thomas.shaffer@LIGO.ORG - posted 22:00, Sunday 01 December 2024 - last comment - 14:26, Monday 02 December 2024(81569)
Ops Eve Shift End
TITLE: 12/02 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 142Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: A long relock today from DRMI locking struggles and lock losses at Transition_From_ETMX. Once back up to observing the range hasn't been very stable, hovering between 140-150Mpc. I was waiting for a drop in triple coincidence before trying to tune squeezing, but that didn't happen before the end of my shift. The 15-50Hz area in particular looks especially poor.
LOG:
- Relocking notes
- MICH and PRMI caught no problem, but DRMI would not catch. I tried moving SRM but nothing seemed to work. MICH and SRCL were triggering and flashes looked good. I ended up doing an initial alignment but skipping green alignment since this looked good before.
- DRMI had basically no flashes after initial alignment. Odd. Did MICH and then couldn't lock PRMI. Trying a full initial alignment.
- Flashes better this time, but it still took 4 min to lock. Finally locked DRMI though.
- Lost lock at Transition_From_ETMX
- And again.
- One more lock loss at Transition_From_ETMX. I had it sitting in this state for 5 min while I was looking at the state code, then there was an ASC pitch ringup. I'm not sure which was the worst of the ASCs.
- Another initial alignment. Another struggle for DRMI after PRMI and with seemingly great flashes.
- Bumped SUS-ITMX_L3_LOCK_BIAS_TRAMP to 25 from 30 during the transition to ETMX state, similar to what Sheila did on Nov 22. The hope was to move faster to a safer place and avoid the CHARD P ringup.
Plot of range and glitches attached.
It didn't look like the explicitly squeezing was the issue last night when the range was low as SQZ was stable, sqz plot. The range seemed to correct itself on it's own as we stayed in Observing. If it happens agin, we could have gone to NoSQZ or FIS to check it's not backscatter from SQZ of FC.
Oli and I ran a Bruco during the low range time, bruco website, but Shiela noted that the noise looks un-stationary like scatter so that a bruco isn't the best way of finding the cause.
I ran a range comparison using 50 minutes of data from a time in the middle of the bad range and a time after it stops with good range. Excess noise looks to be mostly below 100 Hz for sensmon, for DARM the inflection point looks to be at 60Hz and there is broadband noise but low frequency again seems larger.
I also checked these same times in my "Misaligned" GUI that compares SUS top mass osems, witness sensors, and OPLEVS avg motion to compare alignments for relocking and to look for drifts. It doesn't look all that useful here, the whole IFO is moving together throughout the lock. I ran it for seperate times within the good range block as well and it look pretty much the same.
As discussed in today's commissioning meeting, if this low range with glitches on Omicron at low frequency happens again, can the operator take SQZ_MANAGER to NO_SQUEEZING for 10 minutes so that we can check this isn't caused by backscatter from something in HAM7/8. Tagging OpsInfo.
Runs of HVeto on this data stretch indicate extremely high correlations between strain glitches and glitches in SQZ FC channels. The strongest correlation was found with H1:SQZ-FC_LSC_DOF2_OUT_DQ.
The full HVeto results can be seen here: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/hveto/day/20241202/1417132818-1417190418/
An example of H1 strain data and the channel highlighted by HVeto can be seen in the following attached plots:
Derek also so kindly ran lasso for that time period (link to lasso run) and the top correlated channel is H1:TCS-ITMX_CO2_ISS_CTRL2_OUT_DQ. Back in May we were seeing correlations between drops in range, FC alignment, and the values in this same TCS channel(78089). Here's a screenshot of the range vs that channel - the TCS channel matches with how it was looking back in May. As stated in that May alog thread, the cable for this channel was and is still unplugged :(