IPAC2018 - List of Keywords (polarization)

Paper	Title	Other Keywords	Page
MOZGBF5	Analysis of Polarization Decay at RHIC Store	resonance, emittance, lattice, target	76
	H. Huang, P. Adams, E.C. Aschenauer, A. Poblaguev, W.B. Schmidke BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. There are polarization losses in RHIC store due to various sources, such as emittance growth and higher order spin resonances. The beam polarization was measured several times over a store by the p-carbon polarimeters situated in both rings. These provide information on the polarization decay over time and also polarization profile development over time. A polarized jet was also used to monitor the polarization continuously through store, though with limited statistical accuracy. These polarization measurements and emittance measurements from the IPM are analyzed and the polarization loss from different sources are reviewed.
	Slides MOZGBF5 [4.526 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF5
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MOPMF004	Spin Dynamics in the JLEIC Alternative Pre-Booster Ring	resonance, booster, proton, dipole	87
	J.L. Martinez Marin, B. Mustapha ANL, Argonne, USA
	In order to reduce the foot-print of the JLEIC ion complex, we have designed a more compact and cost-effective octagonal 3-GeV pre-booster ring half the size of the orig-inal figure-8 design. However, this new ring does not preserve ion polarization by design as the figure-8 shape, making it necessary to study the spin dynamics to find the best solution for spin correction. Different codes, Zgoubi and COSY, are used to model and simu-late the spin dynamics in the octagonal 3 GeV ring, in-cluding spin correction with Siberian snakes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF004
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MOPMF013	eRHIC EIC: Plans for Rapid Acceleration of Polarized Electron Bunch at Cornell Synchrotron	electron, synchrotron, resonance, acceleration	108
	F. Méot, E.C. Aschenauer, H. Huang, C. Montag, V. Ptitsyn, V.H. Ranjbar, E. Wang, Z. Zhao BNL, Upton, Long Island, New York, USA I.V. Bazarov, D. L. Rubin Cornell University, Ithaca, New York, USA L. Cultrera, G.H. Hoffstaetter, K.W. Smolenski, R.M. Talman Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA D. Gaskell, O. Glamazdin, J.M. Grames 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. An option as an injector into the polarized-electron storage ring of eRHIC EIC is a rapid-cycling synchrotron (RCS). Cornell's 10 GeV RCS injector to CESR presents a good opportunity for dedicated polarized bunch rapid-acceleration experiments, it can also serve as a test bed for source and polarimetry developments in the frame of the EIC R&D, as polarized bunch experiments require disposing of a polarized electron source, and of dedicated polarimetry in the linac region and in the RCS proper. This is as well an opportunity for a pluri-disciplinary collaboration between Laboratories. This paper is an introduction to the topic, and to on-going activities towards that EIC R&D project.
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MOPMF014	Polarization at eRHIC Electron Storage Ring, an Ergodic Approach	electron, simulation, lattice, storage-ring	112
	F. Méot BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Based on considerations of ergodicity of the dynamical system of an electron bunch at equilibrium, the preservation of polarization in an electron storage ring is estimated from the tracking of a very limited number of electrons. This has a substantial impact on required High Power Computing resources, in noticeable contrast with the method generally used that tracks tens of electron bunches, each comprised of thousands of particles, for several thousands of turns. It is also shown that a minimum number of tracking turns is required in order to ensure the numerical convergence of the linear regressions that yield depolarizing time constant values from tracking, in both methods.
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MOPMF016	Progress on RCS eRHIC Injector Design	resonance, emittance, lattice, detector	115
	V.H. Ranjbar, M. Blaskiewicz, J.M. Brennan, S.J. Brooks, D.M. Gassner, H.-C. Hseuh, I. Marneris, F. Méot, M.G. Minty, C. Montag, V. Ptitsyn, K.S. Smith, S. Tepikian, F.J. Willeke, H. Witte, B. P. Xiao, A. Zaltsman BNL, Upton, Long Island, New York, USA I.V. Pogorelov Tech-X, Boulder, Colorado, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We have refined the design for the Rapid Cycling Synchrotron (RCS) polarized electron injector for eRHIC. The newer design includes bypasses for the eRHIC detectors and definition of the lattice layout in the existing RHIC tunnel. Additionally, we provide more details on the RF, alignment and orbit control, and magnet specifications.
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MOPMF018	Numerical Simulation of Spin Dynamics with Spin Flipper in RHIC	resonance, dipole, simulation, injection	118
	P. Adams, H. Huang, J. Kewisch, F. Méot, P. Oddo, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Spin flipper experiments during RHIC Run 17 were performed to study its effectiveness as a method for polarization sign reversal during stores. Numerical simulations are reported here, which were performed in accompaniment of these, and are being pursued with the aim of accurately reproducing the experimental conditions and providing thorough insight in the role of various key parameters participating in the dynamics of the spin flip, such as the sweep rate of the AC dipole, chromatic orbit control at RHIC snakes, RF parameters, possible effects of non-linear spin resonances, mirror resonance, tolerance on flipper magnet parameters, etc. The ultimate goal is for these simulations to serve as a guidance toward perfect flip to allow routine use during physics Runs.
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MOPMF028	A Superconvergent Algorithm for Invariant Spin Field Stroboscopic Calculations	simulation, resonance, storage-ring, lattice	145
	D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: National Science Foundation and the Department of Energy Stroboscopic averaging can be used to calculate the invariant spin field \bfn for particles with a finite oscillation amplitude in phase space. The standard technique starts with making a guess for \bfn(\bfr), which is a function of the phase space position \bfr. By tracking a particle's orbital position forward in time and then projecting the guessed \bfn backwards to the starting phase space point, the average of the backward projected spins will converge to the invariant spin direction linearly as 1/N where N is the number of turns tracked. The convergence can be accelerated by an iterative method that uses an approximate invariant spin field constructed by averaging the calculated spin field over points that are close in orbital phase space. This superconvergent algorithm has been built into a new program based upon the Bmad toolkit for charged particle and X-ray simulations.
