Tue Aug 12 10:07:51 2025 INFO: Fill completed in 7min 48secs

Lockloss at 2025-08-12 14:57UTC right before the start of maintenance. Haven't looked yet to see if it was caused by the SUS charge meaurements or by something else

TITLE: 08/12 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 12mph Gusts, 6mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.13 μm/s
QUICK SUMMARY:

Currently have been Locked for over 5.5 hours and out of Observing to run injections

TITLE: 08/12 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 147Mpc
INCOMING OPERATOR: Tony
SHIFT SUMMARY:

Very easy shift with H1 locked over 11.5hrs (we've also "cooled" down to 85degF!)
LOG:  n/a

J. Kissel, C. Compton

Camilla and I took some pictures of what supply of picomotor assembly materials we (existing ICS Supply vs. what SPI) have and in what state of assembly they are in order to familiarize myself with the process of building up new assemblies. 

To the best of my knowledge, there's no assembly procedure. Instead, we have the Picomotor Fact Page (E2100196) [which I've, as of this aLOG, heavily updated / curated]:
    - A well-labeled exploded assembly drawing with only minor assembly errors, (Page 2 of D2100433)
    - a hand illustration from Rich on the wiring connections for an IXM100.C2, right-handed mount (D1400279) 
    - the expected two-motor pinout of the receiving D25M to 4x MM4F quadrapus cable (D1101516) 
    - Some instruction on how dis-mount and re-mount fully assembled picomotors (E2500163)
and thru a linear combination of these, you could fumble your way through it.

The picomotors themselves have evolved over the years as the original prefer vendor, New Focus, was bought out by Newport. 
:: First picture shows the difference between an old picomotor (left), and the modern 8301-UHV-KAP that we buy now (right). I've created D2500246 (as opposed to the old, non-specific E1000197) that captures the specific features of this model. The key differences between old vs. new being
    - The wires' insulation is kapton, not colored teflon
    - The wire lengths is a nice healthy 7 [in], not a short 2 [in] that required icky extension
    - The label of which wire is which is stamped into the metal (a "-" in the lower-left corner to indicate that the wire closest to that stamp is the negative lead, or "return") vs. indicated by color of wire.

:: Second picture shows the modern 8301-UHV-KAP picomotor by itself. Note, the "1" in 8301 indicates that we've chosen the 0.5" throw.

:: Third picture shows the cable unfurled and compared against the 1 [in] hole pattern of the optical table beneath the foil.

OK, now that you've gotten to know the raw picomotor, let's talk about cnonnectorizing and modifying it to suit our needs. We only have the old style picomotor fully assembled to picture as example, but it'll serve the purpose.

:: Fourth picture shows the real manifestation of Rich's artist impression of the fully connectorized two-motor system.

:: ECR E1400327 has us install a motion limiting shaft collar along the throw of the picomotor to limit the motion from the edge of its range where it's been found to get stuck. The collar was originally a custom D1400189 per -v1 of the ECR, but now it's a stock McMaster Carr shaft collar (6436k131, with the black-oxide steel #4-40 x 3/8 [in] L SHCS replaced with a stainless, otherwise identical, SHCS, 92196A108). The stock collar is then modified to be a bit thinner, per D1800220. Finally, to prevent the shaft collar from freezing against the picomotor body, we install a slip-on LIGO-cut kapton "washer" (D1400226; cut from 12 [in] x 12 [in] x 0.005 [in] sheet stock) around the threaded adjustment screw.
    - Fifth and Sixth pictures show how the shaft collar is shaved thinner,
    - Seventh picture shows the Kapton washers,
    - Eighth picture shows the collars assembled on the motor, and where the washer would be placed (these didn't have washers at the time of the picture, but we've since installed the on their to form a complete, albiet not-so-vacuum-compatible assembly).

:: Once connectorized, per Rich's drawing, to the 4-pin MMF connnector 803-003-07M6-4PN-598A, then the connector is secured to a custom L-bracket D1002763 via the connector's thumb screw. That L-bracket then secures to the optic mount's "other" 1/4"-20 mounting hole (with "the" 1/4"-20 mounting hole, 90-deg away, is presumably used to secure the mount to a post or breadboard). Note -- the L-bracket's thru-hole for the MM connector is keyed, but it's not sized for any feature on the actual connector, so you're free to orient the connector in any way in within the bracket. Of course, each socket connector on the legs of the quadrapus it'll connect to are much better keyed, so there's no worry of pin-clocking or anything nasty like that.
    - Ninth picture shows the D1002763 L-bracket. Note -- this a D1002763-v2 Type 1 bracket, so it's mounting hole is threaded for 1/4"-20 bolt (rather than Type 2 which has a thru-hole requiring a nut).
    - Tenth, Eleventh, Twelth, and Thirteenth pictures show how the MM connector is assembled on to that portion of the D1002763 L-bracket.

