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Reports until 13:43, Tuesday 30 May 2023
H1 ISC (OpsInfo)
thomas.shaffer@LIGO.ORG - posted 13:43, Tuesday 30 May 2023 - last comment - 11:11, Thursday 01 June 2023(70013)
SRY locking thresholds changed

We've been having issues during initial alignment with the ALIGN_IFO node falsely convinced that SRY is locked when SRM is actually very misaligned. This was due to the SRCL trigger turning on too early (see H1:LSC-SRCL_TRIG_MON). Sheila and I looked at the LSC SRCL trig thresholds and decided to bump these up to ON:0.3 OFF:0.2 (last two changes of this - alog54799 and alog63678). I also added a trigger delay of 0.5s since it seems to flash above this threshold even at times that we are very misaligned. This trigger looks at the POP A DC signal, so we aren't sure why the amount of light has changed on this PD. These settings worked for the one time we tried it with a well aligned SRM, so we should keep an eye on it the next few times we do alignments.

This second alog63678 reminds future us that we should recommission SRY to use the AS WFS rather than the REFL WFS. I'll remind future, future us the same thing.

Comments related to this report
camilla.compton@LIGO.ORG - 21:33, Tuesday 30 May 2023 (70029)

Had this issue again. Described with symptoms in alog 70028

thomas.shaffer@LIGO.ORG - 11:11, Thursday 01 June 2023 (70071)

I've bumped the trigger thresholds up a bit more as it still was triggering for very poor alignments. Looking back over the last week or two as a reference I changed enable threshold to 0.35 and the disable at 0.23. During an initial alignment this morning I tried it out by heavily misaligning SRM by ~70urads to check trigger values, then I brought it back. All seemed good. These values are loaded into ALIGN_IFO and committed to the svn.

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