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MOPMF071	Polarization Studies for the eRHIC electron Storage Ring	storage-ring, electron, coupling, solenoid	292
	E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA S. Tepikian BNL, Upton, Long Island, New York, USA
	Funding: Manuscript authored by Fermi Res. All., LLC under Contr. No. DE-AC02-07CH11359 and Brookhaven Sc. Ass., LLC under Contr. No. DE-AC02-98CH10886 with the U.S. DOE, Office of Science, Office of HEP. A hadron/lepton collider with polarized beams has been under consideration by the scientific community since some years, in the U.S. and Europe. Among the various proposals, those by JLAB and BNL with polarized electron and proton beams are currently under closer study in the U.S. Experimenters call for the simultaneous storage of electron bunches with both spin helicity. In the BNL based Ring-Ring design, electrons are stored at top energy in a ring to be accommodated in the existing RHIC tunnel. The transversely polarized electron beam is injected into the storage ring at variable energies, between 5 and 18 GeV. Polarization is brought into the longitudinal direction at the IP by a couple of spin rotators. In this paper results of first studies of the attainable beam polarization level and lifetime in the storage ring at 18 GeV are presented.
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MOPML007	Analysis of Spin Response Function at Beam Interaction Point in JLEIC	resonance, collider, proton, sextupole	400
	V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang JLab, Newport News, Virginia, USA Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under con-tracts DE-AC05-06OR23177 and DE-AC02-06CH11357. The spin response function is determined by a collid-er's magnetic lattice and allows one to account for con-tributions of perturbing fields to spin resonance strengths. The depolarizing effect of an incoming beam depends significantly on the response function value at the interaction point (IP). We present an analytic calcula-tion of the response function for protons and deuterons at the IP of Jefferson Lab Electron Ion Collider (JLEIC) over its whole momentum range. We find a good agreement of the analytic calculation with our numerical modeling results obtained using a spin tracking code, Zgoubi.
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TUXGBD3	Ideas and Concepts for Future Electron Ion Colliders	electron, luminosity, collider, detector	590
	F.C. Pilat ORNL, Oak Ridge, Tennessee, USA
	Different versions of future electron-ion colliders have been proposed by Brookhaven National Laboratory (BNL) and Thomas Jefferson National Laboratory (JLAB), one based on colliding protons in a ring with electrons from an Energy Recovery Linac (ERL), the other two based on ring-ring colliders. To attain the luminosity goal strong hadron cooling is required, as could be provided with several proposed new cooling schemes. Polarization of both colliding beams is essential. This invited talk will compare the various designs and highlight some of the novel ideas and concepts.
	Slides TUXGBD3 [76.608 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBD3
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TUYGBE4	Optically-pumped Polarized H⁻ and 3 He++ Ion Sources Development at RHIC	injection, ion-source, electron, solenoid	644
	A. Zelenski, G. Atoian, E.N. Beebe, A. Poblaguev, D. Raparia, J. Ritter BNL, Upton, Long Island, New York, USA J.D. Maxwell, R. Milner, M. Musgrave MIT, Cambridge, Massachusetts, USA
	The RHIC Optically-pumped Polarized H⁻ Ion Source (OPPIS) upgrade with the atomic beam hydrogen injector and the He-ionizer cell was commissioned for operation in the Run-2013. The use of the high brightness primary proton source resulted in higher polarized beam intensity and polarization delivered for injection to Linac-Booster-AGS-RHIC accelerator complex. The proposed polarized 3He++ acceleration in RHIC and future electron- ion col-lider (eRHIC) will require about 2·10¹¹ ions in the source pulse. A new technique had been proposed for production of high intensity polarized 3He++ ion beam. It is based on ionization and accumulation of the 3He gas (polarized by optical-pumping and metastability-exchange technique in the high magnetic field of a 5.0 T) in the Electron Beam Ion Source (EBIS). We present a status of the 3He++ ion source development.
	Slides TUYGBE4 [4.596 MB]
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TUPMF022	Electron Beam Scanning in the Delta-Type Undulators for Sirius	undulator, electron, radiation, storage-ring	1300
	A. B. da Cruz, L. Liu LNLS, Campinas, Brazil
	We report on simulation studies to analyze the possibility of scanning the electron beam, and not scanning the sample, in CDI experiments using a Delta-Type undulator in the 3GeV Sirius electron storage ring presently under construction at LNLS. This would allow much faster scans in diffraction limited storage rings such as Sirius. We study displaced beam trajectories through the undulators and analyze the effects on the emitted radiation. It is possible to show that displacements on the order of ± 500 micrometers around the center will introduce variations in the radiation spectrum that are less that 1 per cent and thus acceptable for Coherent Diffraction Imaging experiments.
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TUPMK003	Advances in the Sirius Delta-Type Undulator Project	undulator, lattice, storage-ring, MMI	1491
	L.N.P. Vilela, R. Basílio, J.F. Citadini, J.R. Furaer, F. Rodrigues LNLS, Campinas, Brazil
	The Delta undulator is a compact adjustable-phase insertion device that provides full light polarization control. Five undulators of this type will be installed in the initial operation phase of Sirius, the new 4th generation synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). In this work we present the recent advances in the development of Sirius Delta-type undulator, the studies of the effects of this device in the storage ring beam dynamics and assembly and measurements strategies.
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TUPML020	Beamline Design of EMuS - the First Experimental Muon Source in China	solenoid, proton, target, experiment	1574
	Y. Bao, Y.K. Chen, Z.L. Hou, Y.P. Song, J.Y. Tang, N. Vassilopoulos, Y. Yuan, G. Zhao, L. Zhou IHEP, Beijing, People's Republic of China H.T. Jing IHEP CSNS, Dongguan, People's Republic of China
