WP12620

09:35 I started the copy of the past 6 months of raw minute trend files from h1daqtw0 to h1ldasgw0-RAID using h1daqfw0. This copy typically takes about 26 hours. It is running in nice mode to minimize its impact on daqd.

Fully automatic relock except for an unsurprising adjustment of PRM to lock DRMI.

Also accepted a batch of SDFs to start observing:

• MCL trigger thresholds (details in alog85012)
• ETMY roll mode damping filter ramptime

TITLE: 06/13 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Corey
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 12mph Gusts, 5mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.13 μm/s
QUICK SUMMARY: Looks like H1 unlocked at 14:00 and just finished up running an initial alignment. Starting lock acquisition now.

Received phone call at 1:20amPDT.

Saw that H1 was at NLN, and ready to go to Observing, but could not due to SDF Diffs for LSC & SUSETMY (see attached screenshot):

1) LSC

• H1:IMC-MCL_FM_TRIG_THRESH_ON at 100 (should be 1300)
• H1:IMC-MCL_FM_TRIG_THRESH_ON at 90 (should be 200)

I was not familiar with these channels, so I went through the exercise of trying to find their medm, but for the life of me I could not get there!  The closest I got was LSC Overview / IMC-MCL Filter Bank, but they were not on that medm.  (probably spent 30min looking everywhere and in between with no luck).   Looked at these channels in ndscope & these channels were at their nominals for the last lock.  Also looked in the alog, and only saw SDF entries for them from 2019 & 2020.  Ultimately, I just decided to do a REVERT (and luckily, H1 did not lose lock).

2) SUSETMY

• This was just a TRAMP, so I also REVERTed this.

Then H1 automatically went back to Observe.

Maybe Guardian, for some reason took these channels to these settings?  At any rate, going to try to go back to sleep since it has been an hour already (hopefully this does not happen for the next lock!).

TITLE: 06/13 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 148Mpc
INCOMING OPERATOR: Corey
SHIFT SUMMARY:

Observing at 148 Mpc and have been Locked for almost 6 hours. I just turned the Roll damping off for ETMY so we don't get any sdf diffs if we have to relock overnight.

When we first got back up, we were noticing the ETMY roll mode ringing up again, which we had been hoping to have solved by Elenna's changes to the SRCL FF (84998). We tried turning damping back on where we had had it in previoius locks (at 20), but this didn't seem to be doing anything this time. We eventually tried a gain of 30 instead, and this finally started damping it.

Near the beginning of the lock, we also had the SQZer unlock and it was having trouble relocking by itself because the LO could not relock due to the ASC having pulling ZM4 and ZM6 out of range. To fix this, Camilla took us to NO_SQZ, then cleared the history on the P and Y lock filters on ZM4/6. Afterwards, she verified that we would've also been able to do this by just taking SQZ manager to RESET_SQZ_ASC, and then back to FDS once that finishes.

In the hours after that, we've had the SQZer unlock multiple times, which is why we've been popping in and out of Observing so much, but each time it has been able to relock itself fine.

LOG:

21:30 Working on PRMI
21:41 Decided to just try and relock bc wind is rising
    - Started an IA due to DRMI not being able to catch
    - Lost lock during ENGAGE_ASC_FOR_FULL_IFO (the glitch that happens during it got too big)
23:32 NOMINAL_LOW_NOISE
23:39 Observing
23:41 Quickly out of Observing to turn on ETMY Roll damping
23:41 Back into Observing
23:54 Out of Observing due to turning ETMY roll damping back on
23:54 Back into Observing
00:01 Out of Observing due to SQZer unlocking
    - LO could not relock due to the ASC running away
00:15 Back into Observing
00:17 Out of Observing to try bumping up the ETMY Roll damp gain
00:17 Back into Observing
02:17 Out of Observing due to SQZ unlock
02:20 Back into Observing
02:49 Out of Observing due to SQZ unlock
02:57 Back into Observing
03:37 Out of Observing due to SQZ unlock
03:38 Back into Observing
05:11 Out of Observing to turn the ETMY roll damping off
05:12 Back into Observing                                                                                                                                                                                                                                                                                                                                        

Observing at 145 Mpc and have been Locked for 4  hours. We've been bumped out of Observing a couple times due to SQZ unlocking, but it's been able to get everything back in order by itself each time.

Jennie, Sheila, Camilla

Ran the userapps/.../sqz/h1/scripts/SCAN_PSAMS.py script with it optimizing SQZ with the 350Hz BLRMS rather than the high frequency ones to set SQZ angle.

