Mar 1, 2011 SiPM Electrical and Cooling

Action Items from previous meetings

1. Determine if swapped bias pins was accidental or in design (Chris)
2. Make low voltage cables for the SiPM test (Chris)
3. Acquire material to absorb water for the box (Carl)
4. Order dew point sensor (Jim)

Tentative Agenda

1. Announcements
2. Action Items
3. Schedule, reporting, and manpower (Elton)
4. SiPM production testing (everyone)
5. Mechanical assembly (Scot)
6. Mechanical (Jim)
7. Mechanical drawings (Chuck)
8. Temperature compensation (Jack)
9. Preamp-summing (Chris is out but sent these notes)

Minutes

Attending: Jack, Carl, Jim, Chris, Chuck, Scot, Eugene, Nick, Yi, Elton.

1. Announcements
2. Action Items
3. Schedule, reporting, and manpower (Elton)
4. SiPM production testing (everyone)
   1. Optical
      • Optical calibration complete and in log book
      • Suggestion to keep one SiPM array for reference between measurement sets
      • Static dissipation equipment installed
      • micro-switches ready to install to interlock HV
   2. Testing preparations
      • Checking all channels
      • Nine V792 QDC modules. One mod has a single bad channel
      • Cables are ok
      • 3 out of 4 boards are fine. One has some dead channels.
      • Connector to QDC boards miss connections, but seem to be ok on the bench. Investigating
      • Different locations give different gains by 20-30%. Appear to have baseline oscillations which may be causing the problem. Will ask Fernando to take a look.
      • Once the channels are checked, a full check of gain and light uniformity using SiPMs will be performed.
5. Mechanical assembly (Scot)
   • All light guides have been measured for dimensional uniformity and look good.
   • Have 11 J guides and 9 K guides. Have informed USM of the count.
   • Gluing setup will require adding set screws to keep pressure on light guide while gluing. For the mini-Bcal will glue one guide at a time.
6. Mechanical (Jim)
7. Mechanical drawings (Chuck)
   • Brackets have been designed for the mini-Bcal mount and they are in the machine shop for quotes.
   • Clarification comment on light guide drawings have been added and drawings re-released.
8. Temperature compensation (Jack)
   • Spread sheet has been sent out with list of proposed voltage settings.
   • Does not yet include the 80 FA + 120 last guides. They will be added soon.
   • Patent disclosure has been requested so we are holding off on making detailed design and calculations available to external collaborators.
9. Preamp-summing (Chris)
   • Wedge board is complete with connectors and ready to be tested
   • U-boards have come in. They will be assembled as time permits
   • Fischer connectors are expensive and have long lead times. We will substitute them with trim trio connectors.
10. Wrapping (Elton)
    • Presented measurements of light transmission for no wrapping, tedlar, acid-free paper and Al mylar. No significant difference was seen.
    • Tedlar was chosen for the wrapping material. Tedlar is the thinnest option. There is a concern that paper may absorb water over time and Al mylar is partially transparent.