	Funding: This work is supported by National Natural Science Foundation of China under Grants 11575217 and 11527811. Yu Bao thanks Hundred Talents Program of Chinese Academy of Science. We report the beamline design of the Experimental Muon Source (EMuS) project in China. Based on the 1.6 GeV/100 kW proton accelerator at the Chinese Spallation Neutron Source (CSNS), EMuS will extract one bunch from every 10 double-bunch proton pulses to hit a stand-alone target sitting in a superconducting solenoid, and the secondary muons/pions are guided to the experimental area. The beamline is designed to provide both a surface muon beam and a decay muon beam, so that various experiments such as muSR applications and particle/nuclear physics experiments can be conducted. In this work we present the conceptual design and simulation of the beamlines, and discuss the future aspects of the project.
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TUPML025	Long Lifetime Spin-Polarized GaAs Photocathode Activated by Cs2Te	cathode, electron, vacuum, photon	1589
	J. Bae, L. Cultrera, P. Digiacomo Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA I.V. Bazarov Cornell University, Ithaca, New York, USA
	Funding: This work was supported by the Department of Energy Grant Nos. DE-SC0016203 and NSF PHY-1461111. High intensity and highly spin-polarized electron source is of great interest to the next generation Electron Ion Colliders. GaAs prepared by the standard activation method, which is the most widely used spin-polarized photocathode, is notorious for its vacuum sensitivity and short operational lifetime. To improve the lifetime of GaAs photocathodes, we activated GaAs by Cs2Te, a material well known for its robustness. We confirmed the Cs2Te layer forms negative electron affinity on GaAs with a factor of 5 improvement in lifetime. Furthermore, the new activation method had no adverse effect on spin-polarization. Considering Cs2Te forms much thicker activation layer (~ 2 nm) compared to the standard activation layer (~ monolayer), our results trigger a paradigm shift on new activation methods with other robust materials that were avoided for their thickness.
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TUPML031	Characterization of Polarization-Dependent Emittance From an Array of Au Nanorods using Velocity Map Imaging Spectrometer	electron, laser, emittance, experiment	1612
	H. Ye, F.X. Kärtner, S. T. Trippel Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany A. Fallahi, J. Küpper, O. Muecke CFEL, Hamburg, Germany F.X. Kärtner MIT, Cambridge, Massachusetts, USA F.X. Kärtner, J. Küpper, S. T. Trippel, H. Ye The Hamburg Center for Ultrafast Imaging, University of Hamburg, hamburg, Germany J. Küpper, G.M. Rossi DESY, Hamburg, Germany H. Ye University of Hamburg, Hamburg, Germany
	Electron beams of high quality, e.g., low emittance, are of crucial importance for cutting-edge scientific instruments, such as x-ray free electron lasers (XFELs) and ultrafast electron diffraction (UED) setups. A velocity-map-imaging (VMI) spectrometer was implemented to characterize the intrinsic root-mean-square (rms) normalized emittance from photocathodes. The spectrometer operated in both, spatial map imaging (SMI) and VMI modes. Therefore, spatial- and velocity-coordinates were recorded independently and quickly. The technique allows for fast complete emittance measurements, within minutes. A 75 μm pitch array of Au nanorods of dimension 100×30~nm, was studied under strong-field-emission regime by 100 fs 1 kHz 1.3 μm laser pulses with a 300×30 μm² focus spot size on the sample. A patterned electron bunch was observed, each emitted from a single nanorod within the array. A polarization dependent photoemission study was performed showing a smaller rms-normalized divergence of 0.8 mrad with the laser polarization normal to the sample surface, compared to 1.15 mrad for the parallel case.
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WEPAL073	Enhanced Bunch Monitoring by Interferometric Electro-Optic Methods	pick-up, laser, proton, optics	2353
	S.M. Gibson, A. Arteche, A. Bosco Royal Holloway, University of London, Surrey, United Kingdom S.E. Bashforth, A. Bosco, S.M. Gibson JAI, Egham, Surrey, United Kingdom M. Krupa, T. Lefèvre CERN, Geneva, Switzerland
	Funding: We acknowledge funding by UK STFC grant ST/N001583/1, JAI at Royal Holloway University of London and CERN A prototype Electro-Optic Beam Position Monitor has been installed for tests* in the CERN SPS to develop the concept for high-bandwidth (6-12GHz) monitoring of crabbed-bunch rotation and intra-bunch instabilities at the High Luminosity LHC*. The technique relies on the ultrafast response of birefringent MgO:LiNO3 crystals to optically measure the intra-bunch transverse displacement of a passing relativistic bunch. This paper reports on recent developments, including a new interferometric electro-optic pick-up that was installed in the CERN SPS in September 2017; in first beam tests with nominal bunch charge, a corresponding interferometric signal has been observed. The interferometric arrangement has the advantages of being sensitive to the strongest polarisation coefficient of the crystal, and the phase offset of the interferometer is controllable by frequency scanning of the laser, which enables rapid optimisation of the working point. Novel concepts and bench tests for enhancements to the pick-up design are reviewed, together with prospects for sensitivity during the first crab-cavity beam tests at the CERN SPS in 2018. A. Arteche et al "First beam tests at the CERN SPS of an electro-optic beam position monitor for the HL-LHC" TUPCF23, IBIC 2017. ** HL-LHC TDR v0.1 doi.org/10.23731/CYRM-2017-004
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THPAK079	New Algorithms in Zgoubi	dipole, proton, simulation, factory	3418
	D.T. Abell RadiaSoft LLC, Boulder, Colorado, USA F. Méot BNL, Upton, Long Island, New York, USA
	Funding: This work was supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics under Award No. DE-SC0017181. The particle tracking code Zgoubi,* is used for a broad array of accelerator design studies, including FFAGs* and EICs,**. In this paper, we describe recent work aimed at improving Zgoubi's speed and flexibility. In particular, we describe a new implementation of the Zgoubi tracking algorithm that requires significantly less memory and arithmetic. And we describe a new algorithm that performs symplectic tracking through field maps. In addition, we describe the current efforts to parallelize Zgoubi. https://sourceforge.net/projects/zgoubi/ F. Méot, FERMILAB-TM-2010, 1997 F. Lemuet et al., NIM-A, 547:638, 2005 *F. Méot et al., eRHIC/45, 2015 ***F. Lin et al., IPAC17, WEPIK114, 2017
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THPAK144	A Pseudospectral Method for Solving the Bloch Equations of the Polarization Density in e^- Storage Rings	storage-ring, electron, ion-effects, synchrotron	3589
	K.A. Heinemann, O. Beznosov, J.A. Ellison UNM, Albuquerque, New Mexico, USA D. Appelö University of Colorado at Boulder, Boulder, USA D.P. Barber DESY, Hamburg, Germany
