Mar 29, 2011 SiPM Electrical and Cooling

Action Items from previous meetings

1. Determine if swapped bias pins was accidental or in design (Chris)
2. Develop front and back views of jumper sheets. Also get latest version of drawings (Jack)
3. Request Hamamatsu data sheets from Chile to be used as input to jumper settings for boards (Elton)
4. Double-check that the jumper settings for #37 (U-board counting) are correct (Jack)

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)

Minutes

Attending: Elton, Jack, Yi, Eugene, Scot, Jim, Carl, Fernando, (Chris and Nick arrived toward the end)

1. Announcements
2. Action Items
3. Schedule, reporting, and manpower (Elton)
4. SiPM production testing (Yi)
   1. Running systematic scans to study dark rate and cross talk as a function of gate width
   2. Non-linearity of dr vs gate width may be due to cross talk
5. SiPM production testing (Carl)
   1. Problem with filter wheel disappeared. It may have been due to the switch that chooses the filter port was incorrectly set. Works fine now
   2. Filter configuration has been changed so that filter light settings change monotonically.
   3. OSP is in signature queue.
6. Mechanical assembly (Scot)
   1. Writing down procedures for light guide gluing.
7. Mechanical (Jim)
   1. Interconnect board now wedge shape can be attached to cover at a later stage
   2. Scot asked for clamps to hold cooling tubes
   3. Screws added to hold thermistor boards
   4. Concern about insulation between cable connectors for thermistors and other components. Add Kapton?
   5. Fernando: Request section views to check out ideas to streamline assembly.
   6. Hold-down frame for SiPM production testing. Use 6/32 screws to attach
   7. Light guide gauges: column and single guides. Nominal tolerance is 0.005", which is ok for column but comparable to guide tolerance. Might need to have these made in machine shop
   8. Light guide placement template updated to adjust for tolerances as the template moves right.
   9. Make another set of first article pieces to verify all changes.
   10. Eugene: Make spreader plate out of Al (2x Cu thickness still lower in radiation lengths)
   11. Eugene: Should rerun thermal map to check gradients on cooling plate.
8. Mechanical drawings (Chuck)
9. Temperature compensation (Jack)
10. Preamp-summing (Fernando)
    1. Checking signals from mini-Bcal on the scope
    2. One issue found is that there is ringing on all channels at various levels. Investigating. The ringing is present if any bias is present on the readout board. Additional filtering may be needed
    3. In order to study some of these issues in the lab, propose to populate the third wedge board so that it can be studied for electronic issues, input power, etc.