Finally, just because it came up during the pre-clean-and-bake inspection (see discussion in CNB:2225), 
    - Fourtheenth picture shows the inside of the 803-003-07M6-4PN-598A MM connector -- a  black plastic that Glenair calls a "High Grade Rigid Dialectric," without specifying the material (see table in Section 3.1 on page 2 of Mighty_Mouse_Series 80_performance-test-report-iaw-mil-dtl-810.pdf from T2500025). 
I mostly show the picture of the old connectorized picomotor system to indicate that we've indeed been using this connect and its inner material for a long time, and the Clean-and-bake process (T2100001) appears to be enough (see e.g. bake loads ICS:10543 and ICS:10557).

TITLE: 08/11 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 147Mpc
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 11mph Gusts, 7mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.17 μm/s
QUICK SUMMARY:

H1's been locked almost 7hrs and Tony took care of the SQZ guardian thing they discovered during the day shift (yay!).  With just that said, it's smooth sailing thus far.

TITLE: 08/11 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 147Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY:
Power supply issues as soon as I walk in.

Viewports got covered by Robert.
Fil got the 18V power supply working again, and we started to relock but got stuck in AS Shutters because a PST driver was still not yet powered because it's breaker had tripped.
Alogs:  86290 & 86296

NLN reached by 17:21:50 UTC.
Comissioners Comissioned some Scattered Light Investigations and some quasi anti-SQZin.  

Observing reached by 19:47:01 UTC

Dropped from Observing due to the SQZ_MAN going to NO_Squeezin at 21:33:42 UTC for some strange reason. Mystery!
Back to Observing at 21:38:43 UTC after requesting FDS.

Mystery solved! Ryan Short found out that when a Guardian node is stalled, the unstalling node calls a revive function which returns a node to the "Last Requested State".    
And since we were now in a strange state that may wake up the OWL Operator....
We resolved it By: 

UnManage H1 Manager.
Manual ISC_LOCK to Inject_Squeezing
Allow SQZ_MAN to reach FDS
Then Manual ISC_LOCK back to NLN.

LOG:
 

FAMIS 31098

The PMC alignment last Tuesday seems to have made the PMC REFL signal a bit less noisy, so even though there wasn't much power improvement, the alignment is slightly better. Also, the RefCav alignment is drifting again (as always, likely due to temperature changes) as evidenced by the dropping TPD signal, but Jason will touch this up tomorrow on-table.

At 05:47:34 there was an unknown Lockloss https://ldas-jobs.ligo-wa.caltech.edu/~lockloss/index.cgi?event=1438926473
This Lockloss's plots are showing that the DARM signal was the first signal to deviate from nominal.



 

J. Kissel

I took some pictures of the SPI pathfinder's (QTY 4) IXM100.C2-VC (right-handed) and (QTY 2) IXM100.C2L-VC (left-handed) mounts in their "raw" pre-assembled clean state since 
    (1) it's my first time dealing with Siskiyou mounts,
    (2) the "assembly procedure" D1100362-v1 thus far is only an exploded view of numbered-but-not-labeled and out-dated parts for am unspecified, but left-handed mount, 
    (3) they come out of the clean-and-back process quite disassembled but maybe in the same bag,
    (4) it's always useful to show what each company's convention of "right" vs. "left" handed optics mounts so you can tell them apart, when you've got lots of unlabeled clean mounts in front, and
    (5) "right" and "left" are perspective-dependent descriptions of convention, and so it's useful to unambiguously specify.

So -- to determine if they're right- or left- handed -- orient the optic holder with the optic (back) side towards you, and the adjustment knobs (back) side away from you. Rotate the mount such that the optic-securing #8-32 set screw hole is up. Hold up your trusty left-o-meter -- your left hand formed into a capital L shape with your index finger and and thumb (palm facing away from you). If it matches what you see, it's a left-handed IXM100.C2L mount with the "opening" to your upper right from the described perspective. If it doesn't match, it's an IXM100.C2 with the "opening" to your upper left from the described perspective.

