GlueX Start Counter Meeting, May 2, 2019

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GlueX Start Counter Meeting
Thursday, May 2, 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. 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 .



  • FIU: Mahmoud Kamel
  • JLab: Mark Ito (chair), Simon Taylor, Beni Zihlmann

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


Mahmoud reported that Thomas Britton asked him for efficiency numbers for the start counter as part of his presentation to the Workshop on Comparison of Data and Monte Carlo at the Collaboration Meeting. Mahmoud plans to generate efficiency as a function of z for recent data. He is hoping for the best as the code has not been run for several months.

SiPM Dark Current

Beni looked a bit more at the data collected during the last run. There are slight variations counter to counter. From the beginning to the end of the run he sees slight degradation, but not enough to cause concern.

He recommends that we keep an eye on the dark current, especially with the upcoming run at high intensity. We should get into the habit of taking data to check the dark rate.

On a related issue, Beni notes that the nominal rates per paddle have been 300 kHz. If we double the intensity, that would present a challenge to the counters.