GlueX Start Counter Meeting, July 12, 2018

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GlueX Start Counter Meeting
Thursday, July 12, 2018
10:00 am EDT
CEBAF Center, Room L207
BlueJeans: 556 286 544


  1. Announcements
  2. Review minutes from the meeting on June 28
  3. Calibration and Efficiency
  4. Time-dependent geometry adjustments
  5. NIM/TDR
  6. Action Item Review




Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2018 on the JLab CUE. This directory is accessible from the web at .



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

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

Review minutes from the meeting on June 28

We reviewed the minutes without significant comment.

Propagation Time Corrections and Time Resolution

Mahmoud presented his latest results, a refinement of his results from last time. See his slides for details and plots. His summary slide is reproduced here:

  • New propagation time constants are obtained using one dimensional fits (3-start-counter-z-region constants) for 2017 & 2018 run periods.
  • 3-region and 4-region (with variable vertices) fits were tested. There is no significant difference.
  • The time resolution from ST_Tresolution plugin, where the RF time is determined based on the hit to the SC, is calculated. This time resolution is better by ~20ps than that calculated from the PT plugin.
  • Coming soon: Push the changes to github and the constants to CCDB.

There are still some checks to do; those should take about a week on the farm. We suggested that he consult with Sean Dobbs before putting these new constants into the CCDB, especially since a reconstruction launch over the 2017 data is imminent.