• RTV cookie prototype: Hakob used the silicon rubber to make cookies on two PMTs. He used some kind of scotch tape as a frame around the phototube, then poured RTV. After removing the tape, it seems the optical coupling between the cookie and the glass of the PMT is perfect. Although, there is a negative mesnique on the other side. In order to make it positive, we will have to use a mold release compound first. Also, the manual says it takes about 7 days for the silicon rubber to dry and make a cookie.

 
• PMT Heating issue: It seems that a reasonnable number is 2 W per unit, which makes a total of about 1500 W for the whole calorimeter. If this number is correct, we will definitely need cooling. Charles brought up some numbers for the cooling we would need, he will finalize them and tell us at the next meeting.

 
• PMT wrapping: as an answer to a common question, the phototubes will be wrapped in mu-metal.

 
• Flash-ADCs: Pierre was here this morning and told us about the Flash-ADCs that the LPC Clermont could work on for the calorimeter. The main points are: 
• it will take quite a while and it might be too late to use them for the RCS experiment. Although, it is still interesting since other experiment will use that calorimeter. 
• there is  manpower and money at Clermont.
• electronicians will actually build the chips. The sampling rate would be 1 GHz during 100 ns. The resolution would be 10 bits.
• the trigger would have to be redesigned (with fast logic for instance).

 
• PMT gain test: Hakob has finalized his tests and is writing a technical note. To make sure the testing apparatus has no problem, he will perform the same test on another PMT for which we know the rate gain dependence.

 
• Veto detector test: The prototype lucide block has been received, we will probably be able to compare scintillator vs lucide during commissioning time ealy July (Alan will ask for 1 day of dedicated beam time). The shielding issues as well as the fastbus can also be worked on at that point.

 
• Optical fiber holder: Eugene has looked into some catalogs to find holders. So far, it seems that what he has found was either expensive or too big. It is always possible to design and build them ourselves. Eugene will continue his search.

 
• PMT base electronics: there is a couple things to change in the PMT bases electronics. I will commit the changes and make sure it is done pretty fast. The 25 block array prototype has to be ready before June, it is important to not waste time.

 
Franck Sabatie -3/17/1999


PLEASE, fill free to mail any remarks or advice to Franck Sabatie, 
they will be transmitted and discussed at the next meeting.

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