Jun 16, 2011 SiPM Electrical and Cooling

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References

Action Items from previous meetings

  1. Check impact of material at low end of readout, both in the tubes for cooling fluid but also in the Cu cooling plate. Need to check effect on particle trajectories.
  2. Fernando will check son SEMTEC cable assemblies.

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Schedule, reporting, and manpower (Elton)
  4. SiPM testing (Carl and Yi)
  5. Mechanical (Jim)
  6. Mechanical drawings (Chuck)
  7. Geometry (Elton)
  8. Temperature compensation (Jack)
  9. Preamp-summing (Fernando)

Minutes

Attending: Carl, Jim, Elton, John, Fernando, Chuck, Eugene, Chris, Jack

  1. Announcements
    • No meeting next week. We will reconvene on Jun 30
  2. Action Items
  3. Schedule, reporting, and manpower (Elton)
    • Should complete mechanical prototype before end of month
  4. SiPM testing (Carl)
    • Collecting components for test
    • VME crate obtained
    • PC ordered
    • diffuse reflector received and checking illumination, compared to original setup
    • 4 QCDs in hand, need 4 more (may be available from hall A)
    • Yi to order pico-Ammeter
    • Connections/cables from board to QDCs not decided. Fernando will investigate options. Present test setup has 24 ft Lemo cables
    • Transition board from cables to QDC electronics header will have to be fabricated
  5. SiPM packaging
    • Fernando: Andrei mentioned yesterday that the SiPMs sent from JLab arrived with bent pins. We think this might have been caused during custom inspection. Will need to develop a more robust packaging scheme for production units.
  6. Mechanical (Jim)
    • Mechanical prototype brought for discussion. Many comments and questions.
  7. Mechanical drawings (Chuck)
    • Final comments and surface specifications are under discussion
  8. Geometry (Elton)
    • Showed acceptance calculations including flat section (6 mm) at the base of the light guide. This geometry leads to non-uniform acceptance at the edges of the light guide.
    • We discussed options for reducing the flat sections and gluing of guides to calorimeter
    • Elton will run simulations with different heights of the flat section.
  9. Temperature compensation (Jack)
    • LabView program and control "mostly" complete (Ivan had to leave suddenly).
    • Need board to test bias circuitry. Chris will give a completed board to Jack early next week. Jack requested that the connections be on a 6" cable with a matching connector available for mating to the other cable.
    • Setup is almost ready to closeup and start tests
  10. Preamp-summing (Fernando)
    • Two coaxial cables connect the U board to the preamp/summ board. Off-the-shelf assemblies were 4". Rise time of output pulse was measured to be 20-24 ns, compared to 10-12 for a preamp directly connected to a SiPM
    • Cutting the cables in 2, reduced the rise time to about 17 ns.
    • New standard assemblies of 2" and thicker conductor did not reduce the rise time any further. This may require moving the preamp to the U board.
    • Note: the SiPM cells have a capacitance of 320 pF, the assembly 5.1 nF.
    • Placing the preamp on the U board will require additional cables (+5V, -5V, ground).
    • Jack: The thermal scheme for isolating the heat from the electronics will change also. Each preamp dissipates about 180 mW power, accounting for about 3/4 of the power consumption on the electronics board.
    • John and Eugene: Emphasized that before the preamp is moved to the U board, we need to understand the source of the additional resistance in the circuit.