GlueX Start Counter Meeting, August 26, 2016

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GlueX Start Counter Meeting
Friday, August 26, 2016
11:00 am EDT
CEBAF Center, Room F326/327


  1. Announcements
  2. Review minutes from the last meeting
  3. Calibration/Efficiency Update
  4. Run Readiness
  5. NIM/TDR
  6. 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: Mahmoud Kamel, Werner Boeglin
  • JLab: Mark Ito (chair), Paul Mattione, Simon Taylor, Beni Zihlmann
  • NU: Sean Dobbs

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

Efficiency Update

Mahmoud presented slides with updated efficiency calculations and time resolution measurements. He used the output of the start counter efficiency plugin, written by Paul, from the reconstruction launch.

He showed efficiency results for each counter for all tracks, protons, π+, π, K+, K where he used the nominal particle ID provided by the plugin.

He also showed efficiency for various sections along the length of the start counter, 25 in all. There are some azimuth variations in the raw occupancy, but they do not show up in the efficiency calculation except for the extreme forward sections.

Time resolution was steady for most of the period of the Spring 2016 run, with an average value of 281 ps. There appears to be some slight reduction, about 25 ps, of the resolution for 1350 A of solenoid current and 2 ns RF bucket separation. The origin of the effect is not understood.

Run Readiness

  • Beni remarked that final readiness checks of the detector cannot be performed until the FADC firmware has been upgraded.
  • Mark will contact Eric Pooser and see if he can help us with physical check-out in the Hall.
  • The hot-checkout procedure is straight-forward, once everything is installed and powered up.
  • Beni mentioned that we will probably want to reduce the time window for ADC read-out to keep the VME backplane as quiet as possible.


Sean encouraged the group to write up the procedure for start counter calibration in a GlueX Note. Werner agreed, noting that the document should include step-by-step instructions for performing the calibration and we should develop the procedure so that those steps are fairly well automated.