GlueX TOF Meeting, December 20, 2012
GlueX TOF Meeting
Thursday, December 20, 2012
10:00 am EDT
JLab: CEBAF Center, F326
- Review of last TOF bi-weekly meeting
- Mechanical design
- PMT testing
- 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: Sasha Ostrovidov
- JLab: Chuck Hutton, Mark Ito (chair)
- There are four undergraduates working on testing PMTs now.
- 130 PMTs have been received (batches 1, 2, and 3).
- All of them have been tested with an LED, with gain measured via a visible single-photoelectron peak. All tubes passed.
- 70% of them have been tested with an americium source to look at photocathode efficiency
- 10% of them have been tested with a cesium source on a sodium iodide crystal.
Paul Eugenio has succeeded in negotiating purchase of rolls of ESR material from 3M, rather than in the 2×3 foot sheets that were originally offered. The rolls are 8 inches wide and about 1000 feet long. Also, there will be no adhesive layer attached to the material; the total thickness will be 1 mil. The purchase order has already been sent to 3M. Shipment is expected sometime in January.
The six scintillator bars for the mini-TOF have been received at FSU: 2 regular, 2 half-width, and 2 half-length bars. Eljen's measurements of the dimensions show that some are out of tolerance by one or two mils less than the 5 mil limit. Eljen also shipped performance data on the scintillator. (The interpretation of the "light output" spectrum a mystery currently.)
Although they have not been shipped yet, Eljen reports that in the next batch of 76 regular bars, 12 of them are 1/8 inch short. A decision on whether to accept these has not been made. Chuck will look at the mechanical implications.
Sasha is setting up for measurements on the scintillator received. They will be put into the dark box, with a spring loaded mechanism to hold the PMTs, and tested with a strontium source at various locations along the bar. Both ADC and TDC data will be taken to get attenuation length and speed of light.
All parts have been made for the support structure. Sasha plans to finish testing the scintillator this week so that gluing of the light guides can start in January. The schedule for starting assembly of the complete schedule will also depend on when the ESR material arrives.
Chuck is putting the mini-TOF ideas as they currently stand into the design of the complete TOF.