GlueX TOF Meeting, October 25, 2012
GlueX TOF Meeting
Thursday, October 25, 2012
10:00 am EDT
JLab: CEBAF Center, F326
- Review of last TOF bi-weekly meeting
- Mechanical design
- Contract status
- Calibration and Alignment
- Technical Design Report contribution
Talks can be deposited in the directory
/group/halld/www/halldweb/html/talks/2012-4Q on the JLab CUE. This directory is accessible from the web at https://halldweb.jlab.org/talks/2012-4Q/ .
- FSU: Paul Eugenio, Sasha Ostrovidov
- JLab: Eugene Chudakov, Chuck Hutton, Mark Ito (chair),
- The second shipment of 30 PMTs has been sent from Hamamatsu. they have not yet arrived at FSU. The nominal shipment schedule is posted on this wiki.
Paul reviewed his wiki page (standard GlueX username and password) showing progress and status. Photos of some of the machined parts are also shown.
TOF Gluing Fixture
Machine shop work for the gluing structure is underway. Parts for a nine-bar fixture are being made though only a five-bar version will be constructed initially. Ian Winger will start assembly next week.
TOF Module Wrapper
Paul will put together a wiki page on this item, a long rectangular channel to help wrap the scintillator. An example was shown as part of his talk at the last collaboration meeting.
Assessment of PMT batch 1
Sasha has been looking at the 38 PMTs received from Hamamatsu on October 5. A MySQL database has been set up to store parameters and test results for each tube. See his wiki page for details.
H showed results from gain measurements done on each tube done by measuring the position of the single-photo-electron peak. The results track the data sheet from Hamamatsu to about 5% for a given tube.
The results for quantum efficiency show the first two tubes with vastly different values (a factor of four difference). The measurement is done with a Americium source and after correction for gain, give a relative value for the cathode sensitivity between the two tubes. Sasha is checking his set-up.
FSU will send four tubes, including the two already tested, to JLab and the quantum efficiency measurement will be repeated.
The two long-lead-time items are the scintillator and the light guide material.
- scintillator The PO went out on October 3rd. since then Paul called Eljen and he expects the first-article counters to arrive on November 21.
- light-guide material The order got stuck in FSU Purchasing, but was finally issued earlier this week. Ninety-two feet of acrylic bar (in four-foot sections) is expected to arrive November 5. The machine shop is set up to machine the long light-guides for the half-width counters. The first patch of acrylic will feed that process. Then they will set up for the standard light-guides.
Paul is still pursuing getting ESR material in rolls rather than in small sheets. He is putting together a specification document to explain the intended use and importance of the larger sheets.
Mark posted, on the DocDB, documents related to the TOF change request we submitted at the end of September. The schedule changes were made to facilitate tracking under the Project's earned-value management system (EVMS).