DQ shifters: Riley McNeil and Emil Lofquist-Fabris

• Daily observing duty cycle: 57.05%, 67.36%. 99.68%, 59.91%, 91:23%, 69.16%, 100.00%. Week average: 77.77%.

• The BNS range this week sat around 150 Mpc, however there were a few sudden drops in the range by about 5-10 Mpc. These were seen on Tuesday, Thursday, and Friday.

• There were several issues with the squeezer this week that resulted in sudden increases in noise and glitching, as well as a couple drops from observing.

• There was a recurring spike in the y-manifold beam tube motion [X] at 17:00 every day. This was seen in the previous week as well, this is caused by the daily dewar fill noise at the Y-manifold cryopump. (alog)

• There was also recurring noise from ~11:00-14:00 in several corner station accelerometers also seen in previous shifts.

• Just above 20 Hz (~22-25 Hz) there has been a line of glitching that we believe to be light scattering. This has been seen since at least the start of July 2025.

  • There has also been a lot of glitching/noise from ~20-40 Hz, consistent with previous weeks, likely from an AC unit housed inside the VPW. (alog)

• There was a 34 hour lock segment this week, from Tuesday August 5th 22:19 to August 7th 08:31.

  • The detector also spent all of Sunday observing as well.

See full report here: https://wiki.ligo.org/DetChar/DataQuality/DQShiftLHO20250804

This morning a 6.2 magnitude earthquake near Vanuatu happened during the commissioning window, so we tested the asc gain reversion scripts Elenna came up with in this alog. It took a little longer than I would have liked to get the scripts working, so we didn't actually transition until basically the peak ground velocities, but the transition went pretty smoothly. I think this eq is tied for the biggest  we stayed locked through for all of O4.

Attached image shows ground velocities on the top row (both peakmon and the ITMY Z STS 30-100mhz blrms, second row is the ISC_LOCK state, third and fourth show channels related to the asc transition. Fourth row is the first gain changed by the script CHARD Y, the third row is the SRCL FF gain, which is the last thing changed in the script. The dashed white vertical lines on the CHARD trace and the top row ground traces show the time the transition took to complete.

Even if the transition was a little late I think that this test likely still saved the lock, I have often seen on eqs like this that the IFO stays locked through the peak ground motion, but loses lock some time shortly after, while the eq is still ringing down.

There is still a lot of work to be done as the transition is currently handled by a couple of scripts on the ISI_CONFIG overview medm and the transition will knock us out of Observe, still unclear what the best way to automate this would be, but still a pretty good test.

Thu Aug 14 10:08:28 2025 INFO: Fill completed in 8min 24secs

Running another calibration measurement today following the usual broadband and simulines.

Simulines Start:

PDT: 2025-08-14 08:36:33.095985 PDT
UTC: 2025-08-14 15:36:33.095985 UTC
GPS: 1439221011.095985

Simulines End:

PDT: 2025-08-14 08:59:53.303431 PDT
UTC: 2025-08-14 15:59:53.303431 UTC
GPS: 1439222411.303431
 

Files:

2025-08-14 15:59:53,136 | INFO | File written out to: /ligo/groups/cal/H1/measurements/DARMOLG_SS/DAR
MOLG_SS_20250814T153633Z.hdf5
2025-08-14 15:59:53,145 | INFO | File written out to: /ligo/groups/cal/H1/measurements/PCALY2DARM_SS/
PCALY2DARM_SS_20250814T153633Z.hdf5
2025-08-14 15:59:53,150 | INFO | File written out to: /ligo/groups/cal/H1/measurements/SUSETMX_L1_SS/
SUSETMX_L1_SS_20250814T153633Z.hdf5
2025-08-14 15:59:53,156 | INFO | File written out to: /ligo/groups/cal/H1/measurements/SUSETMX_L2_SS/
SUSETMX_L2_SS_20250814T153633Z.hdf5
2025-08-14 15:59:53,161 | INFO | File written out to: /ligo/groups/cal/H1/measurements/SUSETMX_L3_SS/
SUSETMX_L3_SS_20250814T153633Z.hdf5
 

TITLE: 08/14 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 2mph Gusts, 0mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.10 μm/s
QUICK SUMMARY: Observing for 4 hours, automated relock. Environment is calm. The only active alarm is the known vacuum PT242B pressure. Planned calibration and commissioning time today 1530-1930 UTC.

