E. Capote, J. Kissel, A. Sanchez, D. Barker, E. von Reis

Per WP#12649, the ASCIMC model was updated. Two test points were added to the IMC-WFS_B_{PIT,YAW}_OUT outputs that were then DQed to 16k, see attached screenshot of the new testpoints. These channels are being saved at the higher rate so they can be used as jitter witnesses, see attached screenshot of the channel list. The new channel names are "IMC-WFS_B_{PIT,YAW}_16K_OUT". Erik helped me set up these new test points, and Dave took care of the model and DAQ restart.

Before the model restart, I had checked the ASCIMC model and saw no SDF differences, so I assumed that we were good to go to restart the model. Here are two errors I made:

• the IMC WFS should be offloaded before this, and the resulting PZT offset should be SDFed
• the IMC should be taken offline, so the restart doesn't kick the suspensions

Once the restart had happened, and SDF reverted, the IMC came back very poorly aligned. Jeff and Tony had to move the IMC PZT offset by "hundreds of counts" to get us back to a good enough alignment to lock. After that, Jeff, Tony, and I proceeded to engage the IMC WFS, and turned up the WFS gain to 0.5 to help the loops converge faster. Once they converged, we took the IMC guardian to "MCWFS offloaded". Here, we made another mistake by forgetting to accept the PZT offsets in SDF, so when ISC_LOCK went through the "SDF revert" state, the offsets were set to some old value, which put the IMC back in a bad alignment. We repeated the process again, and this time remembered to save the new offsets in the SDF. I have attached a screenshot of this change.

Per WP12651 we investigated and replaced the IO Chassis supply for H1SEI23 which supports seismic on HAM 2 & 3.  This supply is located in Mezanine rack C3, location U2 Right Side, provides +24V, and measured ~3.5A draw.  The fan was chirping and grinding which suggests a failing fan bearing.

Old Supply = S1202002 old fan worn out bearing to be refurbished.
New Supply = S1201919 new fan with ball bearing.

F. Clara
M. Pirello

F. Clara, E. Capote

Per WP#12646, Fil and I went out to the floor and realigned the ITMX green camera, as Sheila noted it was poorly aligned in alog 84819. (Before we began, Corey transitioned the LVEA to laser hazard per WP#12647).

Before going out to align, I locked the X arm in green only using the camera offsets for the alignment. I offloaded this X arm alignment, so it could be preserved once we moved the camera.

With the X arm still locked, Fil and I connected a computer to the green camera output, which gave us a faster, live view of the camera as we adjusted it. Fil used a Rainbow controller to zoom out very far to reduce our chances of moving the beam too much and losing it. Fil then removed the camera housing cover, and adjusted the nobs on the camera. As he adjusted in the desired direction, I zoomed the camera in slowly, to ensure that we were moving the beam closer to center. We iterated this process several times. The first time Fil went to put the camera cover back on, we noticed that the action of placing the cover bumped the aligment a little bit, so we had to overcorrect in the opposite direction slightly so that the beam stayed centered as Fil replaced the cover. I then tried adjusted the zoom and lens slightly, and decided that the image was well-centered enough to finish the work.

Once we were back in the control room, I updated the camera offsets. I have attached the SDF of these new offsets.

Per WP 12570 we stopped the cameras on h1digivdeo[45] and updated the pylon and pylon-camera-server software.  This was to bring in a fix in the pylon library for leaked file descriptors when a camera dropped and reconnected.

Last week we just restarted the software to close all the leaked file descriptors.  This should solve the problem.  This was not a feature update of the camera software, just a rebuild against a newer pylon library.

This was done 8:50-9:00am local time (16:00 UTC).

The procedure was to:

1. run apt-get update

2. stop all the camera processes via the management web page

3. run apt-get install pylon pylon-camera-server

4. restart all the camera processes via the management web page

5. spot check a few cameras to make sure things come back.

