Lockloss @ 06/18 05:34 UTC after only 35 minutes locked. I don't believe this one is wind related.

Lockloss @ 06/18 03:09 UTC from the wind

TITLE: 06/17 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
INCOMING OPERATOR: Oli
SHIFT SUMMARY:

IFO is in NLN and OBSERVING as of 18:33 UTC (6 hrs)

It has been a calm day after minimal trouble relocking (multiple post-initial alignment locklosses) at and before DRMI with one at CARM_TO_TR. Planned comissioning occured from 8:30-11:30 and was timely.

Nothing else of note

LOG:

TITLE: 06/17 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 10mph Gusts, 6mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.06 μm/s
QUICK SUMMARY:

Observing at 155 Mpc and have been Locked for 5.5 hours

FAMIS

27791

Added 150mL to TCSX, none to TCSY. Filters lookded okay for now.

Further testing on the revised A2L script today. On Friday Sheila added a settling time between steps that seemed to help (alog78438), and had increased the run time of the script to just under 7 minutes. Today we wanted try two things: i.) run it a few times in succession to see if we get the same results  ii.) swap the furthest quad frequencies and see if we get the same results. This was only for Y and was right after we relocked and were still thermalizing.

Swapping the line frequencies didn't seem to change much, rather the quads that kept their frequencies changed more. This might hint that we are drifting at the frequencies that A2L should help with, so we will get different answers each time we run it. We only ran it 3 times and while we were still thermalizing, so perhaps we need to run it again after thermalized and see if we still get the same answers.

Camilla, Andrei, Naoki, Sheila

There have been many examples of times when the filter cavity length locking error signal peak to peak seems to be correlated with worse range over the last 3 months, I've attached some screenshots of examples. This was true before the May 16th change in the status of the CO2 ISS channel , 78217, and before the output arm damage that happened April 22nd.

Some of these times correspond to times when there is a whistle visible in the FC WFS signals 78263, others do not.  These whistles in the FC WFS channel have been present throughout all of O4, but they do go away sometimes for several days, this last week they do not seem to have been present.  Andrei has identified a candidate wandering line in the IOP channels for these WFS that was last week ~10 kHz away from the 105kHz RLF-CLF signal, today that line seems to be gone.

Last week, the filter cavity error signal peak to peak became much noisier than it was previously (screenshot), until June 15th at around 15 UTC when things returned to the previous state.  Camilla identified that this started a few hours after the time of the ringdown measurement attempt, 78422, and that there haven't been any ZM1/2/3 alignment changes.  During that time period, the FC error signal from around 0.7-9 Hz has higher and variable, in addition, the low frequency noise was changing and varriying the RMS as it has done before.  The attached screenshot shows some of the typical low frequency variation (compare yellow to blue), a whistle in the yellow trace, and in red a time during last week's elevated noise when the low frequency was relatively quiet but there is elevated noise from 0.7-9Hz. 

Link to Report

• Duty Cycle : 73.28 % (Average from 100%, 47.18%, 45.98%, 59.42%, 85.13%, 82.3%, 92.98%) Which is higher than the previous week.
• 4000 Hz Glitches present on multiple days for significant portions of the day (Specifically on Wednesday to Sunday).
• Low Frequency Noise present on days with "jagged" range drops. (Specifically on Monday and Friday)
• Number of FScan Lines each day was 1000, 700, 600, 900, 900, 1100, and 1100 -- Under Alert Threshold all days.

Andrei, Naoki

Following 78422, we did FC visibility and ringdown measurement to get the FC loss and finesse. The measured FC loss is 44+-27 ppm, which is consistent with before within the error. The measured FC finesse is 8000-11000, which is higher than expected value ~6700. We don't know why the estimated finesse is higher than before, but both results would indicate that there is no obvious excess FC loss compared to before.

After the cabling in 67409, the OPO dither lock did not work well as before. We increased the dither lock gain from -10 to -30 and the dither lock got much better. The SDF is accepted.

We needed to flip the sign of FC CMB to lock the FC green. We engaged one boost in FC CMB as before.

We turned off LP100 in FC IR trans PD. We reduced the seed power down to 0.2 mW. More than 0.2 mW seed saturated the FC IR trans PD without LP100. 

For visibility measurement, we put the seed on resonance of FC by adjusting green VCO tune and put the large offset on green VCO tune to make the seed off resonance of FC. The first attachment shows the visibility measurement. 

Using the formula in TAMA paper, Andrei calculated the FC loss. The calculated FC loss is 44+-27 ppm assuming 909 ppm of FC1 transmissivity and 2% of misalignment, mode mismatch. The FC misalignment and mode mismatch are not measured recently, but they do not affect the result much. 

The seed lock on FC is not very stable so the seed dither lock for FC is necessary for more precise measurement.

For ringdown measurement, putting the large offset on green VCO tune is not fast enough. We requested OPO guardian to DOWN. The second and third attachment show the ringdown measurement for TRANS and REFL. The measured finesse was 11000 for TRANS and 8000 for REFL, which is higher than expected value ~6700.
 

We've been talking about moving LSC FF back from ETMY L2 to ETMX L3 73420 as we think that it's been harder to fit the SRCL FF since using the L2 stage. Also LSC FF needs regular readjustment now.  We originally moved LSC FF off EX L3 as thought that changing actuation strength may have been changing them (may have not have been the reason), but we now have a script to adjust actuation strength based on kappa_tst 78403.

