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Singh, O.

Paper Title Page
FRPMN106 Progress toward a Hard X-ray Insertion Device Beam Position Monitor at the Advanced Photon Source 4342
 
  • G. Decker, P. K. Den Hartog, O. Singh
    ANL, Argonne, Illinois
  • G. Rosenbaum
    UGA, Athens, Georgia
  
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

Long-term pointing stability at synchrotron light sources using conventional rf-based particle beam position monitoring is limited by the mechanical stability of the pickup electrode assembly. Photoemission-based photon beam position monitors for insertion device beams suffer from stray radiation backgrounds and other gap-dependent systematic errors. To achieve the goal of 500-nanoradian peak-to-peak pointing stability over a one-week period, the development of a photon beam position detector sensitive only to hard x-rays (> several keV) using copper x-ray fluorescence has been initiated. Initial results and future plans are presented.

 
FRPMN120 Tuning the Narrow-band Beam Position Monitor Sampling Clock to Remove the Aliasing Errors in APS Storage Ring Orbit Measurements 4402
 
  • X. Sun, O. Singh
    ANL, Argonne, Illinois
  
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

The Advanced Photon Source storage ring employs a real-time orbit correction system to reduce orbit motion up to 50 Hz. This system uses up to 142 narrow-band rf beam position monitors (Nbbpms) in a correction algorithm by sampling at a frequency of 1.53 kHz. Several Nbbpms exhibit aliasing errors in orbit measurements, rendering these Nbbpms unusable in real-time orbit feedback. The aliasing errors are caused by beating effects of the internal sampling clocks with various other processing clocks residing within the BPM electronics. A programmable external clock has been employed to move the aliasing errors out of the active frequency band of the real-time feedback system (RTFB) and rms beam motion calculation. This paper discusses the process of tuning and provides test results.