Sheila, Camilla

We can see large SQZ changes dependent on the OPO PZT value, we;vee seen this before, some alignment changes from this PZT should be adjusted for by FC AS and FC beamspot control. The FC beamspot control has been off since the vent, but we're turned FC beamspot control on again in the hope to reduce this dependency.

Yesterday we needed to turn the ASC on to improve high freq sqz 85147 and since we've started using the THERMALIZATION guardian 85083 to slowly adjust SRCL Offset, our squeezing and ASC error signals are reduced slightly (see below). We have turned back on the SQZ ASC as expect this new guardian will stop the ASC running away.

Now we have the THERMALIZATION guardian working, the ADF measured sqz ang change has reduced (see below), we want to try turning back on SQZ_ANG_SERVO which will take a little tuning of settings. You can see in this plot that when the OPo PZT changed, the servo would have adjusted the sqz angle too.

• THERMILIZATION GRD on, SQZ ASC off plot: ASC error 0.35, ADF sqz ang change 7.
• THERMILIZATION GRD off, SQZ ASC off plot: ASC error 0.4, ADF sqz ang change 18.
• THERMILIZATION GRD off, SQZ ASC on plot: ASC error N/A, ADF sqz ang change 11.

Also touched the SHG launch waveplates to decrease the rejected power in H1:SQZ-SHG_FIBR_REJECTED_DC_POWER.

A single blank line was added to the end of the filter file for H1SUSAUXEX to test whether the IFO can enter the OBSERVE state with unloaded filter changes.

If loaded, this change would have no effect on the behavior of the filters.

We should be ready to go to laser safe in the LVEA.

Alenna noted that we will have CP-Y spots on the ballast baffle even when the CP is propertly aligned (which is why we eventually want to remove/fix the baffle), so I swept the CP in pitch and yaw and found a minimum in scatter coupling at about -300 p, 300 y.  The varying noise from the pump on HAM1 interfered with the measurement, so I think I can further minimize the coupling once the pump is off.

The figure shows that the “mystery” beam spot on the HAM3 spool piece dropped dramatically in intensity over the break. I don’t know if it was the compensation plate move or something else that we did. Im a little skeptical that it was the compensation plate move because, before the break, I moved the compensation plate while filming the spot and saw no change (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=82252). However, I think that this is worth doing again to double check.  

Kiet and Sheila,

Following up on the investigation posted in aLOG 84136, we examined the impact of higher-order violin mode harmonics on the contamination region.

We found that subtracting the violin peaks near 1000 Hz (1st harmonic) from those near 1500 Hz (2nd harmonic) results in frequency differences that align with many of the narrow lines observed in the contamination region around 500 Hz.

Violin peaks that we used (using O4a+b run average spectra)

F_n1 = {1008.69472,1008.81764, 1007.99944,1005.10319,1005.40083} Hz 
F_n2 = {1472.77958,1466.18903,1465.59417,1468.58861, 1465.02333, 1486.36153, 1485.76708} Hz 

Out of the 35 possible difference pairs (one from each set), 27 matched known lines in the contamination region to within 1/1800 Hz (~0.56 mHz)—most within 0.1 mHz. Considering that each region actually contains >30 peaks, the number of matching pairs likely increases significantly, helping explain the dense forest of lines in the comtaimination region.

Next steps:

• Testing all the peaks in the 1st and 2nd harmonic region.
• We propose to identify lines with highest power in the contamination region, trace them back their source modes and discuss the feasibility of target damping them. 

The Fscan run average data are available here (interactive plots): 

Fundamental region (500 Hz): 

• 400–500 Hz
• 500–600 Hz

1st harmonic region (1000 Hz): 

• 900–1000 Hz
• 1000–1100 Hz

2nd harmonic region (1500 Hz): 

• 1400–1500 Hz
• 1500–1600 Hz

Summary of (our knowledge about) 2nd loop array units are available on DCC: https://dcc.ligo.org/LIGO-D1101059

We opened the container of S1202966 in the optics lab for inspection. This is a unit removed from LHAM2 in 2016.

