Apr 18, 2013 SiPM Electrical and Cooling

Action Items from previous meetings

1. • Nick to send location of files with the SiPM assignment information to Elton and Yi.

Tentative Agenda

1. Announcements
2. Action Items
3. Light guides (Tina)
4. SiPM production testing (Yi)
5. Mechanical assembly (Jim)
6. Electronic boards and SiPM sorting (Fernando and Chris)

Minutes

Attending: Elton, Chris, tina, Tim, Nic, Yi, Jim

1. Announcements
2. Action Items
3. Light guides (Tina, Jim and Elton)
4. Separation of light guides from module
   • Detachment of light guides from the module had been noticed when the modules were in the hall ready to be assembled onto the craddle
   • Detachment was found to begin hours after gluing, appearing the day following.
   • Last Wed, a phone conference with Tim Norland discussed this problem.
   • The symptoms point to adhesive failure of the glue. This is usually caused by non-uniform curing, where the shrinkage of the glue during curing will create stresses which can lead to detachment.
   • Solutions to the problem include developing a more uniform illumination procedure, or roughening the light guide surface so that there is better adhesion.
   • Tests of both of these solutions has started.
   • It was found that the illumination of the light guide from near the top end of the guide, nearly parallel with the side of the light guide, visually provides a more uniform illumination
   • Gluing tests onto an acrylic sheet with 400, 600 and 1200 grit paper points to best clarify using 600 and 1200 grit. For each grit paper, four pieces were roughened in a single figure '8', clouding the surface. Three of the pieces were glued and the other was kept for visual comparison with the others.
   • Considered lowering intensity and increasing cure time
5. Test setup (Elton and Jim)
   • Jim has made pieces that will allow testing of individual cells with an LED at one end and the radiometer at the other. The fixtures locate the LED and the radiometer with respect to the light guides by attaching to the end of the module.
6. SiPM production testing (Yi)
7. Mechanical assembly (Jim)
   • Two fixtures will be made
   • One to hold the wand at the proper location and inclination for illumination
   • A second to enable the gluing of a single light guide in the middle of the module. This is done by a piece that can press on the end of the module but open at the center so the wand can illuminate the light guide.
8. Electronic boards and SiPM sorting (Fernando and Chris)
   • Ten readout assemblies have been completed (1 per day per person).
   • The tubes on the cooling plate are shifted from their nominal position. Chris will give Tom a cover plate so that it can be used as a template for the gluing.
   • Will need more SiPMs in about one month.