GlueX Start Counter Meeting, November 16, 2017

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GlueX Start Counter Meeting
Thursday, November 16, 2017
11:30 am EST
CEBAF Center, Room F326/327


  1. Announcements
  2. Review minutes from the last meeting
  3. Calibration and Efficiency
    1. Update on attenuation corrections (Mahmoud)
    2. Sean's Start Counter Issues (all)
  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/2017 on the JLab CUE. This directory is accessible from the web at .



  • FIU : Mahmoud Kamel
  • JLab : Thomas Britton, Eugene Chudakov, Mark Ito (chair)

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


Mark noted that the next step in run preparation is to complete Hot check-Out for the start counter. That should start this week.

Review minutes from the last meeting

We went over the minutes from November 2.

Mahmoud asked for 5 M bggen events from Thomas once the code from the impending reconstruction launch stabilizes. These will be used for comparison between Monte Carlo and data.

Update on attenuation corrections

Mahmoud presented slides on his latest work on attenuation corrections. He fits the dE/dx distribution in each paddle separately for different bins in distance-from-photo-detector. He then fits to two exponentials, one in the straight section, one in the bend+nose section where the continuity between the two is enforced at the boundary. The resulting correction makes a visible improvement in proton-pion separation. Please see his slide for details.

NIM Paper

Mahmoud finished all of the requested attenuation plots for the paper and passed them on to Werner Boeglin.