We have evidence that DARM noise in the 10-50 Hz region seems to be modulated by residual motion of DHARD_Y at 2.6 Hz.

At the same time, now DHARD_Y is not limiting DARM by linear coupling above 10 Hz, due to the improved A2L (-30 db)

So there's room to test a new DHARD_Y controller that could give us 2x more suppression at 2.6 Hz, at the price of about 2x more noise above 10 Hz.

Attached a proposed new controller that could be tested to see if DARM stationarity improves.

All pumps are running smoothly. Temps are within operating range.

Mon Jul 24 10:08:00 2023 INFO: Fill completed in 7min 56secs

Travis confirmed a good fill curbside.

FAMIS 19986

Jason's incursion last Tuesday shows clearly on the environmental trends; these settled just fine. There are also noticable changes to some of the amp laser diodes, but overall power output of each amp is relatively the same as what they were before.

Both PMC transmitted and reflected power are lower following the incursion. RefCav transmission is higher and has remained stable.

TITLE: 07/24 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 141Mpc
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 9mph Gusts, 4mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.04 μm/s
QUICK SUMMARY:

Handed a recently-put-to-OBSERVING H1 by RyanC.  Sent Bubba a text regarding RO alarm.  L1 reports logging until about noon-1pm PT.  I also touched base with Dave about nuc34 (he plans to wait to reboot with Erik).  Winds are mostly low (Corner Station is noticeably above the weeds.), and only 77degF outside this morn.

TITLE: 07/24 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 139Mpc
SHIFT SUMMARY:

• Lockloss at 11:40UTC (LL tool failed) 9:14 lock duration, EX then DCPD saturation. Relocking was fully automated aside from pausing at OMC_WHITENING as usual to damp the violins. The violins were worse than the past few locks I've done, over 2.2 million counts.
• 14:14 RO water alarm (Tagging FMCS)
• Livingston's currently down for logging and will be until the early afternoon
• Back to NLN and Observing at 14:48UTC, handing off to Corey

LOG:

No log

Last Saturday, while damping violin modes, I wanted to check if DHARD_Y noise below 7-8 Hz was limited by test mass M0 Y damping, as suspected (71466).

I tried to reduce all test mass M0 Y damping loop gains from -1 to -0.5, but with that gain the peak at about 1 Hz was slowly rising, so I aborted that test.

I then reduced all M0 DAMP_Y loop gains from -1 to -0.7, and this configuration was stable:

• all DAMP_Y_IN signals had comparable noise levels, except for the 1 Hz line that got larger
• all DAMP_Y_OUT signals reduced as expected by 0.7
• DHARD_Y_IN1 also reduced everywhere between 0.4 and 7 Hz.

You can see the reduction in the spectra clearly for the damping loop signals. It's harder to judge how much DHARD_Y improved, so the second plot shows the ratio of all signals when the gains were -0.7 to when they were -1. The reduction is evident and pretty close to the expected factor 0.7.

So in conclusion: DHARD_Y signal below a few Hz is dominated by test mass damping noise.

No clear reason for the lockloss

STATE of H1: Observing at 145Mpc

We've been locked for 8:33, everythings stable.

TITLE: 07/24 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 146Mpc
SHIFT SUMMARY:

23:17 Detector locked for 7:51 and in Observing

00:41 Moved itself out of Observing and into Commissioning, and then immediately lost lock (71635). H1_MANAGER did good with relocking

1:36 Got into OMC_WHITENING

2:25 Moved into NOMINAL_LOW_NOISE

2:26 Got into Observing

3:10 On SEISMON_ALERT bc of incoming earthquake from Tonga

3:52 Back to CALM

4:09:01 Pushed out of Observe and into Commissioning by SDF_DIFF syscssqz but diffs immediately disappeared

4:09:10 I put us back into Observing

7:00 In Observing and Locked for 4:36

Relocking after the lockloss went smoothly and quickly.

ISC_LOCK went through CHECK_VIOLINGS_BEFORE_POWERUP so quickly that Verbals didn't even register it.

