Difference between revisions of "Run Coordinator report:2025run w9"
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We continue to have difficulty obtaining a consistent picture of how well the electron beam optics at the radiator are matched to the aperture of the primary collimator, based on harp scans. This is an ongoing development, in collaboration with our Accelerator Liaison Edy Nissan and other machine experts. A systematic investigation is underway. Repeated harp scans taken days apart show that the convergence properties are changing considerably with time. The collimator transmission factor, as measured by Alexandre using a variety of coincidence rates taken downstream of the collimator, shows a corresponding variability at the level of 10-15% over the same period. Over the longer term, it is important for the experiment to improve our ability to measure and control these degrees of freedom. | We continue to have difficulty obtaining a consistent picture of how well the electron beam optics at the radiator are matched to the aperture of the primary collimator, based on harp scans. This is an ongoing development, in collaboration with our Accelerator Liaison Edy Nissan and other machine experts. A systematic investigation is underway. Repeated harp scans taken days apart show that the convergence properties are changing considerably with time. The collimator transmission factor, as measured by Alexandre using a variety of coincidence rates taken downstream of the collimator, shows a corresponding variability at the level of 10-15% over the same period. Over the longer term, it is important for the experiment to improve our ability to measure and control these degrees of freedom. | ||
| − | AMO: | + | * AMO: 11.6 hours, 2.3 Gevents |
| − | PARA 0/90 deg: | + | * PARA 0/90 deg: 18.4 hours, 4.3 Gevents |
| − | PERP 0/90 deg: | + | * PERP 0/90 deg: 17.8 hours, 4.2 Gevents |
| − | PARA 45/135 deg: | + | * PARA 45/135 deg: 20.6 hours, 5.2 Gevents |
| − | PERP 45/135 deg: | + | * PERP 45/135 deg: 20.1 hours, 4.9 Gevents |
Latest revision as of 20:15, 28 May 2025
The goal for week 9 was to continue taking production data.
When MCC tried to establish beam after the maintenance period, there was an over-temperature alarm in one of the ARC 10 magnets that prevented beam delivery to Hall D. Thursday was spent flushing this magnet, and by the end of the day the over-temperature condition was resolved. But then when MCC tried to restore beam, over-temperature faults several other of the even-numbered arc magnets. On Friday they were able to trace the problem down to a cooling water valve that had stayed closed after the work on Thursday was completed. This valve was opened, and around 4:00pm on Friday afternoon, beam first beam was delivered to Hall D since the Wednesday maintenance period. After that, operation was fairly continuous over the long weekend and through Wednesday morning of the following week. A total of 93 hours of beam was delivered, of which 84 hours were used for physics. Of the 9 lost hours, 6 of them were taken in planned radiator changes and stopping/starting runs, and 3 of them were due to DAQ problems (hanging daq at run stops and starts, and sometimes in the middle).
Included in the 84 hours of useful beam are two periods (2hr + 2hr) where regular data taking was interrupted to allow Sasha to carry out trigger studies. In these studies, he explored the dependence of the new FCAL+ECAL trigger rate on the size of the masked zone around the beam hole in the ECAL, and on the thresholds on the non-masked region of the ECAL and the FCAL that are used in the main physics trigger. These data will be part of a larger optimization of the physics trigger, which also looks at the preliminary acceptance for select final states, as tracking and calorimeter calibrations converge.
We continue to have difficulty obtaining a consistent picture of how well the electron beam optics at the radiator are matched to the aperture of the primary collimator, based on harp scans. This is an ongoing development, in collaboration with our Accelerator Liaison Edy Nissan and other machine experts. A systematic investigation is underway. Repeated harp scans taken days apart show that the convergence properties are changing considerably with time. The collimator transmission factor, as measured by Alexandre using a variety of coincidence rates taken downstream of the collimator, shows a corresponding variability at the level of 10-15% over the same period. Over the longer term, it is important for the experiment to improve our ability to measure and control these degrees of freedom.
- AMO: 11.6 hours, 2.3 Gevents
- PARA 0/90 deg: 18.4 hours, 4.3 Gevents
- PERP 0/90 deg: 17.8 hours, 4.2 Gevents
- PARA 45/135 deg: 20.6 hours, 5.2 Gevents
- PERP 45/135 deg: 20.1 hours, 4.9 Gevents
