Reports until 17:08, Monday 07 July 2025
H1 ISC
elenna.capote@LIGO.ORG - posted 17:08, Monday 07 July 2025 (85596)
DRMI locking is a struggle- maybe not an alignment issue

Today we've had to run many initial alignments and mess around with mirror alignments to cajol DRMI into locking. In the first part of the day, we were coming back from a big earthquake which had kept us down for hours. I don't know what we can attribute the struggle to lock to, but it can't be related to the BS heating since we had been down for many hours.

Later in the day, we were relocking after a few hours up, and just after the lockloss we proceeded to DRMI locking. The alignment was very poor. The guardian quickly took us to PRMI and then MICH FRINGES because of the very bad alignment. This is perhaps a sign that the BS slow release method isn't working so well, since it should keep the alignment decent just after lockloss. I cleared the history on the BS M1 pitch lock bank, and proceeded to help the MICH FRINGES and PRMI state by hand. Once we got back to DRMI we were able to lock relatively quickly.

I am suggesting that our DRMI locking problems are "maybe not an alignment issue" because this morning after several alignments, DRMI took a very long time to lock, and just after lockloss in the afternoon, where the slow release method should help keep the alignment good, the alignment was very bad. Maybe we should look into the triggers or engagement of the locking to see if there is a problem there. Just based on my experience this afternoon, I would want to turn off the BS slow release, or recheck that it is doing what we want it to do.