Sep 13, 2011 SiPM Electrical and Cooling

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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. Investigate source of discrepancy between measured and predicted test voltages on wedge boards (Jack)
  4. Resort the SiPMs according to input bias groups to make sure the maps correspond to the spread sheets.

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: Jack, Fernando, Scot, Nick, Jim, Ivan, Yi, Elton.

  1. Announcements
  2. Action Items
  3. Schedule, reporting, and manpower (Elton)
    • First two production sets of light guides delivered last week
    • USM has shipped another batch of tested SiPMs to JLab
    • Fernando, Chris and Nick have successfully assembled and tested BCAL-01 upstream and downstream modules on the bench
  4. mini-Bcal (Elton)
    • Testing of BCAL-01 readout boards on mini-Bcal
    • Ringing (viewed on scope) ~ 2mV peak-to-peak relative to 550 mV input LED signal ~ 0.4%. This is compared to old BCAL-00 module of ~ 20 mV/600mV ~ 3.3%, a reduction of x8.
    • Ringing (amplitude) ~ 5.5counts/3012 counts ~ 0.2%
    • Ringing (sum) ~ 19 counts/39780 counts ~ 0.05%, Ringing (sum RMS) ~ 136/39780 ~ 0.3%
    • These numbers are consistent with a 1:400 dynamic range.
    • Still want to digest the information and estimate the number of pixels firing.
  5. SiPM testing (cross talk and after pulsing) (Ivan and Yi)
    • Data have been analyzed that study the dependence of cross talk and afterpulsing as a function of the gate width and input light levels.
    • The two components are roughly equal in size and depend quadratically on the over bias. At Vover=1.2, they are 15-20%.
    • Note that the afterpulsing does not affect the linearity as it does not fire any additional pixels.
  6. Mechanical assembly (Jim)
    • All metal parts need to be ordered. There are milled parts and water jet-cut pieces. The drawing set will be checked when Chuck and James return next Monday. They should be finalized and readied for procurement.
  7. Temperature compensation (Jack)
    • Work with Shaun to write up a procedure for substituting a sensor on one of the boards to be assembled.
    • Develop an automatic procedure for producing the jumper sheets.
  8. Electronic boards (Fernando and Chris)
    • Plan to increase the Cu weight on the board
    • When can we start ordering the production systems? Elton: Would like to digest the test information before making a final decision, but should be soon. We should be ready with orders in case there are available funds.
    • During assembly of the readout modules they found 6 U-boards with defects (out of 80). A total of 2500 have now been tested and only 30 failures found. These will be returned under their warranty.
  9. Light guide gluing setup (Scot)
    • Parts have been received for the light guide wand. He will assemble them tomorrow. A washer need to be returned for the correct size.
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