We found no damage (1st picture), all photodiodes and the QPD look OK, no chipping of the optics, but many components are missing.

• Missing upgrade components to lift QPD higher to make it closer to the optical plane of the array photodiodes. We'll search for spares.
  • D1300718. This is a kit comprising two 4.501" poles with cutout, one 6.511" pole and two thinner 3" poles.
  • D1300719. This is called QPD MT PLATE, it's a top platform to mount the QPD as well as the ISS array cover assembly.
  • Related hardware.
• Missing upgrade components to tilt QPD. We have spare parts.
  • D1400146 Beveled C-bore Washer to tilt the QPD assy by 1.41deg to avoid direct reflection back. We have spares we can use.
  • D1300963-V2 updated QPD clamp plate to accomodate 1.41deg tilt. V1 doesn't work. We have spares we can use.
•  Missing extended ISS array cover/lid assembly parts (ECR https://dcc.ligo.org/LIGO-E1300662). We will search for spares.
  • D1300717 Array Cover (Extended). Unlike the name would make you believe, this is not the cover assembly, but is a kit comprising one each of 5 different panels i.e. D1300717-101, D1300717-102, D1300717-103, D1300717-104 and D1300717-105. 
    • At least 5 kits have been made according to ICS. We know of four kits used for existing arrays, i.e. two in the existing IFOs (one each at LHO and LLO), one in the optics lab for S1202965, and the last one for S1202967 that was bent and contaminated. Assuming that the 3IFO unit (S1202968) has the cover, we might not have a spare.
    • But the same ICS record also shows 5 pieces of mysterious (to me) D1300717-00, four of which are supposed to be at LHO. If D1300717-00 means the entire kit comprising 5 panels, we might have spares.
  • D1300890 Array Cover Corner Support. This is a kit of 3 different corner braces, i.e. 1 piece of D1300890-1, 2 pieces of -2 and 1 piece of -1. 
    • According to ICS we seem to have produced 9 kits. Like D1300717, we know four kits used for existing assemblies (H1, L1, S1202965, S1202967), and I assume that the 3IFO unit (S1202968) has one. So we should have four spares somewhere.

I decided to disassemble the damaged/contaminated S1202967 partially to send some of the parts to C&B and keep them as the last-resort spares. Jennie sent the following parts to C&B. There are deep scuffs which should be the result of repeated metal-to-metal contact/scratching, but they should be OK for use once they go through C&B.

• D1300718. A kit comprising two 4.501" poles with cutout, one 6.511" pole and two thinner 3" poles.
• D1300719. Top platform to mount the QPD as well as the ISS array cover assembly.
• Related hardware.

ISS array cover might be salvageable but the place where the poles are attached is bent so badly, bending it back might break it. See the 2nd picture, the surface is supposed to be flat.

Kiet, Robert, and Carlos

We report the results of calibrating the LEMI magnetometers in the Vault outside of the X arm; 

We went out on May 15th, 2025 and took the following measurement with each lasted 2 minutes.
Far field injection: to calibrate the LEMI 

1) 17:36:45 UTC; X-axis far-field injection; without preamp on the Bartington 

2) 17:43:23 UTC; X-axis far-field injection; without preamp on the Bartington 

3) 18:01:53 UTC, X-axis far-field injection; without preamp on the Bartington 

4) 18:04:15 UTC, X-axis far-field injection; without preamp on the Bartington 

5) 18:23:25 UTC; Y-axis far-field injection; with preamp on the Bartington 

6) 18:26:00 UTC; Y-axis far-field injection; with preamp on the Bartington 

The preamp gain is 20; all injections are done at 20Hz. The coil used for far field injection has 26 turns, 3.2 Ohms.

