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!

Jennie W

Francisco is helping me read data from the oscilloscopes we are using for the PD readout so we can measure a QPD to PD transfer function to figure out how the PDs are mis-aligned.

While he was working on this I went to re-align the input beam to the array as our last measurements of the coupling amplitude in the horizontal direction showed that the coupling was much larger than Shiva and Mayank had previously measured.

I found we could get better coupling with the input beam off in yaw on the QPD - I got this by moving the closest steering mirror to the input aperture in pitch and yaw (as these are both coupled slightly due to the QPD y and x axis not being perfectly aligned with the steering mirrors pitch and yaw directions).

Pictures I took are attached, photos one (showing AC voltage of PDs 1-4) and two (AC voltage of PDs 5-8) are only moving the steering mirror in yaw but the light went off the centre of the QPD too much (we expect it to be above 10000 counts but here it is ~6000), so I found another spot with less power drop on the QPD that still has pretty good alignment coupling to the PDs. For this latter spot I also included the photo of the QPD readout.

Photo 3 shows the QPD readout and the oscilloscope with the AC voltage values of PDs 1-4. The power on the QPD is about 9000 counts.

Photo 4 shows the oscilloscope with the AC voltage values for PDs 5-8.

Photo 5 shows the oscilloscope with the DC voltage values for PDs 1-4.

Photo 6 shows the oscilloscope with the DC voltage values for PDs 5-8.

Photo 7 shows the x, y and sum channels for the QPD on an oscilloscope.

We might have to move the QPD in yaw to centre it for this pointing into the PD array.

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

This morning the Well water tank located behind the carpenter shop was found to be nearly empty with under 1ft of water. At approximately 7:50am the Well water pump was energized and used to fill the tank back up. For noise and vibration considerations the well pump ran water from approximately 7:50am until 8:18am. The well tank is now full again. 

TITLE: 08/11 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Aligning
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 4mph Gusts, 2mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.11 μm/s
QUICK SUMMARY:
H1 was down and trying to do an Initial_Alignment but saturating a number of suspensions, verbals warning about  IFO_OUT from 14:17 UTC to 14:28 UTC so over 10 minutes of shaking the IFO OUT of the output arm. 

I'm getting a persistent DIAG_MAIN message:
FAST_SHUTTER_HV: Fast Shutter HV not Ready

@ 1309 UTC Fast shutter channels: 
H1:SYS-MOTION_C_SHUTTER_G_TRIGGER_VOLTS went to 3.877 V when it should have already dropped down to 0.5V or so.
H1:SYS-MOTION_C_SHUTTER_G_TRIGGER_POWER has increased to 1.9 mW when I'd expect it to go back down to 0

Both increased to levels that seem within the operational bound but not what their trends would suggest they should be operating at.

I cannot Close the fast shutter either. 
H1:SYS-MOTION_C_FASTSHUTTER_A_READY says Busy.

Error Fault; Not Ready ; Not Closed.
 

TITLE: 08/11 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 155Mpc
INCOMING OPERATOR: Oli
SHIFT SUMMARY:

IFO is in NLN and OBSERVING as of 04:48 UTC

Just got to Nominal Low Noise after a 5.8 EQ from Guatemala (lockloss alog 86288).

Otherwise, just the most uneventful of shifts. Relocking was fully auto and DRMI lock was swift post-earthquake.

LOG:

None

Earthquake caused lockloss. This was a 5.8 EQ in Guatemala.

Recently, I noticed that the mystery beam spot on the spool piece near HAM3 was much dimmer after the break this spring than in was before ( 85079) To see if this change may have been associated with the CP-Y move we made during the break, we swept through nearly the entire range of pitch and yaw (-300 to 300) while taking a video.  The linked video (https://www.youtube.com/watch?v=DIwnx13NzEU&ab_channel=RobertSchofieldLIGO)  shows the view from the MC2 camera viewport before the break and after the break. The drop in intensity over the break is quite obvious, but I can see no further change in intensity during the sweep. The sweep can be monitored in the video, both before the break and after, by the motion of the ghost beam spots on the ballast baffle below PR2 (on the center left of the image).  The CP move during the break was larger than these sweeps, so it is still possible that the move during the break was the source of the drop in intensity. 