First picture is both mounts side-by-side; four right-handed IXM100.C2's on the left and two IXM100.C2L's on the right.
The second-thru-fourth pictures are various views of the IXM100.C2 right-handed mount. In the second picture I'm making the American sign language letter R.
The fifth-thru-seventh pictures are various views of the IXM100.C2L left-handed mount. In the fifth picture I'm making the American sign language letter L.

I ran a series of jitter and frequency noise injections last Thursday to investigate how jitter noise couples. I ran the usual frequency noise injection while we were on one carm sensor. Then, I performed the jitter injections, but I ran a 4 minute injection instead of the usual 1 minute to get better resolution.

Using these injections, I calculated the frequency noise coupling and jitter noise coupling. Then, I calculated the jitter that couples through frequency noise by measuring the jitter-to-frequency coupling, and multiplying that with the frequency-to-darm coupling. I also calculated the coupling measured by all four IMC WFS DC channels (A/B, pit/yaw), where we usually measure the coupling from IMC WFS A for the noise budget. When I estimate the frequency noise, I do not apply any corrections to account for the fact that we usually have two sensors, so in some regions we may be overestimating the frequency noise by sqrt(2).

Frequency noise is about a factor of 10 below DARM, especially at high frequency. This has been the case since we returned from the OFI vent.

Jitter noise is well-measured up to about 2 kHz. I made a higher resolution plot zoomed in from 10-50 Hz to look at the coupling measurement of some of the peaks that Robert noted. I see strong coupling of two narrow peaks.

The jitter noise that couples to frequency noise to DARM seems mostly to be much lower than the direct jitter coupling, except for WFS B yaw at low frequency. Here is another plot that compares the direct jitter coupling, jitter-to-frequency coupling, and frequency coupling as witnessed by each jitter sensor.

I did a similar exercise with frequency and intensity noise in this alog.

The DARM trace shown here is actually GDS CLEAN, meaning that some jitter noise above 100 Hz has been subtracted in the trace. However, to calculate the coupling I used the NOLINES channel, which has no jitter cleaning.

J. Kissel

Clean parts for the SPI pathfinder are starting to roll in! 

I needed to re-characterize the first-of-its-kind-used-in-LIGO SuK fiber collimator S0272502 (DCC, ICS) now that it's been run through a test Class-B process -- and importantly after the 48 bake at 85 [deg C] (w/ 6 hour ramp up and ramp down) -- similar to how it was tested pre-bake per LHO:84825.

That means need to mount it in either Class-A or Class-B equipment. 

So, I assembled 2x Class-A fiber collimator assemblies for production use, D2400146 using
    - (QTY 1) D2500094 60FC-0-A11-03-Ti, S0272502 Fiber Collimator itself [Currently Class-B; new]
    - (QTY 1) The D2500005 12 [mm] to 25.4 [mm] adapter ring stamped with S0272502 [Class-A; new]
    - (QTY 1) D1100705 3/16 [in] length #8-32 PEEK set screw [Class-A; existing stock]
    - (QTY 1) D2400208 Siskiyou IXM100 1 [in] Mirror Mount [Class-A; new], 
       re-assembled*** with
        - (QTY 2) 1/4 [in]-100 x 1 [in] length threaded hex adjusters, with 5/64 [Class-A; new]
        - (QTY 2) 1/8 [in] diameter SS ball bearing [Class-A; new]
        - (QTY 1) D1100705 3/16 [in] length PEEK #8-32 set screw [Class-A; existing stock]

With these fully assembled, I used the following existing stock of Class-B hardware and tooling to mount it and adjust it for practical use:
    - (QTY 1) 1/4-20 x 5/8 [in] length SS (non-vented, non-plated) SHCS [these were actually Class-A]
    - (QTY 1) 0.50 [in] diameter x 3 [in] length SS optics post 
    - (QTY 2) 0.75 [in] diameter "large" adjustment knob with 2.0 [mm] hex key extension 
    - (QTY 1) 5/64 [in] ~ 2 [mm] hex key (for #8-/32 set screws) 
    - (QTY 1) 3/16 [in] hex ket (for 1/4-20 SHCS) 

*** Pro-tip for assembly of these IXM mounts :: Use the 5/64 hex key or 0.75 [in] diameter "large" adjustment knobs to insert the 1/4 [in]-100 x 1 [in] length threaded hex adjusters most of the way into the "raw" IXM mount. Then, open up the adjuster-plate-to-mounting-plate spring, gently wedge the 3/16 hex key between the front and adjuster surfaces to hold it open, leaving gloved hands free enough to insert the tiny 1/8 [in] ball bearing in place at the tip of the threaded adjuster. Then gently expand and release the 3/16 key from the spring and resume setting the adjusters to nominal position.

