Displaying report 1-1 of 1.
Reports until 10:49, Wednesday 28 May 2025
H1 SUS
jeffrey.kissel@LIGO.ORG - posted 10:49, Wednesday 28 May 2025 - last comment - 11:05, Wednesday 28 May 2025(84622)
This Morning's Beam Splitter Excursion; Glitches and ISC Excursion
J. Kissel, S. Dwyer, others

Just so others can see what we're seeing, here's the glitch at 2025-05-28 15:36 UTC that drove us to swap the F1/F2/F3/LF Triple Top coil driver on the H1SUSBS. 

Everything's wrapped in loops, so it's difficult to point fingers at any one component.
ISI is in FULLY_ISOLATED_NO_ST2_BOOST per normal for MICH lock acquisition
SUS has 
    - M1 OSEM PD to M1 OSEM Coil damping loops ON (L, T, V, R, P, Y)
    - M3 Oplev QPD to M2 OSEM Coil damping loops ON (P and Y)
The IFO was attempting to lock PRX.
This is unexpected, but apparently there's also some slow ISC loop that is really causing the majority of the alignment excursion.

Will keep investigating other times to see if this is a consistent issue. 
We've looked at a few other times where we suspect optical lever glitching, but the same ISC loops were not on.
Difficult to trend the configuration of the ISC loops at the moment, 'cause folks are trying lots of different configurations to get DRMI relocked.

We'll post if we find an answer.

We swapped the coil driver because the "glitch" showed up "most" in the F1 sensor, and we feared it was something like we've seen in the past -- SR3 top mass coil driver failures that took us a long time to find (see LHO:62038 and LHO:62123).
Images attached to this report
Comments related to this report
filiberto.clara@LIGO.ORG - 11:05, Wednesday 28 May 2025 (84624)

Chassis Removed: S1100194
Chassis Installed: S1001086

Displaying report 1-1 of 1.