GlueX Start Counter Meeting, November 29, 2012

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GlueX Start Counter Meeting
Thursday, November 29, 2012
10 am EST
JLab: CEBAF Center F326/327


  1. Announcements
  2. Review minutes from previous meeting
  3. Counter shaping and polishing at McNeal
  4. SiPM read-out status
  5. Light collection study status
  6. Contract

Communication Information

Video Conferencing


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2012-4Q on the JLab CUE. This directory is accessible from the web at .



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

Review minutes from previous meeting

We reviewed the minutes from the November 15th meeting.

FIU has found sufficient HV channels to get by for now. Another CAEN module is on order.

Counter shaping and polishing at McNeal

Eric went through an abridged version of the presentation he gave for the CEO of McNeal on recent experience with the scintillator. See his slides for details. He showed evidence for degradation of the attenuation length that is likely due to mishandling at McNeal.

Werner also points out that we should research how the heating and bending may affect scintillator long-term quality even if mechanical handling is done properly. He will talk to Eljen about this.

SiPM read-out status

  • Eric mailed the broken ST-2 board to Fernando Barbosa. The gain measurement still needs to be done before Fernando finalizes all of the component values.
  • Eugene reported that a shipment of SiPMs from Hamamatsu came in this week. Some of those can be used for more start counter read-out cards.
  • FIU is installing a new version of CODA, version 3. They are getting help from David Abbott and things are going well.
  • FIU could use a few more discrimintator channels. JLab will look into getting one of the new VME discriminators for them.

Light collection study status

Puneet reported on progress with his studies. See his wiki page for details and plots. He has studied light output as a function of

  1. distance from a "track" to the end with light detection,
  2. microscopic surface roughness on the counter edges, and
  3. counter thickness.

Faces are assumed to be smooth. He sees very little dependence of light yield as a function of thickness. This is at odds with experimental experience a couple of years back with counters of varying thickness.

Plans for further study include adding roughness to the faces and a study of cross-talk between adjacent counters in the absence of wrapping[?].


Mark sent Werner an example of a successful proposal he can use as a model for the FIU submission.