Time-of-Flight/Start-Counter/Target Meeting, March 5, 2010

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Location, Time

Friday, March 5, 2010
2:00 pm EDT
JLab: CEBAF Center, Room F326/7
ESNet: 8542553
EVO: direct meeting link
Conference Group: 800-377-8846, participant code: 77438230
Slides: talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2010-03 on the JLab CUE (you have to be a member of the "halld" group). This directory is accessible from the web at https://halldweb.jlab.org/talks/2010-03/ .


  1. Minutes from the last meeting
  2. Announcements
    1. Nominal electronics chain posted: Mark
      TOF electronics chain
      Start counter electronics chain
    2. Nominal schedule highlights: Mark
    3. Meeting outreach: Mark
  3. Time-of-Flight Status: Sasha O.
    • MOU status
  4. Meeting name change, "The PID Meeting?": Mark
  5. Action Items


JLab: Eugene Chudakov, Mark Ito (chair), Elton Smith, Sascha Somov, Simon Taylor, Elliott Wolin, Beni Zihlmann
FSU: Sasha Ostrovidov


  1. Electronics Chain Diagrams: Fernando sent copies to Mark. They are posted on this page. They will also be linked from their respective detector pages.
  2. Schedule Highlights: Mark extracted a few dates of interest from the November snapshot of the 12 GeV Project schedule. Bottom line: we need to have complete design and parts ordered in about a year and a half for the TOF, start counter and target.
  3. FSU MOU: Elton announced that Paul Eugenio has circulated a draft of a construction MOU and received comments from Elton, Eugene, and Mark.

Time-of-Flight Status

Most of the meeting was taken up with an open discussion of prototype test activity at FSU. Some items from the discussion:

  • Sasha reported that Chris Cuevas will send a flash ADC to FSU, and perhaps a VXS crate.
  • Elton asked about the need for using flash for tests at this point. It may introducing complication, perhaps an integrating ADC would suffice. Sasha mentioned that he does have a CAEN integrating ADC. Eugene shared with Elton's concern.
  • Elliott mentioned that the existing read-out libraries won't work in the FSU set-up.
  • Sasha stated that one of the next major questions is to decide between constant fraction discriminators and leading edge.
  • Using Hamamatsu 10534's (comes with the base)
  • He is getting 100% efficiency only at highest voltages for Hamamatsu tubes
  • He wants to buy 6 new Hamatsu PMT's. These will come with higher gain (4×106) than those in hand (1×106). They are about $900 each.
  • Eugene if efficiency poor, pulse height may be small, and so timing resolution may not be optimal. We need to demonstrate signals with robust amplitude and appropriate thresholds.
  • Prototype upgrade plans:
    • FSU has bought UV lucite for making 6 more light guides
    • Want to go to 4 paddles (from current 1 paddle setup)
    • Have 6 TOF paddles in hand, of different sizes, two of correct size (6.00 x 2.54 cm)
    • Settled on a single-piece light guide design. Machine shop has new equipment; can now make the one piece design.
  • The tests were done with and without light guides, 1% efficiency degradation seen by adding the light guides.
  • The light guide are coupled to the paddle with optical grease.
  • Eugene suggested trying to use an amplifier; resolution should not suffer much.
  • The discriminator threshold is currently set at 30 mV. 10 mV has been tried.
  • Sasha is seeing a counting rate of about 2 kHz at 2000 V on the tube.
  • Also planning to get a parallel trigger paddle, take signal from both ends to measure mean time resolution as suggested by Elton.
  • Eugene suggested using XP2020's to check that set-up is working; we want to see a plateau
  • Sasha reminded us: he has obtained a resolution of 125 ps with the Hamatsu tube and a CAEN CFD. With a NIM CFD [manufacturer?] he got 100 ps.

New Meeting Title: "The PID Meeting"

"Time-of-Flight/Start-Counter/Target Meeting" as a title has gotten to be a mouthful. Mark suggested we revert to "PID Meeting"; a choice that is pithy if not strictly accurate. No objections were raised.

New Action Items

  1. Post electronics chains on detector pages.
  2. Check dates on schedule highlight page, especially those for the start counter.
  3. Try to use an integrating ADC with the TOF prototype.