Elenna Capote, Camilla Compton, Sheila Dwyer, Derek Davis

This afternoon we had a repeat of the bad low frequency noise that we have been suspecting was from filter cavity backscatter 86596.  We saw that the symptom of elevated noise in the filter cavity error signal was similar to previous incidents plot. 

We compared squeezing with and without the filter cavity, and no squeezing, and see that this noise is there when squeezing is injected no matter what the filter cavity state is.  plot and plot with mean sqz and anti squeezing. 

We repeated the fringe wrapping measurements, we saw a higher scattered amplitude when moving ZM5 than last week. (shelf is higher by 10dB). the ZM2 shelf is about the same. plot

We also did some 30 Hz excitations in ZM5 + ZM2, we can see a bilinear coupling of these but the background didn't change during this excitation. plot

Derek and Elenna looked at the glitches in DARM that showed up at the time of the noise.  Derek ran some hveto runs for times with frequency dependent squeezing and frequecy independent squeezing, and saw that filter cavity length signals are a good witness when the filter cavity is locked, when the filter cavity is not locked the giltches stay but aren't witnessed by the FC error signal. 

Camilla found that she could reproduceably make the noise go away by moving the ZM4 +5 PSAMs small amounts.  She moved the PSAMs and adjusted the alignment to get a good level of high frequency squeezing back.  She also tried to do this with alignment only. 

I added bandstop filters to the ETMY top mass damping into FM4 of each degree of freedom. We're trying to prevent the driving of the ETMY roll mode. We have increased the attenuation of the ISC signal on L2, reported here. All ISC signal that makes it to M0 gets filtered through L2. Local damping does not see any bandstop on the top until now.

SDFed in safe and observe.

There was some issue with diag_main with these new filters, adding other SDFs related to resolving that issue.

TITLE: 09/22 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY: Currently in Commissioning due to SQZ filter cavity issues. We've been Locked for almost 7.5 hours. The ETMY Roll mode is still decently high, but it is damping, and it might take multiple days until it's all the way back down.
LOG:
14:30 UTC Observing and have been Locked for 4.5 hours
14:41 Earthquake mode activated
14:41 Out of Observing and ASC Hi Gains turned on for earthquake
14:43 Lockloss
16:05 NOMINAL_LOW_NOISE
    18:40 Observing
    19:55 Out of Observing to fix up SDFs
    20:01 Back into Observing
    21:14 GRB-Short E601590
    22:01 Out of Observing to commission SQZ FC issues

TITLE: 09/22 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Commissioning
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 11mph Gusts, 7mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.28 μm/s 
QUICK SUMMARY:

• We've been locked for 7 hours
• currently comissioning  SQZ

Chris and Eric O. will be isolating the water supply to the VPW/Weld Shop overnight tonight. We believe there is either a new leak or an existing one that has worsened significantly.
As a result, there will be no running water on either end of the VPW building from 3:15pm today until early tomorrow morning. 
If you have any questions please reach out to Eric or me.

Updated: The overnight water isolation will include the Staging Building. No water in this building from now until early tomorrow morning. 

Elenna, Jeff, Oli

After Elenna updated the DHARD phasing (87063), the ETMY roll mode started ringing up. The previous settings we had on it were +30 deg and G = 40. We started testing out different settings to try and damp it, and along the way we changed a few other things.

First, we plotted ASC-AS_{A,B}_RF45_Q_{PIT,YAW} and found that AS 45Q WFS B YAW sees this roll mode better than WFS A YAW, which is what we had it on before, so we swapped to using that sensor in the AS WFS selector on the bounce and roll monitor screen and that has been accepted into sdf.

Then, we saw that the current Bounce & Roll filter in ETMY_L2_LOCK_{P,Y}, EvanBR (FM3), wasn't notching out the ISC control signal as much as we would like, so Elenna and Jeff created a new filter, OliBR (FM1), that filters out more of the control noise to a magnitude better than EvanBR. Here's the magnitude and phase difference between the two - where blue is EvanBR and red is OliBR. The cursor on the magnitude plot is at the frequency that this mode is at, 13.75977 Hz. Note that the phase plot shows different x limits on the frequency, as we wanted to show that we don't lose a lot of phase margin between the old and new filters. We loaded this new filter in for ETMY L2 LOCK P and Y, and swapped over to using this filter module instead of FM3. These changes have been accepted in sdf.

