Photon Detector Analysis Tasks

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This page contains a list of analysis tasks that need to be done to quote a polarization number for the photon detector. There is significant overlap with the electron detector in many aspects.

Run list

  • Have we identified the major breaks in the data taking (high voltage changes, spot moves, lead thickness, etc)?
  • Is this information accessible and verifiable?
  • Do we have a list of runs that are supposed to be 'production quality'?
  • Modification of this list will continue after replay.

Replay of data

  • Do we have the best BCM and BPM calibrations? Are they active in the analyzer for the appropriate run range?
  • Do we have analysis scripts for all quantities? Beam charge asymmetry, beam position, beam slope at interaction point?
  • Do we have the ability to look at all quantities on laser cycle level?


  • What is the pedestal for the non-linearity measurements? Do we understand the pedestal differences between first half and second half? Do we understand pedestal differences between the different LED states? How do pedestal effects affect the measured non-linearity?
  • What is the cross talk for various masked-fiber combinations? How do cross talk effects affect the measured non-linearity?
  • What is the measured non-linearity of the photon detector? What is the uncertainty on this non-linearity?

Analyzing power

  • What is the final 'naive' analyzing power?
  • How does the measured non-linearity affect the analyzing power? How does the uncertainty on the non-linearity translate in a non-linearity of the analyzing power?

Asymmetry per laser cycle

  • What is the asymmetry per laser cycle?
  • Are there correlations (as expected) between asymmetry and beam position, beam slope per laser cycle?

Polarization per slug

  • What is the weighted mean asymmetry per slug?
  • What is the polarization per slug?


  • Comparison of the photon polarization over electron polarization per slug: ratio, difference, pull plot.
  • Comparison of the photon polarization over Moller polarization.

Monte Carlo studies

  • Does the shape of the photon spectra triggered on electron detector agree with simulation?
  • Do we understand the energy resolution and energy scale?
  • Can we describe the event mode spectra with Monte Carlo?