EPAC 2006 - List of Keywords

A B C D E F G H I K L M O P Q R S T U V W X

polarization

Paper	Title	Other Keywords	Page
MOPCH011	Jitter Measurement by Spatial Electro-optical Sampling at the Flash Free Electron Laser	laser, electron, FEL, diagnostics	71
	A. Azima, S. Düsterer, J. Feldhaus, H. Schlarb DESY, Hamburg A.L. Cavalieri MPQ, Garching, Munich D. Fritz Michigan University, Ann Arbor, Michigan K. Sengstock Uni HH, Hamburg
	For pump-probe experiments carried out at the VUV-FEL at DESY, FEL laser pulses with 32 nm wavelength have to be synchronized with high precision to optical laser pulses generated by a TiSa oscillator. To measure the relative timing variations between the FEL and the optical laser, an electro-optical experiment to determine the electron beam arrival time at the undulator has been installed. Here, the electron beam profile is encoded spatially into the laser pulse and readout by an intensified camera. A similar experimental setup has been successfully used at the sub-picosecond pulsed source (SPPS) at higher charge and shorter rms bunch length. In this paper, we report about the achievements and difficulties of the Timing Electro-Optical (TEO) setup, that allows to post-order experimental user data with a precision of 100 fs rms and better.

MOPCH083	Design Study for an Antiproton Polarizer Ring (APR)	antiproton, APR, target, quadrupole	223
	A. Garishvili, A. Lehrach, B. Lorentz, S.A. Martin, F. Rathmann FZJ, Jülich P. Lenisa INFN-Ferrara, Ferrara E. Steffens Erlangen University, Erlangen
	In the framework of the FAIR* project, the PAX collaboration has suggested a new experiments using polarized antiprotons*, in particular the study of the transverse spin structure of the proton. To polarize antiprotons the spin filtering method is proposed. The PAX collaboration is going to design the Antiproton Polarizer Ring (APR). In this contribution the design of this storage ring is described. The basic parameters of the APR are antiproton beam energy of 250 MeV and emittance in both planes of 250 pi mm mrad. The APR consists of two 180 degree arcs and two straight sections. One straight section houses the injection/extraction and the polarized internal target cell, in the other straight section, the electron cooler and a Siberian snake are located. Different optical conditions have to be fulfilled in the straight sections: (1) The target cell requires a beta function of less than 0.3 m. (2) The beam has to be circular and upright in the phase space ellipse at the target, the electron cooler, and the snake. (3) The antiproton beam should have a size of 10 mm for an emittance of 250 pi mm mrad. (4) The momentum dispersion has to be zero in both straight sections. Conceptual Design Report for an International Accelerator Facility for Research with Ions and Antiprotons, available from www.gsi.de/GSI-Future/cdr.**PAX Technical Proposal, available from www.fz-juelich.de/IKP/pax.

MOPCH100	Polarized Proton Acceleration in the AGS with Two Helical Partial Snakes	resonance, AGS, injection, extraction	273
	H. Huang, L. Ahrens, M. Bai, A. Bravar, K.A. Brown, E.D. Courant, C.J. Gardner, J. Glenn, A.U. Luccio, W.W. MacKay, V. Ptitsyn, T. Roser, S. Tepikian, N. Tsoupas, J. Wood, K. Yip, A. Zelenski, K. Zeno BNL, Upton, Long Island, New York F. Lin IUCF, Bloomington, Indiana M. Okamura, J. Takano RIKEN, Saitama
	Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and it is not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes with double pitch design have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results. The effect of horizontal intrinsic resonances in the presence of two partial snakes are also discussed.

