GlueX Start Counter Meeting, June 26, 2014

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GlueX Start Counter Meeting
Thursday, June 26, 2014
10:00 am EDT
CEBAF Center, Room F326/327


  1. Announcements
  2. Review minutes from previous meeting
  3. Detector Construction Status (Eric)
  4. Schedule Review (all)

Meeting Information

JLab Meeting Room: CEBAF Center F326


The BlueJeans Meeting ID is 556286544 .

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Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2014-2Q on the JLab CUE. This directory is accessible from the web at .



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

Readiness Review

Eric reported that he has a rough draft of all procedures for construction, with the exception of the polishing procedures (which have not been finalized, see below). He plans to compile all of them into one document in advance of the review.

At the last meeting we decided on July 8 for the review. We thought that that was still a good date, even considering recent events (see below).

Construction News

Eric gave us an update.

  • The support structure arrived safe and sound at FIU. It has been mounted on the assembly jig; no problems with the fit.
  • They are starting to play around with the assembly jig now that the support structure is in place. They are practicing with old scintillator test pieces.
  • Werner has sent an email to Robert McNeal detailing the problems we have encountered with their work and asking for some form of compensation. McNeal has responded via voice-mail; they are looking into it.

Scintillator Rehabilitation

Eric gave a presentation on steps being taken to improve surface quality of the scintillators and on timing test results. See his slides for complete details. Some take-aways:

  • Polishing improves surface quality, both visually and in the timing tests.
  • The haze reported previously is not visible after polishing.
  • Time resolution from unpolished scintillator is not much different from "good" prototype counters.

These are encouraging results.

There is the remaining question about long-term damage due to use of an inappropriate cleaning solution. It is too early to judge now; if effects appear, they may not occur for another few weeks.

Other Items

  • Werner proposed looking at the paddles under a microscope as had been done in the past.
  • The light tightening discussion has been deferred due to recent events.
  • FIU asked about dates for Nick Sandoval's trip to Miami.
  • It turned out that there was no problem with the SiPM in the test set-up at FIU. Nick looked at it and returned it to FIU. The trigger circuit for the test set-up was the culprit.