IPAC2012 - List of Keywords (polarization)

Paper	Title	Other Keywords	Page
MOOBA03	Development of a High-power Coherent THz Sources and THz-TDS System on the basis of a Compact Electron Linac	electron, radiation, linac, laser	37
	M. Kumaki, K. Sakaue, M. Washio RISE, Tokyo, Japan R. Kuroda, H. Toyokawa, K. Yamada AIST, Tsukuba, Ibaraki, Japan
	The high-power terahertz time-domain spectroscopy (THz-TDS) has been developed on the basis of a compact S-band electron linac at AIST, Japan. It is strongly expected for inspection of dangerous materials in the homeland security field. The linac consists of a photocathode rf-gun, two acceleration tubes and a magnetic bunch compressor. The 40 MeV, 1 nC electron bunch is generated and compressed to less than 1 ps. THz radiations are generated in two methods with the ultra-short bunch. One is THz coherent synchrotron radiation (CSR). The other is THz coherent transition radiation (CTR). In the preliminary experiment, it was observed that the focused CTR had the donut profile in a transverse fields due to its initial radial polarization, so that it made Z-polarization. In case of the THz-TDS experiment, CTR was controlled to linearly polarization with the polarizer and focused to an EO crystal to obtain a THz temporal waveform which leads to THz spectrum with Fourier transform. The timing measurement between CTR and a probe laser was realized with OTR using a same optical photodiode. In this conference, we will describe details of our linac and results of the THz-TDS experiment.
	Slides MOOBA03 [3.342 MB]

MOPPC023	Polarization Transmission at RHIC, Numerical Simulations	resonance, simulation, optics, proton	178
	F. Méot, M. Bai, C. Liu, M.G. Minty, V.H. Ranjbar BNL, Upton, Long Island, New York, USA
	Ray-tracing methods, using the computer code Zgoubi, have proven efficient for beam and spin dynamics simulations in RHIC (see earlier PAC and IPAC publications). More simulations and results are being produced, including spin code benchmarking and cross-checking, effects of strongest resonances and working point on transport of polarization, polarization with Run 9 and Run 11 measured ramp orbit and optics, polarization profiles, etc. The numerical methods involved are recalled, a status of the work is given.

MOPPC025	RHIC Polarized Proton Operation in Run 12	luminosity, proton, emittance, acceleration	184
	V. Schoefer, L. A. Ahrens, A. Anders, E.C. Aschenauer, G. Atoian, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, A. Dion, K.A. Drees, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, R.L. Hulsart, A. Kirleis, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, F. Severino, D. Smirnov, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang BNL, Upton, Long Island, New York, USA
	Successful RHIC operation with polarized protons requires meeting demanding and sometimes competing goals for maximizing both luminosity and beam polarization. In Run 12 we sought to fully integrate into operation the many systems that were newly commissioned in Run 11 as well as to enhance collider performance with incremental improvements throughout the acceleration cycle. For luminosity maximization special attention was paid to several possible source of emittance dilution along the injector chain, in particular to optical matching during transfer between accelerators. Possible sources of depolarization in the AGS and RHIC were also investigated including the effects of local coupling and low frequency (10 Hz) oscillations in the vertical equilibrium orbit during the RHIC ramp. The results of a fine storage energy scan made in an effort to improve store polarization lifetime are also reported in this note.

MOPPP064	Challenges of Quasiperiodic APPLE Undulators	undulator, lattice, synchrotron, synchrotron-radiation	705
	J. Bahrdt HZB, Berlin, Germany S. Sasaki HSRC, Higashi-Hiroshima, Japan
	APPLE undulators have become workhorses in many synchrotron radiation facilities for the production of variably polarized light. In helical mode higher harmonics are not produced. In linear mode (horizontal, vertical, inclined) higher harmonics may contaminate the first harmonic and spoil the quality of experimental data. Planar undulators employing a quasiperiodic magnetic structure have been built and they are successfully operated at several places. The implementation of a quasiperiodic lattice in an APPLE undulator is more complicated since the device is operated in various modes of operation. The proposed APS-upgrade includes a quasiperiodic APPLE undulator which is intended to be operated in the range 2.4-27 keV. A detailed analysis of the magnetic and spectral performance of this device is presented.

MOPPP072	Performance of APPLE-II Type Quasi-Periodic Undulator at HiSOR	undulator, radiation, electron, photon	729
	S. Sasaki, M. Arita, K. Goto, A. Miyamoto, T. Okuda HSRC, Higashi-Hiroshima, Japan
	A 1.8-m-long 78-mm-period quasi-periodic APLPE-II undulator was installed in the 700-MeV HiSOR storage ring of Hiroshima Synchrotron Radiation Center. At 23-mm nominal minimum gap, the fundamental photon energies are 3.1 eV, 6.5 eV, and 4.8 eV for horizontal linear, vertical linear, and circular polarization, respectively. The photon energies of observed fundamental and higher harmonic radiations are in good agreement with those of model calculations using measured undulator field and the HiSOR beam parameters. Also, observed flux thorough a slit and a grating monochromator was more than twice larger than that from previously installed 100-mm-period helical undulator for the whole range of radiation spectra. The feedforward COD correction was done to avoid the intensity fluctuation of photon beam in other BM beamlines due to the gap and phase motion of undulator. No fatal effect on the stored electron beam by installing the undulator was observed though a slight beam size change was observed at the minimum gap.

MOPPP088	Control of Nonlinear Dynamics by Active and Passive Methods for the NSLS-II Insertion Devices	undulator, insertion, insertion-device, electron	759
	J. Bengtsson, O.V. Chubar, C.A. Kitegi, T. Tanabe BNL, Upton, Long Island, New York, USA
	Funding: US DOE, Contract No. DE-AC02-98CH10886. Nonlinear dynamics effects from insertion devices (IDs) are known to affect the electron beam quality of third generation synchrotron light sources. In particular, beam lifetime, dynamical aperture and injection efficiency. Methods to model the IDs' non-linear effects are known, e.g. by second-order (in the inverse electron energy) kick maps. Methods to compensate these effects are known as well, e.g. by first-order thin or thick magnetic kicks introduced by "magic fingers," "L-shims," or "current strips." However, due to physical or technological constraints, these corrections are typically only partial. Therefore, a precise model is required for a correct minimization of the residual nonlinear dynamics effects for the combined magnetic fields of the ID and compensating magnets. We outline a systematic approach for such predictions, based on 3D magnetic field and local trajectory calculation in the ID by the Radia code, and particle tracking by Tracy-3. The optimal geometry for the compensating magnets is determined from these simulations using a combination of linear algebra and genetic optimization.