TITLE: 08/14 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
INCOMING OPERATOR: Tony
SHIFT SUMMARY: Very quiet shift with H1 observing throughout, despite a couple hours of high winds blowing through with gusts briefly over 40mph. There's a M5.6 quake inbound from the South Pacific, but the EQ response tool just places it in the lower bound of the "earthquake" region. H1 has now been locked for 14.5 hours.

J. Kissel

Recall the SPI pathfinder is pathfinding more than just the future fully assembled sensor array's roll in improving seismic isolation, but also -- at a low-level -- pathfinding some new individual types optomechanical components for LIGO. This aLOG covers the latest in the path for the Schaefter + Kirchhoff (SuK) fiber collimators.

The first of SPI's Schaefter + Kirchhoff (SuK) fiber collimators (DCC:S0272502, ICS:S0272502) is now Class B clean after having gone through one round of massaging with isopropyl alcohol and air-baking (see CNB:2187), at the planned time and levels for the future Class-A vacuum-bake (peak temp 85 [deg C]; ramp up 6 hours, hold for 48 hours, ramp down for 6 hours).

The first open question was "will the lens remain intact and undamaged through the bake." the definitive answer: YES -- the lens remained whole and, at least visually, without defect.
While I didn't use a optical fiber microscope, the lens appears very much intact with no obvious cracks or glinting. See the attached Visual Inspection.

Next up was to check it's optical performance as (hopefully) a more quantitative measure of performance change (hopefully not peformance degradation).
Prior to the bake, I'd set the lens position on the collimator to achieve some level of collimation, and characterized the beam profile -- see LHO:84825.
After the bake, I used the same characterization setup -- augmented only to keep the now Class-B fiber collimator clean (see LHO:86299) -- to remeasure the beam profile to see if the collimator still projected the same beam quantitatively. 

The beam remains as I had collimated it, with the waist within 100 [cm] of the prebake position.
I did *not* adjust the tuned "before" pre-bake lens position at all prior to taking the "after" data.

Check out the 2025-08-07_spifc_S0272502_beamprofile_fit.pdf attachment. 
    - First page compares the two data sets, X axis (parallel to the optical table surface plane) on the top panel, and Y-axis (perpendicular to the optical table plane) on the bottom panel. You can see that the change in waist position / size is 
        Using Delta = (2025-08-06)' - (2025-06-03), and % Diff = [(2025-08-06)' - (2025-06-03)]/(2025-06-03)

        z0x' - z0x = +0.0544 [m] (+4% difference)
        z0y' - z0y = -0.1103 [m] (-8% difference)

        w0x' - w0x = -12.14 [um] (1.3% difference)
        w0y' - w0y = -10.17 [um] (1.1% difference)
Excellent. 

Because the X waist position moved in +Z, and the Y waist position moved in -Z, the beam has become a bit more astigmatic. This is evident in the "Far Field" projection of the model on pages 3 and 5. But, given that the measurement setup is limited with the furthest data point being z(meas_max) - z0 ~ 5.41 [m] - 1.4 [m] ~ 4.0 [m] away from the waist, I wouldn't claim that the measurements perfectly constrain the far-field behavior. Recall we *want* the waist to be at z=0, at the fiber collimator and this collimator's lens position was *not* tuned to that simply because of user error. I'm fully confident I *can* set the lens position such that the waist *is* at the fiber collimator, and after doing so the 5.41 [m] NanoScan position will get a bit more "in to" the far field, which will hopefully better constrain the model, and thus get a better handle on how astigmatic the beam gets after baking (or even *if* it gets consistently astigmatic).

If we define the dimensionless astigmatism parameter, A, as the (zRx - zRy) difference in Rayleigh range, divided by the (zRx + zRy) sum (with the Rayleigh range defined by the fit waist, zR = pi * w0^2 / lambda), then the change (% Difference) in astigmatism is only
    2025-06-03    A  = +2.3983
    2025-08-06    A' = +2.3409 

    (A' - A)/A       = 0.02494 = 2.5%
which seems totally tolerable from pre- to post-bake. Regardless, for the remaining to collimators that we've yet to bake, we'll be setting the collimation (lens position) post-bake anyways, so how it changes across a bake is moot.
Whether the absolute value of A ~ +2.35 is tolerable an open question, that we'll work to answer in the mean time.

