TITLE: 06/30 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
INCOMING OPERATOR: Tony
SHIFT SUMMARY: We've had to relock twice, the second time we struggled a bit with DRMI. We're currently locked at NLN but trying to fix a SQZ SHG PZT issue.
LOG:                                                                                                                                 

• 15:00 UTC dropped Observing to start commissioning
• 15:40 UTC lockloss
  • 16:50 NLN
• 18:23 UTC lockloss
  • 19:26 UTC NLN
  • UTC Observing after some SQZ work
  • 19:55 UTC Hanford monthly safety notification test
  • 20:45 UTC we dropped Observing to fix the SQZ ANG servo
• 20:46 UTC lock loss
  • I was prompted to find YARM by hand
  • 21:28 UTC I did an alignment after 2x of DRMI being able to lock but too misaligned for ASC
  • We still couldn't get DRMI, on the 2nd round of PRMI I tried to manually help PRMI after it locked
    • DRMI still took another 12 minutes after this, with some more small adjustments by me (~45 minutes in total)
  • 23:21 UTC NLN but the SHG can't lock due to a PZT voltage issue (too low)

The h1daqnds0 system stopped accepting connections on its main nds1 port (8088).  We restarted the rts-nds and rts-daqd services around 2:59pm localtime.

There were no log messages or dmesg output.

20:46 UTC lockloss

Jennie W, Sheila, Ryan C, Ibrahim, Corey

Over the last 3 weeks three DARM offstep measurements (where we change the DARM offset to look at the fraction of the light from the differential mode which makes it past the OMC) have been taken.

This is so we can get data points to compare to my model of ARM to OMC mode-matching. These were done at three different CO2 X power levels.

Measurement 1: 2025/06/18 20:44:55 UTC

CO2 central heating on ITMX: 1.698W

CO2 central heating on ITMY: 1.694 W

The test is run with /ligo/gitcommon/labutils/darm_offset_step/auto_darm_offset.py . The data is processed with plot_darm_optical_gain_vs_dcpd_sum.py .

Graphs of the power after the OMC vs. optical gain are in the first plot,  optical gain vs. offset and anti-symmetric port power vs. power out of the omc are in this document.

The average contrast defect is 1.07 mW, the junk light is 679 mW, the transmission of the differential mode light at the AS port by the OMC is 1/1.217 = 82.2%.

Measurement 2: 2025/06/20 15:11:46 UTC

CO2 central heating on ITMX: 1.698 W

CO2 central heating on ITMY: 1.711 W

The test is run with /ligo/gitcommon/labutils/darm_offset_step/auto_darm_offset.py . The data is processed with plot_darm_optical_gain_vs_dcpd_sum.py .

Graphs of the power after the OMC vs. optical gain are in the first plot,  optical gain vs. offset and anti-symmetric port power vs. power out of the omc are in this document.

The avergae contrast defect is 1.03 mW, the junk light is 677 mW, the transmission of the differential mode light at the AS port by the OMC is 1/1.212= 82.5%.

Measurement 3: 2025/06/30 15:06:50 UTC

CO2 central heating on ITMX: 1.698 W

CO2 central heating on ITMY: 1.721 W

The test is run with /ligo/gitcommon/labutils/darm_offset_step/auto_darm_offset.py . The data is processed with plot_darm_optical_gain_vs_dcpd_sum.py .

Graphs of the power after the OMC vs. optical gain are in the first plot,  optical gain vs. offset and anti-symmetric port power vs. power out of the omc are in this document.

The avergae contrast defect is 1.09 mW, the junk light is 694 mW, the transmission of the differential mode light at the AS port by the OMC is 1/1.212= 82.5%.

This is not a very good test for our purposes as I think we want a larger change in mode-matching from thermal tuning to inform our simulations of Arm->OMC mode-mis-match.

Each time we have stepped the CO2Y down (all these darm offset measurements were meant to be repeated after decreasing the CO2 power) for this test (measurement 2 on the 20th June, alog 85238 shows attempt from 23rd June, alog 85335 shows attempt from the 25th June, alog 85429 is measurement 3) we have lost lock, so we might not be able to repeat this measurement with a larger CO2 step.

Over the weekend the ifo range has been slowly degrading due to loss of squeezing, as noted in both Ryan and Ibrahim's shift alogs. 

The attached trend shows the range drfiting with the sqz blrms 3 (centered at 350 Hz).  We could implement servos for the squeezing angle demod phase using the ADF (error signal for this servo shown in purple), or for the OPO temperature, or both.

I stepped the sqz angle demod phase to look at the ADF error signal, using z step -s 30 H1:SQZ-CLF_REFL_RF6_PHASE_DELAYSTEP +111,24 (second attachment) I then adjusted H1:SQZ-ADF_VCXO_PLL_PHASE to get a zero crossing near where the squeezer blrms were low and repeated a smaller demod angle scan, which had the error signal crossing 0 at good squeezing. I edited the guardian to ask it to turn this servo back on, (and changed the setpoint and nominal state).  The servo was osciallting a bit so I reduced the gain from -0.5 to -0.2.  Then servo went in the wrong directon, and we lost lock. 

After relocking the servo worked well, in the early part of the lock when the SQZ ASC is off. 

LLO has done some work on automating the temperature adjustment:

• Script running out of observing: 77278
• OPO temperature dither set up: 75430
• Masayuki original OPO temp set up: 60886

FAMIS 31092

Nothing much to report other than the FSS TPD signal has been dropping over the past week, so Jason plans to do a RefCav alignment tomorrow. PMC REFL has also come down very slightly.