If we do this, things that will be useful:

1. Script used to go the opposite way (from ETMX L3 to ETMY PUM) in 73393
2. ISC Lock changes made: ISC_LOCK.py commit 26506: FF to EX off and turn off DARM to EY
3. We'll need to think about if NEW DARM effects these changes.
4. Will need to be done before a Tuesday: For In-lock charge measurements, the LSC FF should be turned off while in-lock charge measurements move to ITMX ESD DARM control: revert 27861 SUS_CHARGE.py commit.
5. The FF filters used before the October change have been overwritten, it will be easiest ot remeasure staring with FF's off, at least as a start before we can measure iteratively.

IFO is in NLN and OBSERVING as of 18:33 UTC (1 hr 46 min lock)

One unexplained potentially EQ-related lockloss occured at 15:42 UTC but we managed to relock after an initial alignment.

3 Hours Comissioning time finished on schedule (8:30AM to 11:30 AM PT) and we were back in OBSERVING by 11:33 PT

Sheila, Camilla

Sheila suggested that what happened on June 14th was that SQZ OPO temperature or angle wasn't well tuned for the green OPO power, when the OPO ISS as  off, the SHG launch power dropped from 28.8mW to 24.5mW. it was just chance that SQZ was happier here. Since Saturday we've been injecting  ~25.5mW 78467.

While looking at this, you can see the SQZ-OPO_TRANS_LF signal has got more noisier since the January break in the 0-60Hz region. Plot here. Maybe this is expected from the PMC install?

Woke up to see that the SQZ_OPO_LR Guardian had the message:

"disabled pump iss after 10 locklosses. Reset SQZ-OPO_ISS_LIMITCOUNT to clear message"

Followed 73053, but did NOT need to touch up the OPO temp (it was already at its max value); then took SQZ Manager back to FRE_DEP_SQZ, and H1 went back to OBSERVING.

Sheila and Keita have double-checked the sign convention of what beam positions mean given some A2L gain on an optic.  Since we have had some errors in the past few weeks, I'm summarizing their findings in this alog (and will link to this alog from the 3 measurements we have over the last few weeks).

• P2L gains that are positive mean beam is below center of optic (all optics)
• Y2L gains that are positive on SR3 mean beam is on the -X side of SR3
• Y2L gains that are positive on SR2 mean beam is on the +X side of SR2
• Y2L gains that are positive on SRM mean beam is on the -X side of SRM

Here is a summary table, in units of A2L gain:

Here is that data translated into inferred position on the SRC optics, in mm:

J. Kissel
TIA D2000592: S/N S2100832_SN02
Whitening Chassis D2200215: S/N S2300003
Accessory Box D1900068: S/N S1900266
SR785: S/N 77429

I've finally got a high quality, trustworthy, no-nonsense measurement of the OMC DCPD transimpedance amplifiers frequency response. For those who haven't seen the saga leading up to today, see the 4 month long story in LHO:77735, LHO:78090, and LHO:78165.

For those who want to move on with their lives, like me: I attach a collection plots showing the following for each DCPD:
Page 1 (DCPDA) and Page 2 (DCPDB)
    - 2023-03-10: The original data set of the previous OMC DCPD's via the same transimpedance amplifier 
    - 2024-05-28: The last, most recent data set before this, where I *thought* that is was good, even though the measurement setup was bonkers, 
    - 2024-06-11: Today's data
Page 3 (the Measurement Setup)
    - The ratio of the measurement setup from 2023-03-10 to 2024-06-11.

With this good data set, we see that
    - there's NO change between the 2023-03-10 and 2024-06-11 data sets at high frequencies, which matches the conclusions from the remote DAC driven measurements (LHO:78112) and
    - there *is* a 0.3% level change in the frequency response at low frequency, which also matches the conclusions from the remote DAC driven measurements. 

Very refreshing to finally have agreement between these two methods.

OK -- so -- what's next? Now we can return to the mission of fixing the front-end compensation and balance matrix such that we can 
   - reduce the impact on the overall systematic error in the calibration, and 
   - reduce the frequency dependent imbalance
that were each discovered in Feb 2024 (see LHO:76232).

Here's the step-by-step:
- Send the data to Louis for fitting.
- Create/install new V2A filters for A0 / B0 bank
- Switch over to these filters and accept in SDF
- Update pydarm parameter file with new super-Nyquist poles and zeros.
- Measure compensation performance with remote DAC driven measurement of TIA*Wh*AntiWh*V2A
	confirm bitterness / flatness

Once IFO is back up, running, (does it need to be thermalized?)
- Measure balance matrix, 
	Remember -- SQZ OFF
	confirm better-ness / flatness
- Install new balance matrix
- Accept Balance Matrix in SDF

Once IFO is thermalized
- grab a new sensing function.
- push a new updated calibration

Jennie W, Sheila

After our picoing efforts, at 22:50 UTC today Sheila and I measured the A2L gains of the SRM and SR2.

Sheila notched 31 Hz out of the SRCL control loop and I injected a line at this frequency first at SUS-SRM_M3_LOCK_P_EXC, then SUS-SRM_M3_LOCK_Y_EXC.

Sheila changed the A2L gains for the corresponding degree of freedom so that the line height was minimised in SRCL_IN1 and in DARM using the channels H1:SUS-SRM_M3_DRIVEALIGN_P2L_GAIN and H1:SUS-SRM_M3_DRIVEALIGN_Y2L_GAIN.

SRM spot position:

P2L -1 with precision of 1

Y2L 6 with a precision of 0.5

(not too sure of the precisions as I lost my alog halfway through (d'oh).

We then did the same thing for SR2 by injecting in the M3_LOCK P and Y channels and changing the DRIVE ALIGN gains for SR2.

SR2 spot position was

Y2L 1.5 with precisioon of 0.25

P2L is 8 with precision of 1

The templates for these measurements are in: /ligo/home/jennifer.wright/Templates/Measure_spot_size_SR2.xml and Measure_spot_size_SRM.xml