GlueX Start Counter Meeting, October 27, 2022

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GlueX Start Counter Meeting
Thursday, September 15, 2022
10:00 am EDT

Zoom: link to meeting Passcode: 791663

Benedikt Zihlmann is inviting you to a scheduled ZoomGov meeting.

Topic: Start Counter Time: Sep 15, 2022 10:00 AM Eastern Time (US and Canada)

       Every week on Thu, 7 occurrence(s)
       Sep 15, 2022 10:00 AM
       Sep 22, 2022 10:00 AM
       Sep 29, 2022 10:00 AM
       Oct 6, 2022 10:00 AM
       Oct 13, 2022 10:00 AM
       Oct 20, 2022 10:00 AM
       Oct 27, 2022 10:00 AM

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  1. Announcements
  2. Review of minutes from the last meeting
  3. Current Running (PrimeX)
  4. Calibration efforts
  5. Action Item to be set


present: Sean, Beni


  • look at propagation time corrected timing as a function of z position
    • a clear "slope" is seen that should not be there
    • run 71400 for comparison looks flat as it should
    • the hit multiplicity as a function of paddle number looks different to the past, the intensity distribution has a "hump" that is located at different paddle number than in the past, like run 73262 for example.
      • Question: has the start counter been mounted differently (different offset in phi?)


  • shows similar effects like Sean.
  • the timing resolution for a single paddle at a fixed distance from the SiPMT looks good <300ps
  • conclusion is that the SC is working ok but the timing corrections are failing.
  • The walk correction is slightly over correcting some paddles at low amplitudes.
  • some part of the code in HLDetectorTiming plugin is commented off to avoid compiler warnings. However, this causes some variables to initialized to zero and not updated to the correct values.

Action Items

  • contact Tim to ask about the Start Counter survey data
    • the SC was not surveyed because it is "pinned" and in principle it should not even be possible to mount the SC with a wrong phi orientation.


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2022 on the JLab CUE. This directory is accessible from the web at .