aLIGO LHO Logbook

H1 General

oli.patane@LIGO.ORG - posted 00:38, Sunday 14 January 2024 - last comment - 09:36, Tuesday 16 January 2024(75382)

Ops EVE Shift End

TITLE: 01/14 Eve Shift: 00:00-08:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Lock Acquisition
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY: Struggling with violins and relocking all day, but we were able to reach NOMINAL_LOW_NOISE twice, but lost lock the first time before we could go into Observing (75381). Currently in NLN and Vicky and Daniel are working on getting the SQZ angle to behave because it keeps trying to move towards 0.

Violin modes to keep an eye on: ITMY05/06, ITMY08, ETMY01, ETMY20 (Rahul's alog with some values that work: 75378)

LOG:

00:00UTC Detector Relocking and in MAX_POWER trying to damp violins

03:24 Continuing up towards NLN

03:36 Reached OMC_WHITENING
04:48 Went into NOMINAL_LOW_NOISE
05:10 Lockloss from NOMINAL_LOW_NOISE (Not Observing) (75381)
05:30 Lockloss from LOCKING_ALS
05:41 Lockloss from CHECK_MICH_FRINGES, starting an Initial Alignment
06:10 Initial Alignment completed, relocking

06:56 Reached MAX_POWER, pausing to damp violins
07:42 Reached NOMINAL_LOW_NOISE
- Had to realign FC2 (72084)

08:11 OBSERVING!
08:15 Dropped out of Observing to troubleshoot SQZ Angle issue

Comments related to this report

victoriaa.xu@LIGO.ORG - 01:10, Sunday 14 January 2024 (75384)SQZ

Link

Some SQZ troubleshooting notes:

FC locking issues. With SQZ_FC guardian paused, Oli tweaked FC2 P/Y alignment such that H1:FC_TRANS_C_LF_OUTPUT > 80. 80 is the fc guardian's green-transmission lock threshold, and is set in sqzparams.py. Initially FC2 was misaligned enough that guardian never registered as "green locked", so it would drop lock and restart, and got stuck in this loop. Oli paused SQZ_FC guardian, tweaked FC2 P/Y alignment, unpaused guardian, re-requested FDS, and it worked.
SQZ Angle guardian not stable at first, see screenshot -- ADF SQZ angle servo would rail the sqz angle and send CLF DEMOD PHASE to 0. Unsure if, for a cold IFO, an ADF demod phase of 80 is unstable but maybe becomes optimal later?
Daniel and I reset the H1:SQZ-ADF_OMC_TRANS_PHASE demod phase from 80 to 95, and accepted 95 in SDF. This seems within range of recent adf demod phases used in observing. 95 was stable with high range, so we're going with it, though we don't know if it is totally optimal.

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ryan.short@LIGO.ORG - 01:07, Sunday 14 January 2024 (75385)

Link

H1 is now back to observing at 156Mpc following the SQZ troubleshooting described above as of 08:48 UTC.

camilla.compton@LIGO.ORG - 09:36, Tuesday 16 January 2024 (75422)SQZ

Link

There is notes on getting FC to lock in the Troubleshooting SQZ wiki. There were lots of LVEA temperature swings this weekend, probably causing trouble in FC alignment.

I'm unsure why H1:SQZ-ADF_OMC_TRANS_PHASE would become unstable when it previously worked for 6+ locks, plot. We could again look at moving the position of the ADF line, but couldn't get the servo stable in 75250.

The first unstable incident was from SQZ_ANG_ADJUST adjusting the angle from 170 to 115deg before the FC had locked, plot. SQZ_MANAGER shouldn't request SQZ_ANG_ADJUST to ADJUST_SQZ_ANG_ADF until it's in FDS and the FC is locked at LOCKED_IR, however at 2024-01-14 07:48:01 UTC it was requested, when SQZ_MANGER was still in SQZ_READY_IFO. This looks like someone requested it so wouldn't happen by itself.

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