Pages 2 and 4 show the model zoomed in to the data between z = 0 and 6 [m]. Here you can also see that the fit doesn't *perfectly* match the data their either, so there's another systematic grain of salt to take with the assessment of change.

Minor note: I was not consistent with the orientation of the collimator w.r.t. to the optical table surface; I oriented the collimator 90-deg from the 2025-06-03 vs 2025-08-06 data (because I found out / rediscovered that the 2025-08-06 position is how you align the p-pol transmission with the optical table; see Figure 5 of T2400413). I've flip-flopped the X and Y axes data for the waist size in the 2025-06-03 data to account for this (which is why the careful reader would notice a difference between this entry's version of the 2025-06-03 results from that in LHO:86342).

But -- all in all -- this looks good enough! 

I've taken these results to indicate that we can move forward with the full Class-A clean-and-bake. 

All three collimators, (S0272502, S0272503, S0272504) in the queue now -- see CNB:2243.

In consultation with Sheila, I've added a new flag in lscparams.py called "ignore_sqz" (currently set to False) which when True, removes SQZ_MANAGER from ISC_LOCK's managed nodes list and sets up ISC_LOCK such that no requests are made of SQZ_MANAGER. I've additionally removed all instances of ISC_LOCK requesting SQZ_MANAGER to 'NO_SQUEEZING.'

The motivation for this stems from an issue encountered earlier this week (alluded to in Monday's shift summary) where after H1 dropped observing from the SQZ PMC having to relock, SQZ_MANAGER eventually stalled (which is not unexpected) and ISC_LOCK then requested it to 'NO_SQUEEZING' for a then-not-well-understood reason. After looking into the frequently used "unstall nodes" decorator in ISC_LOCK, I learned that the revive function it calls simply requests the stalled subordinate node to whatever its last requested state was. The catch here is that the last requested state refers only to what the manager's last request was to the subordinate, not whatever request a user, other node, or standalone script may have made, as the manager node has no way of knowing about requests outside of its own. A discrepancy between a manager node's last request to a subordinate and a different request to that subordinate can be seen with a notification on the manager saying the subordinate's request changed.

My understanding of the sequence of events that led to the confusion on Monday is that commissioners had been working with the squeezer and wanted its Guardian manager node to remain in 'NO_SQUEEZING' while H1 was relocking following their work. In its design at the time, in a few different states such as 'INJECT_SQUEEZING', ISC_LOCK would check the status of SQZ_MANAGER, and if it was in 'NO_SQUEEZING', move on with the state and re-request SQZ_MANAGER to 'NO_SQUEEZING'. This makes SQZ_MANAGER's manager's last request 'NO_SQUEEZING', so when SQZ_MANAGER later stalled, it was requested back to 'NO_SQUEEZING' even though a user had set SQZ_MANAGER to its nominal state sometime later. This is why I've removed requests to 'NO_SQUEEZING' in ISC_LOCK; I believe it's a sound assumption that if SQZ_MANAGER is in 'NO_SQUEEZING', someone wants it there and Guardian should just move on. Further, this makes it so that the only request ISC_LOCK ever makes to SQZ_MANAGER is its nominal state (except in 'DOWN', of course, which would then later get updated to the nominal), meaning there should be no confusion as to what its last request was.

Changes have been saved and committed to svn, but ISC_LOCK has not yet been loaded. This should be done at the next drop from observing.

TITLE: 08/13 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY: Observing at 151 Mpc and have been Locked for over 9 hours. Nothing really happened today besides the calibration commissioning from earlier.

