Run Coordinator report: Spring 2018 r10 11
Run coordinator report, March 14th-March 28th. A. Deur
I was run coordinator during the March 14th-March 28th except for the 24th-25th when David Lawrence took over for the week-end.
There was no useful beam during this period, including on Sunday March 25th when a few instances of unacceptable beam was delivered. Aside for the fact that the beam would have been delivered on an opportunistic basis, the main issues were: The replacement of the CHL-1 transformers; Two RF separator vacuum problems (around 20th and on the 25th); A 2K cold box trip; A fire alarm in south linac; Difficulty to tune beam to an acceptable convergence once it was restored.
The details are as follow:
On March 4th, accelerator was still down due to the replacement of the CHL-1 transformers. MCC planned that beam restoration may start on Monday March 21st, with beam to Hall D around the 23rd. Then, the plan was that accelerator would investigate for up to a week the high beam current problem they had before the transformer failure. Although this was the priority, we were told we may potentially get usable beam in the Halls. Earlier on, an extension of the run past March 23rd was discussed, with a run possibly up to Apr. 16th.
Consequently, we started manning the shifts with local collaborators on March 22nd and extended the shift and RC schedules to Apr. 16th. However, a vacuum problem in the RF separator and a demanding focus on fixing the high beam current problem eventually delayed beam delivery to Hall D to Sunday night (March 25th). Anticipating beam in the Hall sometime on Friday March 23rd, we had ramped up on Friday the solenoid to 1350A, cooled the LH2 target, ramped up the other beamline magnets and prepared the beamline for beam delivery.
Although the RF separator vacuum problem seemed to have been fixed on March 22nd, it re-appeared on the 25th after a few hours of attempts to deliver acceptable beam to the Hall. (It was a struggle to do so because the usual tools that the operators use to improved the beam convergence did not help, although the MCC Hall D liaison M. McCaugh was in command).
At that point, accelerator stopped attempting to deliver beam to Hall D and switched to magnetic separation in order to continue its high current studies while delivering useful beam to Halls A, B and C. By the last day of my RC duty, Wed. 28th, the vacuum leak had been apparently sealed and accelerator was assessing the vacuum quality before attempting to restart the RF separator. A fire alarm in the south linac on the 27th and a 2K cold box trip on the 28th (impacting again the south linac) delayed the start of the Hall D beam recovery.
