Tue Nov 18 10:11:33 2025 INFO: Fill completed in 11min 30secs

Famis 27573 Vibration Sensors To Gauge Health Of HVAC Fans Site 

H0:VAC-MR_FAN6_170_1_ACC_INCHSEC seem to be going up in that few days especially the last 24 hours.
This is also the case for H0:VAC-MY_FAN2_270_2_ACC_INCHSEC in the last day saw a fairly large increase in noise.

1616UTC rebooted the h1guardian1 machine. This was originally to switch over nds1, but Erik informed me that we had already done this some time ago. Since we already had a WP in and this seemed like a good time to do it, I went for a reboot anyway.

All nodes came back up on their own, no issues seen.

TITLE: 11/18 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Calibration
OUTGOING OPERATOR: Ryan C
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 4mph Gusts, 2mph 3min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.46 μm/s 
QUICK SUMMARY: Locked for 22 hours, SUS charge and PEM mag. injections running now. Maintenance today, then PEM measurements for the rest of the week, because....

O4C will end in 30 minutes. What a great run! Well done everyone!!

M. Todd, S. Dwyer

I've been polishing up the analysis of models estimating the various couplings of TCS powers to substrate and surface defocus in the test masses. This can be used to test the validity of the HWS estimate of the absorption in the ITMs. For reference, assuming the HWS are correct in their calibration of what the substrate defocus is in the test masses [ITMY = 63.5uD, ITMX = 54.5uD], and that my model is right for the coupling of substrate defocus from absorbed Watts of arm power [250 uD/W], then we have rougly 254mW of absorbed power in ITMY and 218mW of absorbed power in ITMX. Naively this seems too much, but I wanted to see if this could be consistent with measurements of the arm cavity Gouy phase.

Surface Defocus from Ring Heaters -- Models and Measurements

From both models and measurements, we have a much better idea now of how the ring heaters couple into test mass surface defocus. Fitting the HOM spacing in the YARM as a function of different ETMY ring heater powers, we obtain an estimate of the coupling factor of ETM ring heater power to surface defocus [1.53 +/- 0.2 uD/W]. The SQZ dataset which was taken at 2W, can be used to estimate the ring heater coupling as well because the HOM spacing of the YARM is purely the combination of the completely cold RoC (from galaxy) from the test masses plus the defocus from the ETMY ring heater (assuming negligible defocus from absorbed arm power) . The YARM cavity g-factor in the 2W state with ETMY ring heater on (2.93W) is calculated to be 0.8345. The cold cavity g-factor (without ring heaters or absorbed power) is calculated to be 0.8235. This yields a coupling factor (again, assuming negligible defocus from absorbed arm power) of ETM ring heater to surface defocus of 1.77 uD/W , which is almost within the bounds of the estimate above. These are both consistent, however, with modeled coupling factor [2.0 uD/W] with some imperfect efficiency of the ring heater heating. We can do the same analysis for the XARM with the caveat that we must assume a known ratio of the coupling factors of ring heater to surface defocus of the ITM and the ETM (we did not have to do this for the YARM because ITMY has no ring heater power). Assuming the coupling factors have a ratio beta = 1.73 (ITM_coupling/ETM_coupling)  and that the XARM cavity g-factor measured in the 2W state is 0.8373 then the inferred coupling factor for the ETMX ring heater to surface defocus is 1.80uD/W. This is consistent with the inference for ETMY. These values are consistent enough with each other that we can use them in the next inference, I believe.

Surface Defocus from Absorbed Arm Power to Infer the Circulating Power in the Arms

Since now we have a good understanding of the ring heater's contribution to the surface defocus and cavity g-factor shift, we can infer the absorbed arm power's contribution using the cavity g-factor measured at 60W. The measured cavity g-factors, calculated from the HOM spacings, were 0.8173 for the XARM and 0.8228 for the YARM. Assuming all the absorptions reporteed by galaxy are correct we can use the measured cavity g-factor shift along with modeled coupling factors of absorbed arm power to defocus to infer the arm power (JAAPE = Just Another Arm Power Estimate). The absorptions for the ITMs are 0.5 ppm, ETMY is 0.21ppm and ETMX is 0.20ppm. If we assume the coupling factors for ring heater surface defocus from the SQZ dataset and the modeled coupling factors of absorbed power to surface defocus, we get an arm power estimate of 283kW in the YARM and 481kW in the XARM. These indicate that the true absorptions in the test masses are most likely different from the galaxy numbers, as these arm powers are not consistent with the arm gain inference of the arm power, especially for the XARM.