Finally, after lots of testing and installing this new filter, we were able to find damping settings that are working to damp ETMY. The new settings we found that worked to damp ETMY (slowly) is +60 deg, G = -45. We have been able to bump up the gain to G = -100 for a few minutes at a time to get a lot of damping for ETMY, although it also rings up ETMX a bit every time, so we are going between G = -45 and G = -100 to minimize that. We also unmonitored in OBSERVING ETMY_M0_DARM_DAMP_R and ETMY_M0_DARM_DAMP_R_GAIN in order to continue being able to work on damping while in Observing.

Today I rephased the AS WFS 45 segments.

To avoid lockloss, I transitioned the DHARD input matrix to AS WFS 45 A only so I could phase WFS B. Then, I switched DHARD to WFS B and phased WFS A. I switched by using the DHARD blend filters. Set the DHARD_P_B and DHARD_Y_B input matrix values to the desired value, then make sure the DHARD A and B blend filters have the same ramp time. Then, ramp the gain of one blend to zero and the gain of the other to one. I used a similar process here: 85774.

To get the phasing, I drove a DARM line at 255 Hz in DARM2 EXC, after engaging the EBS255 filter in DARM2 FM10. I was able to get good SNR with an excitation of 3000 counts.

I adjusted each segment to reduce the signal in I (red trace) and maximize in Q.  I was able to reduce the line height by between a factor of 2 to a factor of 5 on each segment. The phase changes were between 3-6 degrees on each segment. The light pink and blue traces show the phasing before I started.

This change was SFDed in both safe and observe, shown in attachments below. For some reason, AS A RF45 is in the ASCIMC model but AS B RF45 is in the ASC model.

I attached a comparison of the before and after for each segment. (Note, seg2 on WFS 45A had a strange behavior where it appears the line in Q reduced with the phase change, but that reduction was present before I started changing the phase.)

Link to full report

• Duty cycles (Observing): 0%, 6.23%, 85.64%, 65.05%, 61.33%, 85.86%, 86.28% on the 7 days of the week.
• The range stayed between 145 Mpc and 155 Mpc during most of the observing time. Most brief dips in average range throughout the day appear to correspond to loud glitches (SNR>=10) in the glitchgrams.
• Day-wise short reports:
  • On Monday, IFO was down for corrective maintenance, so there was no data.
  • On Tuesday, IFO was in observing mode for ~ 1.5 hrs. Lockloss was intentional in order to avoid potential harmful locklosses and other issues.
  • On Wednesday, IFO was locked most of the time. H1 SQZ briefly caused the IFO to drop out of Observing in the last one hour. Seismically, there were a couple of EQs which required EQ Mode, but H1 rode right through them.
  • On Thursday, IFO lost lock because of EQ around 15:30 UTC.
  • On Friday, lockloss from Thursday continued. In addition, there were 3 more periods of locklosses throughout the data.
  • On Saturday, there were three locklosses.
  • On Sunday, there was one lockloss.
• The common Hveto channels are the following:
  • H1:ASC-X_TR_B_NSUM_OUT_DQ appears on 3 days - Tuesday (round 2), Thursday (round 3) and Sunday (round 2).
  • H1:ASC-Y_TR_A_NSUM_OUT_DQ appears on 2 days - Friday (round 1) and Saturday (round 1)
• Fscan-Observing: No Fscan on Monday and Tuesday due to absence/lack of data. On Wednesday, the number of lines was close to the alert threshold but still below it. The line count dropped to a minimum on Friday (~ 2420) after which it rose to a maximum on Sunday.

