IPAC2021 - List of Keywords (polarization)

Paper	Title	Other Keywords	Page
MOXC02	Improved Lifetime of a High Spin Polarization Superlattice Photocathode	electron, cathode, gun, vacuum	31
	L. Cultrera BNL, Upton, New York, USA
	Funding: Department of Energy under grant DE-SC0012704 Highly spin polarized electron beams are required for the operation of a wide range of accelerators and instruments. The production of such electrons requires the use of Negative Electron Affinity (NEA) activated GaAs-based cathodes operated in photoelectron guns. Because of their extreme sensitivity to poor vacuum conditions the degradation of the photoemission process is so strong that NEA activated GaAs-based photocathodes can only survive in the extreme vacuums typical of DC gun. State-of-the-art on photocathode technology for spin polarized beam productions are summarized. Recent results on the use of robust NEA coating based on the Cs-Te and Cs-Sb leading to improved operational lifetime of a high spin polarization photocathode are reviewed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXC02
About •	paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 19 August 2021
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MOPAB014	First High Spin-Flip Efficiency for High Energy Polarized Protons	resonance, dipole, proton, experiment	84
	H. Huang, J. Kewisch, C. Liu, A. Marusic, W. Meng, F. Méot, P. Oddo, V. Ptitsyn, V.H. Ranjbar, T. Roser 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. In order to minimize the systematic errors for the Relativistic Heavy Ion Collider (RHIC) spin physics experiments, flipping the spin of each bunch of protons during the stores is needed. Experiments done with single RF magnet at energies less than 2 GeV have demonstrated a spin-flip efficiency over 99%. At high energy colliders with Siberian snakes, a single magnet spin flipper does not work because of the large spin tune spread and the generation of multiple, overlapping resonances. Over past decade, RHIC spin flipper design has evolved and a sophisticated spin flipper, constructed of nine-dipole magnets, was developed to flip the spin in RHIC. A special optics choice was also used to make the spin tune spread very small. In recent experiment, 97% spin-flip efficiency was measured at both 24 and 255 GeV for the first time. The results show that efficient spin flipping can be achieved at high energies.
	Poster MOPAB014 [0.984 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB014
About •	paper received ※ 16 May 2021 paper accepted ※ 08 June 2021 issue date ※ 20 August 2021
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MOPAB015	Feasibility of Polarized Deuteron Beam in the EIC	resonance, solenoid, proton, detector	87
	H. Huang, F. Méot, V. Ptitsyn, V.H. Ranjbar, T. Roser BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The physics program in the EIC calls for polarized neutron beam at high energies. The best neutron carriers are 3He nuclei and deuterons. Both neutron carries are expected to be used by spin physics program in the EIC. Due to the small magnetic moment anomaly of deuteron particles, much higher magnetic fields are required for spin rotation, so full Siberian snake is not feasible. However, the resonance strength is in general weak and the number of resonances is also small. It is possible to deal with individual resonances with conventional methods, such as betatron tune jump for intrinsic depolarizing resonances; and a weak partial snakes for imperfection resonances. The study shows that accelerating polarized deuteron beyond 100GeV/n is possible in the EIC.
	Poster MOPAB015 [0.977 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB015
About •	paper received ※ 16 May 2021 paper accepted ※ 28 May 2021 issue date ※ 13 August 2021
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MOPAB239	Simulation and Optimization of the Spin Coherence Time of Protons in a Prototype EDM Ring	quadrupole, storage-ring, dipole, simulation	771
	M. Vitz, A. Lehrach FZJ, Jülich, Germany R. Shankar INFN-Ferrara, Ferrara, Italy
	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, a strong indication for physics beyond the Standard Model. The JEDI-Collaboration (Jülich Electric Dipole moment Investigations) in Jülich is preparing a direct EDM measurement for protons and deuterons: first at the storage ring COSY (COoler SYnchrotron) and later at a dedicated storage ring. A prototype EDM ring is an intermediate step before building the final storage ring to demonstrate sufficient beam lifetime and SCT (Spin Coherence Time) in a pure electrostatic ring as well as in a storage ring with combined electric and magnetic bending elements. In order to study the effect of E-B-deflectors on the orbit and the spin motion, the software library Bmad is used. The first results of the optics and spin simulations, with a focus on the optimization of the SCT, towards the prototype EDM ring will be discussed.
	Poster MOPAB239 [0.560 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB239
About •	paper received ※ 17 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 August 2021
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TUPAB107	Accelerator and Light Source Research Program at Duke University	FEL, storage-ring, undulator, electron	1636
	Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. The accelerator and light source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring based free-electron lasers (FELs) and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS) driven by the storage ring FEL. With a maximum total flux of about 3·10¹⁰ gamma/s and a spectral flux of more than 1,000 gamma/s/eV around 10 MeV, the HIGS is the world’s highest-flux Compton gamma-ray source. Operated in the energy range from 1 to 100 MeV, the HIGS is a premier Compton gamma-ray facility in the world for a variety of nuclear physics research programs, both fundamental and applied. In this work, we will describe our recent light source development to enable the production of gamma rays in the higher energy range from 100 and 120 MeV. We will also provide a summary of our recent accelerator physics and FEL physics research activities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB107
About •	paper received ※ 26 May 2021 paper accepted ※ 14 July 2021 issue date ※ 15 August 2021
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TUPAB122	SASE3 Variable Polarization Project at the European XFEL	undulator, vacuum, FEL, electron	1678
	S.K. Karabekyan, S. Abeghyan, M. Bagha-Shanjani, S. Casalbuoni, U. Englisch, G. Geloni, J. Grünert, S. Hauf, C. Holz, D. La Civita, J. Laksman, D. Mamchyk, M.P. Planas, F. Preisskorn, S. Serkez, H. Sinn, A. Violante, G. Wellenreuther, M. Wuenschel, M. Yakopov, C. Youngman EuXFEL, Schenefeld, Germany A. Block, W. Decking, N. Golubeva, K. Knebel, T. Ladwig, D.L. Lenz, D. Lipka, R. Mattusch, N. Mildner, E. Negodin, D. Nölle, J. Prenting, F. Saretzki, M. Schlösser, F. Schmidt-Föhre, E. Schneidmiller, D. Thoden, T. Wamsat, S. Wendt, T. Wilksen, T. Wohlenberg, M.V. Yurkov DESY, Hamburg, Germany M. Brügger, M. Calvi, S. Danner, R. Ganter, L. Huber, A. Keller, M.S. Schmidt, T. Schmidt PSI, Villigen PSI, Switzerland D.E. Kim PAL, Pohang, Republic of Korea Y. Li IHEP, People’s Republic of China
	At the European XFEL, two undulator systems for hard and one for soft X-rays have been successfully put into operation. The SASE3 soft X-ray undulator system generates linearly polarized radiation in the horizontal plane. One of the requirements for extending the radiation characteristics is the ability to obtain different polarization modes. These include both right and left circular, elliptical polarization, or linear polarization at an arbitrary angle. For this purpose, a system consisting of four APPLE X helical undulators developed at the Paul Scherrer Institute (PSI) is used. This paper presents the design parameters of the SASE3 undulator system after modifying it with the helical afterburner. It also describes the methods and the design solutions different from those used at PSI. The status and schedule of the project are introduced.
	Poster TUPAB122 [0.553 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB122
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 27 August 2021
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TUPAB275	Enhanced Orthogonal Polarization Component Treatment in COTRI Model for Microbunched Beam Diagnostics	bunching, radiation, diagnostics, laser	2113
	D.W. Rule Private Address, Silver Spring, USA A.H. Lumpkin ANL, Lemont, Illinois, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. We present the results of modifying our coherent optical transition radiation interferometry (COTRI) model’s treatment of the perpendicular polarization of OTR, Iperp. Our previous analytic approximation for Iperp was for beam divergences, sy << 1/g, where g is the Lorentz factor and sy is the rms y-component of the beam divergence. We have replaced our analytical form with a Gaussian quadrature for the convolution of Iperp with the divergence in theta-y. This extends the range of divergences we reliably model to sy > 1/g. Ipar, the parallel polarization in the model, is unchanged. Iperp is polarized along the y-axis and is proportional to the square of the y-component of the beam’s velocity distribution. We illustrate our results with two cases: 1) beam energy E=1 GeV, OTR wavelength 633 nm, Q=235 pC, microbunching fraction, bf=1%, divergences of 0.1-0.7 mrad, and rms beam sizes 2,10, and 30 microns; 2) E=375 MeV, wavelength 266 nm, Q=300 pC, bf=10%, divergences of 0.1-0,7 mrad, and rms beam sizes of 10,25,50, and 100 microns. We will present two cases that would be of interest for the diagnostics of laser-plasma accelerator beams* and pre-bunched FELs*, respectively. A. H. Lumpkin et al., Phys. Rev. Lett. 125, 014801 (2020). ** A. H. Lumpkin and D. W. Rule, in Proc., 39th International FEL Conference, FEL 2019 (JACoW Pub., Hamburg, Germany, 2019), pp. 408-411.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB275
About •	paper received ※ 22 May 2021 paper accepted ※ 10 June 2021 issue date ※ 20 August 2021
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TUPAB373	Design of a Delta-type Superconducting Undulator at the IHEP	undulator, photon, permanent-magnet, radiation	2391
	J.H. Wei IHEP CSNS, Guangdong Province, People’s Republic of China C.D. Deng DNSC, Dongguan, People’s Republic of China L. Gong, X.Y. Li, X.C. Yang IHEP, Beijing, People’s Republic of China Y. Li DESY, Hamburg, Germany
