IPAC2014 - List of Keywords (polarization)

Paper	Title	Other Keywords	Page
MOPRO004	Polarized Ion Beams in Figure-8 Rings of JLab's MEIC	solenoid, collider, controls, ion	68
	Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia Y.S. Derbenev, F. Lin, V.S. Morozov, Y. Zhang JLab, Newport News, Virginia, USA Y. Filatov JINR, Dubna, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. The Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is designed to provide high polarization of both colliding beams. One of the unique features of JLab’s MEIC is figure-8 shape of its rings. It allows preservation and control of polarization of all ion species including small-anomalous-magnetic-moment deuterons during their acceleration and storage. The figure-8 design conceptually expands the capability of obtaining polarized high-energy beams in comparison to conventional designs because of its property of having no preferred periodic spin direction. This allows one to control effectively the beam polarization by means of magnetic insertions with small field integrals. We present a complete scheme for preserving the ion polarization during all stages of acceleration and its control in the collider’s experimental straights.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO004
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MOPRO006	Preservation of Electron Polarization in the MEIC Collider Ring	electron, collider, injection, solenoid	74
	F. Lin, Y.S. Derbenev, V.S. Morozov, Y. Zhang JLab, Newport News, Virginia, USA D.P. Barber DESY, Hamburg, Germany
	Funding: U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. A highly longitudinally-polarized (over 70%) electron beam is required by the nuclear physics programme of the Medium Energy Electron-Ion Collider (MEIC) at Jefferson Lab (JLab). To achieve this goal, a highly vertically-polarized electron beam is injected from the CEBAF. The polarization will be vertical in the arcs to avoid spin diffusion, and longitudinal at the collision points. The polarization rotation will be accomplished by using a total of four spin rotators, each of which consists of a set of solenoids and dipoles, placed at the ends of two arcs. The polarization configuration cancels the 1st order spin perturbation in the solenoids for the off-momentum particles and significantly reduces the synchrotron sideband resonances. In order to compensate the net Sokolov-Ternov depolarization effect, especially at higher energies, a continuous injection of a polarized electron beam from the CEBAF is being considered. We consider to perform a moderate spin matching in some key regions to extend the polarization lifetime so that the continuous injection can work more efficiently, while not imposing a burden on the optics design of the collider ring.
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MOPRO062	Investigating Polarisation and Shape of Beam Microwave Signals at the ANKA Storage Ring	radiation, detector, synchrotron, synchrotron-radiation	4090
	J. Schwarzkopf, M. Brosi, C. Chang, E. Hertle, V. Judin, B. Kehrer, A.-S. Müller, A.-S. Müller, A.-S. Müller, M. Schuh, M. Schwarz, P. Schönfeldt, P. Schütze, J.L. Steinmann KIT, Karlsruhe, Germany F. Caspers CERN, Geneva, Switzerland
	At the ANKA synchrotron radiation facility measurements in the microwave range (~10 to 12 GHz) employing a LNB (Low Noise Block), which is the receiving part of a Satellite-TV system, have been carried out. Experiments showed that the observed signal depends on the length of the electron bunches. Furthermore the temporal shape of the microwave signal depends on the detector's position along the accelerator. Due the LNB antenna's sensitivity to polarisation it was also possible to measure the polarisation along the several ns long signal, revealing polarised and non-polarised regions. This paper describes the experimental setup and summarises the observations of the systematic studies performed with the LNB system.
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MOPME014	Automated Mode Recognition Algorithm for Accelerating Cavities	cavity, coupling, simulation, dipole	409
	K. Brackebusch, T. Galek, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K13HR1. Eigenmode simulations of accelerating structures often involve a large number of computed modes that need to be catalogued and compared. In order to effectively process all the information gathered from eigenmode simulations a new algorithm was developed to automatically recognize modes’ field patterns. In this paper we present the principles of the algorithm and investigate its applicability by means of different single and multi cell cavities. The highest achievable order of correctly recognized modes is of particular interest.
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TUOCB03	Performance of Elliptical Polarization Undulators at TPS	undulator, multipole, photon, FEL	987
	T.Y. Chung, C.-H. Chang, C.H. Chang, J.C. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin, C.Y. Wu NSRRC, Hsinchu, Taiwan
	Design, assembly, field shimming, and performance of APPLE-II type undulators in NSRRC are described in this article. Essentially, the mechanical error has been well controlled based on the optimize design and mechanical arts. Effectively initial sorting of permanent magnets is developed to minimize several adverse effects, such as magnetic inhomogeneities, no perfection geometry of blocks, and mechanical frame issue, those challenge the sorting expectation, especially for an adjusted polarization undulator. The sorting algorithm shows a quantitative prediction of magnetic field and is verified by measurement results. 2D virtual shimming algorithm has been developed to optimize field quality, including multipole, phase error, and particle trajectory. We describe the considering of each procedure and demonstrate the optimization together with measurement results.
	Slides TUOCB03 [1.503 MB]
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TUPRO004	Polarized Protons and Deuterons at NICA@JINR	proton, collider, luminosity, ion	1000
	A.D. Kovalenko, A.V. Butenko, V.D. Kekelidze, V.A. Mikhaylov JINR, Dubna, Moscow Region, Russia Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Different aspects of the NICA facility operation in polarized proton and deuteron modes aimed at reaching the highest possible luminosity and polarization degree as well are analysed. The main aim is to provide average luminosity L ≥ 1•1032 cm^-2 s⁻¹ at √sNN ≥ 26-27 GeV for single-spin proton collisions. Optimal schemes of the Siberian Snake insertions to the Nuclotron and NICA collider rings were proposed. The results of simulations are presented and discussed.
