GlueX Start Counter Meeting, March 7, 2013

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GlueX Start Counter Meeting
Thursday, March 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. VME discriminator for FIU
  6. Light pulsing system or not?
  7. Installation Document
  8. Contract

Communication Information

Video Conferencing

  • ESNet: 8542553
  • 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: Eric Pooser
  • JLab: Chuck Hutton, Mark Ito (chair), Beni Zihlmann


Puneet Khetarpal has gone on to another job. We thank him for his contribution to the start counter effort at FIU, and congratulate him on his new position.

SiPM read-out status

Eric got feedback from Fernando Barbosa; he should include the attenuation in the cables in his estimate for the required gain for the SiPM readout.

More importantly, he suspects that his previous measurements used a 5X amplifier and its effect was not taken into account in his calculations. He will remeasure this afternoon.

Counter Construction

Chuck Hurlbut at Eljen told Eric last week that they are about two days away from finishing the bending fixture and scintillator would be ready to ship to McNeal in a week or two.

Eric also reported that he has a new contact at McNeal, Renee, who is handling the FIU account.

Eric is starting on a design for the test stand for the detector. It will use complete three-channel SiPM read-out boards.

A final decision on wrapping has not been made. Likely it will be aluminized mylar around the scintillator. We have to decide on whether individual counters will be light-tightened with Tedlar or if we rely on wrapping with an exterior layer only. If significant thickness is added between counters it should be reflected in the dimensions of the inner foam support since counter dimensions are fixed at this point.

According to the milestones in the proposal, it looks like the inner foam support needs to be ready sometime in June.

VME discriminator for FIU

We confirmed that FIU could use a discriminator or two for the the full detector test. Mark will work on getting them the unit(s).

Light pulsing system or not?

Talking to folks at JLab, Mark reports that folks thing that light pulsing would be useful, but also that it was a lot of effort and we should think carefully about whether it is worth that effort at this stage of the project. We will have to discuss this further. Mark will check and see if CLAS had any such system for their start counter.

Installation Document

At last week's installation meeting, Curtis showed an installation document for the CDC, essentially a plan with a timeline. We should develop a similar document for the start counter: what needs to be done and when, noting any dependencies on other installation or services in the Hall.


Werner told Mark that the technical proposal would go the university this week for inclusion in the proposal for the construction contract.

Action Items

  1. Decide on wrapping scheme.
  2. Get discriminator(s) for FIU.
  3. Ask about light pulsing for the CLAS start counter.
  4. Start thinking about an installation document.