	Funding: Work supported by DOE under DE-SC0018008 We consider the numerical evolution of Bloch equations for the polarization density in high-energy electron storage rings. Equilibrium polarization is well characterized by the DK formulas for current rings, but deviations may be important at the high energies we have in mind. We believe the Bloch equations derived in* give a more accurate description at all energies. These form a system of three coupled linear partial differential equations for the three components of the polarization density. Following** we formulate the equations in action-angle variables and approximate the Fokker-Planck terms. We aim to integrate these equations numerically in order to approximate the equilibrium and compare with the DK formulas. The smoothness and simple geometry of the problem makes it amenable to pseudospectral discretization using Fourier modes in the angles and Chebyshev polynomials in the actions, leading to a large ODE system. We will explore time stepping algorithms for the needed long time integration. Here, we present results for simple models checking the accuracy of the numerical method but note that our ultimate goal is to simulate polarization in the FCC and CEPC rings. * Ya.S.Derbenev, A.M.Kondratenko, Sov. Phys. Dokl., 19, p.438 (1975). ** D.P.Barber, K.Heinemann, H.Mais, G.Ripken, A Fokker-Planck treatment of stochastic particle motion…, DESY-91-146, 1991.
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THPAL027	Transverse RF Deflecting Structures for the MAX IV LINAC	GUI, linac, klystron, emittance	3684
	D. Olsson, F. Curbis, E. Mansten, S. Thorin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden
	The MAX IV LINAC operates both as a full-energy injector for two electron storage rings, and as a driver for a Short Pulse Facility (SPF). A soft X-ray Laser (SXL) beamline will also be installed in the end of the existing LINAC. For SPF and SXL operation, it is important to characterize beam parameters such as bunch profile, slice energy spread and slice emittance. For these measurements, two 3 m long transverse deflecting RF structures with a matching section are being developed. The structures are operating at S-band and have variable polarizations. When fed via a SLED pulse compressor, the two structures can generate a total integrated deflecting voltage higher than 100 MV which is sufficient for measurements with temporal resolutions down to 1 fs. This paper describes the initial RF design of the deflecting structures.
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THPAL153	High Power Test of the S-Band Spherical Pulse Compressor at Tsinghua University	cavity, FEL, coupling, klystron	4008
	P. Wang, D.Z. Cao, H.B. Chen, C. Cheng, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	We designed, fabricated and high power tested an S-band spherical pulse compressor for the high-power test facility at Tsinghua University. The pulse compressor comprises a spherical resonant cavity with an unloaded quality factor of 100, 000 and an RF polarizer with two rectangular ports and a circular port. To achieve high efficiency and large power gain, the coupling coefficient was optimized to 8 with input pulse length of 3.6 us and compression ratio of 12. After conditioning the RF system, the pulse compressor generated RF pulses with peak power of more than 400MW. And during the operation, the pulse compressor has very low breakdown rate and was extremely stable.
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THPAL155	Fabrication and Cold Test of the Correction Cavity Chain for Klystron-Based CLIC	cavity, operation, klystron, linear-collider	4014
	P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	A proposed RF scheme based on correction cavity chain and storage cavity (CC-SC scheme) for klystron-based CLIC has the ability to generate flat output pulses. In the scheme, the correction cavity chain modulates the amplitude of the input pulse, while the storage cavity compresses the amplitude-modulated pulse. Resonant cavities of the correction cavity chain are of a relatively low unloaded quality factor and of small size, which results in the compactness of the RF scheme. The first prototype of a correction cavity chain was fabricated and cold tested at Tsinghua University and then delivered to CERN for high power test. Both the results of the cold and high power tests show that the correction cavity chain is of good performance. Feasibility and stability of the pulse compression system based on CC-SC scheme were demonstrated.
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THPMK068	High degree circular polarization at x-ray self-seeding FELs with crossed-planar undulators	undulator, FEL, laser, electron	4453
	K. Li, H.X. Deng, Z.F. Gao, B. Liu, D. Wang SINAP, Shanghai, People's Republic of China
	Funding: Work was supported by the National Natural Science Foundation of China (11775293), the National Key Research and Development Program of China (2016YFA0401900). The crossed undulator configuration for a high-gain free-electron laser (FEL) is well-known for the ability of versatile polarization control. However, the degree of polarization is very sensitive to power and phase between the two stages of crossed undulators. In this poster, we introduce the generation of high degree circular polarization hard x-ray FEL with crossed-planar undulator seeded by self-seeding. The reverse taper and taper undulator technology are employed for improving its performance. With the combination of high degree (>95%) circular polarization and flexibility of polarization switching, this scheme might be useful for some scientific research in the future.
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THPML009	Polarized Deuteron Negative Ion Source for Nuclear Physics Applications	plasma, laser, ion-source, electron	4665
	V.G. Dudnikov, M.A. Cummings, R.P. Johnson Muons, Inc, Illinois, USA A.V. Sy JLab, Newport News, Virginia, USA
	The proposed U.S. Electron-Ion Collider (EIC) provides a unique tool to explore the next frontier in Quantum Chromodynamics, the dependence of hadron structure on the dynamics of gluons and sea quarks. Polarized beams are essential to these studies; understanding of the hadron structure cannot be achieved without knowledge of the spin. The existing EIC concepts utilize both polarized electrons and polarized protons/light ion species to probe the sea quark and gluon distributions. Polarized deuterons provide an especially unique system for study by essentially providing a combination of quark and nuclear physics. We note that there are currently no operational polarized deuteron beam sources in the United States. This polarized deuteron source can serve as a polarized deuteron injector for a future EIC, with additional applications in polarimetry and polarized gas targets for experiments at CEBAF or RHIC and would be very useful for our future facilities.
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Paper

