Test Setup for SiPMs

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Test of First Article of Hamamatsu SiPMs at JLab

Time Line

  1. Mid Feb.2012: 10-20pcs partial shipment of first article units
  2. Mid Mar.2012: Delivery remainder first article units (60-70pcs)
  3. End Apr.2012: First article approval
  4. End Jul.2012: 1st delivery 500pcs
  5. End Aug.2012: 2nd delivery 500pcs
  6. End Sept.2012: 3rd delivery 120pcs

Test Items and Instruments Needed

General Devices


  1. Measure ADC spectrum w. or w./o light source
  2. Measure distance between peaks, calculate the corresponding charge and then gain

Photo Detection Efficiency (PDE)

  • Continuous method (DC mode): overestimated due to cross-talk and after pulsing
  1. Measure draw current with calibrated light input
  2. Divide current by gain and photon flux to get "PDE"
  • Pulse mode
  1. Measure ADC spectrum triggered by calibrated pulse light source
  2. Fit the spectrum by the function derived here to extract detected number of photons and cross-talk/after pulsing
  3. Divide the detected number of photons by input to get PDE

Cross-Talk/After Pulsing

  • Cross-Talk and After Pulsing are sometimes mixed, in this context they are defined base on the timing:
  1. Cross-Talk means fast secondary signals which happen almost simultaneously with the primary signal which are likely due to the secondary photon generated by the primary signal leaked to adjacent pixels.
  2. After Pulsing means slow secondary signals which happen after the primary signal which are likely due to the delayed release of trapped electrons.
  • Threshold method
  1. Pure measurement with dark noise
  2. This method is mainly sensitive to Cross-Talk.
  3. Set threshold of counter at 0.5, 1.5 and 2.5 photon electrons, compare the rates at different rates to extract Cross-Talk.
  4. Formalism to extract cross-talk is still needed to be derived, effect of pile up and after pulsing needed to be taken into account.
  • ADC method
  1. Same method as pulse mode discussed in the PDE measurement
  • Flash method
  1. Use Oscilloscope or Flash ADC to record the time spectrum with very weak but instantaneous light input (laser for example),
  2. By comparing the shape of the time spectrum from the single photon events with all events to extract the after pulsing
  3. Such a method was discussed in SiPM radiation test

Test of First Article of Hamamatsu SiPMs at Regina

Time Line