MOPPR001	Resonant Spin Depolarisation Measurements at the SPEAR3 Electron Storage Ring	storage-ring, electron, lattice, synchrotron	771
	K.P. Wootton, R.P. Rassool The University of Melbourne, Melbourne, Australia M.J. Boland, Y.E. Tan ASCo, Clayton, Victoria, Australia W.J. Corbett, M.H. Donald, X. Huang, R.R. Ortiz, J.A. Safranek, K. Tian SLAC, Menlo Park, California, USA
	Accurate electron beam energy measurements are valuable for precision lattice modelling of high-brightness light sources. At SPEAR3 the beam energy was measured using the resonant spin depolarisation method with striplines to resonantly excite the spin tune and a sensitive NaI scintillator beam loss monitor was used to detect resulting changes in Touschek lifetime. Using the combined apparatus an electron beam energy of 2.997251(7) GeV was measured, giving a relative uncertainty better than 3x10^-6. The measured momentum compaction factor was found to be in close agreement with the numerical model value using rectangular defocussing gradient dipoles with measured magnetic field map profiles. In this paper we outline the chosen experimental technique, with emphasis on its applicability to electron storage rings in general.

MOPPR007	Investigation of Techniques for Precise Compton Polarimetry at ELSA	electron, photon, laser, simulation	783
	R. Zimmermann, W. Hillert ELSA, Bonn, Germany
	Funding: Work supported by DFG within SFB/TR16 A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. When the polarization of the laser light is switched from left-hand to right-hand circular polarization, the spatial distribution of the backscattered photons is shifted. The extent of this modification is a measure of the beam's polarization degree. Two different experimental techniques that are suitable for a measurement of the effect were compared and evaluated closer through numerical simulations that will be presented in this contribution.

MOPPR009	Dynamic Closed Orbit Correction During the Fast Energy Ramp of ELSA	closed-orbit, acceleration, electron, controls	789
	J.-P. Thiry, A. Balling, A. Dieckmann, F. Frommberger, W. Hillert ELSA, Bonn, Germany
	ELSA is a fast ramping stretcher ring supplying polarized electrons to hadron physics experiments. To preserve the degreee of polarization, it is necessary to continuously correct the vertical orbit when accelerating the beam from 1.2 GeV to 2.4 GeV. Acceleration is performed within 300 ms, thus with a ramping speed of 4 GeV/s. During the acceleration, beam positions are measured at a rate of 1 kHz using 32 beam position monitors, which are mounted close to the quadrupole magnets. The demanding task is to achieve a vertical rms deviation not exceeding 50 μm all along the fast energy ramp. Therefore, dynamic orbit corrections are applied by means of offline feed-forward techniques, driving 32 vertical steerer magnets which can change currents in less than 10 ms. In our contribution, we show the used concepts and the implementation of the precise closed orbit correction system at ELSA.

TUXA03	Increasing the AGS Beam Polarization with 80 Tune Jumps	resonance, quadrupole, emittance, closed-orbit	1015
	V. Schoefer, L. A. Ahrens, M. Bai, E.D. Courant, W. Fu, C.J. Gardner, J.W. Glenn, H. Huang, F. Lin, A.U. Luccio, J.-L. Mi, J. Morris, P.J. Rosas, T. Roser, P. Thieberger, N. Tsoupas, A. Zelenski, K. Zeno BNL, Upton, Long Island, New York, USA
	Vertical depolarizing resonances in the AGS are removed by partial Siberian snakes. These magnets move the stable spin direction and lead to horizontal depolarizing resonances. The tune jump quadrupole system increases the crossing rate for horizontal resonances by a factor of six. This presentation will review the fundamental mechanism of depolarizing resonances, the partial Siberian snake solution and describe recent experimental evidence at the AGS demonstrating improvements to beam polarization and the beam dynamics challenges posed by the tune jump.
	Slides TUXA03 [5.199 MB]

TUPPC057	RHIC Spin Flipper Commissioning Results	dipole, resonance, injection, proton	1302
	M. Bai, W.C. Dawson, J. Kewisch, Y. Makdisi, P. Oddo, C. Pai, P.H. Pile, 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. The five ac dipole design of RHIC spin flipper in the Blue ring was first commissioned during the RHIC 2012 polarized proton operation. The advantage of this design is to eliminate the vertical coherent betatron oscillations outside the spin flipper. Spin flipping efficiency was measured with both 100 GeV and 250 GeV polarized proton beams. This paper presents the latest commissioning results. M. Bai , T. Roser, C. Dawson, Y. Makdisi, W. Meng, F. Meot, P. Oddo, C. Pai, P. Pile, RHIC Spin Flipper New Design and Commissioning Plan, IPAC10 proceedings, IPAC 2010, Kyoto, Japan, 2010

TUPPC067	How to Achieve Longitudinally Polarized Electrons using Integer Spin Tune Resonances	resonance, synchrotron, dipole, electron	1326
	O. Boldt, A. Dieckmann, F. Frommberger, W. Hillert, J.F. Schmidt ELSA, Bonn, Germany
	Funding: Bundesministerium für Bildung und Forschung Commonly, strong solenoids are used in circular accelerators to achieve longitudinal polarization. In practice, however, these solenoids cause a phase space coupling, which has to be compensated for by sophisticated decoupling schemes. We suggest to adiabatically ramp into an integer spin tune resonance, while preserving the degree of polarization. When appropriately adjusting the driving horizontal field contributions at the final energy, the resulting polarization is longitudinal at predefined positions in the accelerator. Here, depending on the energy spread, the degree of polarization is conserved for several seconds. The contribution shows the numerical analysis of this scenario being confirmed by first demonstration tests at the ELSA stretcher ring.

TUPPC075	Study of Nonlinear Beam Dynamics Effects for DEPU at SSRF	undulator, electron, photon, focusing	1347
	M. Zhang, Q.G. Zhou SINAP, Shanghai, People's Republic of China
	A pair of EPUs (DEPU) with the period 58mm and 148mm, covering the energy ranges from 20 to 200eV and 200 to 2000eV of arbitrary polarized light, will be developed for the SSRF soft X-ray beam line for ARPES and PEEM. The effects of DEPU to tune-shift produced by the nonlinear beam dynamics are studied and the results are presented in this paper. The corresponding magnet field shimming technology to reduce these effects is also investigated.

TUPPC098	Electron Polarization in the Medium-Energy Electron-Ion Collider at JLAB	electron, solenoid, dipole, closed-orbit	1386
	F. Lin, Y.S. Derbenev, V.S. Morozov, Y. Zhang JLAB, Newport News, Virginia, USA D.P. Barber DESY, Hamburg, Germany
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A key feature of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab is high polarization (over 80%) of the electron beam at all collision points for the particle physics program. The equilibrium electron polarization is arranged to be vertical in the arcs of the figure-8 collider ring of the MEIC and anti-parallel to the arc dipole magnetic fields, in order to take advantage of the preservation of polarization by the Sokolov-Ternov (S-T) effect. Longitudinal polarization is achieved at collision points by utilizing energy-independent universal spin rotators each of which consists of a set of solenoids and dipoles placed at the end of an arc. The equilibrium beam polarization and its lifetime depend on competition between the S-T effect and radiative depolarization. The latter must be suppressed by spin matching. This paper reports on investigations of polarization in the MEIC electron collider ring and a preliminary estimate of beam polarization from calculations using the code SLICK. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.