MOPCH101	On the Feasibility of a Spin Decoherence Measurement	RHIC, synchrotron, proton, AGS	276
	W.W. MacKay BNL, Upton, Long Island, New York
	In this paper, we study the feasibility of making a turn-by-turn spin measurement to extract the spin tune of a synchrotron from a polarized beam injected perpendicular to the stable spin direction. For the ideal case of a zero-emittance beam with no spin-tune spread, there would be no spin decoherence and a measurement of the spin tune could easily be made by collecting turn-indexed polarization data of several million turns. However, in a real beam there is a momentum spread which provides a tune spread. With a coasting beam the tune spread will cause decoherence of the spins resulting in a fast depolarization of the beam in a thousand turns. With synchrotron oscillations the decoherence time can be greatly increased, so that a measurement becomes feasible with summation of the turn-by-turn data from a reasonable number of bunches (100 or fewer). Both the cases of a single Siberian snake and a pair of Siberian snakes are considered.

MOPLS024	RHIC Performance as Polarized Proton Collider in Run-6	RHIC, luminosity, emittance, AGS	592
	V. Ptitsyn, L. Ahrens, M. Bai, D.S. Barton, J. Beebe-Wang, M. Blaskiewicz, A. Bravar, J.M. Brennan, K.A. Brown, D. Bruno, G. Bunce, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, J. DeLong, K.A. Drees, A.V. Fedotov, W. Fischer, G. Ganetis, H. Hahn, T. Hayes, H.-C. Hseuh, H. Huang, P. Ingrassia, D. Kayran, J. Kewisch, R.C. Lee, V. Litvinenko, A.U. Luccio, Y. Luo, W.W. MacKay, Y. Makdisi, N. Malitsky, G.J. Marr, A. Marusic, R.J. Michnoff, C. Montag, J. Morris, T. Nicoletti, B. Oerter, F.C. Pilat, P.H. Pile, T. Roser, T. Russo, J. Sandberg, T. Satogata, C. Schultheiss, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang BNL, Upton, Long Island, New York
	The Relativistic Heavy Ion Collider in Run-6 was operating in polarized proton mode. With two Siberian Snakes per ring, the polarized protons were brought into collisions at 100 Gev and 31.2 Gev energies. The control of polarization orientation at STAR and PHENIX experiments was done using helical spin rotators. Physics studies were conducted with longitudinal, vertical and radial beam polarization at collision points. This paper presents the performance of RHIC as a polarized proton collider in the Run-6 with emphasis on beam polarization and luminosity issues.

MOPLS038	Beam Energy Calibration in Experiment on Precise Tau Lepton Mass Measurement at VEPP-4M with KEDR Detector	energy-calibration, resonance, lepton, electron	625
	A. Bogomyagkov, V.E. Blinov, S. Karnaev, V. Kiselev, E.V. Kremyanskaya, E. Levichev, O.I. Meshkov, S.I. Mishnev, I. Morozov, N.Yu. Muchnoi, S.A. Nikitin, I.B. Nikolaev, A.G. Shamov, D.N. Shatilov, E.A. Simonov, A.N. Skrinsky, V.V. Smaluk, Yu.A. Tikhonov, G.M. Tumaikin, V.N. Zhilich BINP SB RAS, Novosibirsk
	Experiment on mass measurement of tau lepton requires an absolute energy calibration. The resonant depolarization technique is used for most accurate (1 keV) but once at a time energy calibration. The measured energy is used for calibration of the germanium detector for Compton backscattering energy monitoring. The developed Compton backscattering facility allows continuous energy monitoring with accuracy of 50 keV for 10 minutes of data acquisition. The tau lepton threshold is in the vicinity of integer spin resonance, which minimizes polarization lifetime in the presence of vertical orbit distortions. Therefore, spin matching of the VEPP-4M is required. The achieved lifetime is sufficient for absolute energy calibration.

