GlueX Start Counter Meeting, November 19, 2015

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GlueX Start Counter Meeting
Thursday, November 19, 2015
10:00 am EST
CEBAF Center, Room F326/327


  1. Announcements
  2. Review minutes from the last meeting
  3. Calibration Update
  4. Calibration Challenge and the Start Counter
  5. Run Readiness
  6. DAQ Tasks for Spring 2015 Commissioning Run
  7. Asymmetry in Monte Carlo
  8. Action Item Review




Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2015 on the JLab CUE. This directory is accessible from the web at .



  • FIU: Werner Boeglin, Mahmoud Kamel
  • JLab: Mark Ito (chair), Eric Pooser, Simon Taylor, Beni Zihlmann

Run Readiness

We will operate the start counter as usual during the upcoming run, even though the plastic target will be downstream of the counter and the tracking chambers will be off.

The target/start-counter have been retracted from the bore. When they are re-installed, Eric will go though the Hot Checkout procedure. He did a similar some weeks ago before the first insertion, at Tom Carsten's request.

Calibration Update

Mahmoud gave us an update on the time-walk calibration plug-in that will be part of the Calibration Challenge. See his slides for the details.

He has checked in the plug-in and associated ROOT macros. The average resolution is about 270 ps. Sector 20 shows noticeably worse resolution and indeed the time-walk function is not fitting the data very well. Mahmoud will push ahead with other components of the Calibration Challenge for now, but we may revisit the procedure for time-walk calibration at a later date.

Asymmetry in Monte Carlo

Mark showed a plot from Sean Dobbs showing an asymmetry in the occupancy of the start counter in recent Monte Carlo data. Simon told us there there is a tilt to the start counter in the Monte Carlo and we concluded that that is likely the cause.