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MOZGBF5

Analysis of Polarization Decay at RHIC Store

resonance, emittance, lattice, target

76

H. Huang, P. Adams, E.C. Aschenauer, A. Poblaguev, W.B. Schmidke
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
There are polarization losses in RHIC store due to various sources, such as emittance growth and higher order spin resonances. The beam polarization was measured several times over a store by the p-carbon polarimeters situated in both rings. These provide information on the polarization decay over time and also polarization profile development over time. A polarized jet was also used to monitor the polarization continuously through store, though with limited statistical accuracy. These polarization measurements and emittance measurements from the IPM are analyzed and the polarization loss from different sources are reviewed.

Slides MOZGBF5 [4.526 MB]

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MOPMF004

Spin Dynamics in the JLEIC Alternative Pre-Booster Ring

resonance, booster, proton, dipole

87

J.L. Martinez Marin, B. Mustapha
ANL, Argonne, USA

In order to reduce the foot-print of the JLEIC ion complex, we have designed a more compact and cost-effective octagonal 3-GeV pre-booster ring half the size of the orig-inal figure-8 design. However, this new ring does not preserve ion polarization by design as the figure-8 shape, making it necessary to study the spin dynamics to find the best solution for spin correction. Different codes, Zgoubi and COSY, are used to model and simu-late the spin dynamics in the octagonal 3 GeV ring, in-cluding spin correction with Siberian snakes.

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MOPMF013

eRHIC EIC: Plans for Rapid Acceleration of Polarized Electron Bunch at Cornell Synchrotron

electron, synchrotron, resonance, acceleration

108

F. Méot, E.C. Aschenauer, H. Huang, C. Montag, V. Ptitsyn, V.H. Ranjbar, E. Wang, Z. Zhao
BNL, Upton, Long Island, New York, USA
I.V. Bazarov, D. L. Rubin
Cornell University, Ithaca, New York, USA
L. Cultrera, G.H. Hoffstaetter, K.W. Smolenski, R.M. Talman
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D. Gaskell, O. Glamazdin, J.M. Grames
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.
An option as an injector into the polarized-electron storage ring of eRHIC EIC is a rapid-cycling synchrotron (RCS). Cornell's 10 GeV RCS injector to CESR presents a good opportunity for dedicated polarized bunch rapid-acceleration experiments, it can also serve as a test bed for source and polarimetry developments in the frame of the EIC R&D, as polarized bunch experiments require disposing of a polarized electron source, and of dedicated polarimetry in the linac region and in the RCS proper. This is as well an opportunity for a pluri-disciplinary collaboration between Laboratories. This paper is an introduction to the topic, and to on-going activities towards that EIC R&D project.

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MOPMF014

Polarization at eRHIC Electron Storage Ring, an Ergodic Approach

electron, simulation, lattice, storage-ring

112

F. Méot
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Based on considerations of ergodicity of the dynamical system of an electron bunch at equilibrium, the preservation of polarization in an electron storage ring is estimated from the tracking of a very limited number of electrons. This has a substantial impact on required High Power Computing resources, in noticeable contrast with the method generally used that tracks tens of electron bunches, each comprised of thousands of particles, for several thousands of turns. It is also shown that a minimum number of tracking turns is required in order to ensure the numerical convergence of the linear regressions that yield depolarizing time constant values from tracking, in both methods.

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MOPMF016

Progress on RCS eRHIC Injector Design

resonance, emittance, lattice, detector

115

V.H. Ranjbar, M. Blaskiewicz, J.M. Brennan, S.J. Brooks, D.M. Gassner, H.-C. Hseuh, I. Marneris, F. Méot, M.G. Minty, C. Montag, V. Ptitsyn, K.S. Smith, S. Tepikian, F.J. Willeke, H. Witte, B. P. Xiao, A. Zaltsman
BNL, Upton, Long Island, New York, USA
I.V. Pogorelov
Tech-X, Boulder, Colorado, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We have refined the design for the Rapid Cycling Synchrotron (RCS) polarized electron injector for eRHIC. The newer design includes bypasses for the eRHIC detectors and definition of the lattice layout in the existing RHIC tunnel. Additionally, we provide more details on the RF, alignment and orbit control, and magnet specifications.

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MOPMF018

Numerical Simulation of Spin Dynamics with Spin Flipper in RHIC

resonance, dipole, simulation, injection

118

P. Adams, H. Huang, J. Kewisch, F. Méot, P. Oddo, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Spin flipper experiments during RHIC Run 17 were performed to study its effectiveness as a method for polarization sign reversal during stores. Numerical simulations are reported here, which were performed in accompaniment of these, and are being pursued with the aim of accurately reproducing the experimental conditions and providing thorough insight in the role of various key parameters participating in the dynamics of the spin flip, such as the sweep rate of the AC dipole, chromatic orbit control at RHIC snakes, RF parameters, possible effects of non-linear spin resonances, mirror resonance, tolerance on flipper magnet parameters, etc. The ultimate goal is for these simulations to serve as a guidance toward perfect flip to allow routine use during physics Runs.

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MOPMF028

A Superconvergent Algorithm for Invariant Spin Field Stroboscopic Calculations

simulation, resonance, storage-ring, lattice

145

D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: National Science Foundation and the Department of Energy
Stroboscopic averaging can be used to calculate the invariant spin field \bfn for particles with a finite oscillation amplitude in phase space. The standard technique starts with making a guess for \bfn(\bfr), which is a function of the phase space position \bfr. By tracking a particle's orbital position forward in time and then projecting the guessed \bfn backwards to the starting phase space point, the average of the backward projected spins will converge to the invariant spin direction linearly as 1/N where N is the number of turns tracked. The convergence can be accelerated by an iterative method that uses an approximate invariant spin field constructed by averaging the calculated spin field over points that are close in orbital phase space. This superconvergent algorithm has been built into a new program based upon the Bmad toolkit for charged particle and X-ray simulations.