We tried the beloiw values, see attached ndscope:

• ZM4 @ 5.6, ZM5 @ -0.55
  • Looked like high frequency would be good and low/mid frequencies fine, but range was bad.
• ZM4 @ 5.6, ZM5 @ -0.4
  • Looks as good as nominal before test started with slightly better high freq, range wasn't as good as original
• ZM4 @ 6.0, ZM5 @ -0.4 (Nominal before test)
  • Reverted to nominal as all other optiois seemed worse.
  • However, range didn't immediately increase back to as high as it was before tests started.

Note we don't think that the 350Hz BLRMS is a good measure of the range as the yellow 350Hz BLRMS  being good don't agree with good range times. We should add a 80-250Hz BLRMS in the place of BLRMS_2 with the hope that it would follow the range better.

TITLE: 06/12 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: Oli
SHIFT SUMMARY:

IFO is LOCKING in ACQUIRE_DRMI_1F

(Started my shift cover at around 10AM PT)

Today we had planned commissioning until 21:00 UTC. We were locked for the majority of it, with much of the commissioning time being spent on SQZ.

We experienced a ETM Glitch Lockloss (not human nor environment caused) - alog 85004. After this, we stopped at PRMI_LOCKED to work on PRMI ASC, but after trying for a while and not making much progress, commissioners decided to continue normal locking.

LOG:

Lost lock due to the ETM Glitch while commissioning.

TITLE: 06/12 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Commissioning
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 28mph Gusts, 21mph 3min avg
    Primary useism: 0.05 μm/s
    Secondary useism: 0.12 μm/s
QUICK SUMMARY:

Currently unlocked and trying to relock the detector before the wind gets worse. Previously work was being done to fix PRMI ASC, but that's been abandoned for now since the wind is supposed to get worse and we can't keep green arms locked for too long with the wind this bad.

WP12620

Dave, Oli:

I have isolated the raw minute trends for the time period 16dec2024 - 12jan2025 from the current data, these static files are now ready for transfer to spinning media.

h1daqnds0 was reconfigured to serve the past 6 month from this temporary location and with Oli's permission its DAQD process was restarted 13:44.

After suggestion from Vicky, I checked the FC de-tuning (was changed from -32 to around -26Hz when we changed the SRC de-tuning). The current setting of -26Hz seems fine, left there. Plot attached.

This post reports on the results from SRCL dither measurement I ran in January, briefly reported in alog 82248. It's taken me a long time to write up this report because I spent significant time processing the results in different ways to try to account for some of the possible pitfalls of this measurement. The overall problem is that, in O4, this measurement has traditionally reported very low arm power compared to our other methods of estimating arm power (for example, see Craig's work in 66860). I have been doing an exhaustive study to understand why that might be.

A full derivation of this measurement can be found in Craig's dissertation Section 3.2.2, which also includes references to work by Daniel and Kiwamu that orignally inspired this method. To summarize, the idea of the measurement is that dithering the SRM creates differential amplitude sidebands due to the radiation pressure coupling in the SRC. This response can be readout as a transfer function from the differential arm length to the relative intensity noise on the arm transmission QPDs. The resulting transfer function takes a simple form of DARM/RIN = alpha/f^2. The arm power is calculated via P_arm = 1/2 * alpha * pi^2 * M * c (M = test mass mass, c = speed of light)

Here are some possible issues with the measurement:

• Achieving good SNR is challenging due to the noise in the TMS QPDs. When driving a SRCL line that is ~10^3-4 above the DARM noise in amplitude, the line height in the TMS QPDs is only about ~10 above the noise in amplitude. Line height uncertainty and bias scale as 1/SNR (in PSD). While this is still a small effect on the order of a few percent for the TMS QPDs, I have other reasons to believe that it is significant enough to make a difference in this measurement.
• A good accounting of the uncertainty and bias is a necessary aspect of this measurement, especially considering that the fit error in Craig's results has always been very small. For example, in 66860, his results include an uncertainty that is less than a percent. Craig's SRCL dither analysis code, found here, uses scipy curvefit and does not include measurement uncertainty in the fit. The reported error comes from the fit error only.
• Dan Brown ran a SRCL dither measurement model in finesse, found here, and he shows that applying a differential test mass curvature change (something that might occur due to to thermal effects), could deviate the DARM/TMS RIN transfer function from 1/f^2 at low frequency. This appears to be a very subtle effect, but it could cause a misestimation of the arm power.

In order to fully study this properly, I ran a bayesian inference on my measurement data with both the amplitude and power law as free parameters. I wanted to confirm that the 1/f^2 trend agrees with the data, and if it agrees, get the arm power estimate (note: if the power law is different from -2, the overall amplitude of the fit cannot be used to measure the arm power). In the process of setting up the inference, I set about making sure that the uncertainty on the line height in both DARM and the TMS QPDs was being correctly calculated.

Uncertainty and Bias:

Appendix E of Craig's thesis is a nice reference for line uncertainty.

