• RTV cookie: Hakob tried to use the mold release compound BYCRON told us about, as well as liquid detergent and teflon. The meniscus is still negative. We will try to slide the tape down (see last meeting's report) when it's not totally dry, in order to make the meniscus the other way. In case this doesn't work, we will try to create a mold, pour RTV in it and place the phototube on top of it. The mold will have the positive meniscus requirement and it should work. In this case, we also need the mold release compound so the cookie doesn't stick to the mold.

 
• PMT Heating issue: Bogdan has another proposition for the PMT cooling. We would use a hose which would go directly in the tube (the can that holds the PMT and the base). The hose has to be of the order of 5 mm in diameter and flexible enough so it's manageable. The question is what kind of debit is needed to cool down the PMT enough. Tom and Bogdan will tell us more about this solution next week. Also it would probably take a lot of space and would make the management of the calorimeter a bit tricky (signal cables + HV cables + the same number of plastic hoses). Water condensation issues have been mentionned too when it's about 100% humid around here. Definitely to keep in mind.

 
• Cable handling issue: I've asked for a quotation for the flexible cable trays, I'll have it by next week and tell more about this solution.

 
• Trigger: Bogdan proposes that the trigger be formed near the electron  arm (which would be our proton arm), with fast signals from there. Then, long cables would go from the photon arm to this electronics hut. The only issue here is the high voltage. The length of cables would be considerably increased (up to 100m, instead of 25m in the former trigger scheme, formed near the photon arm) and it's useless to have 100m of HV cables. Maybe it would be possible to leave the HV near the photon arm and the rest of the electronics near the proton arm. One good thing about this solution is that this electronics hut would be shielded by the spectrometer itself.

 
• PMT base electronics: I've commited the changes on the PMT base electronics and gave it to Hakob who ordered 25 of them for the prototype.

 
Franck Sabatie -3/24/1999


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