	Undulators play an important role in the 4th generation radiation light source. In order to satisfy different requirements of the experiments, various undulator structures have been proposed. The Delta-type undulator can provide circular polarized radiation. Conventional undulators are usually made of permanent magnets, but the application of the superconducting technology in the undulator is developing quickly. Compared to the permanent magnet undulators, superconducting undulators can provide higher photon flux with the same magnetic pole gap and period length, especially when the period length is longer than 20 mm. An R&D project is underway to produce a protype of a Delta-type superconducting undulator with 28 mm long period and 12 mm gap at the IHEP. The structure design and the simulation results of the magnetic field are presented in this paper.
	Poster TUPAB373 [1.752 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB373
About •	paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 15 August 2021
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WEXC05	First Results Operating a Long-Period EPU in Universal Mode at the Canadian Light Source	photon, focusing, undulator, injection	2566
	W.A. Wurtz, C.K. Baribeau, D. Bertwistle, M.J. Sigrist CLS, Saskatoon, Saskatchewan, Canada
	The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source (CLS) requires photons with energies as low as 15 eV with circular polarization at the end station. This energy range is accomplished on the 2.9 GeV CLS storage ring using an elliptically polarizing undulator (EPU) with a 180 mm period, which we call EPU180. In order to realize circular polarized photons at the end station with this low energy, we must overcome two technical issues. First, the beamline optics distort the polarization of the light, so we compensate by providing light with a flattened, tilted polarization ellipse at the source point - a mode of operation known as universal mode. Second, the device has a strong effect on the electron beam due to dynamic focusing and is capable of reducing the injection efficiency to zero. We overcome this non-linear dynamic focusing using current strips adhered to the vacuum chamber. In this report, we present the first results with operating EPU180 in universal mode and we recover the dynamic aperture using the current strips.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXC05
About •	paper received ※ 13 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021
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WEPAB080	Near Threshold Pion Photoproduction on Deuterons	photon, experiment, multipole, scattering	2775
	V. Shastri, V. Aswathi, S.P. Shilpashree Christ University, School of Engineering and Technology, Bangalore, India
	The study of photoproduction of mesons is a prime tool in understanding the properties of strong interactions. The only photoproduction reaction on deuteron with two-body final state is coherent pion photoproduction reaction. Several theoretical studies are being carried out on the pion photoproduction on deuterons since several decades. On the experimental side, the accelerator and detector technology has improved the developments. In the recent years, measurements of tensor analyzing powers associated with coherent and incoherent pion photoproduction are also being carried out at the VEPP-3 electron storage ring. In one of the recent measurements, Rachek et al"" have observed discrepancy between theory and experiment at higher photon energies and have suggested for improvement of the theoretical models. In a more recent analysis,"" the role of D-wave component on spin asymmetries have been identified. In view of these developments, the purpose of the present contribution is to study coherent pion photoproduction on deuterons using model independent irreducible tensor formalism developed earlier to study the photodisintegration of deuterons."*" I A Rachek et al., Few-Body Syst., 58, 29 (2017) H M Al Ghamdi et al, Brazillian Journal of Physics, 50, 615 (2020) * G Ramachandran, S P Shilpashree Phys. Rev. C 74, 052801(R) (2006)
	Poster WEPAB080 [0.203 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB080
About •	paper received ※ 29 May 2021 paper accepted ※ 01 July 2021 issue date ※ 16 August 2021
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WEPAB102	Half-Metal Spin Filter for Highly Polarized Emission from GaAs Photocathodes	electron, cathode, lattice, hardware	2833
	S. Poddar, C.-J. Jing, E.J. Montgomery Euclid Beamlabs, Bolingbrook, USA P. Lukashev University of Northern Iowa, Cedar Falls, Iowa, USA C. Palmstrøm UCSB, Santa Barbara, California, USA M.L. Stutzman, S. Zhang JLab, Newport News, Virginia, USA
	Funding: Work supported by Department of Energy grant number DE-SC0020564. GaAs-based photocathodes are one of the major sources of spin-polarized electrons and are crucial for the upcoming Electron-Ion collider experiments which includes study of proton spin and spin parity violation in the standard model. The theoretical polarization limit in unstrained GaAs photocathodes is 50 % but only 35 % is routinely achieved in experiments. Spin selective filtering allows to boost the spin polarization beyond the 50 % theoretical limit. In this work, first-principle electronic calculations using standard Density Functional Theory are performed to predict possible Heusler alloy half-metal candidates to be used as spin-filter. Simulations are also performed to investigate the half-metallicity as function of the magnetic spin direction. Several devices are experimentally fabricated using dedicated Molecular Beam Epitaxy growth system. We implemented Quantum Efficiency and Polarization testing of these half-metal/GaAs heterostructures using a dedicated Mott polarimeter system. Photoemission can also be seen on magnetically switching the spin-filter direction accompanied by a change in sign of the asymmetry which is a qualitative proof of the spin-filtering effect.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB102