TUPPD052	A New Load Lock System for the Source of Polarized Electrons at ELSA	electron, vacuum, laser, ion	1521
	D. Heiliger, W. Hillert, B. Neff ELSA, Bonn, Germany
	Funding: supported by DFG (SFB/TR16) Since 2000, an inverted source of polarized electrons at the electron stretcher accelerator ELSA routinely provides a pulsed beam with a current of 100 mA and a polarization degree of about 80%. One micro-second long pulses with 100 nC charge are produced by irradiating a GaAs strained-layer superlattice photocathode (8 mm in diameter) with laser light. Future accelerator operation requires a significantly higher beam intensity, which can be achieved by using photocathodes with sufficiently high quantum efficiency. Therefore, and in order to enhance the reliability and up time of the source, a new extreme high-vacuum (XHV) load lock system was installed and commissioned at the beginning of this year. It consists of three chambers: The activation chamber for heat cleaning of the photocathodes and activation with cesium and oxygen. The storage chamber in which up to five different types of photocathodes with various diameters of the emitting surface can be stored under XHV conditions. The loading chamber in which an atomic hydrogen source is used to remove any remaining surface oxidation. Additionally, tests of the photocathodes’ properties can be performed during operation.

TUPPD083	Raising Photoemission Efficiency with Surface Acoustic Waves	electron, photon, linac, vacuum	1596
	A. Afanasev, F. Hassani, C.E. Korman GWU, Washington, USA V.G. Dudnikov, R.P. Johnson Muons, Inc, Batavia, USA M. Poelker, K.E.L. Surles-Law JLAB, Newport News, Virginia, USA
	Funding: Supported in part by DOE STTR Grant DE-SC0006256. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.

TUPPP016	Recent Development of PF Ring and PF-AR	undulator, injection, linac, vacuum	1641
	Y. Tanimoto, T. Aoto, S. Asaoka, K. Endo, K. Haga, K. Harada, T. Honda, Y. Honda, M. Izawa, Y. Kobayashi, A. Mishina, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, T. Ozaki, C.O. Pak, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, K. Satoh, M. Shimada, K. Shinoe, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, M. Yamamoto KEK, Ibaraki, Japan H. Takaki ISSP/SRL, Chiba, Japan
	After the earthquake of March 11, two light sources of KEK, PF ring and PF-AR, have recovered the regular operation from October, 2011. We installed tandem variably-polarized undulators at PF ring in 2009. Recently, the orbit switching system has been completed with sufficient feed-forward orbit compensation at 10-Hz. PF ring is usually operated at 450 mA with a top-up injection using the pulsed sextupole magnet instead of the conventional kicker magnets. The transverse and longitudinal instabilities are suppressed by a digital feedback system using the iGp signal processor. In the longitudinal direction, we observed unstable quadrupole mode oscillation which could not be controlled by the feedback system. We had applied the phase modulation of the main RF cavity to stabilize the quadrupole oscillation before. Old-type RF-shielded gate valves damaged by the earthquake were removed from the ring during the summer maintenance. In the operation after autumn, the quadrupole oscillation can be cured by dividing the bunch train of partial-filling. Without the phase modulation, the effective brightness of SR beam has been improved especially at beam lines of finite dispersion function.

TUPPR001	Spin Tracking Simulation of a Future International Linear Collider	positron, solenoid, electron, simulation	1807
	V.S. Kovalenko, O.S. Adeyemi, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov University of Hamburg, Hamburg, Germany A.F. Hartin DESY, Hamburg, Germany S. Riemann, F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE The full physics potential of the International Linear Collider (ILC) is expected to be optimized by using polarized electron and positron beams. To ensure that no significant polarization can be lost during the transport of the electron and positron beams from the source to the interaction region, spin tracking has to be included in all transport elements which can contribute to a potential loss of polarization. The possible sources of depolarization such as the spin rotators and the damping ring have been investigated for the current ILC baseline. The detailed spin tracking simulations and study depolarization was performed by using BMAD and SLICKTRACK computer codes. The new results of our simulations for the ILC are presented.

TUPPR002	Simulations of Positron Polarization in the Undulator-Based Source	undulator, positron, electron, photon	1810
	A. Ushakov, O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick University of Hamburg, Hamburg, Germany A.F. Hartin DESY, Hamburg, Germany S. Riemann, F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE The generation of an intense and highly polarized positron beam is a challenge. The design for the International Linear Collider proposes a positron source based on a helical undulator located at the end of the electron linac. This design allows us to utilize a high energy linear accelerator with both electron and positron beams polarized. The polarization of the positron beam can be enhanced using a photon collimator. The optimization of positron yield and polarization for a wide energy range has been studied for different undulator parameters and collimator designs, taking into account realistic parameters for the capture section. In particular, the effects of misalignment and tolerances are considered.

TUPPR003	The Design of Spin-Rotator with a Possibility of Helicity Switching for Polarized Positron at the ILC	positron, solenoid, damping, lattice	1813
	L.I. Malysheva, O.S. Adeyemi, V.S. Kovalenko, G.A. Moortgat-Pick, A. Ushakov University of Hamburg, Hamburg, Germany A.F. Hartin, B. List, N.J. Walker DESY, Hamburg, Germany S. Riemann, F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	Funding: Work supported by German Federal Ministry of education and research. Joint Research project R&D Accelerator Spin Management, contract N 05H10CUE At the ILC, positrons are produced with longitudinal polarization at the source. In order to preserve the polarization, the spin must be rotated into the vertical direction prior to injection into the damping rings. A new design of the spin rotator is presented that allows to randomly switch between the two vertical orientations between successive bunch trains. After rotating the spin back to longitudinal polarization, this corresponds to a choice between the two possible helicity states at the interaction point. The fast flipping is achieved by inserting two parallel spin rotation sections with opposite polarities, with a fast magnet that allows to choose between the sections.

TUPPR040	Update on ILC Positron Source Study at ANL	positron, undulator, photon, electron	1906
	W. Liu, W. Gai ANL, Argonne, USA
	As the new ILC baseline has moved the positron production to the end of electron main linac, both the drive beam energy and beamline layouts have also been changed for the positron source. Now the drive beam energy will be varying from 150GeV to 250GeV and 500GeV (for TeV upgrade) as the colliding center of mass (CM) energy changes. Systematic studies on the performance of positron source under different running scenarios have been done at ANL and the results are presented in this paper.

