GlueX Start Counter Meeting, February 7, 2013

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GlueX Start Counter Meeting
Thursday, February 7, 2013
10 am EST
JLab: CEBAF Center F326/327


  1. Announcements
  2. Review minutes from previous meeting
  3. Counter Construction
  4. SiPM read-out status
  5. Light collection study status
  6. Contract

Communication Information

Video Conferencing

  • ESNet: 8542554
  • ReadyTalk Desktop Sharing
    • In addition to the SeeVogh desktop sharing we will try the Readytalk version in parallel. You will need a web browser open to view the desktop at JLab.
    1. Go to
    2. In the "join a meeting" box enter the Hall D code: 3421244
    3. Fill in the participant registration form. A random name alone is sufficient.
  • SeeVogh


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2013-1Q on the JLab CUE. This directory is accessible from the web at .



  • FIU: Werner Boeglin, Puneet Khetarpal, Eric Pooser
  • JLab: Chuck Hutton, Mark Ito (chair), Beni Zihlmann

Counter Construction

Eric is doing wrapping tests with the old McNeal bars. He will try lots of combinations:

  1. no wrapping
  2. Mylar
  3. Mylar and Tedlar
  4. aluminum
  5. aluminum and Tedlar
  6. Tedlar

He would like to have all measurements done in time for the collaboration meeting.

Five bars have been ordered from Eljen, all with the bend. McNeal has quoted a price of $225 per paddle to do the machining.

The assembly jig design is complete. Eric showed several pictures. The idea is to have two rings (orange) with each with 30 springs to hold counters that have been placed on the inner support cylinder. The start entire assembly can be rotated around the axis along a horizontal axis corresponding to the beam line. There are pneumatic plungers at the top position to hold a single counter while it is being positioned (the corresponding springs will be relaxed. This is a lot simpler than the scheme which was proposed previously. Chuck and Tim Whitlatch will review the idea.

Chuck pointed out that his drawings do not account for any space between counters. Estimates for the thickness of any wrapping are less than reasonable mechanical tolerances in any case.

SiPM read-out status

The gain measurements for Fernando Barbosa are complete. Eric will write up the results and send them to Fernando soon.

Monitoring system

Werner points out that our planning for a light monitoring system has fallen by the wayside. We will start collecting ideas.


We discussed where to put the readiness review into the milestones in the proposal. Near the beginning of construction seemed reasonable.