Meeting 2024 04 24
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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!
Contents
Commissioning in GEn-RP
- Thursday night, as we moved to H at 25uA, several shorts occurred in SBS [1]
- To our knowledge, the gas mix and the HV set points to the SBS GEMs are the same as always during running. They have new individual channel power supplies. [2]
- The gain in the SBS GEMs appeared to be very high (so either mix is not what we think or HV too high or both).
- Single sector shorted in BB when the gas mixture spiked to 90% on Friday due to empty CO2 and lack of alarms. Alarms and shutoff script are in place and verified now.
- Gas flow to SBS is now set to 70/30 (what we think is 70/30), and HV is reduced and tweaked across G1 to improve the gain. [3][4]
- Offline software thresholds reduced to 3sigma also shows improvement in efficiencies.
- Work done yesterday to decouple (HV) two of the SBS chambers that were previously unable to run. [5]
- Plan in the near future: install a small wire chamber on the SBS gas line to monitor gas, install a photon filter ~ 0.5" Aluminum plate on the SBS side to reduce occupancies.
Known issues
- L3M3L2M1 (G2 &G3) — L3 faces the analyzer, L2 is high..decoupled now and only running L2M1 (L3M3 off)
- L4M0M1 (G2) — faces the analyzer, high ...decoupled now and only running L4M1 (L4M0 off)
- L5M2M3 (G2) - this one is low and possibly accessible, but needs to be slid out
- L6M0M1 (G3) (beamline side) – it’s high and likely hard to reach
- L6M2M3 (G3) — this one is low and possibly accessible, but probably too tight a fit to check anything
- L8M0M1 (G2 & G3) – might be easily checkable from the platform with a stepladder or the one with handrails. This is on the HCAL side. (currently kept off)
- L6M0 gas issue?
Misc for GEn-RP
- Experts on call: [6]