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TUPRO039	Optimizing Polarization with an Improved Integer Resonance Correction Scheme at ELSA	resonance, electron, quadrupole, closed-orbit	1108
	J.F. Schmidt, O. Boldt, F. Frommberger, W. Hillert, J.-P. Thiry ELSA, Bonn, Germany
	Funding: DFG The Electron Stretcher Facility ELSA of Bonn University provides a polarized electron beam of up to 3.2 GeV. In the stretcher ring various depolarizing resonances are crossed during the fast energy ramp of 6 GeV/s. The high polarization degree of up to 70% can only be conserved by taking several appropriate countermeasures. Concerning integer resonances, additional harmonic horizontal fields are applied by orbit correction magnets around the ring to compensate the resonance driving fields. The correction field has to be adjusted by empirical optimization of polarization. Recent developments enhance this optimization process, especially at high energies: A new magnet system allows for higher correction amplitudes and shorter rising times. Furthermore, a modified correction scheme was implemented. It takes into account the additional fields of the quadrupole magnets, arising from the orbit response of the correction magnets.
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TUPRO040	High Bandwidth Closed Orbit Control for a Fast Ramping Electron Accelerator	closed-orbit, resonance, acceleration, electron	1111
	J.-P. Thiry, A. Dieckmann, F. Frommberger, W. Hillert, J.F. Schmidt ELSA, Bonn, Germany
	ELSA is a fast ramping stretcher ring capable of acceleration and storage of polarized electrons with energies up to 3.2 GeV. To preserve the initial degree of polarization, the acceleration is performed by a fast energy ramp with a maximum ramping speed of 6 GeV/s. During acceleration especially the vertical orbit needs to be continuously corrected so that the vertical rms deviation does not exceed 50 μm at any time. In order to compensate the so called integer resonances, which occur at certain energies, the orbit correction system further needs to provide additional, empirically determined, harmonic field distributions. A successful application of these combined correction measures requires a considerably high bandwidth of up to some 100 Hz. In our contribution we will have a closer look at the performance and the acquired bandwidth of the correction system.
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TUPRO059	Beam Energy Measurements using Resonant Spin Depolarization at ALBA	resonance, beam-losses, feedback, synchrotron	1168
	Z. Martí, U. Iriso, F. Pérez CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	Energy measurements with precision down to 10^-5 are inferred from the lifetime evolution when the beam is depolarized using AC kicks with the Transverse Fast Feedback system. Lifetime measurements are carried out using the DCCT, the BPM sum signals, pin-diode BLMs, and a scintillator based Beam Loss Detector. Results obtained with this instrumentation are reported.
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TUPRO085	Properties, Options and Limitations of PrFeB-magnets for Cryogenic Undulators	undulator, cryogenics, permanent-magnet, induction	1238
	F.-J. Börgermann, C. Brombacher, K. Üstüner Vacuumschmelze GmbH & Co. KG, Hanau, Germany
	The gap induction and thus the K-factor of permanent magnet undulators may be increased by cooling them to cryogenic temperatures. The use of NdFeB-magnets in cryogenic undulators, however, is limited to temperatures above 140 K due to the spin-reorientation transition (SRT) which leads to a reduction of the magnetization level. A further increase of the gap induction in undulators may be achieved by use of PrFeB-magnets at even lower temperatures, as this alloy does not show the SRT phenomenon. Although the effects are well known, up to now only a few undulator prototypes were built using this class of material since the coercivity of ternary PrFeB-magnets is not sufficient to minimize the risk of partial demagnetization when the undulator structure is kept at room temperature. This problem can be solved by applying actual technologies like grain-boundary diffusion in order to achieve coercivities exceeding 20 kOe at RT without sacrificing the high remanence Br of about 1.6 T at 77 K. We will provide actual data of the magnet performance achieved and show up the technological limitations in building PrFeB-based CPMU’s.
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WEPRO024	Simulation of a Long-period EPU Operating in Universal Mode at the Canadian Light Source	alignment, dynamic-aperture, photon, simulation	1995
	W.A. Wurtz, D. Bertwistle, L.O. Dallin, M.J. Sigrist CLS, Saskatoon, Saskatchewan, Canada
	The Canadian Light Source is implementing an elliptically polarizing undulator (EPU) with period 180 mm for the production of soft x-rays with variable polarization. Two issues arise from implementing such a device. First, a long-period EPU can cause significant loss of dynamic aperture due to strong dynamic focusing. Second, to compensate for polarization effects due to beamline optics, the EPU must be able to produce light with an arbitrary polarization at the source point, which is referred to as universal mode. We present a scheme for operating the EPU in universal mode and discuss the use of BESSY-style current strips in order to compensate for dynamic effects. Tracking simulations suggest that dynamic aperture can be sufficiently recovered for all required operating points in universal mode.
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WEPRO038	Possibility for Quasi-periodic Knot-APPLE Undulator	undulator, radiation, synchrotron, synchrotron-radiation	2026
	S. Sasaki, A. Miyamoto HSRC, Higashi-Hiroshima, Japan N. Kawata, T. Mitsuyasu Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan S. Qiao SIMIT, Shanghai, People's Republic of China