TUPPR042	On the Polarization Upgrade of ILC Undulator-based Positron Source	positron, undulator, photon, electron	1912
	W. Liu, W. Gai ANL, Argonne, USA S. Riemann DESY, Hamburg, Germany A. Ushakov University of Hamburg, Hamburg, Germany
	The current nominal polarization for ILC undulator based positron source is 30% without photon collimators. In order to improve the effective luminosity, an upgrade of positron source with higher polarization is required. Some studies on the upgrade options have been done at both DESY and ANL, and the results are presented in this paper.

TUPPR079	Ion Polarization in the MEIC Figure-8 Ion Collider Ring	ion, proton, resonance, collider	2008
	V.S. Morozov, Y.S. Derbenev, Y. Zhang JLAB, Newport News, Virginia, USA P. Chevtsov Paul Scherrer Institut, Villigen, Switzerland Y. Filatov MIPT, Dolgoprudniy, Moscow Region, 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. The nuclear physics program envisaged at the Medium-energy Electron-Ion Collider (MEIC) currently being developed at the Jefferson Lab calls for collisions of 3-11 GeV/c longitudinally polarized electrons and 20-100 GeV/c, in equivalent proton momentum, longitudinally or transversely polarized light ions. In this paper, we present a scheme based on figure-8 shaped booster and collider rings that provides the required ion polarization arrangement in the MEIC's ion collider ring. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

TUPPR082	MEIC Design Progress	ion, electron, collider, booster	2014
	Y. Zhang, Y.S. Derbenev, D. Douglas, A. Hutton, G.A. Krafft, R. Li, F. Lin, V.S. Morozov, E.W. Nissen, F.C. Pilat, T. Satogata, C. Tennant, B. Terzić, B.C. Yunn JLAB, Newport News, Virginia, USA D.P. Barber DESY, Hamburg, Germany Y. Filatov JINR, Dubna, Russia C. Hyde Old Dominion University, Norfolk, Virginia, USA A.M. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia S.L. Manikonda, P.N. Ostroumov ANL, Argonne, USA M.K. Sullivan SLAC, Menlo Park, California, USA
	Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and No. DE-AC02-06CH11357. This paper will report the recent progress in the conceptual design of MEIC, a high luminosity medium energy polarized ring-ring electron-ion collider at Jefferson lab. The topics and achievements that will be covered are design of the ion large booster and the ERL-circulator-ring-based electron cooling facility, optimization of chromatic corrections and dynamic aperture studies, schemes and tracking simulations of lepton and ion polarization in the figure-8 collider ring, and the beam-beam and electron cooling simulations. A proposal of a test facility for the MEIC electron cooler will also be discussed.

WEPPD032	Heat Load Studies in Target and Collimator Materials for the ILC Positron Source	photon, positron, undulator, target	2576
	F. Staufenbiel, S. Riemann DESY Zeuthen, Zeuthen, Germany O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov University of Hamburg, Hamburg, Germany
	An intense polarized positron beam for future linear colliders can be produced using a high power beam of circularly polarized photons which penetrates a thin titanium-alloy target. The degree of polarization can be increased by cutting the outer part of the photon beam generated in a helical undulator using a collimator in front of the target. However, the photon beam induces substantial heat load and stress inside the target and collimator materials. In order to avoid failure of these components the stress evolution has been simulated. The results as well as the corresponding material arrangements for the photon collimator design are presented.

THPPP026	Experimental Effects of Orbit on Polarization Loss in RHIC	resonance, acceleration, injection, proton	3788
	V.H. Ranjbar Tech-X, Boulder, Colorado, USA M. Bai, H. Huang, A. Marusic, M.G. Minty, V. Ptitsyn 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. We are performing several experiments during the RHIC ramp to better understand the impact of orbit errors on the polarization at our current working point. These will be conducted by exciting specified orbit harmonics during the final two large intrinsic resonance crossing in RHIC during the 250 GeV polarized proton ramp. The resultant polarization response will then be measured.

THPPP029	Simultaneous Global Coupling and Vertical Dispersion Correction in RHIC	coupling, quadrupole, proton, heavy-ion	3794
	C. Liu, Y. Luo, M.G. Minty 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. Residual vertical dispersion on the order of ±0.2 m (peak to peak) has been measured at store energies for both polarized proton and heavy ion beams. The hypothesis is that this may have impact on the polarization transmission efficiency during the energy ramp, the beam lifetimes, and, especially for heavy ions, the dynamics aperture. An algorithm to correct global coupling and dispersion simultaneously using skew quads was developed for RHIC. Simulation results together with the measured coupling and dispersion functions before and after correction will be shown for both injection and store together with an assessment of overall collider performance improvement.

THPPP030	Near Integer Tune for Polarization Preservation in the AGS	optics, acceleration, injection, resonance	3797
	N. Tsoupas, L. A. Ahrens, M. Bai, K.A. Brown, J.W. Glenn, H. Huang, W.W. MacKay, T. Roser, V. Schoefer, K. Zeno BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the US Department of Energy. The high energy (T=250 GeV) polarized proton beam experiments performed in RHIC, require high polarization of the beam. In order to preserve the polarization of the proton beam, during the acceleration in the AGS, which is the pre-injector to RHIC, two partial helical magnets have been installed in AGS. In order to minimize the loss of the beam polarization due to the various intrinsic spin resonances occurring during the proton acceleration, we constrain the value of the vertical tune to be higher than 8.97. With the AGS running at near integer tune the perturbations caused by the partial helical magnets is large resulting in large beta and dispersion waves. To mitigate the adverse effect of the partial helices on the optics of the AGS, we have introduced compensation quads** in AGS. In this paper we present the beam optics of the AGS which ameliorates this effect of the partial helices. * H. Huang, et al., Proc. EPAC06, p. 273, (2006). ** N. Tsoupas et al., Proc. PAC07, p. 3723 (2007).

