GlueX Start Counter Meeting, June 2, 2011

From GlueXWiki
Jump to: navigation, search

Location, Time

Thursday, June 2, 2011
3:30 pm EDT
JLab: CEBAF Center, Room F326/7


  1. Announcements
  2. Review minutes from previous meeting: all
  3. Start Counter News
    1. Fiber information
    2. New SiPM amplifier, see
    3. SiPM order for FIU, see
  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/2011-2Q 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: Mark Ito (chair), Sascha Somov, Beni Zihlmann

Fiber Order

Lei contacted Kuraray and ordered 1 × 1 mm fibers. They have arrived. They will be clamped into a shape that can be attached to a scintillator.

Scintillator Order

The scintillator will arrive from Plastic Craft by June 13.

Resolution Studies

Werner is doing measurements with the SiPM array he has to try to understand the source of the timing variance. Using a leading-edge discriminator he is trying to predict the resolution one should expect from the width of the pedestal (noise), and the measured rise time of signals. He corrects for time walk in software. So far he sees resolution consistent with noise driving the observed resolution.

SiPM's for FIU

The SiPM's that Sascha ordered some time ago have arrived, again, some time ago. Fernando has made pre-amps for single 3 × 3 mm cells of two varieties, one with a gain of 35, the other with 70. Measurements in Vitaly Baturin's set-up look good. Sascha is trying to create our own set-up so we can do the tests ourselves.

Werner is anxious to test any of the new SiPM configurations we can get to him. So far he has only been working with an array with an older version of the pre-amp. He will be here next week and will talk to Fernando about getting something to take back to Miami.


Werner is still considering segmentation of 30 counters rather than the nominal 40. If the thickness is kept constant then this might help light output since the higher aspect ratio of the cross-sectional area has more perimeter on the faces relative to the edges. Previous studies showed that a large part of the light loss was coming from the edges of the scintillator.

MOU Status

  • Sent latest version to Allison on May 5.
  • Got comments from Glenn Young on May 17.
  • Sent Glenn's comments to Werner today.
  • Will incorporate Glenn's comments and re-submit to Allison.

We agreed that we should not wait for the MOU to be signed before starting work on the construction contract. Werner mentioned that he does not have easy access to a designer at FIU. As such, the drawings will be done here as they have been done for other detectors.