ※ 16 May 2022 — Accepted ※ 15 June 2022 — Issue date ※ 22 June 2022

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WEPOPT019

RHIC Blue Snake Blues

closed-orbit, operation, optics, simulation

1881

F. Méot, E.C. Aschenauer, H. Huang, A. Marusic, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, V. Schoefer
BNL, Upton, New York, USA

Funding: Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Two helical full snakes are used in both Blue and Yellow rings of RHIC collider, in order to preserve beam polarization during acceleration to collision energy and polarization lifetime at store. A snake in RHIC is comprised of four 2.4m long modules, powered by pair. During the startup of RHIC Run 22 in December 2021, two successive power dips have caused the 9 o’clock RHIC BlBrookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.ue ring snake to loose two of its four modules. In spite of this regrettable loss, it has been possible to maintain near 180deg snake precession, by proper powering of the remaining two modules, as well as, by re-tuning the 3 o’clock sister snake, vertical spin precession axis around the ring and spin tune 1/2. Determining these new settings, in order to salvage polarization with the handicapped Blue snake pair, has required series of numerical simulations, a brief overview is given here.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT019

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Received ※ 03 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 07 July 2022

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WEPOPT026

Possibilities for Upgrading to Polarized a SuperKEKB

electron, experiment, lattice, cathode

1901

Z.J. Liptak
HU/AdSM, Higashi-Hiroshima, Japan

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 presentation lays out the goals and motivations of polarizing the electron beam, considers the necessary changes to the existing accelerator and their feasibility and reports progress in investigations to this point.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT026

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Received ※ 12 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022

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WEPOTK040

Spin-Tracking Simulations in a COSY Model Using Bmad

simulation, resonance, dipole, experiment

2158

M. Vitz
FZJ, Jülich, Germany

The matter-antimatter asymmetry might be understood by investigating the EDM (Electric Dipole Moment) of elementary charged particles. A permanent EDM of a subatomic particle violates time reversal and parity symmetry at the same time and would be, with the currently achievable experimental accuracy, an indication for further CP violation than established in the Standard Model. The JEDI-Collaboration (Jülich Electric Dipole moment Investigations) in Jülich has performed a direct EDM measurement for deuterons with the so called precurser experiments at the storage ring COSY (COoler SYnchrotron). In order to understand the measured data and to disentangle an EDM signal from systematic effects, spin tracking simulations in an accurate simulation model of COSY are needed. Therefore a model of COSY was implemented using the software library Bmad. Systematic effects were considered by including element misalignments, effective dipole shortening and steerer kicks. These effects rotate the invariant spin axis additional to the EDM and have to be analyzed and understood. The most recent spin tracking results as well as the methods to find the invariant spin axis will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK040

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Received ※ 02 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 05 July 2022

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WEPOMS051

Spin Matching for the EIC’s Electrons

emittance, electron, lattice, storage-ring

2369

M.G. Signorelli
Cornell University, Ithaca, New York, USA
J.A. Crittenden, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J. Kewisch
BNL, Upton, New York, USA

The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will provide spin-polarized collisions of electron and protons or light ion beams. In order to maximize the electron polarization and require less frequent beam re-injections to restore the polarization level, the stochastic depolarizing effects of synchrotron radiation must be minimized via spin matching. In this study, Bmad was used to perform first order spin matching in the Electron Storage Ring (ESR) of the EIC. Spin matches were obtained for the rotator systems and for a vertical chicane, inserted as a vertical emittance creator. Monte Carlo spin tracking with radiation was then performed to analyze the effects of the spin matching on the polarization.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS051

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Received ※ 31 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 05 July 2022