About •	paper received ※ 20 May 2021 paper accepted ※ 28 July 2021 issue date ※ 27 August 2021
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WEPAB188	New Method to Search for Axion-Like Particles Demonstrated with Polarized Beam at the COSY Storage Ring	resonance, storage-ring, experiment, dipole	3057
	S. Karanth Jagiellonian University, Kraków, Poland
	The axion was originally proposed to explain the small size of CP violation in quantum chromodynamics. It might be a candidate for dark matter in the universe. Axions or axion-like particles (ALPs) when coupled to gluons induce an oscillating Electric Dipole Moment (EDM) along the nucleon’s spin direction. At the Cooler Synchrotron (COSY) in Jülich, this principle was used to perform a first test experiment to search for ALPs using an in-plane polarized deuteron beam. If the spin precession frequency equals the EDM oscillation frequency, a resonance occurs that accumulates the rotation of the polarization out of the ring plane. Since the axion frequency is unknown, the beam momentum was ramped to search for a vertical polarization jump that would occur when the resonance is crossed. At COSY, four beam bunches with different polarization directions were used to make sure that no resonance was missed because of the unknown relative phase between the polarization precession and the EDM oscillations. We scanned a frequency window of about a 1-kHz width around the spin precession frequency of 121 kHz. This talk will describe the experiment and show preliminary results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB188
About •	paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 31 August 2021
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WEPAB405	Supercontinuum Generation for the Improvement of Pulse Radiolysis System	laser, radiation, photon, electron	3657
	M. Sato, Y. Kaneko, Y. Koshiba, M. Washio RISE, Tokyo, Japan K. Sakaue The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan
	Pulse radiolysis is one of the absorption measurement methods for investigating the fundamental, ultrafast process of radiation chemical reactions. Analytical light is transmitted simultaneously with the timing of electron beam irradiation, and its absorption by reactive species is detected. Since the target reactions arise in pico second time scale or even shorter, analytical light is required to have such duration. Besides, so as not to be buried in noise of the radiation source, the optical power of the analytical light must be high enough. Furthermore, it is desirable that the analytical light covers visible region because important absorptions caused by irradiation products such as hydrated electron, hydroxyl radical, or so exist in the region. We considered that the supercontinuum light generated from an ultrashort pulse laser is suitable as an analytical light because it has all these characteristics. In this study, we generate the second harmonic (775 nm) of an erbium fiber laser (1550 nm) as a seed laser for supercontinuum generation. In this presentation, we report the current situation of our laser system and prospects.
	Poster WEPAB405 [0.734 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB405
About •	paper received ※ 18 May 2021 paper accepted ※ 01 September 2021 issue date ※ 20 August 2021
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THPAB022	Possibilities for Upgrading to Polarized SuperKEKB	electron, experiment, lattice, cathode	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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THPAB123	Pytomic: A Python Tool for Polarized Atomic Beam Tracking	simulation, detector, sextupole, target	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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB123
About •	paper received ※ 20 May 2021 paper accepted ※ 21 June 2021 issue date ※ 27 August 2021
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THPAB131	Spatio-Temporal Measurements of THz Pulses	electron, radiation, laser, FEM	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB131
About •	paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 17 August 2021
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THPAB170	RF Deflector Design for Rapid Proton Therapy	proton, cavity, simulation, quadrupole	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB170
About •	paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021
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THPAB174	T-BMT Spin Resonance Tracker Code for He3 with Six Snakes	resonance, emittance, HOM, betatron	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
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB174
About •	paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 28 August 2021
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THPAB177	Simulation Model Improvements at the Cooler Synchrotron COSY Using the LOCO Algorithm	simulation, storage-ring, quadrupole, dipole	4111
	V. Poncza, A. Lehrach FZJ, Jülich, Germany A. Lehrach, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB177
About •	paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 12 August 2021
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Paper