Per "best effort," and since S0272502 has to go thru clean-and-bake again to get "classed up" to Class-A, I used 
    - (QTY 1) 2 [m] length FC/APC to FC/PC patch cable (P5-980PM-FC-2)  
with the FC/PC end wiped extensively with IPA and then wrapped in sealed wipes and UHV foil to inject ~100 [mW] of light from the existing optics lab fiber-coupled laser into the Class-B fiber collimator.

The first attached picture shows all of this equipment as it comes "out of the bags" from the clean-and-bake process.
The second attached picture shows the fully-assembled system in use during characterization.
The third attached picture shows the label on the bag that contains the fully-assembled IXM100. (This bag doesn't contain the fiber collimators or adapters themselves, though, as these are with clean-and-bake for the collimators to become Class-A and married with their respective adapter ring.)

Janos has requested these alarms be bypassed and PT243 temporarily disabled in VACSTAT. Full list is:

Bypass will expire:
Wed Aug 13 12:24:46 PM PDT 2025
For channel(s):
    H0:VAC-LY_CP1_TE102A_DISCHARGE_TEMP_DEGC
    H0:VAC-MX_X1_PT343B_PRESS_TORR
    H0:VAC-MY_Y1_PT243B_PRESS_TORR
 

Closes FAMIS26544, last checked in alog86165

HAM2_CPSINF_H3 has increased lines just over 60Hz

HAM4 has some increased lines at high frequency

BS ST2 has increased lines at high frequency, V3 mainly.

Mon Aug 11 10:08:07 2025 INFO: Fill completed in 8min 3secs

Edgard, Ivey

A few weeks ago, Oli ran some tests on the SR3 Yaw estimator (see LHO: 85745 for results). Edgard and I did some math to see if the OSEM estimator is requesting drive as expected by theory (we want our theoretical plot to align with the yellow trace in the third plot in the pdf below).

Attached below are images of the theoretical drive estimates compared against the empirical drive requests (yellow trace). The "old" theoretical drive estimate is made with the old blend filters (see LHO: 84004), and the "new" theoretical drive estimate is made with the new blend filters (see LHO: 86265).

A few notes on how we calculated the theoretical drive estimate: Because OSEM noise dominates, except at the resonances where suspoint motion dominates, we only considered OSEM noise when generating our theoretical drive estimate. We multiplied the theoretical plot by 1/3, which we eyeballed. The difference of a factor of 3 is likely an error in our math, which we can easily check. The theoretical plot deviates significantly from the empirical results below 0.6 Hz because the OSEM noise data we are using is not ideal (see the first plot in the pdf for a more accurate depiction of OSEM noise). However, the main concern is to show that the general shape is accounted for.

What the theoretical drive estimate plots show:

     The "old" plot shows that the peak at 2 Hz is expected. This peak is likely not noise as we had originally believed, but a part of a larger peak that consists of the peak at 2 Hz and its adjacent peak. For the yellow trace, the dip between the two peaks is a result of the suspoint motion dipping below OSEM noise. For the black trace, the dip between the two peaks is a result of not including suspoint motion in our math. The same can be said about the peak at around 3 Hz.

     An objective of the new blend filters was to damp the 2nd and 3rd peaks, as well as make the peaks more symmetrical. The "new" plot shows the peaks are successful at request less drive, but the symmetry of the peaks has not changed significantly.

Overall, the theoretical drive plot shows that the major characteristics from Oli's test are accounted for by the theory, and the estimator is working as expected!

WP 12747

The negative rail power supply for ISC-R3 and ISC-R5 failed this morning. Fan seized and power supply tripped off. We opted to also replace the positive 18V since IFO was already down. When power was restored, we verified the fast shutter chassis HV was enabled. Control room reported issues with the PZT/shutter readback signals. On the floor we found the PZT driver chassis was powered off. Chassis was power on.