However, another possibility is that the movement of the PR2 beamspot, and the reduction in clipping on the PR2 scraper baffle was the source of the drop in intensity.  The last pictures I took of the mystery beam spot before the break were in  January of 2025. After that, there were a series of moves of the PR2 beam spot and associated reductions in the intensity of the beam coming out the HAM3 viewport that were made in February of 2025 (82670, 82722, 82740, 82793), reducing the power in the beam that comes out of the viewport from about 17mW to about 3.5mW. The ”before” clip in the video below was made in December of 2024, when the HAM3 viewport beam was in the 17mW era, while the ”after” clip is at 3.5 mW, if we assume it is the same now as before the break (could be worth checking).  If the ”mystery” beam spot comes from the edge of the scraper baffle (see figure), then the PR2 spot moves might have reduced its intensity, by a factor of about 5 if it is proportional to the light at the viewport.

The figure shows that there is a spot on the edge of the scraper baffle (which is only there when laser light is present) that seemed to get dimmer when the mystery spot got dimmer. The diagram shows how the reflection/diffraction would light up the wall of the spool piece as seen in the photographs. The edge of the aperture would be lit by the beam that is clipped and especially by the beam reflected off of the baffle to the viewport and reflecting back to the baffle.

Samantha Callos, Robert Schofield

There is a persistent peak at 20 Hz that has been appearing and disappearing intermittently for several months. I have found the times it existed corresponded to work hours during week days. Robert and I looked at the summary pages and DTT for the floor accelerometers and noted that the noise was most present in the area around YCRYO, we ruled out other locations around site and determined the source of the noise was coming from the Vacuum Prep Warehouse. We tested seismic isolation of the various HVAC units around the warehouse and found the Liebert AC unit inside the VPW which can manually be turned on and off and was moved there sometime in the last year.

I cycled through intervals of turning the Liebert unit off and on and checked the CS floor accelerometers for those times (see times below, Fig. 1, and blue arrows in Fig. 4). When the unit is off, the spike at 20 Hz in the accelerometers disappears. I then checked coupling to DARM and noted the noise at 20 Hz was present and that there was a harmonic at 40 Hz as well (see Fig. 2).

Additionally, for the external AC (Daikin), we noted that the springs it is mounted on are entirely compressed, so there is little to no seismic isolation for the entire unit. Noise from the previous unit has been found in DARM before (see alog 77477). The closest accelerometer to this HVAC unit is the YCRYO floor accelerometer and the shut down period can be seen in the spectrogram for it (see Fig. 3). It can also be seen automatically turning off and on the summary page 24-hour spectrogram (see Fig. 4). Comparing this shut down period to when it is on, it does not look like the noise is making its way into DARM for now, however, we recommend seismically isolating the Daikin as we have seen it couple to DARM before. 

Liebert AC on/off times for 08-05-2025:

• On 19:15 UTC
• Off 19:20 UTC
• On 19:25 UTC
• Off 19:30 UTC
• On 19:35 UTC
• Off 19:40 UTC
• On 19:45 UTC

Liebert AC on/off times for 08-06-2025:

• On 17:00:00 UTC
• Off 17:05:00 UTC
• On 17:10:00 UTC
• Off 17:15:00 UTC
• On 17:20:00 UTC
• Off 17:25:00 UTC
• On 17:30:00 UTC
• Off 17:35:00 UTC

Liebert/Daikin on/off times 08-06-2025:

• Liebert and Daikin ON: 20:50:00 UTC
  • Both on for 20 minutes
• Liebert OFF and Daikin ON: 21:10:00 UTC
  • Daikin on for 20 minutes
• Liebert and Daikin OFF: 21:30:00 UTC
  • Both off for 20 minutes
• Liebert ON and Daikin OFF: 21:50:00 UTC (technically 21:49)
  • Liebert on for 20 minutes
• Liebert and Daikin OFF: 22:10:00 UTC
  • Both off for 20 minutes
• Liebert OFF Daikin switch FLIPPED TO ON (it has a warm-up period): 22:23:50
• Liebert OFF and Daikin ON: 22:29:00 (ish)

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