Title

Other Keywords

Page

MOXC02

Improved Lifetime of a High Spin Polarization Superlattice Photocathode

electron, cathode, gun, vacuum

31

L. Cultrera
BNL, Upton, New York, USA

Funding: Department of Energy under grant DE-SC0012704
Highly spin polarized electron beams are required for the operation of a wide range of accelerators and instruments. The production of such electrons requires the use of Negative Electron Affinity (NEA) activated GaAs-based cathodes operated in photoelectron guns. Because of their extreme sensitivity to poor vacuum conditions the degradation of the photoemission process is so strong that NEA activated GaAs-based photocathodes can only survive in the extreme vacuums typical of DC gun. State-of-the-art on photocathode technology for spin polarized beam productions are summarized. Recent results on the use of robust NEA coating based on the Cs-Te and Cs-Sb leading to improved operational lifetime of a high spin polarization photocathode are reviewed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXC02

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

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MOPAB014

First High Spin-Flip Efficiency for High Energy Polarized Protons

resonance, dipole, proton, experiment

84

H. Huang, J. Kewisch, C. Liu, A. Marusic, W. Meng, F. Méot, P. Oddo, V. Ptitsyn, V.H. Ranjbar, T. Roser
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.
In order to minimize the systematic errors for the Relativistic Heavy Ion Collider (RHIC) spin physics experiments, flipping the spin of each bunch of protons during the stores is needed. Experiments done with single RF magnet at energies less than 2 GeV have demonstrated a spin-flip efficiency over 99%. At high energy colliders with Siberian snakes, a single magnet spin flipper does not work because of the large spin tune spread and the generation of multiple, overlapping resonances. Over past decade, RHIC spin flipper design has evolved and a sophisticated spin flipper, constructed of nine-dipole magnets, was developed to flip the spin in RHIC. A special optics choice was also used to make the spin tune spread very small. In recent experiment, 97% spin-flip efficiency was measured at both 24 and 255 GeV for the first time. The results show that efficient spin flipping can be achieved at high energies.

Poster MOPAB014 [0.984 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB014

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paper received ※ 16 May 2021 paper accepted ※ 08 June 2021 issue date ※ 20 August 2021

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MOPAB015

Feasibility of Polarized Deuteron Beam in the EIC

resonance, solenoid, proton, detector

87

H. Huang, F. Méot, V. Ptitsyn, V.H. Ranjbar, T. Roser
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The physics program in the EIC calls for polarized neutron beam at high energies. The best neutron carriers are 3He nuclei and deuterons. Both neutron carries are expected to be used by spin physics program in the EIC. Due to the small magnetic moment anomaly of deuteron particles, much higher magnetic fields are required for spin rotation, so full Siberian snake is not feasible. However, the resonance strength is in general weak and the number of resonances is also small. It is possible to deal with individual resonances with conventional methods, such as betatron tune jump for intrinsic depolarizing resonances; and a weak partial snakes for imperfection resonances. The study shows that accelerating polarized deuteron beyond 100GeV/n is possible in the EIC.

