The goal of the shift was to try to improve the mismatch between the cavities acting on the NI DASes powers.
After the work on DRMI locking with the CHRoCC on (56646) and a first attempt to tune PR CHRoCC at CITF (56648), Francesco performed a cavity scan around 18.40 UTC and after that, the NI DAS outer ring power was changed by around 200 mW, going from 1.8 W to 2 W (around 10% variation).
Francesco performed some other cavities scan during the thermal transient and one last at the end of the shift. A summary of the results is in table 1.
| Morning shift (56644) | 18.40 UTC | 19.57 UTC | 20.30 UTC | 20.50 UTC | |
| NI DAS IN | 0.075 W | 0.075 W | 0.075 W | 0.075 W | 0.075 W |
| NI DAS OUT | 1.8 W | 1.8 W | 2.0 W | 2.0 W | 2.0 W |
| W arm mismatch | 1.5 % | 1.4 % | 1.3 % | 1.5 % | 1.4 % |
| N arm mismatch | 1.7 % | 1.9 % | 1.9 % | 1.9 % | 1.9 % |
At the end of the shift no more time was left to further investigate the effect of NI DASes power changes on cavities mismatch; since no significant change has been observed in arm’s mismatching values, we decided to leave the last NI DAS powers:
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NI DAS IN = 0.075 W
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NI DAS OUT = 2.0 W
The activity will continue in the next shift.
We asked, if it is possible, to perform one last cavities scan tomorrow morning, before morning’s shift activities start.
The ITF was left locked on IR.