MOPLS072	Status of the HeLiCal Contribution to the Polarised Positron Source for the International Linear Collider	undulator, positron, electron, photon	715
	J.A. Clarke, O.B. Malyshev, D.J. Scott CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire I.R. Bailey, P. Cooke, J.B. Dainton, L.I. Malysheva Liverpool University, Science Faculty, Liverpool D.P. Barber DESY, Hamburg E. Baynham, T.W. Bradshaw, A.J. Brummitt, F.S. Carr, Y. Ivanyushenkov, J. Rochford CCLRC/RAL, Chilton, Didcot, Oxon G.A. Moortgat-Pick Durham University, Durham
	The baseline positron source for the International Linear Collider is a helical undulator-based design, which can generate unprecedented quantities of polarised positrons. A major thrust of the global design in this area is led by the UK-based HeLiCal collaboration. The collaboration takes responsibility for the design and prototyping of the helical undulator itself, which is a highly demanding short period device with very small aperture, and also leads the start to end simulations of the polarised particles to ensure that the high polarisation levels generated are maintained from the source, right through the beam transport systems and up to the interaction point itself. This paper will provide an update on the work of the collaboration, focusing on these two topic areas, and will also discuss future plans.

MOPLS083	Higher Order Mode Study of Superconducting Cavity for ILC Baseline	KEK, pick-up, coupling, dipole	747
	K. Watanabe GUAS/AS, Ibaraki H. Hayano, E. Kako, S. Noguchi, T. Shishido KEK, Ibaraki
	The superconducting cavity of ILC baseline shape is being developed at KEK-STF (Superconducting RF Test Facility). The Higher Order Mode (HOM) of the cavity is one study item for the development. The purpose of the HOM study is further optimization of TTF HOM coupler and measurement of the HOM field distribution and the polarization of the main dipole modes. The result will be applied to HOM readings of beam induced signal for the purpose of cavity offset position and angle of axis measurement relative to the beam. We tried to improve of TESLA-type HOM coupler for more small size and relaxation of second stop-band. The cold-model coupler was made, and the RF characteristic was measured. After HOM couplers welded to the KEK Baseline nine-cell SC cavity, Qext of fundamental mode and each HOM, field pattern of each HOM and polarization of dipole modes were measured by the network analyzer. The results of the improved HOM coupler are presented.

MOPLS115	A Spin Rotator for the ILC	emittance, linac, coupling, dipole	831
	P.O. Schmid, N.J. Walker DESY, Hamburg
	A spin rotator featuring an optic axis with straight vision is presented. This rotator utilizes three bends, two solenoid pairs and two correction devices. These correctors, named reflectors, are mandatory for removing the cross plane coupling introduced by the solenoids. It is shown how the solenoids have to be set up to achieve longitudinal IP polarization taking into account non-zero crossing angles at the interaction region and a linac following the curvature of the earth. Furthermore, the stability requirements for mechanical and electrical imperfections are analyzed.

TUPCH075	Dependence of the Electron Beam Polarization Effect in the Intra-beam Scattering Rate on the Vertical Beam Emittance	electron, scattering, emittance, coupling	1184
	S.A. Nikitin, I.B. Nikolaev BINP SB RAS, Novosibirsk
	Measurement of the Intra-beam scattering rate is applied in the resonant depolarization technique to detect beam polarization in electron/positron storage rings. A depolarization jump in the counting rate of scattering particles occurs at the instant when the beam becomes unpolarized due to fulfillment of the external spin resonance condition. The magnitude of the jump depends on polarization quadratically. It also depends on some other beam parameters as well as the position of counters relative to the beam orbit. A larger jump implies higher accuracy in absolute calibration of particle energy because the latter is proportional to the spin precession frequency. In contrast to an ordinary one-dimensional approach, we calculate the magnitude of jump subject to, among other things, the vertical component of relative velocity in particle collisions inside the beam. For this purpose, the transverse momentum distribution function is properly modified. Calculations performed for the VEPP-4M storage ring-collider show that the jump may depend significantly on the ratio between the vertical and radial beam emittance. We present results of our recent experiments on study of this dependence.

