GlueX Start Counter Meeting, June 15, 2017

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GlueX Start Counter Meeting
Thursday, June 15, 2017
11:30 am EDT
CEBAF Center, Room F326/327


  1. Announcements
  2. Review minutes from the last meeting
  3. Calibration
  4. Time-dependent geometry adjustments
  5. Mcsmear procedure and parameters for the start counter
  6. NIM/TDR
  7. Meeting time discussion
  8. Action Item Review




Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2017 on the JLab CUE. This directory is accessible from the web at .



  • FIU: Mahmoud Kamel
  • JLab: Thomas Britton, Mark Ito (chair), Eric Pooser, Simon Taylor

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


  • Mahmoud showed progress with determination of the counter attenuation lengths from data. He is currently having difficulties in having fits converge to the distributions of pulse area in various bins of position. Please see the recording for the plots. The data themselves looks good. There were various suggestions on how to get reliable convergence (e. g., removing pedestal noise peak completely from the fit region).
  • Mahmoud also showed updated efficiency measurements. See his slides for the details. His efficiency has dropped compared to previous studies, but we think that that may be because the time cut he uses to identify accidental background includes a significant amount of signal, causing over-subtraction.
  • In the same set of slides he showed the projected intersection position of charged tracks with the start counter, for all sectors, in the r-z projection. The looser matching cut in the new software is manifest.