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MOPMF071

Polarization Studies for the eRHIC electron Storage Ring

storage-ring, electron, coupling, solenoid

292

E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
S. Tepikian
BNL, Upton, Long Island, New York, USA

Funding: Manuscript authored by Fermi Res. All., LLC under Contr. No. DE-AC02-07CH11359 and Brookhaven Sc. Ass., LLC under Contr. No. DE-AC02-98CH10886 with the U.S. DOE, Office of Science, Office of HEP.
A hadron/lepton collider with polarized beams has been under consideration by the scientific community since some years, in the U.S. and Europe. Among the various proposals, those by JLAB and BNL with polarized electron and proton beams are currently under closer study in the U.S. Experimenters call for the simultaneous storage of electron bunches with both spin helicity. In the BNL based Ring-Ring design, electrons are stored at top energy in a ring to be accommodated in the existing RHIC tunnel. The transversely polarized electron beam is injected into the storage ring at variable energies, between 5 and 18 GeV. Polarization is brought into the longitudinal direction at the IP by a couple of spin rotators. In this paper results of first studies of the attainable beam polarization level and lifetime in the storage ring at 18 GeV are presented.

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MOPML007

Analysis of Spin Response Function at Beam Interaction Point in JLEIC

resonance, collider, proton, sextupole

400

V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under con-tracts DE-AC05-06OR23177 and DE-AC02-06CH11357.
The spin response function is determined by a collid-er's magnetic lattice and allows one to account for con-tributions of perturbing fields to spin resonance strengths. The depolarizing effect of an incoming beam depends significantly on the response function value at the interaction point (IP). We present an analytic calcula-tion of the response function for protons and deuterons at the IP of Jefferson Lab Electron Ion Collider (JLEIC) over its whole momentum range. We find a good agreement of the analytic calculation with our numerical modeling results obtained using a spin tracking code, Zgoubi.

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TUXGBD3

Ideas and Concepts for Future Electron Ion Colliders

electron, luminosity, collider, detector

590

F.C. Pilat
ORNL, Oak Ridge, Tennessee, USA

Different versions of future electron-ion colliders have been proposed by Brookhaven National Laboratory (BNL) and Thomas Jefferson National Laboratory (JLAB), one based on colliding protons in a ring with electrons from an Energy Recovery Linac (ERL), the other two based on ring-ring colliders. To attain the luminosity goal strong hadron cooling is required, as could be provided with several proposed new cooling schemes. Polarization of both colliding beams is essential. This invited talk will compare the various designs and highlight some of the novel ideas and concepts.

Slides TUXGBD3 [76.608 MB]

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TUYGBE4

Optically-pumped Polarized H⁻ and 3 He++ Ion Sources Development at RHIC

injection, ion-source, electron, solenoid

644

A. Zelenski, G. Atoian, E.N. Beebe, A. Poblaguev, D. Raparia, J. Ritter
BNL, Upton, Long Island, New York, USA
J.D. Maxwell, R. Milner, M. Musgrave
MIT, Cambridge, Massachusetts, USA

The RHIC Optically-pumped Polarized H⁻ Ion Source (OPPIS) upgrade with the atomic beam hydrogen injector and the He-ionizer cell was commissioned for operation in the Run-2013. The use of the high brightness primary proton source resulted in higher polarized beam intensity and polarization delivered for injection to Linac-Booster-AGS-RHIC accelerator complex. The proposed polarized 3He++ acceleration in RHIC and future electron- ion col-lider (eRHIC) will require about 2·10¹¹ ions in the source pulse. A new technique had been proposed for production of high intensity polarized 3He++ ion beam. It is based on ionization and accumulation of the 3He gas (polarized by optical-pumping and metastability-exchange technique in the high magnetic field of a 5.0 T) in the Electron Beam Ion Source (EBIS). We present a status of the 3He++ ion source development.

Slides TUYGBE4 [4.596 MB]

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TUPMF022

Electron Beam Scanning in the Delta-Type Undulators for Sirius

undulator, electron, radiation, storage-ring

1300

A. B. da Cruz, L. Liu
LNLS, Campinas, Brazil

We report on simulation studies to analyze the possibility of scanning the electron beam, and not scanning the sample, in CDI experiments using a Delta-Type undulator in the 3GeV Sirius electron storage ring presently under construction at LNLS. This would allow much faster scans in diffraction limited storage rings such as Sirius. We study displaced beam trajectories through the undulators and analyze the effects on the emitted radiation. It is possible to show that displacements on the order of ± 500 micrometers around the center will introduce variations in the radiation spectrum that are less that 1 per cent and thus acceptable for Coherent Diffraction Imaging experiments.

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TUPMK003

Advances in the Sirius Delta-Type Undulator Project

undulator, lattice, storage-ring, MMI

1491

L.N.P. Vilela, R. Basílio, J.F. Citadini, J.R. Furaer, F. Rodrigues
LNLS, Campinas, Brazil

The Delta undulator is a compact adjustable-phase insertion device that provides full light polarization control. Five undulators of this type will be installed in the initial operation phase of Sirius, the new 4th generation synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). In this work we present the recent advances in the development of Sirius Delta-type undulator, the studies of the effects of this device in the storage ring beam dynamics and assembly and measurements strategies.

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TUPML020

Beamline Design of EMuS - the First Experimental Muon Source in China

solenoid, proton, target, experiment

1574

Y. Bao, Y.K. Chen, Z.L. Hou, Y.P. Song, J.Y. Tang, N. Vassilopoulos, Y. Yuan, G. Zhao, L. Zhou
IHEP, Beijing, People's Republic of China
H.T. Jing
IHEP CSNS, Dongguan, People's Republic of China

Funding: This work is supported by National Natural Science Foundation of China under Grants 11575217 and 11527811. Yu Bao thanks Hundred Talents Program of Chinese Academy of Science.
We report the beamline design of the Experimental Muon Source (EMuS) project in China. Based on the 1.6 GeV/100 kW proton accelerator at the Chinese Spallation Neutron Source (CSNS), EMuS will extract one bunch from every 10 double-bunch proton pulses to hit a stand-alone target sitting in a superconducting solenoid, and the secondary muons/pions are guided to the experimental area. The beamline is designed to provide both a surface muon beam and a decay muon beam, so that various experiments such as muSR applications and particle/nuclear physics experiments can be conducted. In this work we present the conceptual design and simulation of the beamlines, and discuss the future aspects of the project.

