GlueX Start Counter Meeting, January 14, 2016

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GlueX Start Counter Meeting
Thursday, January 14, 2016
10:00 am EST
CEBAF Center, Room F326/327


  1. Announcements
  2. Review minutes from the last meeting
  3. Missing channels in Fall 2015
  4. Calibration Update
  5. Run Readiness
  6. Collaboration Meeting
  7. Action Item Review




Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2016 on the JLab CUE. This directory is accessible from the web at .



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

There is a recording of this meeting on the BlueJeans site.


  • Eric has finished writing his thesis!

Review of Minutes from the Last Meeting

We looked at the minutes from December 3. Items of note appear on the agenda of this meeting.

Missing channels in Fall 2015

  • We reviewed the log entry from Nick Sandoval. Mark will follow up with Nick on any new news.
  • Eric mentioned that he has seen this kind of disconnect of the low voltage before when the pre-amps were not well seated.
  • Mark spoke with Tim about Tim's idea of adding a fixture for ensuring that the pre-amps stay plugged in. Tim thought that even though the problem this time had nothing to do with those connections, he is going ahead and has assigned a designer. In light of Eric's remark, this makes sense.
  • [Added in press] Mark talked to Nick. The low-voltage cable checked out fine. It is back in the system. Nick mentioned that when this kind of disconnect occurs, it shows up as a 10% reduction in current from the power supply. That current is monitored in EPICS; we should alarm on it.

Calibration Update

Mahmoud has done a complete calibration of the light propagation delay on a counter-by-counter basis. The code is contained in plug-ins appropriate for inclusion in the calibration challenge. He measures a time resolution for the start counter of less than 300 ps. For details, please see his slides.

Run Readiness

Mahmoud went through the slides he presented at yesterday's Run Coordination meeting. The bias scan we did last Spring needs to be repeated because the FADC thresholds were changed in the middle of the scan.

Collaboration Meeting

We agreed that Mahmoud should present his calibration results, pending approval from his thesis adviser.