GlueX TOF Meeting, March 1, 2012
Thursday, March 1, 2012
10:00 am EST
JLab: ARC, Room 428
- Minutes from the last meeting
- Sasha's talk at the Collaboration Meeting (for reference)
- Mechanical design: Tim, Chuck
- Prototype status: Paul, Sasha
- TDC choice: all
- Contract Status: Mark, Paul
Talks can be deposited in the directory
/group/halld/www/halldweb1/html/talks/2012-1Q on the JLab CUE. This directory is accessible from the web at https://halldweb1.jlab.org/talks/2012-1Q/ .
Chairman's Cell Phone
- FSU: Paul Eugenio, Kurt Koetz, Sasha Ostrovidov, Ian Winger
- JLab: Chuck Hutton, Mark Ito (chair), Tim Whitlatch
Note: Chuck brought his PC into the meeting room so we were able to look at the 3-D I-DEAS drawings.
- The TOF detector modules are clamped between two U-channels that run along the entire edge of the array.
- Tim proposed lengthening the long scintillators by 1 cm, so that the edges protrude another 0.5 cm. This is to make the clamp share load equally between scintillator and light guide.
- [Added in press] Elton Smith pointed out that it is not a good idea to put any pressure on the scintillator surface. That practice promotes crazing. So it looks like in fact we want to make the counters shorter.
- Tim proposed building a 1/4-scale model of the entire frame, including some of the detector modules, to see if there are any assembly issues with the current design.
- Paul proposed building a full-scale model of one corner of the frame, to test whether mechanical tolerances in the assembled array are sufficient.
- Kurt expressed some skepticism that the clamping U-channels could be made with enough precision to both hold the scintillator and provide a suitable mounting surface for the outer steel magnetic shields. In fact the current design does not have a provision for adjusting the angle of the long axis of the shields so that they miss the PMT's and their bases. That would have to be added.
- Kurt advocated a different approach, where the support for each end of each module is a separate mechanical assembly, each assembly supported on a common backbone. These assemblies would allow adjustment of more of the degrees of freedom and would have greater precision in doing so. Ian had drawn up a concept some months ago.
We decided that a lot of issues had been raised that require some study and further discussion. We agreed to meet again, in a week, Thursday, March 8, at 10 am (in ARC 428, so Chuck can bring his PC again).
There was not much to report since the collaboration meeting. The next step is to measure next measure light transmission through the light guides.
Paul repeated his preference for using the CAEN TDC's.
Paul is working on documents to respond the the RFP. Elton sent him examples from the Indiana contract; Paul has found them helpful.