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Walston, S.

Paper Title Page
FRPMS049 Resolution of a High Performance Cavity Beam Position Monitor System 4090
 
  • S. Walston, C. C. Chung, P. Fitsos, J. Gronberg
    LLNL, Livermore, California
  • S. T. Boogert
    Royal Holloway, University of London, Surrey
  • J. C. Frisch, S. Hinton, J. May, D. J. McCormick, S. Smith, T. J. Smith, G. R. White
    SLAC, Menlo Park, California
  • H. Hayano, Y. Honda, N. Terunuma, J. Urakawa
    KEK, Ibaraki
  • Yu. G. Kolomensky, T. Orimoto
    UCB, Berkeley, California
  • P. Loscutoff
    LBNL, Berkeley, California
  • A. Lyapin, S. Malton, D. J. Miller
    UCL, London
  • R. Meller
    Cornell University, Department of Physics, Ithaca, New York
  • M. C. Ross
    Fermilab, Batavia, Illinois
  • M. Slater, M. Thomson, D. R. Ward
    University of Cambridge, Cambridge
  • V. Vogel
    DESY, Hamburg
 
  International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved – ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. A metrology system for the three BPMs was recently installed. This system employed optical encoders to measure each BPM's position and orientation relative to a zero-coefficient of thermal expansion carbon fiber frame and has demonstrated that the three BPMs behave as a rigid-body to less than 5 nm. To date, we have demonstrated a BPM resolution of less than 20 nm over a dynamic range of ± 20 microns.  
FRPMS073 Picosecond Bunch Length and Energy-z Correlation Measurements at SLAC's A-Line and End Station A 4201
 
  • S. Molloy, P. Emma, J. C. Frisch, R. H. Iverson, D. J. McCormick, M. Woods
    SLAC, Menlo Park, California
  • V. Blackmore
    OXFORDphysics, Oxford, Oxon
  • M. C. Ross
    Fermilab, Batavia, Illinois
  • S. Walston
    LLNL, Livermore, California
 
  Funding: US DOE Contract #DE-AC02-76FS00515

We report on measurements of picosecond bunch lengths and the energy-z correlation of the bunch with a high energy electron test beam to the A-line and End Station A (ESA) facilities at SLAC. The bunch length and the energy-z correlation of the bunch are measured at the end of the linac using a synchrotron light monitor diagnostic at a high dispersion point in the A-line and a transverse RF deflecting cavity at the end of the linac. Measurements of the bunch length in ESA were made using high frequency diodes (up to 100 GHz) and pyroelectric detectors at a ceramic gap in the beamline. Modelling of the beam's longitudinal phase space through the linac and A-line to ESA is done using the 2-dimensional tracking program LiTrack, and LiTrack simulation results are compared with data. High frequency diode and pyroelectric detectors are planned to be used as part of a bunch length feedback system for the LCLS FEL at SLAC. The LCLS also plans precise bunch length and energy-z correlation measurements using transverse RF deflecting cavities.