Difference between revisions of "Run Coordinator report: Fall 2021 w1"

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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.  
 
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.
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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. The problem with Hall C beam delivery was not resolved and continued to puzzle Ops and CASA. A couple of accesses to the tagger hall were made to address recurring issues with a TAGH board and the tagger magnet NMR but the interventions did not fix these problems. Pre-production data were taken overnight, with the CTOfF removed from the trigger, which allows to run at 100nA on aluminium radiator with high livetime (~98%, 12 kHz DAQ rate). In the morning (Tuesday), the TAGM high voltage scan was finalized and a third CToF high voltage scan (more precisely, high voltage studies) was performed. more pre-production data were taken following that. After the 14h beam down time off Monday, the Program Deputy decided to maximize beam delivery to Hall B and D for Tuesday, and not repeat the studies of the Hall C beam delivery problem. This was to allow Hall B to move to their 5-pass program on Wednesday and Hall D to have stable enough beam to align its diamond. This was done (two directions, 45° and 135° as specified in the runplan) and took slightly more than 8h, which is relatively fast for such task. Preliminary studies of the coherent peak shows a beam polarization peaking above 70%. Ops then did the ion chamber calibration on the diamond. In the evening, the Pb absorber study was conducted until slightly after midnight and we spent the night on pre-production using the aluminum radiator and 60 nA (the current reduced from 100nA because of low livetime). Several DAQ issues occurred during the night with the symptoms being either very low lifetime or widely fluctuating livetime. It was decided to not run on diamond overnight because the collimator was not well aligned yet, which means we may not have had a good photon beam polarization. The beam went down for more than an hour Wednesday morning and an opportunistic access was decided to install steel shielding to see if it would help reduce large background seen in the CToF. Pre-production was them resume for 1h (which allowed us to see the the steel shielding was not successful) and then beam was shut down (7:40am) for a long period to address a RF cavity issue and the Hall C beam delivery problem. The beam came back late Wednesday evening. In Hall, this first week of commissioning was successful despite low beam delivery (mostly due to Hall C high current delivery problem) and not ideal Hall B beam quality. The main issues for us during that time was the large background seen in the new CToF detector. Beside understanding this, the other important items before being ready for production were to establish the Level-1 trigger (only very preliminary trigger was set-up during the week) and align the collimator with the beam, which was prevented due to beam instability coming from either a lock problem or/and the fact that the beam is inherently instable because only Hall B and D are running (no high current beam in the machine to stabilise the orbits).

Revision as of 08:02, 19 June 2022

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. The problem with Hall C beam delivery was not resolved and continued to puzzle Ops and CASA. A couple of accesses to the tagger hall were made to address recurring issues with a TAGH board and the tagger magnet NMR but the interventions did not fix these problems. Pre-production data were taken overnight, with the CTOfF removed from the trigger, which allows to run at 100nA on aluminium radiator with high livetime (~98%, 12 kHz DAQ rate). In the morning (Tuesday), the TAGM high voltage scan was finalized and a third CToF high voltage scan (more precisely, high voltage studies) was performed. more pre-production data were taken following that. After the 14h beam down time off Monday, the Program Deputy decided to maximize beam delivery to Hall B and D for Tuesday, and not repeat the studies of the Hall C beam delivery problem. This was to allow Hall B to move to their 5-pass program on Wednesday and Hall D to have stable enough beam to align its diamond. This was done (two directions, 45° and 135° as specified in the runplan) and took slightly more than 8h, which is relatively fast for such task. Preliminary studies of the coherent peak shows a beam polarization peaking above 70%. Ops then did the ion chamber calibration on the diamond. In the evening, the Pb absorber study was conducted until slightly after midnight and we spent the night on pre-production using the aluminum radiator and 60 nA (the current reduced from 100nA because of low livetime). Several DAQ issues occurred during the night with the symptoms being either very low lifetime or widely fluctuating livetime. It was decided to not run on diamond overnight because the collimator was not well aligned yet, which means we may not have had a good photon beam polarization. The beam went down for more than an hour Wednesday morning and an opportunistic access was decided to install steel shielding to see if it would help reduce large background seen in the CToF. Pre-production was them resume for 1h (which allowed us to see the the steel shielding was not successful) and then beam was shut down (7:40am) for a long period to address a RF cavity issue and the Hall C beam delivery problem. The beam came back late Wednesday evening. In Hall, this first week of commissioning was successful despite low beam delivery (mostly due to Hall C high current delivery problem) and not ideal Hall B beam quality. The main issues for us during that time was the large background seen in the new CToF detector. Beside understanding this, the other important items before being ready for production were to establish the Level-1 trigger (only very preliminary trigger was set-up during the week) and align the collimator with the beam, which was prevented due to beam instability coming from either a lock problem or/and the fact that the beam is inherently instable because only Hall B and D are running (no high current beam in the machine to stabilise the orbits).