GlueX Start Counter Meeting, February 5, 2015

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GlueX Start Counter Meeting
Thursday, February 5, 2015
10:00 am EST
CEBAF Center F326/327


  1. Announcements
  2. Review minutes from the January 29 meeting
  3. Calibration
    1. Track matching
  4. Plans for Spring run
  5. 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

Start Counter Re-Installation

  • Next week we will get a new flange for the target cart to solve interference reported at the last meeting. Re-assembly can start then.
  • There is a plan to attache a 1.5 mm plastic target to the nose of the start counter. It will be attached to the light-tighting tape in some manner or another.
  • Tim Whitlatch's plan is to evaluate any tilt once the start counter is mounted on the target cart and then evaluate if any further adjustment is necessary.

Matching with Charged Tracks, Etc.

Simon led us through his recent log book entry.

  • There appears to be some sort of cabling or translation transposition in two places in the start counter. The azimuthal difference between the center of a counter and the intersection point of a charged track shows anomalies for counters 1 and 2 and for counters 22 and 23.
  • He has rotated the start counter in the geometry. This turns out to be a somewhat tedious exercise; it is not simply a rotation of a single solid body. The tilt is visible in the r-z distribution of intersection points that he showed.
  • The "fuzziness" noted last time in the nose region was due to an overly wide azimuthal matching cut. Improvement is marked. The more reasonable value has been checked into the commissioning branch.

Basic Signal Assessment

We had some discussion on understanding and controlling our thresholds, both for the FADCs and TDCs.