Run Coordinator report: winter 2023 w7

The plan for the week was to continue physics production at 300 nA on the diamond and aluminum radiators. The week had a rough start, with no beam for much of Wednesday 2/22 and on Thursday at about 9:40 pm the Hall-D dipole (which directs the electron beam into the tagger hall) tripped off due to over-temperature. Recovery did not take place until the following morning. A back-flush to remove some debris was required to bring this back on line. Hall D was down the entire day on Friday. During the extended down time a new Compton Calorimeter assembly was installed in the hall. Beam was restored to Hall D early Saturday morning but the coherent edge could not be seen on the tagger microscope channels, which prompted a realignment of the diamond. Smooth running (finally) took place over the weekend, only to be interrupted on Monday when the south linac dropped to restricted access twice. Overall we saw about 82 hours of CW beam and an ABU of 75.4 hours out of 168 scheduled hours. We estimate that we have only completed about 50% of the program so far but have expended about ¾ of the running time. We lost about 10 hours during the week: significant sources of down time included the usual overhead of starting and stopping runs and changing the goniometer orientation. Some time was spent addressing FCAL base lockups and understanding the scaler distribution in the tagger microscope. Other issues not causing down time include the NMR probe for the tagger magnet failing to work and hot pixels showing up in the DIRC.

The coherent edge spectrum in the microscope has been degrading over time since the beginning of the run. In order to try to understand this we took special runs on Tuesday evening with individual rows turned on in the tagger microscope. With only row 4 turned on the spectrum looks similar to the expected coherent bremsstrahlung distribution. The position of the beam on the microscope had been moved before the beginning of the run to fall onto row 4 because row 3 has accumulated radiation damage over the years. At the end of the week only rows 4 and 5 out of 5 were enabled in the microscope.