July 23, 2009 Calorimetry

Teleconference Time: 11:00 a.m. EST

• ESNET and EVO session
• Phone:
  • +1-800-377-8846 : US
  • +1-888-276-7715 : Canada
  • +1-302-709-8424 : International
  • then enter participant code: 77438230# (remember the "#"). Note: code changed 7/2/09

Items for followup from previous meeting(s)

1. Procedure to avoid vaseline in Bcal fabrication needs to be approved.
2. Documentation on fiber first-article
3. Review calibration procedures

Tentative Agenda

1. Announcements
2. Review of Action Items
3. FCAL Update
4. BCAL Fabrication
5. Simulations
6. BCAL Readout
7. Bcal Readout Review (July 21)
   1. Recommendations (my interpretation)
      1. Develop a comprehensive test plan for evaluating "production" SiPM units
      2. Invest the time to test and evaluate the SiPM units before proceeding with procurement
   2. Discussion
8. Other business

Minutes

Attendees:JLab: Beni, Elton, Fernando, John, Eugene, Carl, USM: Will, Sergey, Alam, Pedro Toledo, Joaquin Delgadillo.

1. Announcements
   1. Yuki Shiomi and Hui Yao from Kuraray are visiting the lab tomorrow. Elton will give them a tour of the accelerator and Hall B. Beni will show Yuki the lab where fibers are being tested.
   2. Hamamatsu has an update to the delivery schedule for their arrays: current estimate is late October. Also they request a change of the pins from 6mm down to 3mm. Fernando will check.
2. BCAL Readout
3. Bcal Readout Review (July 21)
   1. Recommendations (my interpretation)
      1. Develop a comprehensive test plan for evaluating "production" SiPM units
      2. Invest the time to test and evaluate the SiPM units before proceeding with procurement
4. Discussion of test plan for SiPM evaluation. A straw-man plan is shown below based on discussions, and will be refined further
   1. Testing of electronic components (Fernando)
      1. Fernando showed a tentative SiPM_Dev_Schedule, showing that testing of the electronics should be completed by mid Sep.
      2. Output of the preamp will be one signal per array.
   2. Single sensor tests at room temperature (Carl)
      1. Check that all cells are operational by scanning across array.
      2. Calibrate a light source and determine a (relative) gain for each cell. Determine PDE if possible.
      3. Measure dark current. (Dark rate is not possible at room temperature).
   3. Single sensor tests at 5 deg (nominal) (Carl)
      1. Install Peltier on each sensor gluing the Peltier to the "hot plate" and attaching the hot plate to the sensor package using a thermal paste.
      2. Repeat measurements performed at room temperature, but at a nominal operating temperature
      3. If possible measure the dark rate in this configuration.
   4. Track performance of sensors during light irradiation in the fiber lab (low radiation, guestimated to be about 0.01 Gy/month)
      1. Place 6-8 arrays in a box with Sr source (Keep a few for reference)
      2. Arrays should be powered continuously
      3. Arrays should be operated at the nominal operating temperature (~5deg) using Peltier
      4. Arrays should be exposed to temperature cycles
      5. Output may be monitored using a picoAmmeter
   5. Track performance of sensors during more realistic exposures to radiation (e.g. Hall B).
5. Discussion of further plans for testing light guides
   1. Elton obtained a quote from Plastic Craft on Monday for two types of light guides (90 circular bend) and (90 mirror reflector).
   2. Quotes for 2 prototype pieces of each was about ~2k$ (4 weeks delivery). We discussed whether we should purchase light guides for testing and qualification of vendor, and who would do this. It was decided that we might want to delay this decision until the situation vis-a-vis the SiPMs was better understood.
   3. Vitali (from Hall B) mentioned to guarantee material quality, we might want to provide qualified material.
   4. The 90 deg curve light guide has not been simulated and should be checked before ordering the prototypes
   5. John: suggested that optimization/prototyping of the short light guides for the SiPMs might be a good project to start with at USM. The optimization would involve checking geometries that could work well with an air light guide. Air coupling has considerable simplifications for the mechanical design (thermal isolation from light guide, eliminating the need for pressure adjustments on individual SiPMs, etc).
   6. Alam: Mentioned that the testing of light guides at USM would use a blue LED to excite fibers which would be used to illuminate the light guide and measure the uniformity across the face. This could also be compared to simulations.
6. Other business