GlueX PID Meeting, June 11, 2010
Contents
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
- Announcements
- Minutes from the last meeting
- Time-of-Flight
- Prototype progress
- Status of the MOU
- Start Counter
- prototype progress
- attenuation length measurements
- prototype progress
- Target
- Status of the MOU
- Status of refrigerator plan
- 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 is to look for residual signal
- We talked about the light guide to PMT coupling scheme.
- current plan: silicon cookies
- initially glued used (still being used on one of the current counters)
- Tim has done lay-outs that incorporate compression of the cookie
- Eugene mentioned RTV glue as a possibility; joint can easily be broken with a razor blade
Wrapping
- large sample of ESR DF2000 MA in hand at FSU
- studies about to start
- final light tight overwrapping: still waiting for delivery
Other TOF issues
Changing the Data Acquisition
- Sasha has received TI board
- Will be running with LED system to explore time-walk; naturally will result in trigger rate increase over cosmics; the TI will help here to correctly correlate ADC and TDC hits
- Note: using a VME64 bridge (not using a CODA ROC)
New Counters
FSU is changing change the trigger to use a longer counter; this will improve the rate for cosmic triggers.
MOU
Progress will resume now that DOE grant work is done.
New Action Items
- Ask Elton about experience with the CLAS TOF laser calibration system.