Run Coordinator report: Fall 2021 w1

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My RC tenured covered the beam restoration and first week of physics beam delivery. In summary, it was a relatively successful week given that it consisted of commissioning done with accelerator operation still trying to establish physics beam to Halls B, C and D. Beam became available nearly on time and at the end of my RC tenure, we were well along in commissioning, with beam quality checkout mostly done, detector/beamline calibration/checkout done, the new detectors commissioning ongoing, trigger set-up started and diamond (JD70-103) aligned, with the diamond quality (from the coherent peak shape) appearing to be quite good. There was no important problem on the Hall D side. The major tasks that remained before being ready for data production were understanding the new detectors, in particular the CToF, optimizing the photon flux/polarization, and setting up the level-1 trigger. The more detailed summary follows:

Physics beam delivery was scheduled for Wednesday June 8 2022. The beam came nearly on-time, with Beam Operation Group (Ops) asking us to be ready by 11am-noon for physics beam. We required shifts to be manned starting at noon but beam came the next day (Thursday 9th) around 8am-9am mainly due to problem trying to tune beam to Hall C (Hall B was still open: they started a few days late due work on their polarized target). One significant item was regarding our beam tuning was that one of the quadrupole (MQP5C09) on Hall D line is currently not operable. CASA devised a tune for us that does not use this quad, so we have an unusual beam tuning at the moment. Our program started after Ops did our Ion Chamber calibration. We started by checking our radiation levels checks, which were reasonably good. We then did the radiation levels scans with current (50nA, 75nA, 100nA) and radiator thickness (RL=0, 1E-4 and 3E-4). They show similar behaviors than those of the latest run (Fall 2021), which had some marked differences with those of previous runs. Then, the beam envelope and convergence was checked and found to not be good. Beam transport was refined during Friday night. Although the beam was unavailable for about 10h during the rest of Friday, it was still a productive day: preliminary Level-1 trigger studies were conducted, part of the detector general calibration was done, the ToF and CToF high-voltage scans were done (although it was realized that CToF HV will need to be redone). This was followed by the CDC high-voltage scan done early on Saturday. The beam was unavailable again Saturday morning for 4h. When it came back early afternoon, detector general calibration was finalized, some more work was done on the level-1 trigger and an attempt was made as calibrating the Active collimator and optimizing the photon flux. The later failed however because the beam position locks at the collimator level were not working. Sunday during the night, we took some first pre-production data using the 3E-4 radiation length aluminum foils, and the newly tuned (but still preliminary) L1 trigger. High rates in the CTOF resulted in low DAQ livetime (~50%) even with beam current limited to 60 nA. Sunday morning, the beam was down again for 6h (half of it due to a severe thunderstorm) and we took the opportunity to access the Hall to switch the target from the Pb foil to no-foil target. We ran 2.5h in that condition and, as the beam was down again far an additional 3h, we accessed the Hall again to switch back the target to Pb foil position. When the beam came back in the evening, we performed a few special runs to diagnose some issues seen in the FDC and CToF, redid the high-voltage scan (which again to be redone a third time as understanding this detector turned out to be difficult) and spend the night taking pre-production data on the Pb target. After a 2h beam down time Monday morning, the TAGM high-voltage scan was started but could not be completed because it Ops decided to spend the day for beam study in order to understand why they cannot deliver high current beam to Hall C. Consequently the beam was taken away for 14h and came back only shortly before midnight.