GlueX Start Counter Meeting, April 20, 2017

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GlueX Start Counter Meeting
Thursday, April 20, 2017
11:00 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. 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, Beni Zihlmann

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

Review minutes from the last meeting

We looked at the minutes from March 23.

Time-dependent geometry adjustments

Simon has received the latest survey spreadsheet from Tim. The next step is to encode the data into an HDDS file. Because of the large shifts we are seeing from run to run, Simon will simply create a new global offset for each run period. Shifts as large a centimeter seem to occur; it is not understood why. The pitch of the counter also seems to change, though a systematic study of the shifts has not been done.

Mahmoud has tried out Simon's recent changes to matching of charged particles to the start counter. He does not see improvement. Simon reports crashes in this part of the code after recent tracking changes were checked in. The precise cause is still under investigation.


Eric has a draft of the NIM paper. Currently, the files are stored in his private GitHub repository. There is a PDF file on the site. At some point the paper will migrate to the gluex_documents repository.

Eric is getting help with the mechanical drawings from Stephanie Worthington. She has translated several of his original drawings into her CAD system. Also Mahmoud has agreed to contribute plots illustrating the calibration procedure.

Collaboration Meeting

Mahmoud proposed not having a Start Counter talk this time; not enough has changed to justify a dedicated talk. He will provide slides to either Sean (calibration) or Paul M. (analysis) for inclusion in one of their talks.