May 21, 2009 Readout

Teleconference Time: 11:00 a.m. EST

• EVO session
• Phone:
  • +1-800-377-8846 : US
  • +1-888-276-7715 : Canada
  • +1-302-709-8424 : International
  • then enter participant code: 39527048# (remember the "#")

Items for followup from previous meeting

1. Bcal section
   • Zisis will get a quote from Ross machining to find out how much it would cost to polish a segment (both ends)
2. JLab to determine how many fibers could be spared now to use in this project .
3. Elton: Feedback to Will on estimate of photons in Bcal . See halld-cal e-mail
4. Will, update references on "alternative readout page" with those found by Zisis
5. Zisis, Elton: Suggestion to USM on testing prototype
6. USM: sketch of test setup to facilitate feedback

Documents to Review

1. GlueX-doc-1279 Comments for bullets on agenda 5 and 6

Tentative Agenda

1. Announcements
2. Review of Action Items
3. USM report (Will)
4. Keepout zones for light guides and magnetic shielding
5. Discussion of readout options
   • Time for internal review (end of June / beginning of July)?
   • Number of photons per GeV (Sasha and Elton)
   • Budget comparison (Elton)
6. Location of FM pmts relative to B-field
7. Prototyping
8. Simulations
9. Discussions on MOU with USM

Minutes

Attending: Elton, Sasha, Tim, Eugene, Beni, George, Will, Irina, Andrei

1. Announcements
2. Review of Action Items
   • Reviewed and updated.
   • Shipment of Bcal wedge from Edmonton expected next week. After careful measurements of fiber pitch can make this available to Chile for prototype tests
   • Beni has made an inventory of fibers at JLab. Will to decide how many are needed for prototyping and see if fibers purchased previous to first-articles can be used.
   • Unclear precisely what items 3 and 4 were. Will will make a detailed plan for prototyping for feedback. George emphasized that using cosmics provides a useful testbed for understanding the energy deposition and can be used to cross check calculations.
3. USM report (Will)
   • Estimates of components to the resolution were presented and discussed.
   • Threshold was discussed. Eugene pointed out that noise is important when considering the threshold.
   • The floor term was discussed. Arises due to leakage, and calibration issues. There are differences that are expected between the prototype and the final detector. Eugene suggested that 2% is to be expected for a large number of channels. Non-uniformities and how well these can be calibrated plays a role in that term.
   • Andrei: The 'a' term changes by about 20% between 90deg and 20deg according to simulations.
4. Discussion of readout options
   • Time for internal review (end of June / beginning of July)? Tentative date set for July 14.
   • Number of photons per GeV (Sasha and Elton)
     • Elton presented a summary of numbers already documented.
   • Budget comparison (Elton)
     • Table of budgets (from last fall) was shown. Eugene: The FM option is nominally 350k more expensive, but assumed $0.4k/SiPM. The balance may change if the SiPMs are more expensive than this initial estimate. Therefore, this option should still be considered seriously.
     • A detailed accounting of both options needs to be redone.
     • Will pointed out that the cooling of SiPMs is not yet included.
     • Beni noted that the dynamic range might require a change in the channel count for electronics.
5. Location of FM pmts relative to B-field
6. Keepout zones for light guides and magnetic shielding
   • Elton presented plots of Btot and angles relative to z-axis. It appears that there will be room to place FM pmts (oriented radially) with Btot<0.2T and oriented along the field direction.
7. Simulations (for next time)
   • Sasha will send a link to studies of energy deposition in the Bcal and present his work next time.
   • Andrei will complete simulations of number of visible photons per GeV.
8. Discussions on MOU with USM