FRXAB01	Symplectic Tracking and Compensation of Dynamic Field Integrals in Complex Undulator Structures	undulator, permanent-magnet, simulation, dipole	4165
	J. Bahrdt, G. Wüstefeld HZB, Berlin, Germany
	This presentation covers analytical models that describe the interaction of an electron beam with the magnetic field of undulators. Analytic approximations to the Hamilton-Jacobi equation yield generating functions useful for particle tracking and therefore efficient simulation. Analytic expressions for kick maps of APPLE II undulators are presented as well. Passive and active shimming schemes including magic fingers and current sheets are also modeled. Applications at BESSY II are discussed which ensure efficient injection during top-up to satisfy machine protection and radiation safety requirements.
	Slides FRXAB01 [1.922 MB]

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MOOBA03

Development of a High-power Coherent THz Sources and THz-TDS System on the basis of a Compact Electron Linac

electron, radiation, linac, laser

37

M. Kumaki, K. Sakaue, M. Washio
RISE, Tokyo, Japan
R. Kuroda, H. Toyokawa, K. Yamada
AIST, Tsukuba, Ibaraki, Japan

The high-power terahertz time-domain spectroscopy (THz-TDS) has been developed on the basis of a compact S-band electron linac at AIST, Japan. It is strongly expected for inspection of dangerous materials in the homeland security field. The linac consists of a photocathode rf-gun, two acceleration tubes and a magnetic bunch compressor. The 40 MeV, 1 nC electron bunch is generated and compressed to less than 1 ps. THz radiations are generated in two methods with the ultra-short bunch. One is THz coherent synchrotron radiation (CSR). The other is THz coherent transition radiation (CTR). In the preliminary experiment, it was observed that the focused CTR had the donut profile in a transverse fields due to its initial radial polarization, so that it made Z-polarization. In case of the THz-TDS experiment, CTR was controlled to linearly polarization with the polarizer and focused to an EO crystal to obtain a THz temporal waveform which leads to THz spectrum with Fourier transform. The timing measurement between CTR and a probe laser was realized with OTR using a same optical photodiode. In this conference, we will describe details of our linac and results of the THz-TDS experiment.

Slides MOOBA03 [3.342 MB]

MOPPC023

Polarization Transmission at RHIC, Numerical Simulations

resonance, simulation, optics, proton

178

F. Méot, M. Bai, C. Liu, M.G. Minty, V.H. Ranjbar
BNL, Upton, Long Island, New York, USA

Ray-tracing methods, using the computer code Zgoubi, have proven efficient for beam and spin dynamics simulations in RHIC (see earlier PAC and IPAC publications). More simulations and results are being produced, including spin code benchmarking and cross-checking, effects of strongest resonances and working point on transport of polarization, polarization with Run 9 and Run 11 measured ramp orbit and optics, polarization profiles, etc. The numerical methods involved are recalled, a status of the work is given.

MOPPC025

RHIC Polarized Proton Operation in Run 12

luminosity, proton, emittance, acceleration

184

V. Schoefer, L. A. Ahrens, A. Anders, E.C. Aschenauer, G. Atoian, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, A. Dion, K.A. Drees, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, R.L. Hulsart, A. Kirleis, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, F. Severino, D. Smirnov, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
BNL, Upton, Long Island, New York, USA

Successful RHIC operation with polarized protons requires meeting demanding and sometimes competing goals for maximizing both luminosity and beam polarization. In Run 12 we sought to fully integrate into operation the many systems that were newly commissioned in Run 11 as well as to enhance collider performance with incremental improvements throughout the acceleration cycle. For luminosity maximization special attention was paid to several possible source of emittance dilution along the injector chain, in particular to optical matching during transfer between accelerators. Possible sources of depolarization in the AGS and RHIC were also investigated including the effects of local coupling and low frequency (10 Hz) oscillations in the vertical equilibrium orbit during the RHIC ramp. The results of a fine storage energy scan made in an effort to improve store polarization lifetime are also reported in this note.

MOPPP064

Challenges of Quasiperiodic APPLE Undulators

undulator, lattice, synchrotron, synchrotron-radiation

705

J. Bahrdt
HZB, Berlin, Germany
S. Sasaki
HSRC, Higashi-Hiroshima, Japan

APPLE undulators have become workhorses in many synchrotron radiation facilities for the production of variably polarized light. In helical mode higher harmonics are not produced. In linear mode (horizontal, vertical, inclined) higher harmonics may contaminate the first harmonic and spoil the quality of experimental data. Planar undulators employing a quasiperiodic magnetic structure have been built and they are successfully operated at several places. The implementation of a quasiperiodic lattice in an APPLE undulator is more complicated since the device is operated in various modes of operation. The proposed APS-upgrade includes a quasiperiodic APPLE undulator which is intended to be operated in the range 2.4-27 keV. A detailed analysis of the magnetic and spectral performance of this device is presented.

MOPPP072

Performance of APPLE-II Type Quasi-Periodic Undulator at HiSOR

undulator, radiation, electron, photon

729

S. Sasaki, M. Arita, K. Goto, A. Miyamoto, T. Okuda
HSRC, Higashi-Hiroshima, Japan

A 1.8-m-long 78-mm-period quasi-periodic APLPE-II undulator was installed in the 700-MeV HiSOR storage ring of Hiroshima Synchrotron Radiation Center. At 23-mm nominal minimum gap, the fundamental photon energies are 3.1 eV, 6.5 eV, and 4.8 eV for horizontal linear, vertical linear, and circular polarization, respectively. The photon energies of observed fundamental and higher harmonic radiations are in good agreement with those of model calculations using measured undulator field and the HiSOR beam parameters. Also, observed flux thorough a slit and a grating monochromator was more than twice larger than that from previously installed 100-mm-period helical undulator for the whole range of radiation spectra. The feedforward COD correction was done to avoid the intensity fluctuation of photon beam in other BM beamlines due to the gap and phase motion of undulator. No fatal effect on the stored electron beam by installing the undulator was observed though a slight beam size change was observed at the minimum gap.

MOPPP088

Control of Nonlinear Dynamics by Active and Passive Methods for the NSLS-II Insertion Devices

undulator, insertion, insertion-device, electron

759

J. Bengtsson, O.V. Chubar, C.A. Kitegi, T. Tanabe
BNL, Upton, Long Island, New York, USA

Funding: US DOE, Contract No. DE-AC02-98CH10886.
Nonlinear dynamics effects from insertion devices (IDs) are known to affect the electron beam quality of third generation synchrotron light sources. In particular, beam lifetime, dynamical aperture and injection efficiency. Methods to model the IDs' non-linear effects are known, e.g. by second-order (in the inverse electron energy) kick maps. Methods to compensate these effects are known as well, e.g. by first-order thin or thick magnetic kicks introduced by "magic fingers," "L-shims," or "current strips." However, due to physical or technological constraints, these corrections are typically only partial. Therefore, a precise model is required for a correct minimization of the residual nonlinear dynamics effects for the combined magnetic fields of the ID and compensating magnets. We outline a systematic approach for such predictions, based on 3D magnetic field and local trajectory calculation in the ID by the Radia code, and particle tracking by Tracy-3. The optimal geometry for the compensating magnets is determined from these simulations using a combination of linear algebra and genetic optimization.

