Jul 21, 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. Ongoing study by Beni
2. Check the possibility of enlarging the 4-40 screws to hold the cooling plate (Jim)

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)

Minutes

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

1. Announcements
2. Action Items
   • Possible update on bias activity next week
3. Schedule, reporting, and manpower (Elton)
4. SiPM testing (Carl and Yi)
   • computer has arrived and is being preped by the computer center
   • Beni's crate should work fine.
   • Home-made light source should work fine for this setup
   • Carl will be in only a few days next week. Will get computer setup so that Yi can start setting up the software
5. Mechanical (Jim)
   1. Discussed options for using the chiller/cooling plate for the SiPM production testing.
      • Concept developed, where the cooling plate and electronic board are interchanged relative to the detector configuration. (In this geometry, the electronics and sensor are in the same plane.
      • A concept for 4 SiPMs at a time was developed and will be tried out.
   2. Glue samples have been ordered from Norland Optical for testing gluing of light guides to Bcal wedtes
   3. Checking options for thermocouples for each cooling plate
   4. Summarized the work of summer students Joseph and Stephanie
6. Mechanical drawings (Chuck)
7. Geometry (Elton)
8. Temperature compensation (Jack)
   • Problem with Peltier resulted in device not cooling below 10 deg. Once Peltier was replaced, cooling tracks down to 1.6 deg in about 20 min.
   • Ready to initiate tests. Will separate the electronic board to speed up cooling
9. Preamp-summing (Fernando)
   • Initial rise time of array was about 15 ns (at the saturation for the T-channel)
   • Tracked rise time limitation to decoupling capacitor on bias voltage. After moving capacitor to U board, rise time decreased from 15 ns to 5 ns, which includes the width of the diode pulse
   • Borrowed a very fast laser light source (100 ps width) from Carl, which is used to determine the intrinsic rise times of the devices
   • Still tracking down some problems with the circuit. Some difficulties with capacitor leakage. Pulse shape/decay time is still not quite understood.