GlueX Start Counter Meeting, April 4, 2013

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GlueX Start Counter Meeting
Thursday, April 4, 2013
10 am EDT
JLab: CEBAF Center F326/327


  1. Announcements
  2. Review minutes from previous meeting
  3. Construction Status
  4. Contract
  5. Calibration Document
  6. TDR contribution
  7. Installation Document

Communication Information

Video Conferencing

  • ESNet: 8542553
  • SeeVogh
    • Direct meeting link
    • Phone Bridge ID: 15 4136

Desktop Sharing

  1. Go to
  2. In the "join a meeting" box enter the Hall D code: 3421244
  3. Fill in the participant registration form.


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2013-2Q on the JLab CUE. This directory is accessible from the web at .



  • FIU: Werner Boeglin, Eric Pooser
  • JLab: Mark Ito (chair), Beni Zihmann


Mark talked to Youri Sharabian about how he bent the scintillator for the CLAS start counter. Turns out he had Eljen do all of the shaping of the bars, both bending and milling of the edges. His contact at Eljen: Chuck Hurlbut.

Construction News

Scintillator Manufacturing

Eric reported that Eljen has finished manufacturing five counters with a precision bend. Chuck Hurlbut explained the procedure:

  • Clamps of polished aluminum are used.
  • Scintillator is heated 2 inches beyond bend region.
  • The clamp is heated as well.
  • The system allowed to cool, enough to handle.
  • The scintillator bar is turned on its side and placed on a surface with a drawn line that indicates the proper shape and then allowed to cool for 24 hours.
  • If the bar does not hold its shape, heating and clamping is repeated.

Eljen has internal discussions on packaging the bars for shipment. They will apply a clear light-tack adhesive film to all of the counters. The idea is to leave this film on the broad surfaces while the edges are machined at McNeal.

Eric is waiting to see if McNeal has received the bars. In the meantime, he has been discussing minor details on the contract with them including packaging and handling procedures. The insured value for the package of 5 bars is about 4 k$.

Test Stand

Eric walked us through drawings of the stand designed for acceptance testing of incoming scintillator bars. There is a fixture with a Sr source and trigger scintillator that can be moved to reproducible positions along the scintillator under test. There is also an XYZ motion stage to hold the SiPM detectors. The entire structure will be inside a dark box.

Eric would like to have the stand constructed and working before the five bars arrive from McNeal. Machining will be done in the FIU shop by Carlos Ortega.


Ludmilla Ettiene sent the technical proposal to JLab Procurement. The terms and conditions are still being worked on at FIU. Sponsored Research has received comments from Legal, but nothing major. Werner has been asked to respond to a few questions. JLab should recieve the complete package by next week sometime.