MOPPR001

Resonant Spin Depolarisation Measurements at the SPEAR3 Electron Storage Ring

storage-ring, electron, lattice, synchrotron

771

K.P. Wootton, R.P. Rassool
The University of Melbourne, Melbourne, Australia
M.J. Boland, Y.E. Tan
ASCo, Clayton, Victoria, Australia
W.J. Corbett, M.H. Donald, X. Huang, R.R. Ortiz, J.A. Safranek, K. Tian
SLAC, Menlo Park, California, USA

Accurate electron beam energy measurements are valuable for precision lattice modelling of high-brightness light sources. At SPEAR3 the beam energy was measured using the resonant spin depolarisation method with striplines to resonantly excite the spin tune and a sensitive NaI scintillator beam loss monitor was used to detect resulting changes in Touschek lifetime. Using the combined apparatus an electron beam energy of 2.997251(7) GeV was measured, giving a relative uncertainty better than 3x10^-6. The measured momentum compaction factor was found to be in close agreement with the numerical model value using rectangular defocussing gradient dipoles with measured magnetic field map profiles. In this paper we outline the chosen experimental technique, with emphasis on its applicability to electron storage rings in general.

MOPPR007

Investigation of Techniques for Precise Compton Polarimetry at ELSA

electron, photon, laser, simulation

783

R. Zimmermann, W. Hillert
ELSA, Bonn, Germany

Funding: Work supported by DFG within SFB/TR16
A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. When the polarization of the laser light is switched from left-hand to right-hand circular polarization, the spatial distribution of the backscattered photons is shifted. The extent of this modification is a measure of the beam's polarization degree. Two different experimental techniques that are suitable for a measurement of the effect were compared and evaluated closer through numerical simulations that will be presented in this contribution.

MOPPR009

Dynamic Closed Orbit Correction During the Fast Energy Ramp of ELSA

closed-orbit, acceleration, electron, controls

789

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

ELSA is a fast ramping stretcher ring supplying polarized electrons to hadron physics experiments. To preserve the degreee of polarization, it is necessary to continuously correct the vertical orbit when accelerating the beam from 1.2 GeV to 2.4 GeV. Acceleration is performed within 300 ms, thus with a ramping speed of 4 GeV/s. During the acceleration, beam positions are measured at a rate of 1 kHz using 32 beam position monitors, which are mounted close to the quadrupole magnets. The demanding task is to achieve a vertical rms deviation not exceeding 50 μm all along the fast energy ramp. Therefore, dynamic orbit corrections are applied by means of offline feed-forward techniques, driving 32 vertical steerer magnets which can change currents in less than 10 ms. In our contribution, we show the used concepts and the implementation of the precise closed orbit correction system at ELSA.

TUXA03

Increasing the AGS Beam Polarization with 80 Tune Jumps

resonance, quadrupole, emittance, closed-orbit

1015

V. Schoefer, L. A. Ahrens, M. Bai, E.D. Courant, W. Fu, C.J. Gardner, J.W. Glenn, H. Huang, F. Lin, A.U. Luccio, J.-L. Mi, J. Morris, P.J. Rosas, T. Roser, P. Thieberger, N. Tsoupas, A. Zelenski, K. Zeno
BNL, Upton, Long Island, New York, USA

Vertical depolarizing resonances in the AGS are removed by partial Siberian snakes. These magnets move the stable spin direction and lead to horizontal depolarizing resonances. The tune jump quadrupole system increases the crossing rate for horizontal resonances by a factor of six. This presentation will review the fundamental mechanism of depolarizing resonances, the partial Siberian snake solution and describe recent experimental evidence at the AGS demonstrating improvements to beam polarization and the beam dynamics challenges posed by the tune jump.

Slides TUXA03 [5.199 MB]

TUPPC057

RHIC Spin Flipper Commissioning Results

dipole, resonance, injection, proton

1302

M. Bai, W.C. Dawson, J. Kewisch, Y. Makdisi, P. Oddo, C. Pai, P.H. Pile, 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.
The five ac dipole design of RHIC spin flipper in the Blue ring was first commissioned during the RHIC 2012 polarized proton operation. The advantage of this design is to eliminate the vertical coherent betatron oscillations outside the spin flipper*. Spin flipping efficiency was measured with both 100 GeV and 250 GeV polarized proton beams. This paper presents the latest commissioning results.
* M. Bai , T. Roser, C. Dawson, Y. Makdisi, W. Meng, F. Meot, P. Oddo, C. Pai, P. Pile, RHIC Spin Flipper New Design and Commissioning Plan, IPAC10 proceedings, IPAC 2010, Kyoto, Japan, 2010

TUPPC067

How to Achieve Longitudinally Polarized Electrons using Integer Spin Tune Resonances

resonance, synchrotron, dipole, electron

1326

O. Boldt, A. Dieckmann, F. Frommberger, W. Hillert, J.F. Schmidt
ELSA, Bonn, Germany

Funding: Bundesministerium für Bildung und Forschung
Commonly, strong solenoids are used in circular accelerators to achieve longitudinal polarization. In practice, however, these solenoids cause a phase space coupling, which has to be compensated for by sophisticated decoupling schemes. We suggest to adiabatically ramp into an integer spin tune resonance, while preserving the degree of polarization. When appropriately adjusting the driving horizontal field contributions at the final energy, the resulting polarization is longitudinal at predefined positions in the accelerator. Here, depending on the energy spread, the degree of polarization is conserved for several seconds. The contribution shows the numerical analysis of this scenario being confirmed by first demonstration tests at the ELSA stretcher ring.

TUPPC075

Study of Nonlinear Beam Dynamics Effects for DEPU at SSRF

undulator, electron, photon, focusing

1347

M. Zhang, Q.G. Zhou
SINAP, Shanghai, People's Republic of China

A pair of EPUs (DEPU) with the period 58mm and 148mm, covering the energy ranges from 20 to 200eV and 200 to 2000eV of arbitrary polarized light, will be developed for the SSRF soft X-ray beam line for ARPES and PEEM. The effects of DEPU to tune-shift produced by the nonlinear beam dynamics are studied and the results are presented in this paper. The corresponding magnet field shimming technology to reduce these effects is also investigated.

TUPPC098

Electron Polarization in the Medium-Energy Electron-Ion Collider at JLAB

electron, solenoid, dipole, closed-orbit

1386

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

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A key feature of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab is high polarization (over 80%) of the electron beam at all collision points for the particle physics program. The equilibrium electron polarization is arranged to be vertical in the arcs of the figure-8 collider ring of the MEIC and anti-parallel to the arc dipole magnetic fields, in order to take advantage of the preservation of polarization by the Sokolov-Ternov (S-T) effect. Longitudinal polarization is achieved at collision points by utilizing energy-independent universal spin rotators each of which consists of a set of solenoids and dipoles placed at the end of an arc. The equilibrium beam polarization and its lifetime depend on competition between the S-T effect and radiative depolarization. The latter must be suppressed by spin matching. This paper reports on investigations of polarization in the MEIC electron collider ring and a preliminary estimate of beam polarization from calculations using the code SLICK.
Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.

