Run Meeting: Feb 25th, 2019

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3:30PM Run Meeting, Counting house meeting room (200C)

RC: Cameron Clarke

Status

Control access to fix LHRS Dipole Quench

• After recovering from a spontaneous (no clear cause) RQ2 quench, 2.5 hours later we got another spontaneous L Dipole quench
• The hall will go into controlled access and Jack will diagnose the LHRS Dipole in the morning when he arrives
• After recovering the LHRS Dipole we will return to 50uA running, depending on the status of PQB studies during Monday Day shift

Experiment Updates

• Deadtime from Trigger Supervisor fluctuates a lot and seems to grow during a CODA run: https://logbooks.jlab.org/entry/3658989
• Bob Michaels adjusted the coincidence timing window by shortening T5 and T2 triggers: https://logbooks.jlab.org/entry/3659062, https://logbooks.jlab.org/entry/3659071
  • 10 uA, we see a large increase in relative "good" T6s vs. total including accidentals, but this may just be because we were at 10 uA where accidentals are rarer: https://logbooks.jlab.org/entry/3659071
  • We don't see the expected reduction in T6 scaler rate: https://logbooks.jlab.org/entry/3659238, https://logbooks.jlab.org/entry/3659266
  • A number of plots will need adjusted now that the data looks different (starting in run 4348), so time should be allocated to paying attention to plots, old and new, during the daily meeting: https://logbooks.jlab.org/entry/3659137
• Sci Fi testing (many more log entries precede this one): https://logbooks.jlab.org/entry/3659086
  • This was simultaneous with DAQ timing change, see log entry summarizing both sets of extra activities here: https://logbooks.jlab.org/entry/3659117
  • An access was taken to reboot the raspberry pi connected to the motion control system. Possible causes of network failure are internal clock issues, or possibly a bad serial connection to the motion controller: https://logbooks.jlab.org/entry/3659121#comment-20384
• RQ2 magnet quenched (summary https://logbooks.jlab.org/entry/3659232): https://logbooks.jlab.org/entry/3659148
  • Lost a few hours while working with Matt and Jessie to bring the magnet back with some considerable effort: https://logbooks.jlab.org/entry/3659207
  • Jessie's note that the magnet should be treated carefully: https://logbooks.jlab.org/entry/3659218
  • After coming back up the regulator is still not hitting the exact set point, see achieved current readback here: https://logbooks.jlab.org/entry/3659223
• L Dipole quenched at 3:30 AM (after 2.5 hours of good production during Owl, after a couple of hours of good production during Swing surrounded by sci fi, magnet trips, and DAQ tuning accesses): https://logbooks.jlab.org/entry/3659238
  • Mode of failure not clear: https://logbooks.jlab.org/entry/3659291
  • Hall A will go up to controlled access and Jack will repair this magnet (and probably look at a number of other magnets as well): https://logbooks.jlab.org/entry/3659292
• Hall A controlled access after PQB beam studies was successfully able to work on the DAQ and bring back the LHRS Dipole:
  • Dipole: https://logbooks.jlab.org/entry/3659482
  • DAQ: https://logbooks.jlab.org/entry/3659475

Plan for Monday - Achieved

• Attempt to bring the LHRS Dipole back online as fast as possible to take advantage of beautiful 50uA running
• Continue production data on Tungsten 2.8% target at 50uA, and move higher if possible.
• Possibly (though still under discussion) take data during Monday Beam Studies Day shift if it takes place. Parity Quality Beam studies would be performed during Day shift and should not affect heavily the quantity or quality of beam delivered to the tungsten foil target.
• Investigate changes to the DAQ timing and T6 signal
  • Bob looked into it, found one questionable cable, and we added a new independent copy of T6 to a new scaler and to the 3rd channel of the digital oscilloscope

Plan for Monday - swing plan

• Production data on Tungsten 2.8% foil target at 50 uA current
• Investigate DAQ and data:
  • I think the issue with extra T6 triggers in the data may likely stem from a persistent FADC timing cut
  • Or of course this could be my fault in analysis and stem from inadequate understanding of the data analysis cuts used in the plots in question
  • These are both issues for qualified experts to investigate
• Keep investigating the data and perform more robust analysis to make plots more useful and clear up concerns
• Develop a set of contingencies and data collection plan for using high quality 50uA beam
  • We need to avoid doing anything non-trivial outside of regular business hours
  • We need to develop a very clear set of goals along with a contingency flow chart for the experiment data collection so that the RC and shift crew to know how to respond to non-ideal conditions in an efficient manner

Slides/Links

MCC scheduling Whiteboard: http://accboard.acc.jlab.org/

APEX wiki page: https://hallaweb.jlab.org/wiki/index.php/APEX

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