GlueX Start Counter Meeting, August 23, 2012

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GlueX Start Counter Meeting
Thursday, August 23, 2012
10 am EDT
JLab: CEBAF Center F326/327


  1. Announcements
  2. Review minutes from previous meeting
  3. Mechanical Design
  4. Read-out Design
  5. Simulation
  6. Contract

Communication Information

Video Conferencing


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2012-3Q on the JLab CUE. This directory is accessible from the web at .



  • FIU: Werner Boeglin, Lei Guo, Puneet Khetarpal
  • JLab: Fernando Barbosa, Chuck Hutton, Mark Ito (chair), Tim Whitlatch, Beni Zihlmann

Prototype News

  • Chuck sent the latest drawings to Werner. Werner reviewed the drawings and after an exchange with Chuck, all dimensions are now agreed on.
  • The scintillator material (EJ-212) will be recorded on the drawings.
  • The scintillator material has been ordered from Eljen.
    • The dimensions are 70 mm x 600 mm x 3 mm.
    • It is made by hot pressing between stainless steel surfaces.
    • Werner will get further manufacturing details from Eljen for Tim's records.
  • The costs from McNeal have changed and better reflect their process.
    • To make the tooling: $1,500
    • To form and polish a single counter: $300
  • McNeal is order materials for the tooling.
    • The first sample that we have been testing was made with a jury-rigged form.
  • The final dimensions have been transmitted to McNeal.
  • Werner revisited the idea of bending the scintillator at FIU and sending the pieces to Eljen to use their diamond fly-cut milling machine. Eljen reported that they would have a problem mounting the bent pieces. For now we will stick with the McNeal plan.
  • Werner has received a sample of the 2-micron Mylar sheets, doubly aluminized. The sample looks good.

Read-Out Design

  • Puneet has been looking at the new read-out boards with an LED light source. So far things look good. Rise times are as seen before (3.2 ns). There has been a lot of consultation with Fernando to check that settings and behaviors are indeed nominal. Single photon signals have been observed.
  • We need to finalize the gain setting. This will be done after testing is complete. The issue is principally dynamic range. FIU will look at signals on a scope to study the issue.
  • The mini-coax cable arrangement (from the ST2 board to the ST3) board had too much cross-talk via the connectors. As a result we are using Lemo cables for the two read-out channels (from a single counter = 4 MPPCs) as a temporary measure. ST2 and ST3 will have to be re-designed to accommodate a different cable choice.
  • We discussed whether we need to do a full (30 channel) test of the read-out at FIU before shipping to JLab. More discussion needed here.
  • If a full test is not done, we also discussed whether we want to mount the ST1 and ST2 boards on the support ring at FIU or after shipment to JLab. Again more discussion is needed.
  • Detailed design of the distribution box will be left for latter. Real estate is not considered a problem.

Mechanical Design

  • Tim clarified the responsibilities we had agreed to at a previous meeting. JLab will be responsible for all drawings and construction of the inner foam shell and the aluminum (or stainless) support ring. FIU will be responsible for the counters themselves and any tooling necessary for construction and assembly. This needs to be corrected in the current draft of the SOW.


  • Mark has written a draft SOW and circulated it. Tim responded with corrections and comments.
  • Fernando estimated that the ST1 and ST2 boards will be done by the end of the year.
  • According to the schedule, the start counter will be installed in January 14, 2014.

Action Items

  1. Summarize the schedule and distribute it to the group.
  2. Make a plan for testing at FIU with an eye toward the electronics necessary to carry it out.