Jun 16, 2011 SiPM Electrical and Cooling
From GlueXWiki
References
Action Items from previous meetings
- 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.
- Fernando will check son SEMTEC cable assemblies.
Tentative Agenda
- Announcements
- Action Items
- Schedule, reporting, and manpower (Elton)
- SiPM testing (Carl and Yi)
- Mechanical (Jim)
- Mechanical drawings (Chuck)
- Geometry (Elton)
- Temperature compensation (Jack)
- Preamp-summing (Fernando)
Minutes
Attending: Carl, Jim, Elton, John, Fernando, Chuck, Eugene, Chris, Jack
- Announcements
- No meeting next week. We will reconvene on Jun 30
- Action Items
- Schedule, reporting, and manpower (Elton)
- Should complete mechanical prototype before end of month
- 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
- 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.
- Mechanical (Jim)
- Mechanical prototype brought for discussion. Many comments and questions.
- Mechanical drawings (Chuck)
- Final comments and surface specifications are under discussion
- 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.
- 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
- 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.