• The line height bias is measured as 1/SNR, following E.4 and E.5. "So even with an SNR of 100, you will expect a 1% bias in the calibration line." Line height bias in the TMS QPDs from these measurements ranges from less than a percent to 7%, depending on how noisy the QPD is.
• The line height uncertainty is shown in E.25, 1/(2*N_avg * SNR) *(1 + 1/SNR)
• I pulled the DARM calibration uncertainty from the time nearest to my measurement, which provides an uncertainty and bias in the DARM estimate (a measurement taken at GPS time 1420853061)
• Overall, the uncertainty is still very small, but accounting for the bias in both the DARM and TMS QPD line height estimates increases the estimate of the transfer function by a few percent

Testing frequency dependence:

I set up a bayesian inference using a model that fits the frequency dependence and "power", assuming a gaussian distribution of my uncertainty. Following Craig's discussion in his thesis appendix E, with SNR > 5 the ASD distribution of a line can be well-approxmiated by a gaussian distribution. I assume a flat prior, with possible powers ranging from 0-1000 kW, and possible power laws from -3 to -1. I fix the inference to assume the same arm power in each arm, so it uses both A and B QPDs in each arm to fit one X arm power and one Y arm power. I then fix the frequency dependence to be the same for both arms and both QPDs in each arm.

The results from this inference do not favor a slope of -2, with a fit that gives m=-2.016 +-0.014 (95% CI).

However, fixing the slope to -2, following the model, gives the following power results (95% CI):

X arm power = 319.6 +- 2.8 kW

Y arm power = 303.5 +- 2.4 kW

These are the highest power results achieved with this method during O4. However, they are still very low compared to what we know about the interferometer, namely that our PRG at full power is about 50, and we have about 56-57 W of power on the PRM, which predicts about 360 kW of arm power, assuming an arm gain of 260. Craig, Sheila, and I have all done work to verify these numbers before and during O4. This result also indicates a significant mismatch in the arm powers; a surprising result since our pre-O4 test mass replacement of ITMY should have made the arms more well-matched to each other than in O3.

Some commentary:

One aspect of this measurement that is very constraining on the slope of the transfer function is the overall uncertainty on each transfer function measurement point, which is very narrow. This makes sense, since we are achieving fairly good SNR overall. However, while processing the data I did notice that there is modulation of the DARM/RIN transfer function, that is on the order of a Hz to a few Hz. My guess is that this is coming from the ASC modulating DARM, SRCL, or both. I'm not sure overall what effect this could have on the estimation of the transfer function or the uncertainty. Returning to the results from Dan's finesse model, the sparseness of points in this measurement also makes it harder to determine if the slope has diverged from -2 at lower frequency due to a different effect, such as some differential mismatch in the test mass radius of curvatures.

If we choose to use these measurement results, they would certainly place a lower bound on our possible arm power, which is compatible with some of Sheila's quantum noise modeling work (see 82097). However, those models require minimal or no readout losses to achieve such a low arm power, which is incompatible with some of our other results measuring readout loss, such as the work Jennie Wright has been doing.

Back to the measurement itself, we could try to improve the result slightly by integrating longer at each point, and measuring more points to get a better idea of the slope. Instead of running Craig's swept sine measurement, I injected several lines by hand because I found it easier to verify that we were achieving good SNR this way. I'm not sure if there is a way to overcome the modulation of the injection.

Elenna, Camilla, Jenne, Ryan Short, Tony

We saw an increase in the DCPD monitor screen, which the roll monitor identified as ETMX roll mode.  The existing settings from a long time ago used AS A YAW to damp roll modes, I attempted to damp this by actuating on ETMY, which seems to have worked with a gain of 20. (settings in screenshot)

Camilla trended the monitor, and sees that this started to ring up slowly around 7 am today. 

We've gone back to observing with this gain setting, but we plan to turn it off when this looks well damped (if we are still locked by the end of the eve shift, we should turn it off so the owl operator doesn't get woken up by SDF diffs).

Sheila, Elenna, Camilla

Sheila was questioning if something is drifting for us to need an initial alignment after the majority of relocks. Elenna and I noticed that BS PIT moves a lot both while powering up /moving spots and while in NLN. Unsure from the BS alignment inputs plot what's causing this.

This was also happening before the break (see below) but the operators were similarly needing more regular initial alignments before the break too.  1 year ago this was not happening, plot.

• Now:
  • While locking (Power up state #500 to NLN #600) BS PIT moves 40urad  plot
  • During a 2hr lock BS PIT moves 13urad plot
• Before Break:
  • While locking (Power up state #500 to NLN #600) BS PIT moves 43urad  plot
  • During a 4hr lock BS PIT moves 20urad plot