Jul 7, 2011 SiPM Electrical and Cooling

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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. Check the possibility of enlarging the 4-40 screws to hold the cooling plate (Jim)
  3. Update the light guide drawings to eliminate the flat section (Chuck)

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: Fernando, Chris, Jim, Chuck, John, Yi, Eugene, Elton, Jack

  • Note: due to network disruptions this week, the minutes were not posted to the wiki till 7/13.
  1. Electrical preamp/sum (Fernando
    1. Three tested boards ready.
      • Chris: need to coordinate with Jack to provide requested cabling
    2. Need to determine timing response of this system to approve design
      • Sasha has contacted Vitali to see if they can use his setup to measure the time response of this circuit.
  2. Mechanical (Jim)
    1. Screws size for holding fixtures can likely be changed from #4 to #6 screws
    2. Cooling measurements
      • Checking flow of dry nitrogen
      • Thermocouples installed at inlet and outlet of cooling plate
      • Using 20% propylene glycol mixture, useful to -10 C
      • At low flow rates the input temperature is about 17C. Moved flow meter to back side and remeasure
      • Eugene: Concern about rapid temperature fluctuations. Need a buffer to smooth out temperature changes
      • Discussion regarding options to do this. Will measure time constant for the fluctuations.
  3. Drawings (Chuck)
    • Updated drawings to latest design. They are being checked
  4. SiPM testing (Yi)
    • Writing paper on radiation tests, in final stages
    • Will help Sasha with timing tests
  5. Electronics bias/temp comp (Jack)
    • Control circuits are almost ready, not yet connected to scope. May need to get feedback from Yi
  6. Discussion on temperature stab for production testing
    • Decided to make measurements at room temperature, but would like a stable environment
    • Need a thermistor at each SiPM to monitor temperature
    • First article stabilization time was about 30 min
    • Fernando: could use a single SiPM which is measured repeatedly and used as a reference.
    • The temp stabilization will have to be using the ambient air, as connections to all 16 cells inhibits close contact to cooling plate with liquid control
    • Fernando suggests using a thicker PC board to insulate the SiPM from the electronics hear source.
    • Fernando: remembers that Hamamatsu has provided us a temperature range for SiPM operation. We should dig it out.
  7. Other
    • Fernando has investigated commercial options for multiplexing signals: a 16/1 multiplexer is available for $4k with each additional multiplexer for $1.6k. The multiplexer can be controlled using many options (GPIB, USB, et). For the moment we will stay with our initial plan of using VME 792 QDCs.
    • Elton asked Jim to think about how to maintain a constant temperature inside the dark box. Possibly heating air slightly above room temperature would be a good option.
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