GlueX PID Meeting, July 23, 2010

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Location, Time

Friday, July 23, 2010
2:00 pm EDT
JLab: CEBAF Center, Room F326/7
ESNet: 8542553
EVO: direct meeting link[1]
Conference Group: 800-377-8846, participant code: 77438230
Slides: talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2010-07 on the JLab CUE (you have to be a member of the "halld" group). This directory is accessible from the web at .


  1. Announcements
  2. Minutes from the last meeting
  3. Time-of-Flight
    1. Prototype progress [1]
    2. Status of the MOU
  4. Start Counter
    1. prototype progress
  5. Target
    1. Status of the MOU
    2. Status of refrigerator plan
  6. Action Items


  • FSU: Paul Eugenio, Sasha Ostrovidov
  • JLab: Eugene Chudakov, Hovanes Egiyan, Mark Ito (chair), Yi Qiang, Sascha Somov, Simon Taylor, Elliott Wolin, Beni Zihlmann

Review of minutes from the last meeting

We went over the minutes from the July 9th meeting:

  • PMT purchase: The eight phototubes purchased for the TOF prototype have not arrived at FSU.
  • LED pulsing system: Paul reminded us that although we have been discussing a calibration system for the TOF in the Hall, the LED system they have put together at FSU is aimed solely at understanding the prototype.
  • Trip to Columbia?: Mark raised the idea, originally suggested by Elton Smith, that some of us visit Ralf Gothe at the University of South Carolina to see his TOF set-up and discuss issues with him. USC is building the forward TOF for CLAS12. Elton was there recently and saw the set-up. We agreed that this was a good idea. Paul thought that a good time would be after the semester starts up.
  • USC items: Paul has been taking to Ralf from time to time.
    • They are using the same multi-paddle readout scheme that FSU will try.
    • They are using CAEN discriminators with a 25 ps least count, finer that what we are planning to use.
    • They are using much thicker scintillator than we are.

Time-of-flight prototype progress

Sasha O. showed a series of plots (similar to those shown last time but with other materials included) that show the effect of various wrapping material on light output from a prototype counter. The improvement with ESR over an unwrapped counter looks very good.

Paul made some comments on ESR.

  • It comes with adhesive backing, with or without UV inhibitor
  • Longevity: others have not reported problems, even in outdoor use (solar energy applications)
  • It is non-metallic
  • Paul and Beni both wondered if IU might be interested for the FCAL.
  • It does have a mirror-like surface (not a difuse reflector).

Paul has a sample, enough for one paddle, maybe two if not cut up. He will look into purchasing a roll. It should run about 1.2-1.5 k$.

Paul also noted that they have been holding off on the new data acquisition configuration until these studies are done. Now they plan to go back to it, merging TDC's and ADC's in triggered events.


Paul sent a draft just before the meeting. He made some remarks:

  • This might be an opportunity to negotiate additional lab space. Production will require quasi-permanent space (stations) for various production steps.
  • Section 5.1 does not have any discussion of the calibration system.
  • He has added Elton's latest set of comments and corrections.

Action Item Review

We went over them. We still need a meeting with Fernando on the signal splitting scheme for the TOF.


  1. This link is good through 8/20