We don't think it affected anything, but at 20:48 UTC, we had a staff member in a car drive up to the LVEA receiving door, idle there for 5 minutes, and then drive away at 20:53UTC, so I'm tagging detchar in case we see anything weird in the data during that time.
LOG:

14:30UTC Just got to NOMINAL_LOW_NOISE
    14:32 Observing
    15:30 Out of Observing for calibration measurements
    15:30 NLN_CAL_MEAS
    16:01 NOMINAL_LOW_NOISE
    16:12 NLN_CAL_MEAS
    16:43 NOMINAL_LOW_NOISE
    17:41 NLN_CAL_MEAS
    18:12 NOMINAL_LOW_NOISE
    18:20 NLN_CAL_MEAS
    18:30 NOMINAL_LOW_NOISE
    18:31 Observing
    20:48 Staff member in car driving up to receiving and idling
    20:53 Car drove away from receiving

TITLE: 08/13 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 22mph Gusts, 11mph 3min avg
    Primary useism: 0.05 μm/s
    Secondary useism: 0.11 μm/s
QUICK SUMMARY: Windy, smokey, and hot afternoon on site, but so far H1 has been locked for 8.5 hours following commissioning time this morning.

• Wind moderate with gusts over 20mph
• All other systems nominal

Camille Makarem (CIT), Rahul

Last week at CIT we assembled and tested four units of PSAMS (Piezo-SAMS payload - Piezo-deformable Mirrors for Active Mode Matching). These four fully assembled PSAMS are shown in attachment01 and attachment02 and they will be shipped to LLO for O5 HPDS assembly and installation in HAM6. Given below are the test results of the PSAMS payload - PZT actuation and the desired radius of curvature of the mirror at 100V.

1. Optic  E2100053, Type A2, s/n - 02 - PZT voltage tested from 0 to 200V, Pre-load set to 32 in. lbs at 100V DC, RoC = 2.42 m

2. Optic E2100053, Type A1, s/n - 01 - PZT voltage tested from 0 to 200V, Pre-load set to 32 in. lbs at 100V DC, RoC = 5.76 m

3. Optic E2100053, Type B2, s/n - 01 - PZT voltage tested from 0 to 200V, Pre-load set to 30 in. lbs at 100V DC, RoC = 2.41 m

4. Optic E2100053, Type B1, s/n - 03 - PZT voltage tested from 0 to 200V, Pre-load set to 28 in. lbs at 100V DC, RoC = 5.63 m

The Strain gauge readout results will be posted later on. 

PSAMS assembly details and issues (faced) are discussed below,

a.  Attachment03 shows the PZT with five lead wires. We looked into the vendor data to identify + HV PZT (the side which has been marked with dots) and PZT ground (non dotted side). The other 3 leads belong to the Strain Gauge (SG). We crimped pins to all five leads - as shown in attachment04. The wire pins were then pushed into the 7 pin Glenair might mouse connector (MM 803-003-02M6-7PN-598A) - as shown in attachment05. We also used a PEEK zip tie to secure the wires on the PZT stack. We followed D2000383 for the wiring chain diagram.  

b. During the assembly we did not have vendor data to identify the leads for the strain gauge, hence we connected the wires based on the spare units at CIT (which lead to some confusion as the two spare units internal wiring contradicted each other). As per D2000382, the bridge excitation should be connected to pin 1 on the might mouse connector and GND should be at pin 3, strain signal on pin 6. In reality we connected the GND to pin1, strain signal to pin6 and +V bridge excitation to pin 3 (basically pin 1 and pin 3 are inverted).  Later (post assembly), Camille acquired the vendor data for identifying the leads for the strain gauge, which is shown here. After discussing this with Jeff Kissel and Daniel, we concluded that this should not affect the working of the SG - however for future assembly we should use the latest vendor data.

c. The PZTs, washers and the deformable mirror were all stacked vertically (as per T2400260) and torqued as per specification - see pictures for reference here - attachment05, attachment06, attachment07, attachment08 and full assembly shown in attachment09.

d. Electrical testing - we followed E2100371 to confirm the electrical connections for the PZT voltage and strain gauge readout - test set up shown in attachment10 and attachment11.

e. RoC measurement on ZYGO interferometer - after successfully testing and confirming the working of the PZT actuation we started measuring the Radius of Curvature (RoC) of the optic on the ZYGO interferometer - see attachment12, attachment13 and attachment14 for details of the setup - fringes observed as shown here, as an example. The final numbers (pre-load and the RoC for each mirror) are posted above.