	An intense on-axis radiation power from an undulator is a serious problem especially for a low-photon-energy beamline in a facility with high or medium energy storage ring. This problem may be solved by using a Figure-8, a Pera, or a Knot undulator configuration,. However, these schemes are useless for variably polarizing undulators such as an APPLE undulator and other similar variations since such devices are not capable for reducing on-axis power density in the linear mode. In these circumstances, we have completed a conceptual magnet design of Knot-APPLE udulator which is capable to generate elliptically polarized radiation as well as linearly polarized radiation. This pure permanent magnet device is equipped with a motion mechanism of APPLE undulator. In this paper, we present detailed magnet design feature, magnetic field distributions, and radiation properties including variations of polarization in comparisons with other exotic devices. In addition, a possibility to introduce a quasi-periodicity in this type of undulator is considered in order to achieve further reduction of second and third harmonic radiation intensities. S. Sasaki, "Undulators, wigglers and their applications," p.237-243 (Ed. by H. Onuki and P. Elleaume, Taylor & Francis Inc, New York, 2003). **S. Qiao, et. al, Rev. Sci. Instrum., 80, 085108 (2009).
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WEPRO070	Overcoming the Horizontal Depolarizing Resonance in the Brookhaven AGS	resonance, emittance, timing, betatron	2112
	H. Huang, L. Ahrens, M. Bai, M. Blaskiewicz, K.A. Brown, R. Connolly, Y. Dutheil, W. Fischer, C.J. Gardner, J.W. Glenn, T. Hayes, F. Méot, A. Poblaguev, V.H. Ranjbar, T. Roser, V. Schoefer, K.S. Smith, S. Tepikian, N. Tsoupas, K. Yip, A. Zelenski, K. Zeno, S.Y. Zhang 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. Imperfection and vertical intrinsic depolarizing resonances have been overcome by the two partial Siberian snakes in the AGS. The relatively weak but numerous horizontal resonances are the main source of polarization loss in the AGS. A pair of horizontal quads have been used to overcome these weak resonances. This technique needs very accurate jump timing. Fast roll-over magnet cycle has been used and it improves the polarization transmission efficiency near extraction when acceleration usually is slowing down. Emittance preservation is also important to mitigate polarization loss. Recent experimental results including jump quad timing and emittance preservation are presented in this paper.
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WEPRO071	Optics Setup in the AGS and AGS Booster for Polarized Helion Beam	resonance, booster, proton, injection	2115
	H. Huang, L. Ahrens, J.G. Alessi, M. Bai, E.N. Beebe, M. Blaskiewicz, K.A. Brown, Y. Dutheil, W. Fischer, C.J. Gardner, J.W. Glenn, T. Hayes, F. Méot, A. Poblaguev, V.H. Ranjbar, T. Roser, V. Schoefer, K.S. Smith, S. Tepikian, N. Tsoupas, K. Yip, A. Zelenski, K. Zeno 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. Future RHIC physics program calls for polarized He3 beam. The He3 beam from the new EBIS source has a relative low rigidity which requires delicate control of injection and RF setup in the Booster. The strong depolarization resonance strength in both AGS and AGS Booster requires careful consideration of beam energy range and optics setup. Recently, the He3 beam was accelerated to 11GeV/n in the AGS. The near term goal fo 3*10¹⁰ at RHIC requires several RF bunch merges in both AGS and the Booster. The beam test results are presented in this paper.
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THPRO008	Obtaining High Degree of Circular Polarization at X-ray FELs via a Reverse Undulator Taper	undulator, FEL, radiation, bunching	2870
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical (or cross-planar) afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. In this paper we propose a new method for such a suppression: an application of the reverse taper in the main undulator. We discover that in a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. Considering SASE3 undulator of the European XFEL as a practical example, we demonstrate that soft X-ray radiation pulses with peak power in excess of 100 GW and an ultimately high degree of circular polarization can be produced. Phys. Rev. ST-AB 16(2013)110702
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THPRO041	Position of Maximum in Quantum Spectrum of Synchrotron Radiation	radiation, electron, synchrotron, synchrotron-radiation	2952
	A.N. Burimova, D.M. Gitman IFUSP, Sao Paulo, Brazil V.G. Bagrov Institute of High Current Electronics, Tomsk, Russia
	Funding: FAPESP In the framework of quantum theory, we consider the condition for radiation maximum shift between harmonics of SR spectrum for scalar and spinor particles. Since quantum spectrum is discrete and finite, one can find values of radiation parameters such that the maximum in radiation spectrum stays at highest harmonic. It turns out that there exists a "quantization" of magnetic field associated with shift of maximum from one harmonic to another.
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THPRO056	Estimation of Systematic Errors for Deuteron Electric Dipole Moment (EDM) Search at a Storage Ring	simulation, dipole, experiment, extraction	2998
	S. Chekmenev RWTH, Aachen, Germany
	An experimental method which is aimed to find a permanent EDM of a charged particle was proposed by JEDI (Jülich Electric Dipole moment Investigations) collaboration in 2012. EDMs can be observed by their small influence on spin motion. The only possible way to perform a direct measurement is to use a storage ring. For this purpose it was decided to carry out the first precursor experiment at the Cooler Synchrotron (COSY). Since the EDM of a particle violates CP invariance and is expected to be tiny, treatment of all various sources of systematic errors should be done with a great level of precision. One should clearly understand how misalignments of the magnets affects the beam and the spin motion. In reality, one of the methods to investigate spin behavior in the presence of misalignments in a storage ring is to mimic their influence on the beam parameters using small orbit kicks with different amplitudes. In this talk the first simulations of orbit excitations will be discussed. The corresponding spin tune shifts will be considered. The influence of the distorted orbit on the polarization build-up caused by the EDM will be examined. A. Lehrach, F. Rathmann, J. Pretz et al., "Search for Permanent Electric Dipole Moments at COSY. Step 1: Spin coherence and systematic error studies", 2012
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THPRO061	New and Unifying Formalism for Study of Particle-Spin Dynamics Using Tools Distilled From Theory of Bundles	resonance, HOM, lepton, framework	3014
	K.A. Heinemann, J.A. Ellison UNM, Albuquerque, New Mexico, USA D.P. Barber Cockcroft Institute, Warrington, Cheshire, United Kingdom D.P. Barber, M. Vogt DESY, Hamburg, Germany
