Meeting 2021 10 27

GMn GEM commissioning Meetings: WEDNESDAY 10:00am - 11:00am

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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Update on BB GEMs(Sean, Ezekiel, Holly, Anu)

• GEM Alignmnet - Sean
• UV replacement layer is in INFN test lab on nitrogen. HV has been tested. Unclear when we will install (depends on Jessie for support). Resistor replaced photo
• Current BB/SBS experiment status: https://logbooks.jlab.org/entry/3932961
• Resistor changed out on UV layer 0 https://logbooks.jlab.org/entry/3930452
• 10uA on deuterium in last SBS kinematics (highest currents/occupancies so far): https://logbooks.jlab.org/entry/3931870
• BB GEMs currently back on nitrogen while Hall A work is ongoing https://logbooks.jlab.org/entry/3932943
• GEM HV supplies disconnected yesterday for Hall A work https://logbooks.jlab.org/entry/3932945
• BB GEM gas switches ok now. Still plan to calibrate the mixing unit in the future with Jack, but probably lower priority than the Hall A issues.
• INFN trip limits https://logbooks.jlab.org/entry/3931889
• Currents and set voltages in the EPICS archiver as of Monday https://logbooks.jlab.org/entry/3932174. This was always reported as a snapshot in the HALOG with the BB EPICS start of run entries.
• Replay plots post to logbook automagically. Example here: https://logbooks.jlab.org/entry/3932008
• MPD 23 (INFN J2 bottom APV backplane) misbehaves with beam and crashes CODA after some number of events. Consistent problem since beam. Not a problem with cosmics.
• J0 commmon mode drifts sometimes and seems correlated with the LV cable not being held securely (vertically) in connector. Weight of cable over time pulls it down some.
• GEM Current Study with beam at SBS-1 and SBS-4 configurations- SBS-1 LH2 SBS-4 LH2 SBS-4 LD2