• I. Hwang, C. Kim, K.R. Kim, M. Kim, S.H. Nam, S.J. Park, S. Shin
  PAL, Pohang, Kyungbuk
• J. Hou, L.G. Liu
  SINAP, Shanghai

The measurement and the control of the coupling is essential to maximize synchrotron performance. Small coupling is required for small vertical size and high brightness. The Pohang Light Source has a 2.5 GeV storage ring and its coupling constant is measured as about 1%. In addition to errors at quadrupole or sextupole, the condition varying of the insertion device affects the coupling. The coupling for various condition is measured by the resonance and the response matrix and compared with the beam size and the lifetime. The correction and the control of the coupling is presented.

• S.T. Boogert, G.E. Boorman, C. Swinson
  JAI, Oxford
• R. Ainsworth, S. Molloy
  Royal Holloway, University of London, Surrey
• A.S. Aryshev, Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• J.C. Frisch, J. May, D.J. McCormick, J. Nelson, T.J. Smith, G.R. White, M. Woodley
  SLAC, Menlo Park, California
• A. Heo, E.-S. Kim, H.-S. Kim, Y.I. Kim
  Kyungpook National University, Daegu
• A. Lyapin
  UCL, London
• H.K. Park
  KNU, Deagu
• M.C. Ross
  Fermilab, Batavia
• S. Shin
  PLS, Pohang

The Accelerator Test Facility 2 (ATF2) in KEK, Japan, is a prototype scaled demonstrator system for the final focus required for a lepton linear collider. The ATF2 beam-line is instrumented with a total of 38 C and S band resonant cavity beam position monitors (BPM) with associated mixer electronics and digitizers. The current status of the BPM system is described, with a focus on operational techniques and performance.