Rack ISC-C6 (U25-U27)
Power Supplies Removed: S1202017 and S1201944
Power Supplies Installed: S1201912 and S1201915

F. Clara, R. McCarthy, T. Sanchez

DQ Shifters: Riley McNeil and Emil Lofquist-Fabris.

• Daily observing duty cycle: 57.91%, 38.96%, 38.57%, 51.84%, 53.67%, 89.90%, 55.83%. Week average: 55.24% Observing.

• This week was plagued by earthquakes, most notably the 8.8 magnitude earthquake from Russia and its subsequent aftershocks.

  • These really hindered the duty cycle of the detector.

  • The elevated ground motion in the earthquake band appears to be related to light scattering just above 20 Hz.

• BNS range was consistently around 150-155 Mpc throughout the week, with 1 exception being on Sunday, when the detector ran without the squeezer for 2 and a half hours, dropping the range by about 15 Mpc.

• There were also multiple days where the SQZ had issues staying locked, causing the detector to drop out of observing.

• Throughout the shift there has been recurring glitching/noise in the 20-40 Hz range, seen both in the glitch and strain plots. However, they were less significant in the last two days.

  • This has been seen in previous shifts, however relatively inconsistently.

• There was a recurring spike in noise in the H1 Y-manifold beam tube motion [X] at the exact same time every day this week (right after 17:00)

• For the first 4 days of the shift, there was a recurring noise from ~11:00-13:00 in the corner station accelerometers (all degrees of freedom), however starting Friday it stopped showing up.

• There was a low chi-squared PyCBC trigger that appears to be a blip, with the new SNR being the same as its original SNR on August 2.

See the full report here: https://wiki.ligo.org/DetChar/DataQuality/DQShiftLHO20250728

M. Todd, S. Dwyer

As derived in previous alogs, we are able to relate the HOM spacing observed in each arm to the surface defocus of the test masses -- which is a combination of self-heating and ring heater power (ignoring CO2 affects on the ITM RoC). From the fits we've made of the HOM spacing / surface defocus change as a function of ring heater power we can get a value for the ring heater to surface defocus coupling factor.

Theoretically from this we should be able to solve for the self heating contribution in the test masses as well -- allowing us to constrain things like the coupling of absorbed power to surface defocus at the ITMs if we assume to know the arm power and absorption values (from HWS).

Upper Limits

If we assume no absorption in ETMs (obviously not physical), and we assume the HWS values for the ITM absorptions are correct, then with a HOM spacing measurement from each arm we can get an upper limit of the coupling factor of self-heating to surface defocus for each ITM (they shouldn't be different but this is a good exercise).

Assuming alpha is the absorption coefficient, i subscript is for the ITM, and x/y is which arm. P_y,i_rh is the itmy ring-heater. G-factors are the product of ITM and ETM g-factors. Then from the formula in section 1.2 of the notes file : Gy = Gyc - B*L*gyic*(Pyerh+Pyirh) - L*(Ai*alpha_yi*Pyarm*gyec + beta*Ai*alpha_e*Pyarm*gyic), we can solve for Ai which is the coupling factor of self-heating to surface defocus.

Middling Values

If we assume quoted absorption in ETMs (measured by LIGO, on galaxy), and we assume the HWS values for the ITM absorptions are correct, then with a HOM spacing measurement from each arm we can get a more realistic value of the coupling factor of self-heating to surface defocus for each ITM (they shouldn't be different but this is a good exercise).

Assuming alpha is the absorption coefficient, i subscript is for the ITM, and x/y is which arm. P_y,i_rh is the itmy ring-heater. G-factors are the product of ITM and ETM g-factors. Then from the formula in the notes file : Gy = Gyc - B*L*gyic*(Pyerh+Pyirh) - L*(Ai*alpha_yi*Pyarm*gyec + beta*Ai*alpha_e*Pyarm*gyic), we can solve for Ai which is the coupling factor of self-heating to surface defocus.

Summary

Both of these values indicate there is certainly an overestimation of the self-heating impact on surface defocus.

For reference, the current TCS-SIM values for this coupling factor are Ai_y = Ai_x = -36.5 uD/W.   More examination is required into this.

Links to previous alogs:

1. Estimating HOM spacing shift from self-heating alone:  https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=84172