GlueX Start Counter Meeting, August 22, 2019

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GlueX Start Counter Meeting
Thursday, August 22, 2019
10:00 am EDT
CEBAF Center, Room L207
BlueJeans: 556 286 544


  1. Announcements
  2. Review minutes from the last meeting
  3. Calibration and Efficiency
  4. SiPM Dark Rate Studies (Beni) GlueX-doc-4138
  5. Action Item Review


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2019 on the JLab CUE. This directory is accessible from the web at .



  • JLab: Rupesh Dotel, Mark Ito (chair), Simon Taylor, Beni Zihlmann

There is a recording of this meeting on the BlueJeans site. Use your JLab credentials to authenticate.

Review minutes from the last meeting

We went over the minutes of the meeting on June 13 without significant comment.

SiPM Dark Rate Studies

Beni led us through his recent note, GlueX-Doc-4138. Please see his note for all of the details.

  • Data was taken with beam off, sparsification turned off (raw mode) using random triggers at 2 kHz. The read-out window was set to 100 samples.
  • Average pedestal values for each set of four samples in the window (25 measurements per event per channel) are histogrammed and the low side of the pedestal peak is fit to a Gaussian. Then the total integral of the distribution is compared to the area under the Gaussian. The ratio of Gaussian area to total area is plotted for four data-taking runs spanning the PrimEx run period.
  • There is a 5% decrease of the ratio over the course of the run period.
  • Beni proposes that we make these measurements a standard part of all future running. Rupesh volunteered to oversee the operation including data analysis.