WEPCH102	Studies of the Nonlinear Dynamics Effects of APPLE-II Type EPUs at the ALS	dynamic-aperture, multipole, lattice, simulation	2152
	C. Steier, S. Marks, S. Prestemon, D. Robin, D. Schlueter, W. Wan, W. Wittmer LBNL, Berkeley, California
	Elliptically Polarizing Undulators (EPUs) have become more and more popular at synchrotron radiation sources, providing full polarization control of the photon beam. The fields of the most commonly used APPLE-II type EPUs have a very fast, intrinsic field roll-off, creating significant non-linearities of the beam motion with in some cases large impact on the dynamic (momentum) aperture. In general, the nonlinear effects get stronger with longer periods and higher undulator magnetic fields. One of the planned future beamlines at the ALS (MERLIN) will use a quasiperiodic EPU with 9 cm period and maximum B fields of about 1.3 T. We will present simulation studies for the proposed shimming schemes for this future device to reduce the nonlinear effects to acceptable values, as well as experimental studies for the existing 5 cm period EPUs already installed in the ALS.

WEPCH130	Analysis of Symmetry in Accelerating Structures with Group Theory	RF-structure, lattice, KEK	2227
	S. Sakanaka KEK, Ibaraki
	Many rf cavities for modern accelerators have a variety of symmetry. There is a question as to what is the connection between the symmetry of a cavity and of its eigenmodes. This can be clarified* using the representation theory of groups. The geometric symmetry of a cavity can be expressed by a group of symmetry operations. The structure of this group can be represented by a set of matrices called representation. The group is associated with several irreducible representations which can express possible patterns of transformations under the symmetry operations. The irreducible representations are very suitable to express the symmetry of each eigenmode. This method can be used to improve the understanding of non-axially symmetric structures. In this paper, this method is first explained, and then, it is extended to the application of symmetric periodic structures. *S. Sakanaka, Phys. Rev. ST Accel. Beams 8, 072002 (2005).

WEPLS032	Spin Tracking at the ILC	damping, positron, synchrotron, radiation	2454
	G.A. Moortgat-Pick, I.R. Bailey, D.P. Barber, J.A. Clarke, J.B. Dainton, O.B. Malyshev, G.A. Moortgat-Pick, D.J. Scott Cockcroft Institute, Warrington, Cheshire E. Baynham, T.W. Bradshaw, A.J. Brummitt, F.S. Carr, Y. Ivanyushenkov, J. Rochford CCLRC/RAL, Chilton, Didcot, Oxon P. Cooke, L.I. Malysheva Liverpool University, Science Faculty, Liverpool
	Polarized beams will play a key role in the physics programme at the International Linear Collider (ILC). It is expected that the electron and positron sources will be able to produce beams with polarizations of about 90% and 60% respectively. However, to obtain accurate measurements it is essential to have precise knowledge and control of the polarization at the interaction point itself. It follows that the theoretical calculations used for spin tracking must be guaranteed to match the anticipated 0.1% relative measurement uncertainty of the polarimeters. To meet this need, the heLiCal collaboration is developing a computer simulation to track the evolution of the polarization of bunches of electrons and positrons from the sources to the interaction point. We have studied the beam spin dynamics throughout the ILC including spin precession and radiative spin-flip processes in the positron source, damping rings, beam delivery system and the interaction region. We present the result of these studies with special emphasis on the impact of new theoretical calculations for the CAIN bunch-bunch simulation including full spin correlations and higher-order contributions.

