CountingDaq 210929

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Meeting information

 Meeting time:  3:00pm Eastern
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  • Activity updates
  • General discussion
    • Comments from Nilanga about APV cards, backplane, and HDMI cables
    • What timing resolution do we want for the PMT signals? We should have that in the requirements document.


Meeting recording on [1]

Participants: B. Moffit, P. King, H. Liu, C. Ghosh, D. Armstrong

  • Discussion of the GEM readout; email from Nilanga
    • Since the APV cards need to be used in SBS, changing the connector between APV and backplane isn't feasible, but adding addition bolts between the APV and backplane would be possible to consider. Nilanga hasn't had issues with the APV->backplane connections
    • David notes that the Italian GEMs have a flexible backplane, and some issues are related to that flexible backplane.
    • Kondo and Nilanga are working on an idea that could allow us to use longer HDMI cables. Most of the noise occurs in the first few analog channels, so if we simply don't use the first few channels in each APV, we can use longer cables without having significant noise issues. This needs further study to understand how long the cables could be. An old slide from Evaristo indicates a 20-30m cable might be possible.
      • We suggest that Chandan tries to study HDMI cable lengths from ~10m up to 30m or 40m.
  • Change in GEM rotator range is being considered
    • This would allow us to rotate to cover the full azimuth as if we only had 4 GEM pacakges.
    • Allowing 90 degree rotation (instead of ~52degree) should allow us to cover everything if we had just 4; if we have all 7, we're able to get to all measurement positions with at least two GEM sectors
    • This gives a scope contingency in the event that the NSF project is unable to deliver the full number of GEM modules
    • Depends on getting the readout working with longer HDMI cables
  • Consideration of time resolution needs
    • David will think about it. The real issue is being able to define the coincidence between the two trigger scintillators and the coincidence with the quartz detectors
    • Hanjie says that the FADC in integration mode can get ~60ps resolution, depending on pulse shape etc.
    • The TOF between the front and back scintillator is ~4ns, so even with just the 4ns binning we ought to be able to be able to have some suppression of random coincidences. There will also be transit time in the scintillator.
    • David will think about the rates and accidentals to make sure that makes sense. He'll put a short note together and circulate it
  • General discussion
    • Should we have a pulser trigger?
    • Should we take data in raw mode (50 samples per trigger --> 200ns), and how much raw mode data do we want to do?
    • A very low bias trigger would be a pulser trigger and a wide window in the FADCs & GEMS. Could run the FADCs in either raw or integration mode
      • We think we need three APV samples to span the signals in the GEMs. In some previous discussion, we'd talked about using zero suppression and using a wider window but only report 3 samples per hit.