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polarization

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MOP36 Preliminary Study on HOM-Based Beam Alignment in the TESLA Test Facility dipole, alignment, gun, higher-order-mode 117
 
  • N. Baboi, G. Kreps, M. Wendt
    DESY, Hamburg
  • G. Devanz, R. Paparella
    CEA/DAPNIA-SACM, Gif-sur-Yvette Cedex
  • O. Napoly
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  The interaction of the beam with the higher order modes (HOM) in the TESLA cavities has been studied in the past at the TESLA Test Facility (TTF) in order to determine whether the modes with the highest loss factor are sufficiently damped. The same modes can be used actively for beam alignment. At TTF the beam alignment based on the HOM signals is planned to be studied in the first cryo-module, containing 8 accelerating cavities. One of several modes with higher loss factor will be used. Its polarization has to be determined. The options to use single bunches or bunch trains will be analyzed. The results will be discussed in this paper.  
 
MOP39 Positron Transmission and Polarization in E-166 Experiment positron, target, photon, focusing 126
 
  • Y.K. Batygin
    SLAC, Stanford
  The proposed experiment E-166 at SLAC is designed to demonstrate the possibility of producing longitudinally polarized positrons from circularly polarized photons. Experimental set-up utilizes a low emittance 50 GeV electron beam passing through a helical undulator in the Final Focus Test Beam line of SLAC accelerator. Circularly polarized photons generated by the electron beam in undulator hit a target and produce electron-positron pairs. The purpose of post-target optics is to select the positron beam and to deliver it to a polarimeter keeping positron beam polarization as high as possible. Paper analyzes the positron transmission and polarization both numerically and analytically. The value of positron transmission has a maximum of 3% for positron energy of 7 MeV while positron polarization is around 80%.  
 
THP24 Highly Polarized Electrons from GaAs-GaAsP and InGaAs-AlGaAs Strained Layer Superlattice Photocathodes cathode, electron, photon, laser 648
 
  • T. Nakanishi, F. Furuta, M. Kuwahara, K. Naniwa, T. Nishitani, S. Okumi, N. Yamamoto, K. Yasui
    DOP Nagoya, Nagoya
  • H. Horinaka, T. Matsuyama
    OPU, Osaka
  • H. Kobayakawa, Y. Takashima, Y. Takeda, O. Watanabe
    DOE Nagoya, Nagoya-City
  GaAs-GaAsP strained layer superlattice photocathode has been developed for highly polarized electron beams. This cathode achieved a maximum polarization of 92% with a quantum efficiency of 0.5%. Criteria for achieving the highest polarization together with high quantum efficiency using superlattice photocathodes are discussed based on experimental spin-resolved quantum efficiency spectra of GaAs-AlGaAs, InGaAs-AlGaAs and GaAs-GaAsP superlattice structures.