THOBFI03	Record-high Resolution Experiments on Comparison of Spin Precession Frequencies of Electron Bunches Using the Resonant Depolarization Technique in the Storage Ring	electron, positron, storage-ring, radiation	2787
	S.A. Nikitin, O. Anchugov, V.E. Blinov, A. Bogomyagkov, V.P. Cherepanov, G.V. Karpov, V. Kiselev, E. Levichev, I.B. Nikolaev, A.A. Polunin, E. Shubin, E.A. Simonov, V.V. Smaluk, M.V. Struchalin, G.M. Tumaikin BINP SB RAS, Novosibirsk
	The opportunity of performing an experiment on high precision comparison of the electron and positron anomalous magnetic moments following the VEPP-2M experiment is under study at the VEPP-4M storage ring. The record accuracy of 2x10-8 was obtained for comparison of spin precession frequencies in the experiment on resonant depolarization with simultaneously circulating electron bunches, two of them polarized and one unpolarized. It is the first time when the spreading of the spin precession frequency line (~5x10-7,) due to scattering of particle trajectories about the equilibrium orbit in a non-linear field of the storage ring, was presumably observed in experiments. We proposed and realized an RF scheme for controlled separation of the spin precession frequencies of two electron bunches; the first measurements using this scheme were made.
	Transparencies

THPCH132	EPU Assembly Based on Sub-cassettes Magnetic Characterization	undulator, electron, synchrotron, radiation	3107
	G. Tosin, R. Basilio, J.F. Citadini, M. Potye LNLS, Campinas
	A procedure to speed up the magnetic field correction of an EPU type undulator is proposed and its results are shown. Such procedure consists in segmenting each one of the four magnetic blocks linear arrays (cassettes) in seven sub-cassettes and making their individual magnetic and mechanical characterization. One theoretical perfect sub-cassette, which is composed of four segments per period in Halbach configuration, is taken as the standard field profile. The peak fields and the fields integrated in each semi-period of one sub-cassette are chosen to be the optimization parameters. The magnetic blocks are displaced (virtual shims) to minimize the difference of the optimization parameters between the sub-cassette magnetic measurement and the standard profile. The sub-cassette magnetic measurements are performed with Hall probes, using the same bench employed in insertion devices characterization.

THPCH133	Conceptual Design of an EPU for VUV Radiation Production at LNLS	undulator, controls, synchrotron, vacuum	3110
	G. Tosin, R. Basilio, J.F. Citadini, R.T. Neuenschwander, M. Potye, X.R. Resende, M. Rocha, P.F. Tavares LNLS, Campinas
	We describe the magnetic and mechanical design of an elliptically polarizing undulator (EPU) currently under construction at the (Brazilian Synchrotron Light Source - LNLS). The device is designed to cover the photon flux in the range from 100eV to 1000eV (124Å a 12.4 Å), allowing linear, elliptical and circular polarizations. With this device it is possible to reach absorption edges of several elements such as Si, S, Br, C, N, O, Fe, F, Cl and to measure magnetic dichroism. The EPU's magnetic design is conventional, and field corrections are done by means of virtual shims, with horizontal and vertical displacements. Each one of the four magnetic blocks linear arrays (cassettes) is segmented in seven sub-cassettes. The separate magnetic measurement of each sub-cassette allows corrections of the magnetic field profile to be made before final assembly and makes the verification of mechanical tolerances easier and faster, decreasing the expected time that will be spent in the magnetic tuning of the device. The mechanical structure is composed of a C-Frame, gap and phase actuators. The gaps actuators and phase actuators use absolute encoders and bias with springs to eliminate backlash.

THPCH150	Double-pulse Generation with the FLASH Injector Laser for Pump/Probe Experiments	laser, SASE, FEL, radiation	3143
	O. Grimm, K. Klose, S. Schreiber DESY, Hamburg
	The injector laser of the VUV-FEL at DESY, Hamburg, was modified to allow the generation of double-pulses, separated by a few cycles of the 1.3 GHz radio-frequency. Such double pulses are needed for driving the planned infrared/VUV pump/probe facility. Construction constraints of the facility will result in an optical path length about 80 cm longer for the infrared. Although the VUV can be delayed using normal-incidence multilayer mirrors at selected wavelengths, a fully flexible scheme is achieved by accelerating two electron bunches separated by more than the path length difference and then combine the infrared radiation from the first with the VUV from the second. This paper explains schemes for the generation of double-pulses with the laser system. It summarizes experimental studies of the effect on the operation of diagnostic instrumentation and on the tunability of the machine. Of special concern is the effect of wakefields on the quality of the second bunch, critical for achieving lasing.