TUPPD052

A New Load Lock System for the Source of Polarized Electrons at ELSA

electron, vacuum, laser, ion

1521

D. Heiliger, W. Hillert, B. Neff
ELSA, Bonn, Germany

Funding: supported by DFG (SFB/TR16)
Since 2000, an inverted source of polarized electrons at the electron stretcher accelerator ELSA routinely provides a pulsed beam with a current of 100 mA and a polarization degree of about 80%. One micro-second long pulses with 100 nC charge are produced by irradiating a GaAs strained-layer superlattice photocathode (8 mm in diameter) with laser light. Future accelerator operation requires a significantly higher beam intensity, which can be achieved by using photocathodes with sufficiently high quantum efficiency. Therefore, and in order to enhance the reliability and up time of the source, a new extreme high-vacuum (XHV) load lock system was installed and commissioned at the beginning of this year. It consists of three chambers: The activation chamber for heat cleaning of the photocathodes and activation with cesium and oxygen. The storage chamber in which up to five different types of photocathodes with various diameters of the emitting surface can be stored under XHV conditions. The loading chamber in which an atomic hydrogen source is used to remove any remaining surface oxidation. Additionally, tests of the photocathodes’ properties can be performed during operation.

TUPPD083

Raising Photoemission Efficiency with Surface Acoustic Waves

electron, photon, linac, vacuum

1596

A. Afanasev, F. Hassani, C.E. Korman
GWU, Washington, USA
V.G. Dudnikov, R.P. Johnson
Muons, Inc, Batavia, USA
M. Poelker, K.E.L. Surles-Law
JLAB, Newport News, Virginia, USA

Funding: Supported in part by DOE STTR Grant DE-SC0006256. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.

TUPPP016

Recent Development of PF Ring and PF-AR

undulator, injection, linac, vacuum

1641

Y. Tanimoto, T. Aoto, S. Asaoka, K. Endo, K. Haga, K. Harada, T. Honda, Y. Honda, M. Izawa, Y. Kobayashi, A. Mishina, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, T. Ozaki, C.O. Pak, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, K. Satoh, M. Shimada, K. Shinoe, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, M. Yamamoto
KEK, Ibaraki, Japan
H. Takaki
ISSP/SRL, Chiba, Japan

After the earthquake of March 11, two light sources of KEK, PF ring and PF-AR, have recovered the regular operation from October, 2011. We installed tandem variably-polarized undulators at PF ring in 2009. Recently, the orbit switching system has been completed with sufficient feed-forward orbit compensation at 10-Hz. PF ring is usually operated at 450 mA with a top-up injection using the pulsed sextupole magnet instead of the conventional kicker magnets. The transverse and longitudinal instabilities are suppressed by a digital feedback system using the iGp signal processor. In the longitudinal direction, we observed unstable quadrupole mode oscillation which could not be controlled by the feedback system. We had applied the phase modulation of the main RF cavity to stabilize the quadrupole oscillation before. Old-type RF-shielded gate valves damaged by the earthquake were removed from the ring during the summer maintenance. In the operation after autumn, the quadrupole oscillation can be cured by dividing the bunch train of partial-filling. Without the phase modulation, the effective brightness of SR beam has been improved especially at beam lines of finite dispersion function.

TUPPR001

Spin Tracking Simulation of a Future International Linear Collider

positron, solenoid, electron, simulation

1807

V.S. Kovalenko, O.S. Adeyemi, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov
University of Hamburg, Hamburg, Germany
A.F. Hartin
DESY, Hamburg, Germany
S. Riemann, F. Staufenbiel
DESY Zeuthen, Zeuthen, Germany

Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
The full physics potential of the International Linear Collider (ILC) is expected to be optimized by using polarized electron and positron beams. To ensure that no significant polarization can be lost during the transport of the electron and positron beams from the source to the interaction region, spin tracking has to be included in all transport elements which can contribute to a potential loss of polarization. The possible sources of depolarization such as the spin rotators and the damping ring have been investigated for the current ILC baseline. The detailed spin tracking simulations and study depolarization was performed by using BMAD and SLICKTRACK computer codes. The new results of our simulations for the ILC are presented.

TUPPR002

Simulations of Positron Polarization in the Undulator-Based Source

undulator, positron, electron, photon

1810

A. Ushakov, O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick
University of Hamburg, Hamburg, Germany
A.F. Hartin
DESY, Hamburg, Germany
S. Riemann, F. Staufenbiel
DESY Zeuthen, Zeuthen, Germany

Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
The generation of an intense and highly polarized positron beam is a challenge. The design for the International Linear Collider proposes a positron source based on a helical undulator located at the end of the electron linac. This design allows us to utilize a high energy linear accelerator with both electron and positron beams polarized. The polarization of the positron beam can be enhanced using a photon collimator. The optimization of positron yield and polarization for a wide energy range has been studied for different undulator parameters and collimator designs, taking into account realistic parameters for the capture section. In particular, the effects of misalignment and tolerances are considered.

TUPPR003

The Design of Spin-Rotator with a Possibility of Helicity Switching for Polarized Positron at the ILC

positron, solenoid, damping, lattice

1813

L.I. Malysheva, O.S. Adeyemi, V.S. Kovalenko, G.A. Moortgat-Pick, A. Ushakov
University of Hamburg, Hamburg, Germany
A.F. Hartin, B. List, N.J. Walker
DESY, Hamburg, Germany
S. Riemann, F. Staufenbiel
DESY Zeuthen, Zeuthen, Germany

Funding: Work supported by German Federal Ministry of education and research. Joint Research project R&D Accelerator Spin Management, contract N 05H10CUE
At the ILC, positrons are produced with longitudinal polarization at the source. In order to preserve the polarization, the spin must be rotated into the vertical direction prior to injection into the damping rings. A new design of the spin rotator is presented that allows to randomly switch between the two vertical orientations between successive bunch trains. After rotating the spin back to longitudinal polarization, this corresponds to a choice between the two possible helicity states at the interaction point. The fast flipping is achieved by inserting two parallel spin rotation sections with opposite polarities, with a fast magnet that allows to choose between the sections.

TUPPR040

Update on ILC Positron Source Study at ANL

positron, undulator, photon, electron

1906

W. Liu, W. Gai
ANL, Argonne, USA

As the new ILC baseline has moved the positron production to the end of electron main linac, both the drive beam energy and beamline layouts have also been changed for the positron source. Now the drive beam energy will be varying from 150GeV to 250GeV and 500GeV (for TeV upgrade) as the colliding center of mass (CM) energy changes. Systematic studies on the performance of positron source under different running scenarios have been done at ANL and the results are presented in this paper.