The voltage that was used to drive the injection coil for farfield injection: Vp-p: 13.2 +- 0.1V. It was windy out so we decided to use the preamp on the Bartington magnetometer.
The LEMI channels used for this analysis: H1:PEM-VAULT_MAG_1030X195Y_COIL_X_DQ; H1:PEM-VAULT_MAG_1030X195Y_COIL_Y_DQ

Bartington calibration

7) 18:49:38 UTC; with preamp on the Bartington 

8) 18:52:50 UTC;  with preamp on the Bartington 
the voltage that was used to drive the injection coil for farfield injection: Vp-p: 1.88V +- 0.01V 
We inserted the bartington magnetometer to the center of a cylindrical coil to calibrate its z axis(1000 Ohms, 55 turns in 0.087 m) 

The final results of LEMI calibration after taken accound the all the measurements is (9.101 +- 0.210)*10^-13 Tesla/counts, there is a 20% difference between this measurement and the measurement taken pre O3. Robert noted that when taking the previous measurements, the calibrating magnetometer was not fully isolated from the LEMI. This time they are completely independent.

We recommend analyses that use LEMI data to use the calibration value of  9.101 * 10^-13 +- 5% Tesla/counts to be consersative.  

This morning we had a 1Hz instability that started in the LOWNOISE_LENGTH_CONTROL state. 

The next lock we went through this state step by step, and step of reducing the SRCL1 gain from -18 to -7.5 is what started the issue.  Setting this back to -18 seemed to get rid of the 1Hz signal in SRCL, but the oscillation continued to grow in PRG and other channels. 

Then Elenna set CHARD P back to the high bandwith configuration by undo-ing line 4569 in ISC_LOCK, by doing:

            ezca.switch('ASC-CHARD_P', 'FM9', 'ON')
            ezca.switch('ASC-CHARD_P', 'FM3', 'FM8', 'OFF')
            ezca['ASC-CHARD_P_GAIN'] = 80

This stopped the oscillation, then we were able to set the SRCL gain back down to -7.5 without issue, then undo the CAHRD P changes, again wihtout issue. 

We don't understand this, but we have again moved the location of LOWNOISE_ASC in the guardian, so that the CHARD changes will happen before the SRCL gain reduction next time we relock.

Note to operators:  If you see this 1 Hz bussing in the PRG, put CHARD into it's high gain state by pasting the above lines into a guardian shell, all at once.

Jim, TJ, Robert

We damped the periscope on ISCT1 by removing the dog clamps one by one and inserting a strip of 1/16" viton between the dog clamp and the base of the periscope before retightening, making sure that the strips crossed the corner of the base. This is not the most effective way of damping the periscope but it was the fastest, safest and most simple damping we could do. Jim measured the Q to be around 1000, so we didn't have to do much to get an improvement. In Jim's first transfer functions after the damping, the peak looked a little wider.

Bin Wu, Julia Rice

We have been working on writing a new Guardian script that will allow us to switch off the dither loops sooner in the power up process and instead use cameras.

We first looked at the error signals in the ASC cameras to see if we could adjust offsets to better values. We did this for the CAMERA_SERVO guardian, and added new intermediate states, including TURN_ON_CAMERA_25W_OFFSETS and TURN_ON_CAMERA_MOVESPOTS_FIXED_OFFSETS. We've attached screenshots showing the graph before and after our additional states. Below are the values we used for offsets for each. The weight from DITHER_ON to TURN_ON_CAMERA_25W_OFFSETS is set to be 10.

TURN_ON_CAMERA_25W_OFFSETS

TURN_ON_CAMERA_MOVESPOTS_FIXED_OFFSETS

We also adjusted the offsets for TURN_ON_CAMER_FIXED_OFFSETS:

These are added in lscparams.py. We also added the necessary code into CAMERA_SERVO.py.

We also added a parameter in lscparams.py for new ADS camera CLK_GAIN at 25W  ('ads_camera_gains_25W', screenshot included)

Right now the new states are not requestable, so they will need to be ran manually to test. We haven't made any change to the ICS_LOCK guardian.