Surface Defocus from Absorbed Arm Power to check the HWS Estimate of Absorbed Arm Power

We can repeat the above analysis, but instead assume nothing about the absorptions, and instead use the HWS estimates of the absorbed power in each input test mass. Then we can infer what the absorbed powers are in the end test masses to have measured the cavity g-factor as calculated from the HOM spacing. For ITMX, the HWS estimate an absorbed power of 218mW, and for ITMY the HWS estimates 254mW of absorbed power. To have measured a cavity g-factor in the XARM as mentioned above, with the HWS estimate of ITMX absorbed power, the absorbed power in ETMX would have to be 121mW. For the YARM measurement, using the HWS estimate of the ITMY absorbed power, the ETMY absorbed power would need to be -54.5mW. This indicates the HWS may be wrong, especially the ITMY HWS, as it is physically impossible to have measured the cavity g-factor that we did and simulataneously have that much absorbed power in ITMY (assuming the coupling factors from my model are correct).

Summary

Using two different methods, I've come a round-about-way to say that it is unlikely our absorptions are exactly as reported in galaxy, but that the HWS may not be giving us any better estimate (of the absorbed power). I am currently trying to calibrate the HWS using independent measurements, but more work is needed on that. Despite the ITMX HWS SLED just recently being replaced (we thought it was miscalibrated because it was dying), the defocus reported by the two HWS for CO2 heating differs by almost a factor of 2!

I am not well versed in HWS code and I'm not totally sure how these values of defocus are calculated from the deflection of each partitioned beam but these errors may be mis-identification of the position of the centroid.

This is a table of parameters describing the various coupling factors from the modeling. 

This is a summary table using the above modeled parameters

Conclusion: we have much more confidence in our models of various coupling factors thanks to measurements of the ring heaters effect on surface defocus, however we do not have a very good estimate of the absorbed powers or absorptions.

TITLE: 11/18 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 145Mpc
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY:

IFO is in NLN and OBSERVING as of 19:46 UTC (12 hr 40 min lock) - last time I will be writing this for a while.

Extremely calm shift and well behaved interferometer on the last EVE of O4. Wind looks great and microseism is stable.

Wishing the OWL ops a smooth shift and some more spacetime ripples.

LOG:

None

TITLE: 11/18 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 146Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: One lockloss with an easy relock after running IA. We've been locked for 7 hours, Happy last day of 04!
LOG:

• 15:41 UTC IA
  • The IMC lost lock going from GREEN_ARMS to INPUT_ALIGN then struggled to relock after INPUT_ALIGN, it took ~ 7 minutes to relock.
• 17:17 UTC NLN and commissioning
• 19:46 UTC Observing
• 21:38 UTC Superevent S251117dq

TITLE: 11/18 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 146Mpc
OUTGOING OPERATOR: Ryan C
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 8mph Gusts, 6mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.30 μm/s 
QUICK SUMMARY:

IFO is in NLN and OBSERVING as of 19:46 UTC (6hr 45 min lock)

Wind is good. Microseism is ok.

Expecting a calm shift for post-O4's eve EVE.

RyanC, Rahul

I have finished the assembly of two Tip Tilt suspensions (HTTS D1001396_V3), and both of them will be used for Jitter Attenuation Cavity (JAC) for O5 run. These two Tip Tilt suspensions (see two pictures of the finished assembly over here - view01 and view02), named as JM1 and JM3 will be installed in HAM1 chamber in Dec-Jan 2025/26. Give below are the details about the assembly,

1. Wire diameter - 0.0017in or 43 microns (purchased from California Fine Wire company in 2025).

2. Mirror used on JM1 (identified by D1000768_v2 s/n4) -  E1900393_V1_02 s/n 16, AOI = 45 degrees

3. Mirror used on JM3 (identified by D1000768_v2 s/n28) -  E1900393_V1_02 s/n 09, AOI = 5.07 degrees

Details about mirror characterization work is posted in LHO alog 88040.

Both JM1 and JM3 optics have been suspended and coarse balanced, both in pitch and yaw. I will fine tune it once they are plugged-in for electronics testing. 

Wire pulling jig (D1100735_V1) - we faced some issues when we tried using the wire pulling jig - issue captured in this document. I have handed over D1100732 to Tyler for re-work. However, this was not a show stopper as TJ showed us how it was done before (see LLO alog 36765, Nov 2017) and we recreated it - see here for details (using mirror holder with the bottom wire clamp). Also, we have created the intentional wire offset (to compensate for the heavy optic pitching up) on the wire clamps to counterbalance the optic. We have also used a bigger pitch adjuster to give us more dynamic range.

Both the suspensions have their Bosems (four each) attached and next we will connect it to the test stand and start performing SUS health checks. 

I've updated the in-lock charge measurements to start 5 minutes earlier tomorrow morning, changing the start time from 7:45am to 7:40am PT.

These measurements have been finishing either right at 8:00am or 8:01am PT recently, so moving up the start time should allow us to be back in observing mode right up until the very end of the O4 run at 8:00am PT tomorrow morning. The magnetic injections have been finishing at either 7:39am or 7:40am PT, so especially considering ramptimes, I don't expect there to be any overlap issues.

The SUS_CHARGE Guardian has been saved and loaded with this change.

FAMIS 31112

Between 2 and 3 days ago, there were some quick temperature spikes seen in the diode and chiller rooms, which seem to have propagated through to the diode boxes, amplifiers, some pump diodes, and eventually the PMC power. Not sure what caused this or if we've seen them before, but these jumps appear to have stopped and things are running smoothly.