Poster MOPAB015 [0.977 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB015

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paper received ※ 16 May 2021 paper accepted ※ 28 May 2021 issue date ※ 13 August 2021

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MOPAB239

Simulation and Optimization of the Spin Coherence Time of Protons in a Prototype EDM Ring

quadrupole, storage-ring, dipole, simulation

771

M. Vitz, A. Lehrach
FZJ, Jülich, Germany
R. Shankar
INFN-Ferrara, Ferrara, Italy

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, a strong indication for physics beyond the Standard Model. The JEDI-Collaboration (Jülich Electric Dipole moment Investigations) in Jülich is preparing a direct EDM measurement for protons and deuterons: first at the storage ring COSY (COoler SYnchrotron) and later at a dedicated storage ring. A prototype EDM ring is an intermediate step before building the final storage ring to demonstrate sufficient beam lifetime and SCT (Spin Coherence Time) in a pure electrostatic ring as well as in a storage ring with combined electric and magnetic bending elements. In order to study the effect of E-B-deflectors on the orbit and the spin motion, the software library Bmad is used. The first results of the optics and spin simulations, with a focus on the optimization of the SCT, towards the prototype EDM ring will be discussed.

Poster MOPAB239 [0.560 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB239

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paper received ※ 17 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 August 2021

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TUPAB107

Accelerator and Light Source Research Program at Duke University

FEL, storage-ring, undulator, electron

1636

Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
The accelerator and light source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring based free-electron lasers (FELs) and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS) driven by the storage ring FEL. With a maximum total flux of about 3·10¹⁰ gamma/s and a spectral flux of more than 1,000 gamma/s/eV around 10 MeV, the HIGS is the world’s highest-flux Compton gamma-ray source. Operated in the energy range from 1 to 100 MeV, the HIGS is a premier Compton gamma-ray facility in the world for a variety of nuclear physics research programs, both fundamental and applied. In this work, we will describe our recent light source development to enable the production of gamma rays in the higher energy range from 100 and 120 MeV. We will also provide a summary of our recent accelerator physics and FEL physics research activities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB107

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paper received ※ 26 May 2021 paper accepted ※ 14 July 2021 issue date ※ 15 August 2021

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TUPAB122

SASE3 Variable Polarization Project at the European XFEL

undulator, vacuum, FEL, electron

1678

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

At the European XFEL, two undulator systems for hard and one for soft X-rays have been successfully put into operation. The SASE3 soft X-ray undulator system generates linearly polarized radiation in the horizontal plane. One of the requirements for extending the radiation characteristics is the ability to obtain different polarization modes. These include both right and left circular, elliptical polarization, or linear polarization at an arbitrary angle. For this purpose, a system consisting of four APPLE X helical undulators developed at the Paul Scherrer Institute (PSI) is used. This paper presents the design parameters of the SASE3 undulator system after modifying it with the helical afterburner. It also describes the methods and the design solutions different from those used at PSI. The status and schedule of the project are introduced.

Poster TUPAB122 [0.553 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB122

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

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TUPAB275

Enhanced Orthogonal Polarization Component Treatment in COTRI Model for Microbunched Beam Diagnostics

bunching, radiation, diagnostics, laser

2113

D.W. Rule
Private Address, Silver Spring, USA
A.H. Lumpkin
ANL, Lemont, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
We present the results of modifying our coherent optical transition radiation interferometry (COTRI) model’s treatment of the perpendicular polarization of OTR, Iperp. Our previous analytic approximation for Iperp was for beam divergences, sy << 1/g, where g is the Lorentz factor and sy is the rms y-component of the beam divergence. We have replaced our analytical form with a Gaussian quadrature for the convolution of Iperp with the divergence in theta-y. This extends the range of divergences we reliably model to sy > 1/g. Ipar, the parallel polarization in the model, is unchanged. Iperp is polarized along the y-axis and is proportional to the square of the y-component of the beam’s velocity distribution. We illustrate our results with two cases: 1) beam energy E=1 GeV, OTR wavelength 633 nm, Q=235 pC, microbunching fraction, bf=1%, divergences of 0.1-0.7 mrad, and rms beam sizes 2,10, and 30 microns; 2) E=375 MeV, wavelength 266 nm, Q=300 pC, bf=10%, divergences of 0.1-0,7 mrad, and rms beam sizes of 10,25,50, and 100 microns. We will present two cases that would be of interest for the diagnostics of laser-plasma accelerator beams* and pre-bunched FELs**, respectively.
* A. H. Lumpkin et al., Phys. Rev. Lett. 125, 014801 (2020).
** A. H. Lumpkin and D. W. Rule, in Proc., 39th International FEL Conference, FEL 2019 (JACoW Pub., Hamburg, Germany, 2019), pp. 408-411.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB275

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paper received ※ 22 May 2021 paper accepted ※ 10 June 2021 issue date ※ 20 August 2021

