GlueX Start Counter Meeting, August 25, 2011

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Location, Time

Thursday, August 25, 2011
3:30 pm EDT
JLab: CEBAF Center, Room F326/7


  1. Announcements
  2. Review minutes from previous meeting: all
  3. Prototype Report
    • New SiPM pre-amp
  4. MOU status

Communication Information


To connect by telephone:

  1. dial:
  2. enter access code followed by the # sign: 3421244#

Video Conferencing


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2011-3Q on the JLab CUE. This directory is accessible from the web at . You have to be a member of the "halld" Unix group to do this.



  • FIU: Werner Boeglin, Lei Guo
  • JLab, CEBAF Center: Simon Taylor, Beni Zihlmann
  • JLab, ARC: Chuck Hutton, Mark Ito (chair), Puneet Khetarpal

New Meeting Time

We decided to move the meeting time from 3:30 pm to 10:00 am. Same day of the week, every other Thursday.

Prototype News

Light guide tests

FIU tried out the new fiber light guide. If anything, it was a bit worse than the solid light guide that has been used for some time now.

New SiPM pre-amp test

Werner sent the SiPM array FIU had previously tested back to Fernando Barbosa and Fernando outfitted it with his new pre-amp configuration and sent it back to Miami. A test was set-up yesterday, with the SiPM butted up against on of the Plastic Craft scintillators. Without a lot of adjustment a resolution of 350 ps was observed. This is to be compared with the 500-600 ps observed with the SiPM previously.

The next step is to make a small short light guide to match the area of the scintillator to that of the SiPM array.

Scintillator characterization

The tests thus far have been with the worst looking of the Plastic Craft scintillator. All five will be tested and compared. As mentioned before the surfaces to not look all that nice.

Werner's estimate is that the number of photoelectons per MeV is 25 to 35 at a point 10 inches away from the SiPM (in the middle of the barrel section).


Werner sent Tim the latest drawings about a month ago. Chuck will get them from Tim.


The MOU is stuck in legal at FIU. It will be expedited.


Puneet has been working with Sascha on the reconstruction. He hopes to present some results from studies next time.

New action items

  • Move time of meetings on the various calendars. -> Mark
  • Get drawings from Tim. -> Chuck
  • Characterize all Plastic Craft scintillators. -> FIU