I took another round of No BRD vs. BRD measurements for the BBSS BRDs, this time with a higher resolution.

Plots attached, including a comparison slide, on which the damped configuration (BRD installed) is the bottom picture.

Note that in the BRD-installed Roll screenshot, the line at the mode is just the cursor.

Kar Meng, Sheila

About 45 minutes after locking, we turned on the AS42 WFS to track the squeezer alignment while we stepped the ZM5 PSAMs from it's nominal value of -0.4 to -4.5V on the strain guage.  ZM4 is left at it's nominal value of 6.2V.  We doubled the ASC gain to 1 to speed this up, and stepped the psams by 0.5 V at a time waiting for the ASC to catch up a bit between steps. 

After the 42 MHz WFS signals were close to zero at our target psams value, we turned them off and ran SCAN_ALINGMENT, results are here: https://lhocds.ligo-wa.caltech.edu/exports/SQZ/GRD/ZM_SCAN/251117100527/, after that we ran scan sqz angle, results here: https://lhocds.ligo-wa.caltech.edu/exports/SQZ/GRD/SQZANG_SCAN/SQZANG_SCAN_251117101454.png

Then we started a script to move the squeezing angle.  I forgot to turn off the SQZ angle adjust servo for the first 15 minutes of the script, so this data isn't very useful since the ADF servo was running.  Now I've added a reminder to the script if it sees that is on. 

The squeezing angle that scan alignment found to be best was 167 degrees (CLF RF6, servo sign negative), it was at 159.7 from 1447439668 to 1447439844 (2 minutes 27 seconds).  

Went to 167 degrees at 1447442247, then no sqz at 1447442524.  

NLG measurement: amplified max: 0.0198 (drifted down to 0.186) minimum: 0.0007, unamplified 4.9e-5

To restore squeezing we had to trend the osems (once the ASC was cleared and the psams were back to nominal settings), to avoid this in the future we should offload the ASC before we start a psams move. 

Here is the log of times of demod 6 changes from the script:

167.1 : 1447438644.0 
177.1 : 1447438884.0 
172.1 : 1447439124.0 
162.1 : 1447439364.0 
157.1 : 1447439604.0 
200.0 : 1447439844.0 
177.8 : 1447440084.0 
155.6 : 1447440324.0 
133.3 : 1447440564.0 
111.1 : 1447440804.0 
88.9 : 1447441045.0 
66.7 : 1447441285.0 
44.4 : 1447441525.0 
22.2 : 1447441765.0 
0.0 : 1447442005.0 

Mon Nov 17 10:11:48 2025 INFO: Fill completed in 11min 45secs

Gerardo confirmed a good fill curbside.

Ibrahim, Betsy

BBSS Eliptical Baffles (D2500293) were successfully installed today. Pictures from various angles are attached.

Problems - graphics regarding these are attached as slide screenshots

• D2000483 Type 2 - 12 O'Clock Baffle Brace
  • LHO did not recieve coated parts for this*, but it does not seem like this part is visible due to the baffle itself.
    • Note*: LHO recieved one coated part weeks after ours had gone into C&B so wasn't part of same set/load - either way missing one coated.
  • This part is extremely difficult to install due to poor sighting and no room. The screw that fastens this part has to be installed from behind the figure 8, where there isn't even enough room to fit the width of a 9/64 allen wrench. A combination of tweezers, wrenches, bent T-wrenches were used and we finally got it in. However, we could not tighten much in the case of the back.
  • Potential Fix: The sides of that thru hole have free thru holes that could fit another bracket instead of the 12 O'Clock one (~11 and ~1 O'Clock).
• D2000483 Type 1 - 6 O'Clock Baffle Brace
  • Helicoil call-out is incorrectly 1/4-20 X 1.5D but using those results in the helicoils bottoming out and appearing proud. So, removed and used 1D instead - it works. Will redline
• D1900594 V10 Mounting Bracket
  • 2 of these were too long to fit into its recessed spot in the Lower Structure, which seemed like a machining issue (barely 0.2 mm if I had to guess). To fix this, betsy and I filed off the problem surfaces until they fit. The filed surface is a mating surface and we used a clean-file.
  • Part incorrectly called a wire baffle - will edit DCC and redline

Remarks: I added one of those coated screw caps to the Y-Brace (D1900589) strut fasteners since I could see it shining in the head on picture. Comparison pictures for this are below.

Here is how the PR3 and SR3 signals show up at various ports.

I drove a pitch line from PR3 M3 and SR3 M3 at 8.125 Hz with the ASC notches on. I was able to see at signal with a 10 ct drive on PR3 pitch and 60 ct drive on SR3 pitch.

Templates saved as {PR3,SR3}_M3_injection_all_ports.xml in /ligo/home/elenna.capote/POPX_test in case the data is useful to you.

PR3 appears strongly at REFL and POP in I and at AS in Q. SR3 appears strongly at AS in Q and POP in Q.

Will try to repeat for yaw.