TITLE: 05/24 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Lock Acquisition
SHIFT SUMMARY:
Lock#1
Couldn't lock PRMI, lockloss
Lock#2
Went right into an initial alignement, OM1 & OM2 were saturated during PRC in initial alignment
DRMI's lock didn't seem great on the buildups but the spot looked ok
OMC locked first try on its own
NLN @ 08:44, 30 ASC SDF diffs but they were all for the camera servos, I waited for ADS to converge for the camera servos to turn on (~ 16mins) which cleared these diffs
Observing mode @ 09:02 while we thermalize
Out of observing at 11:05UTC for a new FF filter test/measurement and then a calibration suite, new FF filter applied at 11:07UTC
I used Coreys template (/ligo/home/corey.gray/Templates/dtt/DARM_05232023.xml) which I had to enable "read data from tape" for it to run. Measurement started at 11:10UTC, finished at 11:12UTC. My DTT session then immediately glitched and crashed before I could save it, great... I restarted the measurement at 11:15UTC, finished at 11:16UTC. It wouldn't let me save it (error: Unable to open output file), but I added it as ref 27 on the previously mentioned xml file in Coreys directory but this might have not saved from that issue. I grabbed a screenshot of it.
I switched back to the old filters to take the calibration suite at 11:21UTC, I wasn't sure if we wanted them on or not for this, apologies if we did want them on.
Lockloss @ 11:25, possibly from PI29, but on NUC25s scope guardian appeared to be successfully damping it? It was tapering down when when the DCPDs saturated and we lost lock, it also coincided with a ground motion spike from that 5.5 from NZ. I then stepped down the EX ring heaters to 1.2 using the console commands Sheila provided in her alog.
Lock#3:
Yarms power was drastically lower after the lockloss and looked clipped on the camera, increase flashes ran twice and wasn't able to get it above 50%, I stepped in and still wasn't able to even get it to 80%. I gave guardian another shot after this and increase flashes ran another 2 times and was not able to get it, I tried again to lock it and was unsuccesful. Lockloss at LOCKING_ALS after some more rounds of adjusting and trying to lock.
Lock#4-11
ALS locklosses
Lock#12
Beatnotes aren't great, -19 & -20, I'm starting another initial alignment. Lots of SRM saturations during SRC align, trending SRMs OSEMs there doesn't appear to be any unusual motion in the past 20 hours.
After a suggestion from Betsy and Jenne, I check PR3 and it seem to have drifted a bit, I moved PR3 in yaw 0.8 microradians negatively which increased the COMM beatnote. I was able to lock ALS after this but got no flashes on PRMI so I started another initial alignment but it didn't do the SRC align correctly again, TJs going back to try and fix this.
Handing off to TJ
LOG:
| Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
|---|---|---|---|---|---|---|
| 14:23 | FAC | Betsy | FCES | N | Closeout checks | 14:38 |
| 14:56 | EE | Ken | Carpenter shop | N | 15:56 |
I've attached a screenshot of the DARM spectrum and coherences with MICH and SRCL during the feedforward test. This was done 2.5 hours after power up, the second attached screenshot shows where we were on the thermalization transient.
It seems that the MICH FF is worse, while SRCL is better, similar to the test done at the start of a lock here: 69813
If anyone wants to use this template for a future feedforward check, they can find it at /ligo/home/sheila.dwyer/LSC/DARM_FOM_LSC_FF_check.xml
I think this recent attempt at 80 kHz PI damping, which was our first try with this Monday's guardian changes 69800, might have been somewhat successful?
From the screenshot, the DTT shows that when 80 kHz PI damping started, the HOM's were in the same place as that has recently caused locklosses, (comapre the pink/blue vs. black trace). And we see its aliased down 14.76 kHz peak, which visibily shifts down by a few Hz over several averages. Maybe this is a result of our PI damping; we've seen the mode move around before from driving it (68165). And playing the DTT forward in time, you can see the PI doesn't run away like it normally does. It seems likely to me that the 80 kHz didn't cause this lockloss.
From the ndscopes in the screenshot: the first scope shows a recent 80 kHz PI lockloss from Monday, where after the guardian starts damping, the mode's RMS grows ~1e4 in 5 minutes. Then Wednesday, from when the guardian first starts damping, the mode only grew x100 in ~8 minutes! Between Mon/Weds, we started damping with a stonger PI ESD drive in the guardian 69800 (10x DAMP_GAIN, from 5000 --> 50,000), still driving coils differentially (has been like this after 69759).
The ALS issues reported in this aLOG were symptomatic of the true problem: the HAM-ISIs were all drifting off in Yaw (RZ) slowly, but surely, for weeks -- see LHO:69934.
Tagging CAL. It's not super explicit, but this is the aLOG when the ETMX (EX) ring heater power was reduced from 1.3 W to 1.2 W on both segments. It has been later revealed that this has increased the lever of 1064 nm main laser power in the arm cavities, from ~435 kW thermalized to ~440 kW thermalized LHO:70042. This may have changed the optical gain, cavity pole frequency, and the SRCL cavity detuning. The first two should be measured and correct for via the TDCF system, but we should confirm. We should measure more sensing functions and/or turn on the CAL_AWG_LINES low frequency calibration lines to confirm if anything's changes the the SRC detuning.