	Funding: The work of JAE and KH was supported by DOE under DE-FG-99ER41104 and the work of DPB and MV was supported by DESY. We summarize our recent work on spin motion in storage rings . In fact we return to our study * of spin motion in storage rings. We again focus on spin tunes, polarization fields etc. but in contrast to ** we base the description on one turn maps and refine and expand our toolset from that in * by using a rather modern method from Dynamical-Systems theory, developed in the 1980's by R. Zimmer and others based on bundles , . With this we obtain new insights into invariant spin fields, invariant frame fields, spin tunes and spin-orbit resonances. At the same time we get a unified way to treat spin-1/2 and spin-1 particles. The bundle aspect is pointed out and we briefly mention the relation to Yang-Mills Theory as well. K.Heinemann, D.P.Barber, J.A.Ellison, M.Vogt. To be submitted. D.P.B., J.A.E., K.H., PRSTAB 7 (2004) 124002. * K.Heinemann, PhD Thesis, University of New Mexico, 2010 (available on the web).
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THPRO089	New Tune Jumps Scheme in the Low Energy Part of the AGS Cycle	resonance, simulation, acceleration, hardware	3092
	Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, V. Schoefer 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. During the early part of the acceleration of polarized protons, due to strong optical deformations of the lattice, the tune cannot be placed in the spin gap and the first two vertical intrinsic resonances are crossed. Recent multiparticle trackings using the Zgoubi code show that the spin resonances around Gg=5 could cause as much as 5% loss of polarization. The slow acceleration rate, the two vertical and two horizontal intrinsic spin resonances can contribute to the depolarization in the region. While in the current scheme only the two horizontal intrinsic resonances are jumped, it was proposed to use the tune jumps system to also accelerate the crossing of the two weak vertical intrinsic resonances and improve the polarization transmission through this region. We show the design of this new tune jumps scheme and the expected polarization gains expected from multiparticles Zgoubi simulations. We also compare experimental measurements of the polarization transmission to the Zgoubi simulations.
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THPRO090	Energy Calibration and Tune Jumps Efficiency in the pp AGS	timing, resonance, acceleration, extraction	3095
	Y. Dutheil, L. Ahrens, H. Huang, F. Méot, A. Poblaguev, V. Schoefer, K. Yip 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. The AGS tune jump system consists of two fast quadrupoles used to accelerate the crossing of 82 horizontal intrinsic spin resonances. The fast tune jump of ΔQh=+0.04 within 100 μs imposes perfect localization of each of the 82 resonant conditions. Imperfect timing of the tune jumps results in lower efficiency of the system and lower transmission of the polarization through the AGS acceleration cycle. Investigations during the end of the pp AGS Run13 revealed weaknesses in the energy measurement at high energy, causing less than optimal timing of the tune jumps. A new method based on continuous polarization measurement to determine the energy during the acceleration cycle has been developed. Strong operational constraints were taken into account to provide a convenient system of energy measurement. This is also used to calibrate the usual determination of the energy based on revolution frequency of the beam or measured dipole magnetic field. This paper shows the tools developed and the results of the first tests during the AGS Run 14. Simulations of the expected tune jumps efficiency using the AGS Zgoubi model are also presented and compared to experimental results.
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THPRO091	Strength of Horizontal Intrinsic Spin Resonances in the AGS	resonance, emittance, optics, proton	3098
	Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, T. Roser, V. Schoefer 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. Crossing of horizontal intrinsic resonances is today the main source of polarization losses in the AGS, in its dual partial snakes configuration for polarized proton acceleration. Polarization losses were greatly reduced by the AGS tune jump system. However total polarization transmission through the AGS cycle is not yet achieved, still partially due to the horizontal intrinsic resonances. This paper will explore the effect of optical distortions and different horizontal tunes on the strength of horizontal intrinsic resonances. Various options will be presented and practicability will be addressed. Theoretical model and multiparticle trackings using the Zgoubi code will show the expected polarization gains of different scenarios.
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THPME158	Coherent Diffraction and Cherenkov Radiation from Short Electron Bunches in Fibers	radiation, electron, experiment, target	3632
	G.A. Naumenko, V.V. Bleko, A. Potylitsyn, V.V. Soboleva TPU, Tomsk, Russia
	Funding: This work is particularly supported by grant of Russian MES Program "Nauka" number 2456 The ability to use a radiation of relativistic electrons in optical fibers for beam diagnostics was proposed by X. Artu recently . In the cited work the properties of different types of radiation, such as diffraction and Cherenkov radiation in the visible region, induced in fibers by relativistic electron were considered. In our report we present the results of experimental investigation of such a phenomenon for millimeter wavelength radiation. The origin and properties of radiation in fibers were investigated for different geometries of fiber position in respect to the electron beam. The spectral characteristics and dependence on the orientation angle of fibers relative to the electron beam were investigated. One of the useful properties of fibers is the fiber flexibility. The characteristics of radiation accepted by flexible fiber with diameter D=11 mm and length L=600 mm were investigated as a function of curvature radius of the fiber R. The experimental results show the allowable transport factor of radiation for the condition L>R>>D. We believe that fibers for mm and submm range can be used for beam diagnostics also. X Artru and C. Ray, Nucl. Inst. Meth. B 309 (2013)
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Paper

