• RTV cookie/mold: The ideal meniscus radius seems to be 24". Hakob thinks it's better to make a smaller cookie, then stick it to the PMT once it's fully dry. Also we can fill the space between the edges of the PMT and the cookie with RTV (using a tape for instance) to get an even better optical coupling. We will try that out and make the mold for the 25 piece prototype.
 
• Pb-glass radiation damage: As planned, David has done a new measurement on the block that was damage. The results are consistent with what Hakob found in the first place. Also, he tried to cure it with UV lamp and no significant effect has been found on a short time scale. We will repeat the test on a longer time scale. Bogdan has installed three blocks (which transmissions have been measured) at 30, 60 and 180 degrees of the beam line, at about 3 to 4 meters of the target to estimate the radiation damage. The blocks are more or less at the level of the beam line. The 180 degree block is under the beam line. At the next maintenance day, the transmission of those blocks will be measured again.

 
• 9/25-block prototype: Hakob has got all the mechanical parts. he glued the titanium flanges on the Pb-glass blocks with epoxy and made some resistance tests. It seems it can resist at least 20 kg of traction (about a factor two more than what we apply with the string). The bases for the phototubes are not ready yet, but will be shortly. Also, we have to think about the block wrapping, using aluminized mylar and tedlar (?). There are still discussions on the need for single-side aluminized mylar or double-side. If we use the single-side aluminized mylar, which side do we put against the glass. In any case, the prototype has to be light-tight.

 
• Database for the calorimeter: We have discussed the possibility to have a complete database of the blocks/bases/phototubes, using either numbers on tags or bar codes. The bar code solution might be smarter considering the high number of items to be entered in the database.

 
• Misc. issues: Alan wants us to keep in mind that we need all the parts for the whole calorimeter (750 pieces) before the summer to be able to get summer students to work on it. The titanium flanges might take quite a long time to arrive. Also, there has been discussions whether JLab could order and pay the parts with Illinois' money (transfered on some local account) or not. Alan will see if it's possible to transfer the $63k to JLab. We would then create an account for which Eugene would be responsible for. Also let us keep in mind that hakob will leave in 2 to 3 weeks. We need to learn everything he has been working on in the meantime.

 
• Schedule for the next few months: We have discussed a reasonnable schedule till the end of the summer:
 

4/27 - 4/29  Maintenance days	Install the 9-block prototype in the Moller apparatus.Also install a (4x4x10) cm3 lucide block and a similar scintillator piece there
5/8 - 5/10 Facility time	Request 4 hours of beam-time to test the 9-block prototype. Also compare the lucide/scintillator VETO detectors
5/11 - 5/13 Maintenance days	Install the VETO detectors (lucide/scintillator) in hall A for parasitic comparison during HAPPEX data taking (5/14 - 5/28)
5/14 - 5/28 HAPPEX	Parasitic comparison of the VETO detectors
5/29 - 7/8 Shutdown	Prepare/install the 25-block prototype Prepare/install the 6+6 VETO detectors Prepare/install the MWPCs Try to install the Fastbus DAQ electronics
7/9 - 7/30 HAPPEX	Parasitic data taking
7/31 - 8/3 Commissioning	Request 2 shifts for test runs (similar to 1998 test runs)


 
• Other important dates: 

 
• 05/20 - 05/22: Workshop on exclusive reactions at JLab
• 05/23 - 05/25: Hall A collaboration meeting

 
Franck Sabatie - 04/14/1999


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they will be transmitted and discussed at the next meeting.

maintained by  Franck Sabatie