Author: Aryshev, A.S.
Paper Title Page
MOPB69
 Development of Four Mirror Pulsed Laser Wire System for ATF-KEK Damping Ring  
 
  • A.A. Rawankar, N. Terunuma, J. Urakawa
    Sokendai, Ibaraki, Japan
  • A.S. Aryshev, Y. Honda, H. Shimizu
    KEK, Ibaraki, Japan
  • Y. You
    TUB, Beijing, People's Republic of China
  
  Funding: Quantum Beam Technology Program of Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT).
Production and handling of a low emittance beam is one of the key technologies for linear colliders. The Accelerator Test Facility (ATF) was constructed at KEK to study low emittance beam physics and to develop the technologies associated with it. In ATF damping ring, the vertical beam size is less than 10 μm. To measure it precisely, a thin and intense laser beam is required. We utilize a pulsed four mirror optical cavity based on IR laser oscillator to fulfill this requirement. With pulsed green laser oscillator, the beam waist will reduce by factor of 2. Therefore, with green laser oscillator, effective electron-photon collision can be observed. Minimum beam waist is obtained in sagittal plane. Special type of mirror alignment scheme is used to make a compact four mirror optical cavity. With Pulsed laser oscillator the electron beam scanning is very fast as compare to CW Laser wire system. Profile of electron beam can be measured in vertical, horizontal and longitudinal direction within a few second. We report the design studies of such compact resonator and scheme to obtain laser beam size less than 6μm in rms. 		 
 
WECA01
 Theoretical and Experimental Investigation on Resolution of Optical Transition Radiation Transverse Beam Profile Monitor  
 
  • A.S. Aryshev, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • B. Bolzon, E. Bravin, T. Lefèvre
    CERN, Geneva, Switzerland
  • S.T. Boogert, V. Karataev
    Royal Holloway, University of London, Surrey, United Kingdom
  • L.J. Nevay
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  
  Optical Transition Radiation (OTR) appearing when a charged particle crosses an interface between two media with different dielectric constants has widely been used as a tool for transverse profile measurements of charged particle beams in numerous facilities worldwide. The basic tuning methods and operation of conventional OTR monitors are well established for transverse beam sizes not smaller than 3-5 um. Since the Point Spread Function (PSF) dimension defines the resolution of the conventional monitors, for small electron beam dimensions the PSF form significantly depends on a presence of OTR tails diffraction and aberrations in the optical system. In our experiment we have managed to squeeze the electron beam such that we can practically measure PSF distribution in one direction. The revealed PSF structure is such that the visibility depends on the transverse beam size on micron scale. We developed an empirical calibration technique and successfully overcame the resolution limit of the common OTR monitor reaching sub-micron level. Here we represent the recent developments and upgrades in both setup and data analysis of a sub-micrometer electron beam profile monitor.