Title

Other Keywords

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MOPRO004

Polarized Ion Beams in Figure-8 Rings of JLab's MEIC

solenoid, collider, controls, ion

68

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

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is designed to provide high polarization of both colliding beams. One of the unique features of JLab’s MEIC is figure-8 shape of its rings. It allows preservation and control of polarization of all ion species including small-anomalous-magnetic-moment deuterons during their acceleration and storage. The figure-8 design conceptually expands the capability of obtaining polarized high-energy beams in comparison to conventional designs because of its property of having no preferred periodic spin direction. This allows one to control effectively the beam polarization by means of magnetic insertions with small field integrals. We present a complete scheme for preserving the ion polarization during all stages of acceleration and its control in the collider’s experimental straights.

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MOPRO006

Preservation of Electron Polarization in the MEIC Collider Ring

electron, collider, injection, solenoid

74

F. Lin, Y.S. Derbenev, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA
D.P. Barber
DESY, Hamburg, Germany

Funding: U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
A highly longitudinally-polarized (over 70%) electron beam is required by the nuclear physics programme of the Medium Energy Electron-Ion Collider (MEIC) at Jefferson Lab (JLab). To achieve this goal, a highly vertically-polarized electron beam is injected from the CEBAF. The polarization will be vertical in the arcs to avoid spin diffusion, and longitudinal at the collision points. The polarization rotation will be accomplished by using a total of four spin rotators, each of which consists of a set of solenoids and dipoles, placed at the ends of two arcs. The polarization configuration cancels the 1st order spin perturbation in the solenoids for the off-momentum particles and significantly reduces the synchrotron sideband resonances. In order to compensate the net Sokolov-Ternov depolarization effect, especially at higher energies, a continuous injection of a polarized electron beam from the CEBAF is being considered. We consider to perform a moderate spin matching in some key regions to extend the polarization lifetime so that the continuous injection can work more efficiently, while not imposing a burden on the optics design of the collider ring.

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MOPRO062

Investigating Polarisation and Shape of Beam Microwave Signals at the ANKA Storage Ring

radiation, detector, synchrotron, synchrotron-radiation

4090

J. Schwarzkopf, M. Brosi, C. Chang, E. Hertle, V. Judin, B. Kehrer, A.-S. Müller, A.-S. Müller, A.-S. Müller, M. Schuh, M. Schwarz, P. Schönfeldt, P. Schütze, J.L. Steinmann
KIT, Karlsruhe, Germany
F. Caspers
CERN, Geneva, Switzerland

At the ANKA synchrotron radiation facility measurements in the microwave range (~10 to 12 GHz) employing a LNB (Low Noise Block), which is the receiving part of a Satellite-TV system, have been carried out. Experiments showed that the observed signal depends on the length of the electron bunches. Furthermore the temporal shape of the microwave signal depends on the detector's position along the accelerator. Due the LNB antenna's sensitivity to polarisation it was also possible to measure the polarisation along the several ns long signal, revealing polarised and non-polarised regions. This paper describes the experimental setup and summarises the observations of the systematic studies performed with the LNB system.

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MOPME014

Automated Mode Recognition Algorithm for Accelerating Cavities

cavity, coupling, simulation, dipole

409

K. Brackebusch, T. Galek, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K13HR1.
Eigenmode simulations of accelerating structures often involve a large number of computed modes that need to be catalogued and compared. In order to effectively process all the information gathered from eigenmode simulations a new algorithm was developed to automatically recognize modes’ field patterns. In this paper we present the principles of the algorithm and investigate its applicability by means of different single and multi cell cavities. The highest achievable order of correctly recognized modes is of particular interest.

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TUOCB03

Performance of Elliptical Polarization Undulators at TPS

undulator, multipole, photon, FEL

987

T.Y. Chung, C.-H. Chang, C.H. Chang, J.C. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin, C.Y. Wu
NSRRC, Hsinchu, Taiwan

Design, assembly, field shimming, and performance of APPLE-II type undulators in NSRRC are described in this article. Essentially, the mechanical error has been well controlled based on the optimize design and mechanical arts. Effectively initial sorting of permanent magnets is developed to minimize several adverse effects, such as magnetic inhomogeneities, no perfection geometry of blocks, and mechanical frame issue, those challenge the sorting expectation, especially for an adjusted polarization undulator. The sorting algorithm shows a quantitative prediction of magnetic field and is verified by measurement results. 2D virtual shimming algorithm has been developed to optimize field quality, including multipole, phase error, and particle trajectory. We describe the considering of each procedure and demonstrate the optimization together with measurement results.

Slides TUOCB03 [1.503 MB]

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TUPRO004

Polarized Protons and Deuterons at NICA@JINR

proton, collider, luminosity, ion

1000

A.D. Kovalenko, A.V. Butenko, V.D. Kekelidze, V.A. Mikhaylov
JINR, Dubna, Moscow Region, Russia
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Different aspects of the NICA facility operation in polarized proton and deuteron modes aimed at reaching the highest possible luminosity and polarization degree as well are analysed. The main aim is to provide average luminosity L ≥ 1•1032 cm^-2 s⁻¹ at √sNN ≥ 26-27 GeV for single-spin proton collisions. Optimal schemes of the Siberian Snake insertions to the Nuclotron and NICA collider rings were proposed. The results of simulations are presented and discussed.