TUPPR042

On the Polarization Upgrade of ILC Undulator-based Positron Source

positron, undulator, photon, electron

1912

W. Liu, W. Gai
ANL, Argonne, USA
S. Riemann
DESY, Hamburg, Germany
A. Ushakov
University of Hamburg, Hamburg, Germany

The current nominal polarization for ILC undulator based positron source is 30% without photon collimators. In order to improve the effective luminosity, an upgrade of positron source with higher polarization is required. Some studies on the upgrade options have been done at both DESY and ANL, and the results are presented in this paper.

TUPPR079

Ion Polarization in the MEIC Figure-8 Ion Collider Ring

ion, proton, resonance, collider

2008

V.S. Morozov, Y.S. Derbenev, Y. Zhang
JLAB, Newport News, Virginia, USA
P. Chevtsov
Paul Scherrer Institut, Villigen, Switzerland
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, 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.
The nuclear physics program envisaged at the Medium-energy Electron-Ion Collider (MEIC) currently being developed at the Jefferson Lab calls for collisions of 3-11 GeV/c longitudinally polarized electrons and 20-100 GeV/c, in equivalent proton momentum, longitudinally or transversely polarized light ions. In this paper, we present a scheme based on figure-8 shaped booster and collider rings that provides the required ion polarization arrangement in the MEIC's ion collider ring.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

TUPPR082

MEIC Design Progress

ion, electron, collider, booster

2014

Y. Zhang, Y.S. Derbenev, D. Douglas, A. Hutton, G.A. Krafft, R. Li, F. Lin, V.S. Morozov, E.W. Nissen, F.C. Pilat, T. Satogata, C. Tennant, B. Terzić, B.C. Yunn
JLAB, Newport News, Virginia, USA
D.P. Barber
DESY, Hamburg, Germany
Y. Filatov
JINR, Dubna, Russia
C. Hyde
Old Dominion University, Norfolk, Virginia, USA
A.M. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia
S.L. Manikonda, P.N. Ostroumov
ANL, Argonne, USA
M.K. Sullivan
SLAC, Menlo Park, California, USA

Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and No. DE-AC02-06CH11357.
This paper will report the recent progress in the conceptual design of MEIC, a high luminosity medium energy polarized ring-ring electron-ion collider at Jefferson lab. The topics and achievements that will be covered are design of the ion large booster and the ERL-circulator-ring-based electron cooling facility, optimization of chromatic corrections and dynamic aperture studies, schemes and tracking simulations of lepton and ion polarization in the figure-8 collider ring, and the beam-beam and electron cooling simulations. A proposal of a test facility for the MEIC electron cooler will also be discussed.

WEPPD032

Heat Load Studies in Target and Collimator Materials for the ILC Positron Source

photon, positron, undulator, target

2576

F. Staufenbiel, S. Riemann
DESY Zeuthen, Zeuthen, Germany
O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov
University of Hamburg, Hamburg, Germany

An intense polarized positron beam for future linear colliders can be produced using a high power beam of circularly polarized photons which penetrates a thin titanium-alloy target. The degree of polarization can be increased by cutting the outer part of the photon beam generated in a helical undulator using a collimator in front of the target. However, the photon beam induces substantial heat load and stress inside the target and collimator materials. In order to avoid failure of these components the stress evolution has been simulated. The results as well as the corresponding material arrangements for the photon collimator design are presented.

THPPP026

Experimental Effects of Orbit on Polarization Loss in RHIC

resonance, acceleration, injection, proton

3788

V.H. Ranjbar
Tech-X, Boulder, Colorado, USA
M. Bai, H. Huang, A. Marusic, M.G. Minty, V. Ptitsyn
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.
We are performing several experiments during the RHIC ramp to better understand the impact of orbit errors on the polarization at our current working point. These will be conducted by exciting specified orbit harmonics during the final two large intrinsic resonance crossing in RHIC during the 250 GeV polarized proton ramp. The resultant polarization response will then be measured.

THPPP029

Simultaneous Global Coupling and Vertical Dispersion Correction in RHIC

coupling, quadrupole, proton, heavy-ion

3794

C. Liu, Y. Luo, M.G. Minty
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.
Residual vertical dispersion on the order of ±0.2 m (peak to peak) has been measured at store energies for both polarized proton and heavy ion beams. The hypothesis is that this may have impact on the polarization transmission efficiency during the energy ramp, the beam lifetimes, and, especially for heavy ions, the dynamics aperture. An algorithm to correct global coupling and dispersion simultaneously using skew quads was developed for RHIC. Simulation results together with the measured coupling and dispersion functions before and after correction will be shown for both injection and store together with an assessment of overall collider performance improvement.

THPPP030

Near Integer Tune for Polarization Preservation in the AGS

optics, acceleration, injection, resonance

3797

N. Tsoupas, L. A. Ahrens, M. Bai, K.A. Brown, J.W. Glenn, H. Huang, W.W. MacKay, T. Roser, V. Schoefer, K. Zeno
BNL, Upton, Long Island, New York, USA

Funding: *Work supported by the US Department of Energy.
The high energy (T=250 GeV) polarized proton beam experiments performed in RHIC, require high polarization of the beam. In order to preserve the polarization of the proton beam, during the acceleration in the AGS, which is the pre-injector to RHIC, two partial helical magnets* have been installed in AGS. In order to minimize the loss of the beam polarization due to the various intrinsic spin resonances occurring during the proton acceleration, we constrain the value of the vertical tune to be higher than 8.97. With the AGS running at near integer tune the perturbations caused by the partial helical magnets is large resulting in large beta and dispersion waves. To mitigate the adverse effect of the partial helices on the optics of the AGS, we have introduced compensation quads** in AGS. In this paper we present the beam optics of the AGS which ameliorates this effect of the partial helices.
* H. Huang, et al., Proc. EPAC06, p. 273, (2006).
** N. Tsoupas et al., Proc. PAC07, p. 3723 (2007).

FRXAB01

Symplectic Tracking and Compensation of Dynamic Field Integrals in Complex Undulator Structures

undulator, permanent-magnet, simulation, dipole

4165

J. Bahrdt, G. Wüstefeld
HZB, Berlin, Germany

This presentation covers analytical models that describe the interaction of an electron beam with the magnetic field of undulators. Analytic approximations to the Hamilton-Jacobi equation yield generating functions useful for particle tracking and therefore efficient simulation. Analytic expressions for kick maps of APPLE II undulators are presented as well. Passive and active shimming schemes including magic fingers and current sheets are also modeled. Applications at BESSY II are discussed which ensure efficient injection during top-up to satisfy machine protection and radiation safety requirements.

Slides FRXAB01 [1.922 MB]