Dust in the PSL got up to 440pcf >300nm around 2:40

LOG:

No log

TITLE: 07/24 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 147Mpc
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 22mph Gusts, 14mph 5min avg
    Primary useism: 0.07 μm/s
    Secondary useism: 0.06 μm/s
QUICK SUMMARY:

• Taking over from Oli, 4:35 lock duration so far
• CDS/Vac/Sus/Dust/SEI looks good

Got back into Observing from the lockloss (71635) a bit over an hour ago. Currently on SEISMON_ALERT because of an earthquake from Tonga, but the first part of the R-wave has passed and I think we'll be able to ride it out fine.

Lockloss at 00:41. Detector moved itself out of Observing and into Commissioning, and then immediately lost lock. Cause not yet known.

STATE of H1: Observing at 146Mpc

We've been locked for 9:20, no issues aside from another MY low temperature alarm.

Briefly dropped from Observing from 08:18:42 to 08:18:59 from an unknown issue, whatever SDF diff or grd node issue resolved itself before I could open the medms.

Earlier today I did some 2.6 Hz sine injection in DHARD_Y (71590) to understand the upconversion phenomenon seen previously (71505). This is maybe related to the non-stationary noise in the 20-50 Hz (71092) and the observed bicoherence (71005).

In summary: DARM noise between 20 and 80 Hz gets worse for positive excursions of DHARD_Y_IN1 from zero, but not for negative excursions.
It doesn't look like it is necessaarily correlated with the 2.6 Hz peak (although that peak contains a lot of the RMS in normal conditions).
This might indicate that we have a static offset in DHARD_Y alignment.

The first atttached spectrogram shows in the top panel a DARM spectrogram, whitened to the median of a quiet time, so that a value of 1 means normal noise levels. The bottom panel shows the DHARD_Y 2.6 Hz excitation amplitude, and the DHARD_Y error signal value. The most interesting feature is that noise in DARM is higher when DHARD_Y value is positive and large, but not when it is large and negative. The second plot shows a zoom in time of the same spectrogram, which makes the correlation evident.

To better understand, I computed the DARM BLRMS in the 20 to 50 Hz region [using the spectrogram, averaged over 2-s-long windows with 1-s overlap] , and compared it with the maximum value of DHARD_Y [in the corresponding 1-s window]. The third plot shows the corrrelation and the fourth plot is a time zoom showing the clear correlation with the positive peak value of DHARD_Y.

There is a clear correlation between the DARM BLRMS between 20 and 50 Hz and the maximum positive value of DHARD_Y_IN1, but not the maximum negative value. The last plot shows how the BLRMS is correlated with large positive excursions of DHARD_Y.

Possible causes for this behavior:

• do we have a large static misalignment of DHARD_Y (maybe also consistent with the large ITMY A2L needed to reduce the coupling to DARM 71588)
• are we clipping somewhere in the output path, so when the beam moves on one side we have more noise?
• are we saturating some actuators?
• suggested by Daniel: a scattering path that depends on one of the test mass aligments

Some next useful tests:

• repeat the test at a diffferent driving frequency, to confirm it's not necessarily related to 2.6 Hz but to the signal excursion from zero
• add offsets to DHARD_Y to see if they improve th DARM noise, and while injecting a line to see if they fix the observed behavior

As a side note, the RMS of DHARD_Y is dominated by a 1.3 Hz and a 2.6 Hz peaks. The 2.6 Hz peak could be the high frequency plant resonance, but the lowest plant resonance is at 1.05 Hz (71489). Previously I showed that there is some evvidence that the test mass M0 damping could be responsible for most of the DHARD_Y motion below a few Hz (71466). So maybe another useful test would be to check the status of the test mass M0 damping, and do some noise injections to properly project the OSEM noise contribution to DHARD_Y

Daniel, Camilla 

Following on from Ryan's 71420, we looked at the movement of ITMY (only has ASC control) during DHARD_WFS and see there is now larger spikes during locking than before 29th, see attached plot where H1:SUS-ITMY_L2_OSEMINF_{U,L}{L,R}_INMON spikes during locking are larger after the t-cursor (see bottom purple plot for when violins rang up).

Zooming in, attached plot, we can see when the Input to the DHARD_Y filter is turned on that the output to DHARD_Y filter has a large transient lasting ~1second, not seen in DHARD_Y inmon. The only filter that is on during that time FM6 and although it has a larger step response, there is a 5s TRAMP so Daniel doesn't see an issue with this.

Nothing obvious happened to DHARD on the 29th, only alog around that date shows a change that was reverted 70928.