Aug 30, 2011 SiPM Electrical and Cooling

Action Items from previous meetings

1. Decide on cable connections for monitoring cable from Bcal wedge to patch panel. Consider electronics needed for pulsing system (Elton and Fernando)
2. Get the dosage from the radiation badges on the mini-Bcal during the beam test (Yi)
3. Check that the resistor sets on the pre-production boards meet our specifications so that they can be frozen (Jack)
4. Sort out missing SiPMs in Jack's list (10 sensors) (Jack and Yi)

Tentative Agenda

1. Announcements
2. Action Items
3. Schedule, reporting, and manpower (Elton)
4. mini-Bcal (Elton)
5. SiPM production testing (Yi)
6. Mechanical assembly (Jim)
7. Temperature compensation (Jack)
8. Electronic boards (Fernando and Chris)
9. Light guide gluing setup (Scot)

Minutes

Attending: Elton, Ivan, Scot, Chris, Jim, Jack, Yi

1. Announcements
2. Action Items
3. Schedule, reporting, and manpower (Elton)
   • Light guides (80) have been shipped and should arrive late next week
4. mini-Bcal (Elton)
5. SiPM production testing (Yi and Ivan)
   • Measurements of cross talk and after pulsing are being analyzed as a function of over voltage and gate widths. Systematics will continue to be studied.
6. Mechanical assembly (Jim)
   • Materials and work for light guide wand modifications have been ordered.
   • Light guide holder and wrapping die are next
7. Temperature compensation (Jack)
   • Two boards were populated according to the resistor maps
   • The voltage checks resulted in 30 mV low compared to expectations.
   • This is not yet clear the source of the discrepancy. Many checks were made, including leaky capacitors, sources of leakage currents.
   • There are two spare boards (one for upstream and one for downstream). They will be used to continue to understand the source of the discrepancy. [Note added: Jack just sent an e-mail noting that that the internal resistor of the voltmeter is 10 MOhm, which is sufficient to explain the discrepancy. New voltage-loaded test values will be calculated for use during checks].
   • Fernando wants to hook up the thermistors and recheck the entire chain
   • The new LED test box is ready for checking SiPM signals.
8. Electronic boards (Fernando and Chris)
   • There is a mismatch between the spread sheets and the resistor maps. It was confirmed that the spread sheets are sorted first according to bias group and the maps are not. This will be corrected.
   • All parts have been ordered for the electronic boards.
9. Light guide gluing setup (Scot)
   • Batch of glue for the light guides has been ordered and received.