CountingDaq 210106

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Meeting information

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  • Discussion of GEMs in MOLLER
    • Email from Nilanga, 6 January 2021
      1. Could you remind me how many channels per chamber you plan to have?
        We will have 1280 channels per GEM module (assuming a readout pitch of 0.8 mm): this would be 10 APV cards arranged in two sets of 5. One of the MPD modules could support up to 15 cards. So 1.5 modules could be supported by an MPD.
      2. How many samples we will take for each trigger?
        For SBS we are going to take 6 samples. However, using hardware level background hit suppression, we plan to reduce this down to 3 samples. If this does not work as expected, we can switch to 3 samples. Once SBS starts running and we get some experience, we can decide what to use for MOLLER. For your data volume estimations, I think we can assume 3-samples.
      3. Have you thought about using sparsification, pedestal suppression, or some other data reduction options?
        Yes, we are very actively pursuing these background reduction methods now; these include zero suppression at hardware level and also suppression of background hits not correlated with the trigger time. We expect to have both fully tested and working by early running of SBS experiments. In the case of SBS, since the occupancy is very high, the zero suppression is not very useful; while since the background hit rate is very high, the random suppression is very important. For MOLLER I would expect the opposite, with zero suppression being very useful.
    • Total GEM channel counts
      • Tracking GEMS: 28 modules of 1280 channels ==> 36k channels.
      • Pion detector GEMs are not fully defined; David expects there would be 2 modules which would likely have fewer channels than the tracking detectors, so no more than 2.5k channels.
      • Total channel count ==> 38k channels in 300 APV cards read by 20 MPD modules.
    • PREX GEM experience -Chandan docDB683
  • General discussion