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TUPML025

Long Lifetime Spin-Polarized GaAs Photocathode Activated by Cs2Te

cathode, electron, vacuum, photon

1589

J. Bae, L. Cultrera, P. Digiacomo
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
I.V. Bazarov
Cornell University, Ithaca, New York, USA

Funding: This work was supported by the Department of Energy Grant Nos. DE-SC0016203 and NSF PHY-1461111.
High intensity and highly spin-polarized electron source is of great interest to the next generation Electron Ion Colliders. GaAs prepared by the standard activation method, which is the most widely used spin-polarized photocathode, is notorious for its vacuum sensitivity and short operational lifetime. To improve the lifetime of GaAs photocathodes, we activated GaAs by Cs2Te, a material well known for its robustness. We confirmed the Cs2Te layer forms negative electron affinity on GaAs with a factor of 5 improvement in lifetime. Furthermore, the new activation method had no adverse effect on spin-polarization. Considering Cs2Te forms much thicker activation layer (~ 2 nm) compared to the standard activation layer (~ monolayer), our results trigger a paradigm shift on new activation methods with other robust materials that were avoided for their thickness.

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TUPML031

Characterization of Polarization-Dependent Emittance From an Array of Au Nanorods using Velocity Map Imaging Spectrometer

electron, laser, emittance, experiment

1612

H. Ye, F.X. Kärtner, S. T. Trippel
Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
A. Fallahi, J. Küpper, O. Muecke
CFEL, Hamburg, Germany
F.X. Kärtner
MIT, Cambridge, Massachusetts, USA
F.X. Kärtner, J. Küpper, S. T. Trippel, H. Ye
The Hamburg Center for Ultrafast Imaging, University of Hamburg, hamburg, Germany
J. Küpper, G.M. Rossi
DESY, Hamburg, Germany
H. Ye
University of Hamburg, Hamburg, Germany

Electron beams of high quality, e.g., low emittance, are of crucial importance for cutting-edge scientific instruments, such as x-ray free electron lasers (XFELs) and ultrafast electron diffraction (UED) setups. A velocity-map-imaging (VMI) spectrometer was implemented to characterize the intrinsic root-mean-square (rms) normalized emittance from photocathodes. The spectrometer operated in both, spatial map imaging (SMI) and VMI modes. Therefore, spatial- and velocity-coordinates were recorded independently and quickly. The technique allows for fast complete emittance measurements, within minutes. A 75 μm pitch array of Au nanorods of dimension 100×30~nm, was studied under strong-field-emission regime by 100 fs 1 kHz 1.3 μm laser pulses with a 300×30 μm² focus spot size on the sample. A patterned electron bunch was observed, each emitted from a single nanorod within the array. A polarization dependent photoemission study was performed showing a smaller rms-normalized divergence of 0.8 mrad with the laser polarization normal to the sample surface, compared to 1.15 mrad for the parallel case.

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WEPAL073

Enhanced Bunch Monitoring by Interferometric Electro-Optic Methods

pick-up, laser, proton, optics

2353

S.M. Gibson, A. Arteche, A. Bosco
Royal Holloway, University of London, Surrey, United Kingdom
S.E. Bashforth, A. Bosco, S.M. Gibson
JAI, Egham, Surrey, United Kingdom
M. Krupa, T. Lefèvre
CERN, Geneva, Switzerland

Funding: We acknowledge funding by UK STFC grant ST/N001583/1, JAI at Royal Holloway University of London and CERN
A prototype Electro-Optic Beam Position Monitor has been installed for tests* in the CERN SPS to develop the concept for high-bandwidth (6-12GHz) monitoring of crabbed-bunch rotation and intra-bunch instabilities at the High Luminosity LHC**. The technique relies on the ultrafast response of birefringent MgO:LiNO3 crystals to optically measure the intra-bunch transverse displacement of a passing relativistic bunch. This paper reports on recent developments, including a new interferometric electro-optic pick-up that was installed in the CERN SPS in September 2017; in first beam tests with nominal bunch charge, a corresponding interferometric signal has been observed. The interferometric arrangement has the advantages of being sensitive to the strongest polarisation coefficient of the crystal, and the phase offset of the interferometer is controllable by frequency scanning of the laser, which enables rapid optimisation of the working point. Novel concepts and bench tests for enhancements to the pick-up design are reviewed, together with prospects for sensitivity during the first crab-cavity beam tests at the CERN SPS in 2018.
* A. Arteche et al "First beam tests at the CERN SPS of an electro-optic beam position monitor for the HL-LHC" TUPCF23, IBIC 2017.
** HL-LHC TDR v0.1 doi.org/10.23731/CYRM-2017-004

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THPAK079

New Algorithms in Zgoubi

dipole, proton, simulation, factory

3418

D.T. Abell
RadiaSoft LLC, Boulder, Colorado, USA
F. Méot
BNL, Upton, Long Island, New York, USA

Funding: This work was supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics under Award No. DE-SC0017181.
The particle tracking code Zgoubi*,** is used for a broad array of accelerator design studies, including FFAGs*** and EICs****,*****. In this paper, we describe recent work aimed at improving Zgoubi's speed and flexibility. In particular, we describe a new implementation of the Zgoubi tracking algorithm that requires significantly less memory and arithmetic. And we describe a new algorithm that performs symplectic tracking through field maps. In addition, we describe the current efforts to parallelize Zgoubi.
*https://sourceforge.net/projects/zgoubi/
**F. Méot, FERMILAB-TM-2010, 1997
***F. Lemuet et al., NIM-A, 547:638, 2005
****F. Méot et al., eRHIC/45, 2015
*****F. Lin et al., IPAC17, WEPIK114, 2017