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TUPRO039

Optimizing Polarization with an Improved Integer Resonance Correction Scheme at ELSA

resonance, electron, quadrupole, closed-orbit

1108

J.F. Schmidt, O. Boldt, F. Frommberger, W. Hillert, J.-P. Thiry
ELSA, Bonn, Germany

Funding: DFG
The Electron Stretcher Facility ELSA of Bonn University provides a polarized electron beam of up to 3.2 GeV. In the stretcher ring various depolarizing resonances are crossed during the fast energy ramp of 6 GeV/s. The high polarization degree of up to 70% can only be conserved by taking several appropriate countermeasures. Concerning integer resonances, additional harmonic horizontal fields are applied by orbit correction magnets around the ring to compensate the resonance driving fields. The correction field has to be adjusted by empirical optimization of polarization. Recent developments enhance this optimization process, especially at high energies: A new magnet system allows for higher correction amplitudes and shorter rising times. Furthermore, a modified correction scheme was implemented. It takes into account the additional fields of the quadrupole magnets, arising from the orbit response of the correction magnets.

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TUPRO040

High Bandwidth Closed Orbit Control for a Fast Ramping Electron Accelerator

closed-orbit, resonance, acceleration, electron

1111

J.-P. Thiry, A. Dieckmann, F. Frommberger, W. Hillert, J.F. Schmidt
ELSA, Bonn, Germany

ELSA is a fast ramping stretcher ring capable of acceleration and storage of polarized electrons with energies up to 3.2 GeV. To preserve the initial degree of polarization, the acceleration is performed by a fast energy ramp with a maximum ramping speed of 6 GeV/s. During acceleration especially the vertical orbit needs to be continuously corrected so that the vertical rms deviation does not exceed 50 μm at any time. In order to compensate the so called integer resonances, which occur at certain energies, the orbit correction system further needs to provide additional, empirically determined, harmonic field distributions. A successful application of these combined correction measures requires a considerably high bandwidth of up to some 100 Hz. In our contribution we will have a closer look at the performance and the acquired bandwidth of the correction system.

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TUPRO059

Beam Energy Measurements using Resonant Spin Depolarization at ALBA

resonance, beam-losses, feedback, synchrotron

1168

Z. Martí, U. Iriso, F. Pérez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

Energy measurements with precision down to 10^-5 are inferred from the lifetime evolution when the beam is depolarized using AC kicks with the Transverse Fast Feedback system. Lifetime measurements are carried out using the DCCT, the BPM sum signals, pin-diode BLMs, and a scintillator based Beam Loss Detector. Results obtained with this instrumentation are reported.

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TUPRO085

Properties, Options and Limitations of PrFeB-magnets for Cryogenic Undulators

undulator, cryogenics, permanent-magnet, induction

1238

F.-J. Börgermann, C. Brombacher, K. Üstüner
Vacuumschmelze GmbH & Co. KG, Hanau, Germany

The gap induction and thus the K-factor of permanent magnet undulators may be increased by cooling them to cryogenic temperatures. The use of NdFeB-magnets in cryogenic undulators, however, is limited to temperatures above 140 K due to the spin-reorientation transition (SRT) which leads to a reduction of the magnetization level. A further increase of the gap induction in undulators may be achieved by use of PrFeB-magnets at even lower temperatures, as this alloy does not show the SRT phenomenon. Although the effects are well known, up to now only a few undulator prototypes were built using this class of material since the coercivity of ternary PrFeB-magnets is not sufficient to minimize the risk of partial demagnetization when the undulator structure is kept at room temperature. This problem can be solved by applying actual technologies like grain-boundary diffusion in order to achieve coercivities exceeding 20 kOe at RT without sacrificing the high remanence Br of about 1.6 T at 77 K. We will provide actual data of the magnet performance achieved and show up the technological limitations in building PrFeB-based CPMU’s.

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WEPRO024

Simulation of a Long-period EPU Operating in Universal Mode at the Canadian Light Source

alignment, dynamic-aperture, photon, simulation

1995

W.A. Wurtz, D. Bertwistle, L.O. Dallin, M.J. Sigrist
CLS, Saskatoon, Saskatchewan, Canada

The Canadian Light Source is implementing an elliptically polarizing undulator (EPU) with period 180 mm for the production of soft x-rays with variable polarization. Two issues arise from implementing such a device. First, a long-period EPU can cause significant loss of dynamic aperture due to strong dynamic focusing. Second, to compensate for polarization effects due to beamline optics, the EPU must be able to produce light with an arbitrary polarization at the source point, which is referred to as universal mode. We present a scheme for operating the EPU in universal mode and discuss the use of BESSY-style current strips in order to compensate for dynamic effects. Tracking simulations suggest that dynamic aperture can be sufficiently recovered for all required operating points in universal mode.

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WEPRO038

Possibility for Quasi-periodic Knot-APPLE Undulator

undulator, radiation, synchrotron, synchrotron-radiation

2026

S. Sasaki, A. Miyamoto
HSRC, Higashi-Hiroshima, Japan
N. Kawata, T. Mitsuyasu
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
S. Qiao
SIMIT, Shanghai, People's Republic of China

An intense on-axis radiation power from an undulator is a serious problem especially for a low-photon-energy beamline in a facility with high or medium energy storage ring. This problem may be solved by using a Figure-8, a Pera, or a Knot undulator configuration*,**. However, these schemes are useless for variably polarizing undulators such as an APPLE undulator and other similar variations since such devices are not capable for reducing on-axis power density in the linear mode. In these circumstances, we have completed a conceptual magnet design of Knot-APPLE udulator which is capable to generate elliptically polarized radiation as well as linearly polarized radiation. This pure permanent magnet device is equipped with a motion mechanism of APPLE undulator. In this paper, we present detailed magnet design feature, magnetic field distributions, and radiation properties including variations of polarization in comparisons with other exotic devices. In addition, a possibility to introduce a quasi-periodicity in this type of undulator is considered in order to achieve further reduction of second and third harmonic radiation intensities.
*S. Sasaki, "Undulators, wigglers and their applications," p.237-243 (Ed. by H. Onuki and P. Elleaume, Taylor & Francis Inc, New York, 2003).
**S. Qiao, et. al, Rev. Sci. Instrum., 80, 085108 (2009).

