Meeting 2022 10 12

GMn GEM commissioning Meetings: WEDNESDAY 10:30am - 11:30am

Link to all previous meetings: GMn GEM Commissioning Meeting

Please use sbs_gems mailing list for plots/communications and HALOG entries relevant to GEMs!

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Near term work plan

• see the GEM commissioning run plan for GEn-II here: [1] [2]

• Thoughts on special run requests during GEn:
  • Luminosity studies
  • Full readout studies for negative pulse studies
  • HV efficiency scans with beam

Update on BB GEMs

• GEN GEM Update
• Many DAQ issues overnight, see presentation above
• Likely something with INFN LV

Update on layers for GEn-RP

• Alignment/latency/tracking issues
  • SBS GEM latency was incorrectly set at the beginning of the experiment, by using the latency we used for the cosmic paddle trigger - 76
  • The very first day of the GEM commissioning we got more confused as we got some tracks in the SBS GEMs using this latency. Probably this is from background as tracking on the SBS side wasn't done using the calorimeter constraints that time.
  • But when the calorimeter constraints were turned on, we got just only 10's of tracks for like 150K trigger events.
  • Had a discussion with Alex yesterday and we agreed starting around the BB GEM latency (112 now) and scanning around it would be a good place to start. The reasons are:
    • BB and SBS GEMs have the same HDMI cable lengths. SBS INFN GEMs have longer cable lengths but we know how much of an offset they are.
    • BBCal and HCal trigger are well aligned so that the latency component we get from that are similar for BB GEMs and SBS GEMs.
    • TOF difference for between the first GEM layers between BB and SBS is ~9ns. Even less than half latency units so we can take it to be 0.
    • So the only "significant" difference, as we understand, is between the MPD trigger cable length difference in BB and SBS GEMs.
    • Plan is to identify this difference by scoping BB and SBS GEM MPD trigger at the MPD-end today when the Hall reconfiguration is done.
    • BB GEM latency +/- BB and SBS GEM MPD trig time difference => Where the SBS GEM latency should be.
  • The Plan is to start at a latency value of around 100 (12 units less than BB), increase in steps 6, take runs when H2 reference cell is on so we can use elastic e-p scattering where tracking is easy to do, hopefully we will see signals in a few steps. Any comments? Ideas?

• gas

Update monitoring with new GEMs in GEn-RP

• replay times with tracking