Closes FAMIS#27818, last checked 85024 (I am a week late)

TCSX: 30.5, no water added

TCSY: 10.6, no water added

No leak in water cup

Elenna, Sheila, Oli

I've added thermalization ramping for the PRCL2 gain so that it ramps from 1.0 to 1.9 over the first 75 minutes at max power. The 'unthermalized' (1.0) and 'thermalized' (1.9) values are taken from lscparams in the new dictionary 'prcl2_gain', so any changes to be made in the future to those values should be set in that dictionary, and then the THERMALIZATION guardian reloaded so that it grabs those new values.

This addition is pretty much a copy of the way we ramp the SRCL offset, but for PRCL gain of course..

This change to the THERMALIZATION guardian as well as the dictionary addition to lscparams have been committed to svn as r32157.

We continue to have 13 Hz ringups in the LSC that cause locklosses, so I took at look at what's going on with PRCL (it's the usual culprit). I measured the OLG every few minutes after we reached NLN. I found that PRCL loses a factor of 2 gain over the first 40 minutes of NLN. The current design is set to have PRCL with a UGF of 30 Hz once the gain settles after thermalization. However, this leads to >10 dB gain peaking at the start of the lock. There's overall not a lot of phase in the loop design, and if the gain gets too low this is causing the locklosses.

I looked at the loop design, and reminded myself of Gabriele's intentions with the PRCL redesign, here. His design applied the Dcntrl filter, which means to go back to the old design we only have to disengage this filter. You can see from the design comparison in his alog that the original design has a much broader phase. We might inject more noise by going back to the old design, but I'm not sure that will be an issue, especially if we continue to run the PRCL feedforward.

Turning off the Dcntrl filter gives more phase at high frequency, meaning we can increase the PRCL UGF. I increased the PRCL2 gain to 1.9 and got a UGF of 50 Hz, with about 35 deg phase. If we don't change this gain at all, PRCL will start in the lock with a UGF of 100 Hz and a phase margin of 18 degrees if the digital gain is always set to 1.9. This will then thermalize down to 50 Hz.

I also disengaged the 3.4 Hz resgain filter, because we no longer need to suppress motion at that frequency, and hopefully we'll get back a little more phase at low frequency as well.

Oli is reworking the thermalization guardian to ramp the PRCL2 gain from 1 to 1.9 over the first hour, starting after we reach max power.

I commented out the lines in lownoise_length_control that change the PRCL shape and loop gain.

I checked the PRCL noise injection with the feedforward template, and there slightly more noise injection from 20-30 Hz, but I'm not sure that's a problem.

I updated the SDF for the filter changes, and to unmonitor H1:LSC-PRCL2_GAIN since the guardian will now update that gain.

Plot 1 shows the evolution of PRCL olg with the 30 Hz UGF design, Plot 2 shows the evolution of the loop suppression

Plot 3 and Plot 4 show the OLG and loop suppression respectively with the 50 Hz UGF design

Plot 5 compares a PRCL coupling measurement from last week with today.

1435343011

It will probably register as an IMC lockloss, just wanted to make sure people know it was caused by an injection.

18:23 UTC lockloss alog85433

Mon Jun 30 10:12:57 2025 INFO: Fill completed in 12min 53secs

M. Todd, R. Crouch, E. Capote, S. Dwyer

After 5 minutes or so from stepping the CO2 lasers from 1.7W to 0.9W, we began to see the 13Hz ring-up again before losing lock.

We believe this to be PRCL losing gain because of the change in the CO2s. I'm also wondering if the CO2s may be miscentered and causing some roll modes via differential heating of the fibers -- the frequenices do not exactly match up I think but need to check on this.

15:40 UTC lockloss while we were running the CO2 stepper. alog85429

I ran the DARM offset stepping script using Jennie Wright's instructions from 85136.

Writing data to
/ligo/gitcommon/labutils/darm_offset_step/data/darm_offset_steps_2025_Jun_30_15_06_50_UTC.txt

TITLE: 06/30 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 145Mpc
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 8mph Gusts, 4mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.07 μm/s
QUICK SUMMARY:

• We've been locked for just udner 19 hours
  • SQZing doesn't look the best, particularly at high frequency
• Low wind, secondary microseism is starting to creep up a little
• PI24 rang up 6 times overnight, but was damped
• Commissioning is planned from 15:00 - 19:00 UTC today

FRS34130

Upgrading Pylon on h1digivideo[4,5,6] has fixed the problem whereby camera processes continued to open files until they eventually reached the OS num_files limit and the camera crashed (new files were opened each time connection to the camera was restored, old files were not cleaned up).

Since the upgrade Tuesday 24 June 2025 the number of files open per process has remained static. Details in FRS, this ticket has been closed.

Oli, Elenna

Oli and I combed through some of the recent locklosses by hand, and noticed that there are at least two that have a 13 Hz oscillation in the LSC channels just before the lockloss.

1434317297

1434276630

This is reminiscent to us of PRCL losing gain due to thermalization which has caused 11 Hz ring ups before. We should keep an eye out. Note that one of the above locklosses has the "earthquake" tag, but it's very clear that the ring up caused the lockloss.

Oli and I went back about 1 week and checked the NLN locklosses by eye and only found these two so far.

To start, we can periodically check PRCL OLG or other LSC OLGs during thermalization to make sure we aren't losing significant optical gain. Or we can inject a line during commissioning.