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THPAK144

A Pseudospectral Method for Solving the Bloch Equations of the Polarization Density in e^- Storage Rings

storage-ring, electron, ion-effects, synchrotron

3589

K.A. Heinemann, O. Beznosov, J.A. Ellison
UNM, Albuquerque, New Mexico, USA
D. Appelö
University of Colorado at Boulder, Boulder, USA
D.P. Barber
DESY, Hamburg, Germany

Funding: Work supported by DOE under DE-SC0018008
We consider the numerical evolution of Bloch equations for the polarization density in high-energy electron storage rings. Equilibrium polarization is well characterized by the DK formulas for current rings, but deviations may be important at the high energies we have in mind. We believe the Bloch equations derived in* give a more accurate description at all energies. These form a system of three coupled linear partial differential equations for the three components of the polarization density. Following** we formulate the equations in action-angle variables and approximate the Fokker-Planck terms. We aim to integrate these equations numerically in order to approximate the equilibrium and compare with the DK formulas. The smoothness and simple geometry of the problem makes it amenable to pseudospectral discretization using Fourier modes in the angles and Chebyshev polynomials in the actions, leading to a large ODE system. We will explore time stepping algorithms for the needed long time integration. Here, we present results for simple models checking the accuracy of the numerical method but note that our ultimate goal is to simulate polarization in the FCC and CEPC rings.
* Ya.S.Derbenev, A.M.Kondratenko, Sov. Phys. Dokl., 19, p.438 (1975).
** D.P.Barber, K.Heinemann, H.Mais, G.Ripken,
A Fokker-Planck treatment of stochastic particle motion…,
DESY-91-146, 1991.

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THPAL027

Transverse RF Deflecting Structures for the MAX IV LINAC

GUI, linac, klystron, emittance

3684

D. Olsson, F. Curbis, E. Mansten, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV LINAC operates both as a full-energy injector for two electron storage rings, and as a driver for a Short Pulse Facility (SPF). A soft X-ray Laser (SXL) beamline will also be installed in the end of the existing LINAC. For SPF and SXL operation, it is important to characterize beam parameters such as bunch profile, slice energy spread and slice emittance. For these measurements, two 3 m long transverse deflecting RF structures with a matching section are being developed. The structures are operating at S-band and have variable polarizations. When fed via a SLED pulse compressor, the two structures can generate a total integrated deflecting voltage higher than 100 MV which is sufficient for measurements with temporal resolutions down to 1 fs. This paper describes the initial RF design of the deflecting structures.

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THPAL153

High Power Test of the S-Band Spherical Pulse Compressor at Tsinghua University

cavity, FEL, coupling, klystron

4008

P. Wang, D.Z. Cao, H.B. Chen, C. Cheng, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

We designed, fabricated and high power tested an S-band spherical pulse compressor for the high-power test facility at Tsinghua University. The pulse compressor comprises a spherical resonant cavity with an unloaded quality factor of 100, 000 and an RF polarizer with two rectangular ports and a circular port. To achieve high efficiency and large power gain, the coupling coefficient was optimized to 8 with input pulse length of 3.6 us and compression ratio of 12. After conditioning the RF system, the pulse compressor generated RF pulses with peak power of more than 400MW. And during the operation, the pulse compressor has very low breakdown rate and was extremely stable.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL153

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THPAL155

Fabrication and Cold Test of the Correction Cavity Chain for Klystron-Based CLIC

cavity, operation, klystron, linear-collider

4014

P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

A proposed RF scheme based on correction cavity chain and storage cavity (CC-SC scheme) for klystron-based CLIC has the ability to generate flat output pulses. In the scheme, the correction cavity chain modulates the amplitude of the input pulse, while the storage cavity compresses the amplitude-modulated pulse. Resonant cavities of the correction cavity chain are of a relatively low unloaded quality factor and of small size, which results in the compactness of the RF scheme. The first prototype of a correction cavity chain was fabricated and cold tested at Tsinghua University and then delivered to CERN for high power test. Both the results of the cold and high power tests show that the correction cavity chain is of good performance. Feasibility and stability of the pulse compression system based on CC-SC scheme were demonstrated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL155

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THPMK068

High degree circular polarization at x-ray self-seeding FELs with crossed-planar undulators

undulator, FEL, laser, electron

4453

K. Li, H.X. Deng, Z.F. Gao, B. Liu, D. Wang
SINAP, Shanghai, People's Republic of China

Funding: Work was supported by the National Natural Science Foundation of China (11775293), the National Key Research and Development Program of China (2016YFA0401900).
The crossed undulator configuration for a high-gain free-electron laser (FEL) is well-known for the ability of versatile polarization control. However, the degree of polarization is very sensitive to power and phase between the two stages of crossed undulators. In this poster, we introduce the generation of high degree circular polarization hard x-ray FEL with crossed-planar undulator seeded by self-seeding. The reverse taper and taper undulator technology are employed for improving its performance. With the combination of high degree (>95%) circular polarization and flexibility of polarization switching, this scheme might be useful for some scientific research in the future.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK068

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THPML009

Polarized Deuteron Negative Ion Source for Nuclear Physics Applications

plasma, laser, ion-source, electron

4665

V.G. Dudnikov, M.A. Cummings, R.P. Johnson
Muons, Inc, Illinois, USA
A.V. Sy
JLab, Newport News, Virginia, USA

The proposed U.S. Electron-Ion Collider (EIC) provides a unique tool to explore the next frontier in Quantum Chromodynamics, the dependence of hadron structure on the dynamics of gluons and sea quarks. Polarized beams are essential to these studies; understanding of the hadron structure cannot be achieved without knowledge of the spin. The existing EIC concepts utilize both polarized electrons and polarized protons/light ion species to probe the sea quark and gluon distributions. Polarized deuterons provide an especially unique system for study by essentially providing a combination of quark and nuclear physics. We note that there are currently no operational polarized deuteron beam sources in the United States. This polarized deuteron source can serve as a polarized deuteron injector for a future EIC, with additional applications in polarimetry and polarized gas targets for experiments at CEBAF or RHIC and would be very useful for our future facilities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML009

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