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WEPRO070

Overcoming the Horizontal Depolarizing Resonance in the Brookhaven AGS

resonance, emittance, timing, betatron

2112

H. Huang, L. Ahrens, M. Bai, M. Blaskiewicz, K.A. Brown, R. Connolly, Y. Dutheil, W. Fischer, C.J. Gardner, J.W. Glenn, T. Hayes, F. Méot, A. Poblaguev, V.H. Ranjbar, T. Roser, V. Schoefer, K.S. Smith, S. Tepikian, N. Tsoupas, K. Yip, A. Zelenski, K. Zeno, S.Y. Zhang
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.
Imperfection and vertical intrinsic depolarizing resonances have been overcome by the two partial Siberian snakes in the AGS. The relatively weak but numerous horizontal resonances are the main source of polarization loss in the AGS. A pair of horizontal quads have been used to overcome these weak resonances. This technique needs very accurate jump timing. Fast roll-over magnet cycle has been used and it improves the polarization transmission efficiency near extraction when acceleration usually is slowing down. Emittance preservation is also important to mitigate polarization loss. Recent experimental results including jump quad timing and emittance preservation are presented in this paper.

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WEPRO071

Optics Setup in the AGS and AGS Booster for Polarized Helion Beam

resonance, booster, proton, injection

2115

H. Huang, L. Ahrens, J.G. Alessi, M. Bai, E.N. Beebe, M. Blaskiewicz, K.A. Brown, Y. Dutheil, W. Fischer, C.J. Gardner, J.W. Glenn, T. Hayes, F. Méot, A. Poblaguev, V.H. Ranjbar, T. Roser, V. Schoefer, K.S. Smith, S. Tepikian, N. Tsoupas, K. Yip, A. Zelenski, K. Zeno
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.
Future RHIC physics program calls for polarized He3 beam. The He3 beam from the new EBIS source has a relative low rigidity which requires delicate control of injection and RF setup in the Booster. The strong depolarization resonance strength in both AGS and AGS Booster requires careful consideration of beam energy range and optics setup. Recently, the He3 beam was accelerated to 11GeV/n in the AGS. The near term goal fo 3*10¹⁰ at RHIC requires several RF bunch merges in both AGS and the Booster. The beam test results are presented in this paper.

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THPRO008

Obtaining High Degree of Circular Polarization at X-ray FELs via a Reverse Undulator Taper

undulator, FEL, radiation, bunching

2870

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical (or cross-planar) afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. In this paper we propose a new method for such a suppression: an application of the reverse taper in the main undulator. We discover that in a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. Considering SASE3 undulator of the European XFEL as a practical example, we demonstrate that soft X-ray radiation pulses with peak power in excess of 100 GW and an ultimately high degree of circular polarization can be produced.
Phys. Rev. ST-AB 16(2013)110702

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THPRO041

Position of Maximum in Quantum Spectrum of Synchrotron Radiation

radiation, electron, synchrotron, synchrotron-radiation

2952

A.N. Burimova, D.M. Gitman
IFUSP, Sao Paulo, Brazil
V.G. Bagrov
Institute of High Current Electronics, Tomsk, Russia

Funding: FAPESP
In the framework of quantum theory, we consider the condition for radiation maximum shift between harmonics of SR spectrum for scalar and spinor particles. Since quantum spectrum is discrete and finite, one can find values of radiation parameters such that the maximum in radiation spectrum stays at highest harmonic. It turns out that there exists a "quantization" of magnetic field associated with shift of maximum from one harmonic to another.

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THPRO056

Estimation of Systematic Errors for Deuteron Electric Dipole Moment (EDM) Search at a Storage Ring

simulation, dipole, experiment, extraction

2998

S. Chekmenev
RWTH, Aachen, Germany

An experimental method which is aimed to find a permanent EDM of a charged particle was proposed by JEDI (Jülich Electric Dipole moment Investigations) collaboration in 2012*. EDMs can be observed by their small influence on spin motion. The only possible way to perform a direct measurement is to use a storage ring. For this purpose it was decided to carry out the first precursor experiment at the Cooler Synchrotron (COSY). Since the EDM of a particle violates CP invariance and is expected to be tiny, treatment of all various sources of systematic errors should be done with a great level of precision. One should clearly understand how misalignments of the magnets affects the beam and the spin motion. In reality, one of the methods to investigate spin behavior in the presence of misalignments in a storage ring is to mimic their influence on the beam parameters using small orbit kicks with different amplitudes. In this talk the first simulations of orbit excitations will be discussed. The corresponding spin tune shifts will be considered. The influence of the distorted orbit on the polarization build-up caused by the EDM will be examined.
* A. Lehrach, F. Rathmann, J. Pretz et al., "Search for Permanent Electric Dipole Moments at COSY. Step 1: Spin coherence and systematic error studies", 2012

