• J.C. Frisch, R. Akre, F.-J. Decker, Y.T. Ding, D. Dowell, P. Emma, A. Gilevich, G.R. Hays, P. Hering, Z. Huang, R.H. Iverson, R.G. Johnson, C. Limborg-Deprey, H. Loos, E. A. Medvedko, A. Miahnahri, H.-D. Nuhn, J.L. Turner, J.J. Welch, G.R. White, J. Wu
  SLAC, Menlo Park, California
• D.F. Ratner
  Stanford University, Stanford, Califormia

The LCLS accelerator produces a 14GeV beam with a normalized emittance on the order of one micron RMS, and peak current exceeding 10⁰⁰ Amps. The design of the beam measurement system relied heavily on optical transition radiation profile monitors, in conjunction with transverse cavities, and conventional energy spectrometers. It has been found that the high peak currents, and small longitudinal phase space of the beam generate strong coherent optical emission that prevents the use of OTR or other prompt optical diagnostics, requiring the use of wire scanners or fluorescent screen based measurements. We present the results of the beam measurements, measurements of the coherent optical effects, and future plans for diagnostics.

Slides

• P.S. Prieto, C.I. Briegel, R. Dysert, N. Eddy, B.J. Fellenz, E. Gianfelice-Wendt, W. Haynes, D.J. Nicklaus, R. Rechenmacher, D. Slimmer, D.C. Voy, M. Wendt
  Fermilab, Batavia
• J.C. Frisch, J. May, D.J. McCormick, J. Nelson, A. Seryi, T.J. Smith, M. Woodley
  SLAC, Menlo Park, California
• N. Terunuma, J. Urakawa
  KEK, Ibaraki

A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring is currently in progress, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital downconversion techniques, digital signal processing, also implementing a novel automatic gain error correction schema. The technical concept and realization, as well as preliminary results of the beam studies are presented.