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WEPOMS056

Spin Matching and Monte-Carlo Simulation of Radiative Spin Depolarization in e⁺e⁻ Storage Rings with Bmad

resonance, storage-ring, electron, lattice

2383

O. Beznosov, J.A. Ellison, K.A. Heinemann
UNM-MATH, Albuquerque, New Mexico, USA
D.P. Barber
DESY, Hamburg, Germany
J.A. Crittenden, G.H. Hoffstaetter, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award Numbers DE-SC0018008 and DE-SC0018370.
The Bmad/Tao software toolkit has been extended to estimate the rate of radiative spin depolarization in e⁺/e⁻ storage rings. First estimates are made using the SLIM algorithm of linearized spin-orbit motion. The extension implements the effects on s-o motion of stochastic photon emission using a Monte-Carlo tracking algorithm. Spins are tracked in 3-D along particle trajectories with the aid of Taylor expansions of quaternions provided by PTC*. The efficiency of long-term tracking is guarantied by the use of a sectioning technique that was exploited in previous-generation software**. Sectioning is the construction of the deterministic s-o maps for sections between the dipoles during the initialization phase. Maps can be reused during the tracking. In a simulation for a realistic storage ring, the computational cost of initial map construction is amortized by the multi-turn tracking computational cost. The use of 1st-order terms in the quaternion expansions to construct the s-o coupling matrices in the matrices of the SLIM algorithm. These matrices are then available for an extension of the optimization facilities in Bmad to minimize depolarizing effects by spin matching.
*SLICKTRACK and SITROS
** Polymorphic Tracking Code by Etienne Forest

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS056

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Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 08 July 2022

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THPOST004

EIC’s Rapid Cycling Synchrotron Spin Tracking Update

emittance, lattice, resonance, electron

2439

V.H. Ranjbar, H. Lovelace III, F. Méot
BNL, Upton, New York, USA
F. Lin
ORNL RAD, Oak Ridge, Tennessee, 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) to be built will collide polarized electrons and ions up to 140 GeV center of mass with a time averaged polarization of 70% and luminosity up to 10³⁴ cm^-2 s^-1. The EIC’s Rapid Cycling Synchrotron (RCS) will accelerate 2 polarized electrons bunches from 400 MeV to energies of 5, 10 and 18 GeV and inject them into the EIC’s Electron Storage Ring. The design of the RCS has progressed to accommodate a larger magnet free section for the detectors and to meet the space requirements of the RHIC tunnel. We present progress on full 6D spin tracking studies of the RCS with the updated lattice using the Zgoubi code to include magnet misalignments, field errors and corrections as well as radiative effects.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST004

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Received ※ 07 June 2022 — Revised ※ 22 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 29 June 2022

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THPOPT052

The Status of the In-Vacuum-APPLE II Undulator IVUE32 at HZB / BESSY II

undulator, vacuum, shielding, photon

2716

J. Bahrdt, J. Bakos, S. Gaebel, S. Gottschlich, S. Grimmer, S. Knaack, C. Kuhn, F. Laube, A. Meseck, C. Rethfeldt, E.C.M. Rial, A. Rogosch-Opolka, M. Scheer, P.I. Volz
HZB, Berlin, Germany

At BESSY II, two new beamlines for RIXS and for X-Ray-microscopy demand a short period variably polarizing undulator. For this purpose, the first in-vacuum APPLE undulator worldwide is under construction. The parameters are as follows: period length=32mm, magnetic length=2500mm, minimum gap=7mm. The design incorporates a force compensation scheme as proposed by two of the authors at the SRI2018. All precision parts of the drive chain are located in air. New transverse slides for the transversal slit adjustment have been developed and tested. Optical micrometers measure the gap and shift positions, similar to the system of the CPMU17 at BESSY II. They provide the signals for motor feedback loops. A new UHV-compatible soldering technique, as developed with industry, relaxes fabrication tolerances of magnets and magnet holders and simplifies the magnet assembly. A 10-period prototype has been setup for lifetime tests of the new magnetic keeper design. The paper describes first results of the prototype and other key-components and summarizes the status of the full-scale undulator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT052

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Received ※ 19 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 22 June 2022

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