Revision as of 21:04, 12 June 2010

Location, Time

Friday, June 11, 2010
2:00 pm EDT
JLab: CEBAF Center, Room F326/7
ESNet: 8542553
EVO: direct meeting link (good through 8/20)
Conference Group: 800-377-8846, participant code: 77438230
Slides: talks can be deposited in the directory /group/halld/www/halldweb1/html/talks/2010-06 on the JLab CUE (you have to be a member of the "halld" group). This directory is accessible from the web at https://halldweb1.jlab.org/talks/2010-06/ .

Agenda

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

Minutes

FSU: Paul Eugenio, Sasha Ostrovidov Jlab: Tom Carstens, Eugene Chudakov, Mark Ito (chair), Chris Keith, Sascha Somov, Simon Taylor, Tim Whitlatch, Beni Zihlmann

Review of minutes from the last meeting

We went over the minutes].

PMT purchase for TOF prototypes

Paul sent the quote, Mark submitted the purchase requisition, and now the purchase order is all set to go out, we just need a shipping address at FSU to attach to the PO.

Refrigerator for the target

We started from the entry in the minutes about the lab-wide review of helium demand.

• Chris commented that if we do get a pulse tube refrigerator for cryotargets, that it actually might be able to service a frozen spin target. We did note, again, that such a target is not part of any current plan for Hall D.
• Tim is in the middle of a cryogenic requirements review for the Hall and a decision on purchase of the recommended refrigerator is pending on completion of his work.

Time-of-Flight

We spent a lot of time updating issues discussed at the last meeting.

Calibration

• Bein told us the LED system planned for the calorimeters cannot easily change the intensity of the light output, as would be convenient for time-walk calibration.
• We need to talk to Elton Smith or Dan Carman about experience with the CLAS TOF nitorgen laser calibration system.
• Right now, Paul is working on a LED pulser system aimed at developing experience with the prototype counters.
• Stability of pmts is an issue, but not as critical as for the calorimeters.
• Paul informed us that the time-walk calibration was repeated on a time scale of order a year.
• Eugene told of us of a laser system that was being used in Hall A that may be available.
• Tom reminded us that the CLAS electromagnetic calorimeter also has a nitrogen laser calibration scheme. Kevin Giovanetti developed that system.

Change of Thickness of Counters

• Paul is exploring where the effective edge of the photocathode are with the Hamamatsu tubes.
  • PMT spec. states that the minimum cathode diameter is 46 mm
  • Cutting an ERT disk to that diameter to obscure photocathode
  • Plans to look for residual signal

• light reflect out to see if any coming in outside that diameter • current plan: silicon cookies, silicon sheets from eljen[sp?] • initial glued pmt • tim has done lay-outs • rtv glue possibility, eugene

wrapping • large sample of esr df2000 ma • studies about to start • final light tighe overwrapping, still wait

changing the dac

• received ti board • will be running with led • use a real triggered system • to match adc's and tdc's • vme64 bridge, not using coda • working on program to control

changing trigger paddles to use longer counters to improve rate

MOU

• DOE grant has off campus overhead rate • discussion with chair on MOU. waiting to hear back on overhead rate, • argue that saving money to doe by paying a lower rate

two full length some beam hole length to be machined