Time-of-Flight/Start-Counter/Target Meeting, March 5, 2010
Contents
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/ .
Agenda
- Minutes from the last meeting
- Announcements
- Nominal electronics chain posted: Mark
- Nominal schedule highlights: Mark
- Meeting outreach: Mark
- Time-of-Flight Status: Sasha O.
- MOU status
- Meeting name change, "The PID Meeting?": Mark
- Action Items
Minutes
JLab: Eugene Chudakov, Mark Ito (chair), Elton Smith, Sascha Somov, Simon Taylor, Elliott Wolin, Beni Zihlmann
FSU: Sasha Ostrovidov
Announcements
- Electronics Chain Diagrams: Fernando sent copies to Mark. They are posted on this page. They will also be linked from their respective detector pages.
- 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.
- 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
- Post electronics chains on detector pages.
- Check dates on schedule highlight page, especially those for the start counter.
- Try to use an integrating ADC with the TOF prototype.