Run Coordinator report: Spring 2020 w7
The week started off with an unwelcome surprise with a trip of the superconducting solenoid power supply that occurred at 2:30 on Wednesday afternoon. The original cause of the trip was determined to be an over-temperature on one of the components inside the power supply cabinet. The PS chilled water loop was flushed with an acid solution to clear any blockage by scale, and external ventilation was added. That was thought to be sufficient to keep the power supply running until the summer shutdown, when a more permanent solution will be found. Once this was fixed, another problem cropped up related to communications between the power supply and the PLC. This was solved by swapping out the controller card. After 48 hours, the solenoid current was ramped up again, and production data taking started again before midnight on Friday.
During the current ramp-up on Friday, we attempted to insert a fresh diamond radiator JD70-106 for a planned test of accidentals subtraction at high current (2000 nA). This attempt failed when we were unable to find the coherent edge in with this diamond in any of its alignment settings. This was later tracked down, with the help of Hovanes, to a bad set of goniometer settings in EPICS. Meanwhile production continued over the weekend at the new operating current of 350nA on diamond JD70-105. The collimator transmission is observed to be dropping by 10-20% during periods of a few hours, spaced several days apart. This seems to be something new that just started happening during the 2020 run period. Investigation into the cause of this is ongoing. A test of the fast raster was performed on Sunday night, in hopes that this might provide some additional insight into the transmission issue. Those data have yet to be analyzed.
Tuesday afternoon during an opportunistic access, a potentially serious incident took place that resulted in a steel alignment marker was caught in the magnetic field of the solenoid and sucked into the upstream end of the barrel calorimeter. It turned out that no permanent damage was done to the BCAL readout, and additional safety measures were put in place to prevent this from happening again.
In spite of these unexpected interruptions, we still had a productive week of running with 60 hours of acceptable beam used, with a total of 15 billion events and 72 physics production runs.
