Run Coordinator report: summer 2022 w7

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Run coordinator report: Summer 2022 week 7

During this week we took data on both the full Pb and empty targets. We took 10.3 B events on empty target at 60 nA, and 3.8 B triggers on full Pb target at the nominal production current of 30 nA. Our experimental goal is to attain 20% triggers on empty target, and 80% triggers on full Pb target. The experiment received approval for a 3 week extension.

For the most part accelerator interruptions were short. There were several interruptions due to storms moving through the area, with the biggest interruption being the major storm event on Tuesday night. The average frequency of beam trips was considered low to average.

Very preliminary physics analyses have started. Beni has investigated purely neutral channels, and observed an eta peak in the 3pi0 and 2 gamma decay channels. He has also seen a clean signal for omega production in the gamma pi0 gamma channel. The level of background observed in coherent pi0 photo-production indicates the optimal fraction for empty target triggers is approx. 20%, in agreement with previous estimates based on charged particle target vertex distributions. Andrew analyzed Bethe-Heitler e+e- pairs in the data and observed a azimuthal variation approx. consistent with beam polarization and reaction analyzing power.

Problems with the electronics, DAQ, and detector were relatively minor. The FCAL F250 module replaced last week was still problematic (timing), and a firmware update solved that problem. One of the 8 PMTs on the CTOF detector failed, PMT #3, and should be replaced at the next beam study day. We have seen occasional HV trips of the CDC, most often associated with the start of runs and resolved by cycling the HV card. However, CPP/NPP data taking wasn’t compromised by this problem.