RC meeting and Run Plan, Monday December 13th

RC Meeting Information

Run Coordinator: Brian Quinn

Location: Counting House Conference Room

Time: 3:15PM

Remote connection link: https://bluejeans.com/256205934

Toll-Free Number (U.S.& Canada): 1-888-240-2560

Bluejeans Meeting ID: 256 205 934

Upcoming Shift Which Needs Filled

One vacant shift remains until the winter break shutdown:

1. Sat Dec 18th, OWL, TO

Thanks!!! to Thir, Scott, Nathaniel, Maria, Bob, Sean, Albert, and Zeke!!!... and especially Kondo who filled in for Saturday day, at short notice, allowing us to keep running!! ... and to Alexandre for filling two of the final 3 shifts.

Accelerator and Hall Status

• Optics studies Tuesday now scheduled for 9:00-11:30.
  • Requested controlled access.
  • There may be some delay getting sweep, all halls will probably go to controlled.
    • PD suggests we shut off beam to Hall at or before 8:15, and request change to controlled
    • RadCon asks we be ready to shutdown earlier, if they are available.
  • GEM chamber, J2, may be removed from the Hall during the access
    • May have to store somewhere safe, if radioactive (probably table in EEL 126... checking with David Hamlette.

Special runs done

• Friday Day: low current (2 uA) test runs on LD2 with GEM HVs decreased by 50 V, 25 V, and 0V, relative to nominal.
• Friday Swing: SBS-off running 2hr LH2, 3hr LD2 (With SBS-off HV-settings for BBCal)
• Saturday Day: BBCal cosmics 3.2 M events (run 12744)
• Saturday Swing: GRINCH-LED-only runs at 100 Hz with varied HV
• Sunday Day: HCal-LED-only (run 12775)

Unfortunately, the last 3 were made possible by long accelerator-down periods... including one caused by bird-droppings in Richmond!

To be Done During Extended Down Time

(Nothing left, if J2 is removed tomorrow.)

Run Plan

• Finishing cycle 16
  • Continue following cycle pattern and ticking off runs-completed on paper copy at SL desk

(Reviewing the Run List shows that the check-off list has gotten out of phase with the numbering of the cycles. Rather than re-numbering the cycles we've been taking, I annotated the Run List with 'long cycles' (20 M LH2, 80 M LD2) starting with Cycle -3! That's followed by cycles -2, -1, 0 and 1. Using that numbering system, we are now on Cycle 16. There were also 7 'short' cycles (10 M LH2, 40 M LD2). )

Opportunistic Access Requests for Tuesday

• Put network-readable 'scope on trigger signals to quickly identify 70 ns timing shifts. (Alexandre)
• Try changing HV channel for J0 lower module (to see whether lower current is a result of bad read-back) and perhaps check HV divider (if accessible) (Zeke or Holly).
• Remove unused HV card from HV mainframe for hodoscope (Ralph)
• GRINCH (change pulser brightness) (Todd/Maria)
• Maybe, change rpi & SD card in HCal's upper HV mainframe... Probably NOT!! (Sebastian & Ellen)
• Test HCal pulser and make measurements with difference latency (Scott & Sebastian)
• Reboot rpi's for HV mainframes that have been giving trouble (Sebastian)
• Replace Vetroc in slot 6 (Bryan/Alexandre)

Resolved Issues

• Low DAQ rate alarm for hung MPD (End, Reset(twice?), configure, download)
• GRINCH LED pulser now prescaled (PS5=4) to give ~10 Hz
• "MPD NotFound" error:
  • See two-page printout from GEM documentation, on SL desk
  • On page 3, section 3.3 (marked by bracket in the margin) tells how to boot the VTP crate
  • If that doesn't fix it, see the next page for how to boot UVa MPD crate (or call Alexandre or GEM expert on call)

Unresolved Issues

• Hodoscope HV alarms (Ralph and Steve are working on it)
• BBCal HV alarms with CH HV-control showing HV off by more than 50 V while JavaGUI shows it at setpoint
• BBCal HV alarm with JavaGui showing HV at ~500 V
• HCal HV changes (contact Scott or Sebastian to reload the values and make sure everything get's properly loaded)
• Occasional timing shifts of ~70 ns
• GRINCH sync errors (can be ignored)

Subsystem Updates

1. HCal
1. F1 errors (HCal sync errors)... Don't ignore!! End, Reset(twice?), Configure, Download. If that doesn't work, call Alexandre.
2. Correlation plot of HCal ADC time and HCal TDC gives clear sign of 70 ns shift in either ADC or TDC.
3. Binder of good and bad HCal plots for LH2 and LD2 target will be put in CH... if Sebatian can find a binder.
2. BBCal
3. Timing Hodoscope
1. How is progress on identifying right RF pulse???
2. David Hamilton reports Rachel is making progress since discovering left TDC copy of RF signal had a problem.
4. GRINCH
1. HV has been adjusted to give ~10 ns time-over-threshold for single photoelectron
2. Maria is changing HV to gain-match the tubes.
5. GEMS
1. HV was lowered 50 V for test. Efficiency stayed high, but number of tracks dropped ~25% ????
2. Kondo suggests resulting 20% drop of leakage current may increase the gain (because of less sag of last element of divider chain.
3. Kondo opposes increasing beam current to take advantage of decrease in leakage current, if we choose to run with the lower voltage.
4. Diagnosing efficiency would be easier with low current runs (~1-2 uA) on either LH2 or LD2 with low BBcal threshold to give ~3 kHz trigger rate. Done today.
5. Nilanga recommends changing GEM HV with HV turned off, to prevent typo from destroying a GEM.... or set a maximum on the HV control system. (Done for today's test.) It seems to be possible to set channel-by-chanel max magnitude of voltage. This would be an easier solution, but presently the max returns to 6000V if GUI is re-started.
6. J0 top may be usable.
7. Andrew believes it is worthwhile to turn on J0 top. Zeke agrees and will try.
8. J0 bottom may have only a problem with current read-back on HV power supply channel, or problem with HV divider.
6. Beamline
1. Unser has been calibrated with precision-current source
2. BCM calibration w.r.t. Unser can be done with existing data at different beam currents.
3. Bullseye scan using BPM to set beam deflection, and harp to quantify beam deflection calibrates BPM (relative to harp). This is not of obvious use to this experiment.
4. Given that Bullseye scan doesn't calibrate raster, it seems to not be useful for this experiment.
7. Replay analysis
1. Straight-through run of SBS-11 was used to extract GEM alignment info.
2. Andrew's and Holly's results seem to broadly agree.</li.
3. Will re-run optics runs using alignment info.
4. Will look for LH2 elastic events to use them to understand BBCal and HCal responses.