CountingDaq 210623

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Meeting information

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  • Follow-up from collaboration meeting discussions
    • Keep the amplifiers in the plan, but shift them to the SBS bunker. All PMT signals will be routed from detectors, to detector-side patch-panels, to long cables, to bunker-side patch panels (?), then to the amplifiers. Will then just need short patch cables from amplifiers to FADC.
    • Numbers of MPD boards. Nilanga recommends planning for 1 MPD per GEM module, for a total of 30. Splitting them into two crates would give either 16+14 (with 4 septants in one, and three septants plus the pion GEMS in the other) or 18+12 (if the pion gems are instrumented in the crate supporting four septants). If the pion GEM cables can't reach, we'd need three crates with 16+12+2 boards.
    • Mitigation of radiation hazard to MPDs
      • I (Paul) am confused about the radiation hazard to the MPDs. The current simulation with the downstream bunker design (DocDB 759) gives 7.5e10 NIEL/cm2. Previously we've indicated commercial electronic components are generally robust to 1e13 NIEL/cm2. What is Paul missing? Or is it that we want to apply ALARA principles to the electronics dose, which does make sense.
      • A concept proposed in emails or the chat during the meeting would be to disconnect the MPDs during production running and keep them in the SBS bunker (each crate would be on a wheeled cart to allow "quick" movement). The simulation of the SBS bunker gives 1e9 NIEL/cm2. Each MPD has up to 4 analog HDMI, 2 digital HDMI, input NIM/TTL trigger, and one optical cable.
        • We should check the robustness and reproducibility of the HDMI cable connections into the MPD.
          • How many times would we expect to go to tracking mode per run period (and altogether)?
          • Maybe need an extra patch panel next to the crate to allow us to easily swap a damaged cable (the patch panel end should stay connected)? Does that change noise, robustness, or reproducibility?
        • Need to think about what tests are needed each time to verify we've got everything connected correctly, and likelihood of needing multiple accesses to swap/reseat cables
        • If we only have the MPDs near the detectors during tracking, can we avoid having them in mini-bunkers? Should simulate an unshielded dose at low beam current
        • Should think about personnel exposure during installation/removal of the crates. Think about the likely path we'd need to take to get the crates between SBS bunker and detector location and the work time at the detector location
  • Tests we should do
    • Single FADC readout
      • Include tests with long cables and preamplifier? Coordinate with Michael to test with prototype base & PMT?
    • Setting up a single element trigger with FADC & VTP
    • Setting up a coincidence element trigger with FADC & VTP
    • Combining triggers from two VTP crates
    • Robustness/reproducibility of HDMI connection to MPD
    • Noise variation with HDMI cable length
    • Readout of GEM through VTP
  • Activity updates
    • Restarting the counting mode daq design document on JLab OneDrive: [1]
  • General discussion


Meeting recording on [2]

Participants: P. King, D. Armstrong, H. Liu, C. Ghosh, J. Fast

  • Follow-up from collaboration meeting discussions
    • Keep the amplifiers in the plan, but shift them to the SBS bunker after the long cables.
      • We may decide not to use them. We may try to do a parasitic test of a detector + long cable + amplifier + FADC.
      • Should point out to Dustin that the electronics end of the counting mode cables should be the small Lemo connectors (50ohm impedence) whether we use the amplifiers or go directly to the FADCs
      • Possible test with cosmics using a lucite (or quartz) detector with a long cable going into a FADC with or without the amplifier. Could also use a bare PMT and look for the SPE and multiple photoelectron peaks.
    • Plan for the MPDs
      • Nilanga recommends 1 MPD per GEM module, so we'd need a total of 30.
      • Jim is worried about the integrated dose that the MPDs would receive not just from MOLLER, but also from SBS. Using the NIEL total dose that we've simulated, we should have a safety factor of ~100, but how much of that is being used by SBS?
      • The other concern will be single event upsets.
      • Discussion of moving the crates during production running
        • We've heard that the HDMI connections between APV and MPD can be finicky, but is that at teh APV side or the MPD side?
          • Maybe try doing some testing this fall?
        • How many times do we expect to switch into counting mode? See DocDB 634
          • DocDB 634 lists three counting mode times in run II (three days each) and three times in each of the two years in run III (two days each): nine sets of counting mode running in run II and III together.
        • Jim thinks that the MPDs may end up at beam height instead of at floor level; that could complicate moving them in and out
          • Jim also speculates that we could have some special VME chassis that had a remote power connection, that
        • Would we want mini-bunkers for the MPDs if we only had them out during counting mode running? David thinks we would likely
        • David points out that the intention is that we can switch in and out of counting mode without making an access, so moving and installing the MPDs would be the only reason to make an access
    • Discussion of access
      • Jim suggests someone should attend the shielding meetings to ask about access from the labyrinth to both sides of the beamline
      • Jim suggests asking Lorenzo about where radiation areas are likely to be around the target and beamline bunkers after running for a month or so, to get an idea of where in the hall we would be excluded from