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TUPAB373

Design of a Delta-type Superconducting Undulator at the IHEP

undulator, photon, permanent-magnet, radiation

2391

J.H. Wei
IHEP CSNS, Guangdong Province, People’s Republic of China
C.D. Deng
DNSC, Dongguan, People’s Republic of China
L. Gong, X.Y. Li, X.C. Yang
IHEP, Beijing, People’s Republic of China
Y. Li
DESY, Hamburg, Germany

Undulators play an important role in the 4th generation radiation light source. In order to satisfy different requirements of the experiments, various undulator structures have been proposed. The Delta-type undulator can provide circular polarized radiation. Conventional undulators are usually made of permanent magnets, but the application of the superconducting technology in the undulator is developing quickly. Compared to the permanent magnet undulators, superconducting undulators can provide higher photon flux with the same magnetic pole gap and period length, especially when the period length is longer than 20 mm. An R&D project is underway to produce a protype of a Delta-type superconducting undulator with 28 mm long period and 12 mm gap at the IHEP. The structure design and the simulation results of the magnetic field are presented in this paper.

Poster TUPAB373 [1.752 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB373

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paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 15 August 2021

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WEXC05

First Results Operating a Long-Period EPU in Universal Mode at the Canadian Light Source

photon, focusing, undulator, injection

2566

W.A. Wurtz, C.K. Baribeau, D. Bertwistle, M.J. Sigrist
CLS, Saskatoon, Saskatchewan, Canada

The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source (CLS) requires photons with energies as low as 15 eV with circular polarization at the end station. This energy range is accomplished on the 2.9 GeV CLS storage ring using an elliptically polarizing undulator (EPU) with a 180 mm period, which we call EPU180. In order to realize circular polarized photons at the end station with this low energy, we must overcome two technical issues. First, the beamline optics distort the polarization of the light, so we compensate by providing light with a flattened, tilted polarization ellipse at the source point - a mode of operation known as universal mode. Second, the device has a strong effect on the electron beam due to dynamic focusing and is capable of reducing the injection efficiency to zero. We overcome this non-linear dynamic focusing using current strips adhered to the vacuum chamber. In this report, we present the first results with operating EPU180 in universal mode and we recover the dynamic aperture using the current strips.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXC05

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paper received ※ 13 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021

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WEPAB080

Near Threshold Pion Photoproduction on Deuterons

photon, experiment, multipole, scattering

2775

V. Shastri, V. Aswathi, S.P. Shilpashree
Christ University, School of Engineering and Technology, Bangalore, India

The study of photoproduction of mesons is a prime tool in understanding the properties of strong interactions. The only photoproduction reaction on deuteron with two-body final state is coherent pion photoproduction reaction. Several theoretical studies are being carried out on the pion photoproduction on deuterons since several decades. On the experimental side, the accelerator and detector technology has improved the developments. In the recent years, measurements of tensor analyzing powers associated with coherent and incoherent pion photoproduction are also being carried out at the VEPP-3 electron storage ring. In one of the recent measurements, Rachek et al"*" have observed discrepancy between theory and experiment at higher photon energies and have suggested for improvement of the theoretical models. In a more recent analysis,"**" the role of D-wave component on spin asymmetries have been identified. In view of these developments, the purpose of the present contribution is to study coherent pion photoproduction on deuterons using model independent irreducible tensor formalism developed earlier to study the photodisintegration of deuterons."***"
*I A Rachek et al., Few-Body Syst., 58, 29 (2017)
**H M Al Ghamdi et al, Brazillian Journal of Physics, 50, 615 (2020)
*** G Ramachandran, S P Shilpashree Phys. Rev. C 74, 052801(R) (2006)

Poster WEPAB080 [0.203 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB080

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paper received ※ 29 May 2021 paper accepted ※ 01 July 2021 issue date ※ 16 August 2021

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WEPAB102

Half-Metal Spin Filter for Highly Polarized Emission from GaAs Photocathodes

electron, cathode, lattice, hardware

2833

S. Poddar, C.-J. Jing, E.J. Montgomery
Euclid Beamlabs, Bolingbrook, USA
P. Lukashev
University of Northern Iowa, Cedar Falls, Iowa, USA
C. Palmstrøm
UCSB, Santa Barbara, California, USA
M.L. Stutzman, S. Zhang
JLab, Newport News, Virginia, USA

