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Norum, W.E.

Paper Title Page
TUPSM044 Bunch-by-Bunch Diagnostics at the APS Using Time-Correlated Single-Photon Counting Techniques 238
 
  • B.X. Yang, S.E. Shoaf, J.B. Stevens
    ANL, Argonne
  • W.E. Norum
    LBNL, Berkeley, California
  
 

Time-correlated single-photon counting (TCSPC) techniques have been used for bunch purity measurement since the Advanced Photon Source started operations. Over the past three years, improvements made in the monitor have increased the signal-to-noise ratio and dynamic range to above 10 billion. Recently, improvements of the timing resolution of TCSPC to < 50 ps FWHM allowed us to measure the longitudinal profile of individual bunches in the APS storage ring. The profile monitor uses a visible-light single-photon avalanche photodiode (SPAD) and a PicoHarp 300 TCSPC unit. Due to its robustness, the system operates continuously and measures the average longitudinal profile of the stored beam, updating the process variables for bunch phases and bunch lengths in intervals less than 30 seconds. In a third application, using a TCSPC x-ray detector with an x-ray wire scanner in the monochromatic beam of the diagnostics undulator, measurements of transverse profiles of individual bunches can be completed in less than 30 minutes. Since the beam sizes and phases are dependent on the bunch charge, these online tools will provide users with valuable information performing timing experiments.

  
TUPSM064 An FPGA-based Bunch-by-Bunch Tune Measurement System for the APS Storage Ring 315
 
  • C. Yao, Y.-C. Chae
    ANL, Argonne
  • W.E. Norum
    LBNL, Berkeley, California
  
 

A bunch-by-bunch tune measurement system is a very powerful tool for beam diagnostics and machine studies. It can be applied to such machine physics studies as characterization of transverse impedance, observation and identification of coupled-mode instabilities, and electron cloud effects. We developed an FPGA-based bunch-by-bunch tune measurement system that excites a set of driven bunches with a frequency sweep signal, samples a set of monitored bunches, and extracts amplitude and phase information from sampled data using digital demodulation method. We report its hardware and software design, performance, and recent experimental results on the APS storage ring beam.