THPLS118	Status of the SOLEIL Insertion Devices	undulator, SOLEIL, insertion, insertion-device	3556
	F. Briquez, C. Benabderrahmane, P. Berteaud, O.V. Chubar, M.-E. Couprie, L. Dubois, J.-M. Filhol, M. Girault, O. Marcouillé, F. Marteau, M. Massal, F. Paulin, M.V. Valleau, J. Vétéran SOLEIL, Gif-sur-Yvette A. Dael CEA, Gif-sur-Yvette
	SOLEIL is the French 2.75 GeV synchrotron radiation light source of low emittance under construction near Paris. It will provide high intensity photons covering a wide spectral range from the IR to the hard x-rays. The storage ring commissioning will start in April 2006, and the first photons in the beam lines are expected during summer 2006. The first set of Insertion Devices (ID) will be installed before the commissioning or within the first year of operation of the machine. They consist of one 640 mm period and three 256 mm period electromagnetic helical undulators, three 80 mm period Apple II type undulators, and three 20 mm period in-vacuum undulators. All these ID's make use of a wide panoply of technical solutions for generating various types of magnetic fields. Magnetic and conceptual designs were performed by SOLEIL, and the technical realisation was carried out together with the different manufacturers. The design specificities of the different types of ID's and the magnetic field characterisation and optimisation will be reported. The first commissioning on the beam of these undulators will be described.

THPLS134	A General View of IDs to be Installed at ALBA on Day One	undulator, wiggler, ELETTRA, radiation	3598
	J. Campmany, F. Becheri, D. Bertwistle, D. Einfeld, J. Marcos, V. Massana ALBA, Bellaterra Z. Martí LLS, Bellaterra (Cerdanyola del Vallès)
	The new 3rd generation synchrotron radiation source ALBA to be built nearby Barcelona is planned to start operation in 2009 with several different insertion devices installed in the storage ring either from "day one" or within the first year of operation. The list of high-priority insertion devices includes: 2 planar PPM SmCo in-vacuum undulators with the period of 21.3 mm; 2 Apple-II type PPM NdFeB undulators with the period of 71 mm; 1 superconducting planar wiggler with the period of 30 mm and a maximum field of 2 T, and a 1 conventional wiggler with the period of 65 mm and a maximum field of 1.55 T. The emission of these undulators covers wide spectral range extending from hard X-rays to UV. Pre-design of the IDs was done by ALBA. The construction will be done by industrial companies and institutions with production capabilities. ALBA will set up a magnetic measurement laboratory for the acceptance tests. The paper will present peculiarities of the magnetic design, calculated maximum-flux spectra and associated heat load in various modes of operation.

THPLS138	Fast Polarization Switching at the SLS Microspectroscopy Beamline POLLUX	SLS, coupling, dipole, feedback	3610
	M. Böge, U. Flechsig, J. Raabe, T. Schilcher PSI, Villigen
	POLLUX is a new microspectroscopy facility which will be operated at a bending magnet at the Swiss Light Source (SLS). It offers spectroscopy with sub-micrometer spatial resolution for polymer science and magnetism. First user operation is scheduled for summer 2006. One of the novel envisaged options of the beamline is the usage of circular polarized light. The circular polarization will be generated by a localized angular steering of the electron beam within the bending magnet. This is accomplished by means of the global fast orbit feedback system of the SLS which allows to stabilize the electron beam to the sub-micrometer level up to frequencies of ~100 Hz. Due to the adapting coupling compensation involving dedicated adjacent skew quadrupoles, this steering becomes practically transparent to the other beamlines. Polarization switching rates of a few Hz are within reach.