We wanted to capture few things which we faced during the assembly and testing and this will help for assembling future units. These are listed below,

1. Tangless helicoils for mirror mounting - we used tanged helicoils for mirror mounting, however breaking the tang after the assembly was very unsafe for the mirror. Hence, we had to unmount the mirror from the flexure mirror holder, break the tangs and then re-mount the mirror (which involves heating and cooling them). Hence, we would recommend to use tangless helicoils only.

2. We struggled to attach D1900097 to D1900123 since the threads were bad on D1900097. Don got us a 1''-32 size tap from McMaster to chase the threads, however I could only chase a few of them - enough to assemble four units. The threads on the other 6 units (D1900097) at CIT were extremely difficult to chase hence we included it in our future to-do list of things (might have to be made dirty again for proper chasing).

3. PEEK zip tie for wire lacing inside the PSAMS - the old PSAMS used viton ring to lace the PZT electrical leads, this has now been replaced with PEEK zip tie. We were not very convinced with this, as the viton ring felt easier to use and more secure for the wires.

4.  We spent a lot of time trying to understand and interpret the correct wiring diagram - initially Fabrice's FDR and Luis's document contradicted each other. To add to the confusion, the already built unit at CIT (two spare psams, with two different cables and might mouse connections) wiring also contradicted each other. However (long story short), after talking to Fil and Marc at LHO we were able to sort it. We had to change the 18V power supply to the PZT driver D2000555, since the exciting one was faulty. Also, Dean (at CIT) made some quick checks on the PZT driver to confirm that it was healthy. However the most important thing to note over here is as follows - the two spare units at CIT, ZM2 and ZM5 (from the previous build) have wiring diagrams different from the design (I think for ZM2), hence this needs to be checked before future use. 

Camille as noted down the serial number of the parts used during this assembly and they are listed here.

5 day increments.
I chose 5 days before June 16th because on June 16th there was a ReflAir Phase change, and 5 days later there was another change to ReflAir phasing.
So given a window of 5 days in between 2 changes I chose 5 days before, 5 days between changes, and DRMI after the last change for 5 days.

Leo, Camilla

Leo noticed when comparing the data we took in July 85917 to last years OMC scans with different ZM curvature settings 80010, that the minimum value ZM4 can reach has changed. Over ~ an hour or so, the strain gauge can drift around 0.1V, their total ranges are 7.7V so maybe these changes of 0.2/7.7=2.5% are not too surprising.

• In September 2024, 0V on ZM4 was a strain gauge of 2.1V. Drifted to 2.05V after 2 hours.
• In December 2024, 0V on ZM4 was 2.15V and 0V on ZM5 was -5.40V. 185V was 9.25 on ZM4 and 1.95 on ZM5.
• In July 2025, 0V on ZM4 was 2.3V and 0V on ZM5 was -5.45V. 195V was 10 on ZM4 and 2.35 on ZM5

Today, we measured the calibration at three different ESD biases. First, we measured at the current bias of 269 V, and then our O4 standard bias of 136 V. Then, I stepped up to a higher bias of 409 V.

The attached plot compares the three broadband measurements at each ESD bias. It seems like the overall systematic error decreases as we increase the ESD bias.

To step up the ESD bias, I used guardian code that Sheila attached to this alog. Another relevant alog comparing simulines results at different biases is here.

Similar to alog 86227, the BTRP adapter flange and GV were installed on Tuesday at the MY station.  Leak checking was completed today with no signal seen above the ~e-12 torrL/s background of the leak detector.  

Pumping on this volume will continue until next Tuesday, so some additional noise may be seen by DetChar.  This volume is valved out of the main volume, so the pressure readings from the PT-243 gauges can be ignored until further notice.  

Leo, Jennie, Camilla, WP 12694

Jennie followed instructions for set up in 85775. We removed the SQZ beam iris at the bottom of the LPM (added for alignment capture during OFI vent work). Then took beam profiles in this SQZ path of the SEED beam with various PSAMS settings, adjusted PSAMS settings as in 85775 and used the servo for nominal settings. All data is attached. Jennie then reverted settings back to nominal.