Funding: Work supported by Department of Energy grant number DE-SC0020564.
GaAs-based photocathodes are one of the major sources of spin-polarized electrons and are crucial for the upcoming Electron-Ion collider experiments which includes study of proton spin and spin parity violation in the standard model. The theoretical polarization limit in unstrained GaAs photocathodes is 50 % but only 35 % is routinely achieved in experiments. Spin selective filtering allows to boost the spin polarization beyond the 50 % theoretical limit. In this work, first-principle electronic calculations using standard Density Functional Theory are performed to predict possible Heusler alloy half-metal candidates to be used as spin-filter. Simulations are also performed to investigate the half-metallicity as function of the magnetic spin direction. Several devices are experimentally fabricated using dedicated Molecular Beam Epitaxy growth system. We implemented Quantum Efficiency and Polarization testing of these half-metal/GaAs heterostructures using a dedicated Mott polarimeter system. Photoemission can also be seen on magnetically switching the spin-filter direction accompanied by a change in sign of the asymmetry which is a qualitative proof of the spin-filtering effect.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB102

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paper received ※ 20 May 2021 paper accepted ※ 28 July 2021 issue date ※ 27 August 2021

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WEPAB188

New Method to Search for Axion-Like Particles Demonstrated with Polarized Beam at the COSY Storage Ring

resonance, storage-ring, experiment, dipole

3057

S. Karanth
Jagiellonian University, Kraków, Poland

The axion was originally proposed to explain the small size of CP violation in quantum chromodynamics. It might be a candidate for dark matter in the universe. Axions or axion-like particles (ALPs) when coupled to gluons induce an oscillating Electric Dipole Moment (EDM) along the nucleon’s spin direction. At the Cooler Synchrotron (COSY) in Jülich, this principle was used to perform a first test experiment to search for ALPs using an in-plane polarized deuteron beam. If the spin precession frequency equals the EDM oscillation frequency, a resonance occurs that accumulates the rotation of the polarization out of the ring plane. Since the axion frequency is unknown, the beam momentum was ramped to search for a vertical polarization jump that would occur when the resonance is crossed. At COSY, four beam bunches with different polarization directions were used to make sure that no resonance was missed because of the unknown relative phase between the polarization precession and the EDM oscillations. We scanned a frequency window of about a 1-kHz width around the spin precession frequency of 121 kHz. This talk will describe the experiment and show preliminary results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB188

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 31 August 2021

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WEPAB405

Supercontinuum Generation for the Improvement of Pulse Radiolysis System

laser, radiation, photon, electron

3657

M. Sato, Y. Kaneko, Y. Koshiba, M. Washio
RISE, Tokyo, Japan
K. Sakaue
The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan

Pulse radiolysis is one of the absorption measurement methods for investigating the fundamental, ultrafast process of radiation chemical reactions. Analytical light is transmitted simultaneously with the timing of electron beam irradiation, and its absorption by reactive species is detected. Since the target reactions arise in pico second time scale or even shorter, analytical light is required to have such duration. Besides, so as not to be buried in noise of the radiation source, the optical power of the analytical light must be high enough. Furthermore, it is desirable that the analytical light covers visible region because important absorptions caused by irradiation products such as hydrated electron, hydroxyl radical, or so exist in the region. We considered that the supercontinuum light generated from an ultrashort pulse laser is suitable as an analytical light because it has all these characteristics. In this study, we generate the second harmonic (775 nm) of an erbium fiber laser (1550 nm) as a seed laser for supercontinuum generation. In this presentation, we report the current situation of our laser system and prospects.

Poster WEPAB405 [0.734 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB405

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paper received ※ 18 May 2021 paper accepted ※ 01 September 2021 issue date ※ 20 August 2021

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THPAB022

Possibilities for Upgrading to Polarized SuperKEKB

electron, experiment, lattice, cathode

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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THPAB123

Pytomic: A Python Tool for Polarized Atomic Beam Tracking

simulation, detector, sextupole, target

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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THPAB131

Spatio-Temporal Measurements of THz Pulses

electron, radiation, laser, FEM

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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THPAB170

RF Deflector Design for Rapid Proton Therapy

proton, cavity, simulation, quadrupole

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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THPAB174

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

resonance, emittance, HOM, betatron

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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THPAB177

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

simulation, storage-ring, quadrupole, dipole

4111

V. Poncza, A. Lehrach
FZJ, Jülich, Germany
A. Lehrach, 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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