May 5, 2011 SiPM Electrical and Cooling

Action Items from previous meetings

1. Check impact of material at low end of readout, both in the tubes for cooling fluid but also in the Cu cooling plate. Need to check effect on particle trajectories.
2. Suggested mods to mechanical: make SiPM holder one piece (instead of 4), increase thickness of holder to 3/16", increase length of heat spreader to cover all amplifiers.

Tentative Agenda

1. Announcements
2. Action Items
3. Schedule, reporting, and manpower (Elton)
4. SiPM testing (Carl and Yi)
5. Mechanical (Jim)
6. Mechanical drawings (Chuck)
7. Geometry (Elton)
8. Temperature compensation (Jack)
9. Preamp-summing (Fernando)
   • Will present a discussion of cabling and grounding next week.

Minutes

Attending: Jim, Jack, Elton, Carl, Yi, Fernando, John, Eugene

1. Announcements
2. Action Items
3. Schedule, reporting, and manpower (Elton)
4. SiPM testing (Carl and Yi)
   • Carl has an initial draft of the First Article report.
   • Elton: clarify assumptions we have used to obtain the gain. We use the measured charge between p.e. peaks in channels and the nominal QDC calibration per channel.
   • Eugene had suggested that it might be useful to include a study of the temperature dependence in the report. It might be difficult to complete that measurement next week, so it might be provided to Hamamatsu later since that does not bear directly on our specifications.
   • The radiation tests have been completed, so it might be useful to add these to the report.
   • Ivan has completed retesting 20 samples, which now can be shipped to UofR and USM.
5. Mechanical (Jim)
   • The new layout for light guides was shown and discussed.
6. Mechanical drawings (Chuck)
   • No report
7. Geometry (Elton)
   • Elton asked what constraints we have to add an additional radial layer to the readout, which might be necessary to preserve the required resolution. Jim indicated that adding 8 additional coax cables is feasible by compressing the cooling fins. Fernando said he would think about it, but the space is very tight and it might be a challenge.
8. Temperature compensation (Jack)
   • Prototype boards are expected Monday
   • Should be able to start some measurements next week. First will measure circuit output bias vs temperature (recording temp). If the circuit behaves as expected, a sensor response to constant illumination will be checked as the temperature is varied (also recording temp)
9. Preamp-summing (Fernando)
   • Fernando presented an overview of the grounding scheme for the readout, which has three grounds: a) amp/sum/bias ground, b) monitoring ground c) chassis.
   • Power supply from Wiener has been identified that can supply bias for 16 channels (500 V, 1mV setting granularity, <3mV pp) and 8 channels of voltage for preamps. This system can be used for the production SiPM testing and gain experience for the low voltage power supplies for the experiment.