Sheila, Camilla

We had wanted to turn down the CLF launch power to see if ti had any effect on SQZ noise, but couldn't turn down by a factor of 2. Could only reduce from 0.06 to 0.05. We instead we doubled CLF launch from 0.06 to 0.12mW. Note these numbers were when the OPO was unlocked and the CLF launched changed once it was locked.

After changing the settings attached, ran scan_sqz_ang which only changed angle by 2deg. I don't see any extra noise at low frequeuncy. See attached, SQZ was a little worse at high frequency with the higher CLF. Not that the CLF RF6 was noisy, so maybe something was setup incorrectly.

To relock in the nominal settings, I had to realign ZM3 as the FC ASC had moved this away after the test when the SQZ was taken down, unsure why, maybe the way that I changed the ASC settings.

FAMIS 37209, last checked in alog86426

Last month of trends seem to be looking as expected.

FAMIS 31104

In general, things in the PSL are looking good after everything done following the power outage a couple weeks ago. There have been a few incursions in the PSL enclosure over the past week, the most consequential being last Tuesday's FSS path tuneup (alog86972). The biggest difference after that is the reading of the FSS TPD (a gauge of RefCav transmission) is now much lower as a result of recalibrating that PD, so this new reading of ~0.54 V can be considered our new "good" level.

ISS diffracted power has been on the rise for some reason; I'll keep an eye on this and check it when H1 is next out of lock. This could be a result of AMP2 output power having come back up slightly after the last incursion and things settling out.

Overnight we had the ifo drop out of Observing briefly between 2205-09-22 08:23 and 08:27 UTC. This was due to the SQZ PMC PZT running out of range and unlocking. It was able to relock by itself and then get back to FDS

Lockloss at 2025-09-22 14:43 UTC after just over 4.5 hours locked due to earthquake. I took us to ASC Hi Gains once we were passing 700 on peakmon, and it fully transitioned over, but it was still too much movement for the ASC to handle

At the time of starting the calibration suite, we had been locked for 8.5 hours and so were fully thermalized.

Calibration monitor screen

Report (found at /ligo/groups/cal/H1/reports/20250920T183850Z/H1_calibration_report_20250920T183850Z.pdf

Broadband
2025-09-20 18:32:12 - 18:37:23 UTC
/ligo/groups/cal/H1/measurements/PCALY2DARM_BB/PCALY2DARM_BB_20250920T183212Z.xml

Simulines
2025-09-20 18:38:50 - 19:02:14 UTC
/ligo/groups/cal/H1/measurements/DARMOLG_SS/DARMOLG_SS_20250920T183850Z.hdf5
/ligo/groups/cal/H1/measurements/PCALY2DARM_SS/PCALY2DARM_SS_20250920T183850Z.hdf5
/ligo/groups/cal/H1/measurements/SUSETMX_L1_SS/SUSETMX_L1_SS_20250920T183850Z.hdf5
/ligo/groups/cal/H1/measurements/SUSETMX_L2_SS/SUSETMX_L2_SS_20250920T183850Z.hdf5
/ligo/groups/cal/H1/measurements/SUSETMX_L3_SS/SUSETMX_L3_SS_20250920T183850Z.hdf5

Elenna, Ryan S, Sheila

This morning Ryan and Elenna were having difficulty getting DRMI to lock, so we locked PRMI and checked the phase of RELFAIR with the same template/PRM excitation described in 84630.

45 MHz phase changed by 7 degrees, 9MHz phase changed by 5 degrees.  The attached screenshot shows that the phasing of RFL45 did have an impact on the OLG, and improved the phase margin.  In that measurement we also added 25% to the MICH gain. 

We accepted the phases in SDF so they were in effect at our next (quick) DRMI lock, but not the gain change.

When we next locked DRMI, we measured the MICH OLG again, and here it seems that the gain is a bit high.  We haven't changed the gain in the guardian since this seemed to work well, but the third attached screen shot shows the loop gain.

After this we went to DARM to RF, and manually increased the TR_CARM offset to -7.  The REFL power diped to 97% of it's unlocked value while the arm cavity transmission was 24 times the single arm level, so following the plot from 62110 we'd estimate our power recycling gain was between 20 and 30.