Recent Changes and Current Issues

Recent changes

• NEW: when starting a new run after a successful end, do not go from Prestart, but Abort, Download, Prestart, and Go.

• Controlled access to the hall:
  • After 50-60 nA beam current, we ask MCC to stop the beam down, wait for the beacon to stop flashing (15-20 minutes), and then do not need an escort to go in.
  • After 95 nA beam current or a Moller run, the beacon will not stop flashing anytime soon, so we need escorted access, viz the ARM. In that case, we can keep the beam up until the ARM arrives at the counting house.
  • Target change in the hall: In case of questions from MCC about the necessary controlled access, refer to the logbook entry #: 4196113 for the access requirements. We do need escorted access when we had been at >=90nA (on the CuSn target).

• New RICH recovery protocol: see the "Shift Expert" tab the up-to-date information. Avoid unnecessary recoveries.

Current Issues

• Beamline:
  • Especially after the HWP change, check the SLM and FCUP charge asymmetry (Q-Asym on Beamline Overview); the absolute values should be less than 0.1%. If they are out of range, contact the Beamline Expert.
  • The beam position on BPM 2C21A is not essential during production; the beam orbit lock is on BPM 2H01.
  • The Faraday Cup can currently not be used for the beam current measurement as the vacuum is degraded after the ion pump failed.
  • Tagger magnet procedure: If the tagger magnet needs to be turned off, tell the operator to use only the script for degaussing, NEVER do "by hand"! The latter method might/will trip the circuit breaker for the power supply in the hall.

• BMT/FMT/SVT:
  • If new hot channels appear, call the MVT/SVT/MM expert Yuri Gotra (757-541-7539). These channels need to be addressed by the expert.
  • Known Issues:
    • BMT Layer 1 SEC3 is off and mon12 occupancy histograms are empty, different from the current reference run (r18663), https://logbooks.jlab.org/entry/4215690
    • BMT Layer 5 SEC1 and SEC2 are off as and mon12 occupancy histograms are empty

• DAQ:
  • Some ROCs keep printing error messages while functioning properly; please see their list in this logbook entry # 4215299 to avoid unnecessary reboot since the printout in the roc terminal won't change. In case anyone of them gets disconnected, the message will appear in the run control itself!

• RICH:
  • RICH Sector 1 has three missing tiles; this is known, and no action is required from the shift.