• Silicon rubber cookie prototype: Bogdan asked Steve Christo to bring a mold so we can try to make the silicon rubber cookies ourselves. It has been mentionned that we could buy "standard" cookies at Bycron and then modify their shape by heating them, but there are issues about physical properties alterations (like refraction indice).

 
• Background study: several points where discussed at the meeting. First of all, we might need a full Monte-Carlo of the photon arm. So far, Alan uses a simple event generator and a Monte-Carlo of the calorimeter, but it is not enough if we want to study the background (including neutrons). As a parallel determination of the background and to determine the sensibility of the scintillators and the lucide detectors to this background, it has been decided to conduct a parasitic test in Hall A. It would use a scintillator counter (actually one scintillator counter that was used in the test runs prototype) and a (4x4x10) cm³ lucide counter (provided by Alan). Both of them would be read by the same kind of phototube (type to be investigated by Alan). Bogdan pointed out we wanted the phototubes to be small to avoid counting rates on the phototubes themselves. The lucide would first have to be calibrated to understand its response and to tune the high voltage of the PMT. This would be done by using the Moller apparatus in Hall A with fast electrons (investigated by Eugene). We would actually use the Moller DAQ for this purpose. Once the lucide is calibrated, and its HV is tuned, we can determine the counting rates at different places in the Hall with both the sincillator counter and the lucide. That way we would understand the background better. This parasitic measurement would be performed in March. The mounting of the phototubes and the electronics setup would be Hakob's and myself's charge.

 
• FastBus: Charles gave us a list of fastbus items owned by ODU that we could use:
• Model 8152 fastbus blower
• Model 8000 series power supply
• Double width cabinet
• BIRA system crate
• Lecroy 1877 TDC (96 chan)
• Lecroy 1881 ADC
• Lecroy 1810 CAT
• Lecroy 1876 TDC
• Lecroy 1875 TDC
• BIRA 0046 display module
• BIRA 9101 00CF FSCC PC4 (Ethernet card)

Bogdan pointed out there was basically one thing missing here, the STR340, which is a VME interface. We intend to setup a DAQ lab in the EEL building at JLab, which would work with CODA 2.1 and a linux box (if possible). Once it works in JLab, the idea is to move the whole setup in Illinois so Alan Nathan can study it more intensively. Bogdan pointed out JLab already has most of the equipment so it would be possible to make a twin set of DAQ, one staying at JLab and one in Illinois.
 
• Blocks/PMTs/bases: Hakob hasn't finished the tests yet and will definitely write a note about it once it's finished. He gave me a survey done on 153 blocks at the Yerevan Institute, giving different length measurements of the blocks. I will try to enter those numbers and plot some distributions for next week. Late last week, we ordered 25 pieces of the new base prototype, they weren't ready yet. Tom was not here today, but a first prototype of the PMT/base assembly has been built (ask Charles). The latest version of the prototype will hopefully be built for next week and shown at the next meeting.

 
• Detector design: We ended up talking about different designs regarding how to move and align the photon calorimeter in the hall for the different kinematics. There is still two points of view:
• Put the electronics with the detector and move the whole thing around. Al Gavalya designed a prototype of this and it was discussed at the last collaboration meeting. It would be interesting to have a real cost estimate for this design so we can settle for it or move on to some other solution.
• Put the "main" electronics away from the detector in a hut, which would NOT  move. This would mean we only have to move 10 tons around (compared with 60 tons if we got to move everything). The main issues then are: how to move the detector (airpads ?), how to align it (some rail mounted on a pivot ?) and how to handle about 2000 cables which have to "follow" the detector (flexible cable trays: I will investigate how much this costs).
In any case, Alan, Bogdan and myself will talk to Al and/or Paul about this issue so we can move on and take a decision.
 
 
Franck Sabatie - 2/10/1999


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

maintained by  Franck Sabatie