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THPRO061

New and Unifying Formalism for Study of Particle-Spin Dynamics Using Tools Distilled From Theory of Bundles

resonance, HOM, lepton, framework

3014

K.A. Heinemann, J.A. Ellison
UNM, Albuquerque, New Mexico, USA
D.P. Barber
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D.P. Barber, M. Vogt
DESY, Hamburg, Germany

Funding: The work of JAE and KH was supported by DOE under DE-FG-99ER41104 and the work of DPB and MV was supported by DESY.
We summarize our recent work on spin motion in storage rings *. In fact we return to our study ** of spin motion in storage rings. We again focus on spin tunes, polarization fields etc. but in contrast to ** we base the description on one turn maps and refine and expand our toolset from that in * by using a rather modern method from Dynamical-Systems theory, developed in the 1980's by R. Zimmer and others based on bundles **, ***. With this we obtain new insights into invariant spin fields, invariant frame fields, spin tunes and spin-orbit resonances. At the same time we get a unified way to treat spin-1/2 and spin-1 particles. The bundle aspect is pointed out and we briefly mention the relation to Yang-Mills Theory as well.
* K.Heinemann, D.P.Barber, J.A.Ellison, M.Vogt. To be submitted.
** D.P.B., J.A.E., K.H., PRSTAB 7 (2004) 124002.
*** K.Heinemann, PhD Thesis, University of New Mexico, 2010 (available on the web).

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THPRO089

New Tune Jumps Scheme in the Low Energy Part of the AGS Cycle

resonance, simulation, acceleration, hardware

3092

Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, V. Schoefer
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.
During the early part of the acceleration of polarized protons, due to strong optical deformations of the lattice, the tune cannot be placed in the spin gap and the first two vertical intrinsic resonances are crossed. Recent multiparticle trackings using the Zgoubi code show that the spin resonances around Gg=5 could cause as much as 5% loss of polarization. The slow acceleration rate, the two vertical and two horizontal intrinsic spin resonances can contribute to the depolarization in the region. While in the current scheme only the two horizontal intrinsic resonances are jumped, it was proposed to use the tune jumps system to also accelerate the crossing of the two weak vertical intrinsic resonances and improve the polarization transmission through this region. We show the design of this new tune jumps scheme and the expected polarization gains expected from multiparticles Zgoubi simulations. We also compare experimental measurements of the polarization transmission to the Zgoubi simulations.

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THPRO090

Energy Calibration and Tune Jumps Efficiency in the pp AGS

timing, resonance, acceleration, extraction

3095

Y. Dutheil, L. Ahrens, H. Huang, F. Méot, A. Poblaguev, V. Schoefer, K. Yip
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.
The AGS tune jump system consists of two fast quadrupoles used to accelerate the crossing of 82 horizontal intrinsic spin resonances. The fast tune jump of ΔQh=+0.04 within 100 μs imposes perfect localization of each of the 82 resonant conditions. Imperfect timing of the tune jumps results in lower efficiency of the system and lower transmission of the polarization through the AGS acceleration cycle. Investigations during the end of the pp AGS Run13 revealed weaknesses in the energy measurement at high energy, causing less than optimal timing of the tune jumps. A new method based on continuous polarization measurement to determine the energy during the acceleration cycle has been developed. Strong operational constraints were taken into account to provide a convenient system of energy measurement. This is also used to calibrate the usual determination of the energy based on revolution frequency of the beam or measured dipole magnetic field. This paper shows the tools developed and the results of the first tests during the AGS Run 14. Simulations of the expected tune jumps efficiency using the AGS Zgoubi model are also presented and compared to experimental results.

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THPRO091

Strength of Horizontal Intrinsic Spin Resonances in the AGS

resonance, emittance, optics, proton

3098

Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, T. Roser, V. Schoefer
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.
Crossing of horizontal intrinsic resonances is today the main source of polarization losses in the AGS, in its dual partial snakes configuration for polarized proton acceleration. Polarization losses were greatly reduced by the AGS tune jump system. However total polarization transmission through the AGS cycle is not yet achieved, still partially due to the horizontal intrinsic resonances. This paper will explore the effect of optical distortions and different horizontal tunes on the strength of horizontal intrinsic resonances. Various options will be presented and practicability will be addressed. Theoretical model and multiparticle trackings using the Zgoubi code will show the expected polarization gains of different scenarios.

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THPME158

Coherent Diffraction and Cherenkov Radiation from Short Electron Bunches in Fibers

radiation, electron, experiment, target

3632

G.A. Naumenko, V.V. Bleko, A. Potylitsyn, V.V. Soboleva
TPU, Tomsk, Russia

Funding: This work is particularly supported by grant of Russian MES Program "Nauka" number 2456
The ability to use a radiation of relativistic electrons in optical fibers for beam diagnostics was proposed by X. Artu recently *. In the cited work the properties of different types of radiation, such as diffraction and Cherenkov radiation in the visible region, induced in fibers by relativistic electron were considered. In our report we present the results of experimental investigation of such a phenomenon for millimeter wavelength radiation. The origin and properties of radiation in fibers were investigated for different geometries of fiber position in respect to the electron beam. The spectral characteristics and dependence on the orientation angle of fibers relative to the electron beam were investigated. One of the useful properties of fibers is the fiber flexibility. The characteristics of radiation accepted by flexible fiber with diameter D=11 mm and length L=600 mm were investigated as a function of curvature radius of the fiber R. The experimental results show the allowable transport factor of radiation for the condition L>R>>D. We believe that fibers for mm and submm range can be used for beam diagnostics also.
* X Artru and C. Ray, Nucl. Inst. Meth. B 309 (2013)

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