Mar 15, 2011 SiPM Electrical and Cooling

From GlueXWiki
Jump to: navigation, search

Action Items from previous meetings

  1. Determine if swapped bias pins was accidental or in design (Chris)

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: Nick, Jim, Elton, Fernando, Yi, Chris, Jack, Scot, Carl

  1. Reviewed progress toward readying the mini-Bcal for the beam test in Hall B
  2. Overall (Elton)
    • Tom and co. setup the prototype on the base support and practiced for installation in the hall
    • VME crate and NIM bins were installed into racks in EEL 126
    • Cables are labeled and being bundled
  3. Mechanical (Jim)
    1. Light guide dimensions somewhat out of specs
      • Start gluing on left side closer to Bcal edge (to allow extra room on right side)
      • Create templates of max size of each light guide. Also create a template for a full column. What about a full arrangement of 4 columns?
      • Make templates available to USM
    2. Small modification on pole plate to correct screw size
  4. Setting jumpers
    • Initial jumper settings interchanged the two jumpers for each SiPM and had to be redone. After correcting problem, the range of measured test voltages differed from expected by about 110 mV.
    • Jack first suggested to adjust values empirically
    • Fernando suggested to leave boards as they are and adjust the input voltage thereby splitting the max difference of voltage variations of 100 mV. This would correspond to a +/-5% variation in gain. The gain specification of the SiPMs is +/-7.5%, we agreed not to try to optimize the voltages further.
    • Jack found that the major source of variations is likely due to the 85KOhm resistor (0.1%). He will check if it can be obtained with 0.01% [Note added: Yes, this is available]
  5. Starting PR for production of boards
    • Need to provide feedback from present configuration in the next couple of weeks.
  6. SiPM Production testing
    • Carl tested 80 samples in two days
    • Results show gain variations outside expectations
    • Likely due to poor thermal contact. Carl estimates variations correspond to about 3 deg C. Concern is the SiPM pad (4 layers)
    • Yi has replaced all standoffs, which will allow use of a single layer of thermal padding of 1-2 mm thick
    • Fernando: It is best to keep the pads as thin as possible. The thicker material is softer for fit but is not as efficient.
    • Suggestion is to make a frame that holds the SiPMs in compression during the tests.
    • Problem with insertion/extraction: About 75% of samples are easy fits. The remainder 25% cause irritation. For other setups, they are considering a "connector saver", e.g. samtec transition connector with robust bins that serves as a base to which the SiPM is placed once and connections/disconnections is done for the samtec connector. (This is not an option for us at this stage).
  7. Electrical connections
    • Requests that Jack generate front and back views (i.e. also image drawings) for the purpose of testing boards and placing SiPMs in proper location.
    • Also use the latest version of the drawings. (Some of the jumper placements have moved).
  8. Testing of full cooling module
    • Fernando: After assembly of the cooling module with electronics/cooling plate and connectors, etc, they will be tested with an LED source in the dark box.
  9. Light guide / gluing (Scot)
    • All light guides were glued onto the module last week (except for a single "K" guide that has not arrived)
    • Wrapping of guides with tedlar sheets worked well. There is about a 3 mm gap at the base of the light guide that could not be covered. We also needed to peel back the wrapping at the top to allow the SiPM frame to slide over.
    • Mounted Bcal monitoring boards (20 on the center columns on each side).
    • Frames fit over light guides, but hand gluing resulted in some misalignments which were visible by eye.
    • Cooling tubes have been glued into place and the RTDs placed on them.
Retrieved from "https://halldweb1.jlab.org/wiki/index.php?title=Mar_15,_2011_SiPM_Electrical_and_Cooling&oldid=35293"