camilla.compton@LIGO.ORG - posted 09:26, Tuesday 18 February 2025 - last comment - 10:35, Tuesday 18 February 2025(82877)
MICH, PRCL, SRCL displacments in long vs short locks
The operator team have been finding 11Hz oscillation locklosses. Attached is the spectrum of MICH, PRCL and SRCL from one of our last long (2 day) locks to a more recent 6 hour lock. There is a debatable PRCL bump around 10-11Hz.
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I'm comparing plots that Oli made in this alog to a plot I added to this alog from early O4a where we were having frequent locklosses due to marginal stability in PRCL. The ring up looks very similar and I would guess that we should measure the PRCL OLG and adjust the gain. Just scrolling back the last few days on the summary pages, I don't visually see the excess noise around 11 Hz for a long time before the locklosses, like we saw in O4a, but that doesn't mean much since I could be fooled by the color scale.