• RTV cookie: Hakob tried the mold we talked about last time. The idea is to just make a "deep" of the size of the desired cookie, hence to force to meniscus to be what we want. After one day of drying, you then put the PMT on top of it, so the cookie sticks to the PMT too (you can also pour some fresh RTV on the PMT so it sticks better). Unfortunately, the meniscus he asked the machine shop to produce was too big, so it was almost impossible to get a good optical coupling. He ordered another mold with twice as less a meniscus and will try it for next week. The idea seems to work pretty well. Charles mentionned we could maybe achieve a positive meniscus if we put scotch tape around the PMT, so the scotch tape barely goes over the PMT (a couple millimeters or something). Hakob will try that too.

 
• Base heating issue: Tom and Charles have redone the calculation Bogdan made last time to determine what speed and pressure is needed. The better calculation gives some factor two lower speed. Tom will look into what kind of equipment we need to achieve this.

 
• Cable handling issue: Assuming that we use the usual HV and signal cables (which we know we won't but that gives an upper estimate), the quotation I asked gives about $25000 for the flexible tray carrier. This is for a 100 feet carrier. If we lower the weight and most likely the length, but if we had wheels on the tray and some kind of pivot to get both axis mouvement, it seems possible to design a system that will cost at the very most $50000. I've asked Eugene and Jack Segal about the characteristics of the cables we will actually use to give a better estimate and a new quotation.

 
• Trigger: We've had a lot of talk about the trigger, Bogdan still thinks a fast signal coming from the proton spectrometer would be good for fast clear. He proposes to use some data that is going to be taken on April 2nd in Hall A to get an estimate of the singles rate (they will scan different angles or momentum, we can just look at the single rates in S1/S2). I proposed to analyse the data. For more information about the trigger scheme Bogdan proposes, please contact him.

 
• Lucide/Plastic test: It seems we could do the lucide/plastic rate comparison sooner than this summer like in April/May or so. We will talk more about that next week.

 
Franck Sabatie -3/31/1999


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