Following our influx of bees, M. Landry ordered an interior inspection of each beam tube enclosure (BTE) interior to document potential areas of ingress. R. Thompson with Apollo Mech is presently tasked with this inspection. During inspection of the X1 enclosure, roughly 5 sections -X of the X arm overpass, Randy observed cracking at the base of the interior of the enclosure. After further investigation he found 4-5 cracks running parallel of one another across the entire section at roughly the 10 & 2 o'clock positions. I was called to come give this section a second look. The cracks were also immediately concerning to me. The first thing I wanted to better understand was the interior width to assess if the section was shifting.

With Randy's help, I measured the interior spans of each end of the neighboring tube sections (4 measurements) as well as an additional 4 of the same spans of the tube sections on display outside of the LExC. On average, these spans measure 151" +/- .25". The section in question measures 154" at each end. Moreover, during installation Fred Raab has informed us that grouting was done on the BTE interiors to mitigate a "walking" effect that was causing misalignment between sections. This grouting has clearly separated from the BTE interior which confirms that there is in fact splaying of this section.

The current short term "fix" implemented by FAC and VAC has been the erection of scaffolding topped with planking across the 10' area of beam tube at risk of falling debris. This should act as makeshift roof. For the long term, R. McCarthy is currently consulting with structural engineers whom we hope can help us work up a solution to prevent further splaying.

Contained in the photos attached are measurements with appropriate labeling of each section (number counted from second door on X1 traveling -X), as well as a "+X" or "-X" which simply denotes if the measurement is on the +X or -X end of the tube section, photos illustrating the separation of the BTE interior from the as-installed BTE grouting, the scaffolding presently in place, the cracking at the footing/mid sections, and a LIGO Yelp review written in welders soapstone (circa ~96') near the splayed tube section.

C. Soike, E. Otterman, T. Guidry, G. Moreno, T. Sadecki, J. Vanosky, R. McCarthy

J. Kissel, M. Pirello

There are four pico-motor actuated mirrors in the HAM2-3 ISI SPI Pathfinder (or, generically HAM2 = ISI"J" and HAM3= ISI"K"), M_M1, M_C1, M_B4, and M_M2 (see page 3 of D2400108). Those optics have the following mounts:
    - M_M1 = IXM100.C2L-VC LIGO = 1" optic mount, left-handed.
    - M_C1 = IXM200.C2-VC LIGO = 2" optic mount, right-handed.
    - M_B4 = IXM100.C2-VC LIGO = 1" optic mount, right-handed.
    - M_M2 = IXM100.C2-VC LIGO = 1" optic mount, right-handed.

To-date the assembly procedure has been scattered into incomplete pieces, including separated mechanical assembly (D1100362 and E2500163-v1) and electrical assembly (D1400279). 

As such, I've created an all-inclusive assembly procedure in E2500163-v2, and the DCC file-card now perma-links to a google photo album containing many more photos than even what's in the procedure.

So, now I can write this aLOG, which "just" says -- we've completed the assembly for SPI's four pico-actuated mirrors, per E2500163-v2 assembly instructions.

It's always challenging to get a photo highlight, so I'll attach the best one I got mid assembly (i.e. the picomotors weren't yet connectorized, nor were the ECR E1400327 range-limiting shafter collars installed). 

The 2nd, 3rd, and 4th attachment show three photos I got of the completed M_M1 (IXM100.C2L, 1" left-handed) mount.

Jenne allowed us to quickly drop from observing to change the EY camera offsets. Yesterday we updated them 87473 but didn't load the camera servo guardian, so the guardian did not use the correct lscparams file. This meant that the A2L gains (ISC_LOCK controlled) were set for the new spot, but the camera offsets (camera servo guardian controlled) were at the old spot. This was also missed because these values are not monitored in the observe SDF files. We noticed that:

• the buildups were even lower than normal, because the camera offsets were wrong
• therefore kappa c was at 0.96
• the sensitivity was also bad because the A2L and camera offsets were mismatched, causing extra ASC coupling
• the calibration monitoring lines showed 3% uncertainty at 33 Hz, this is usually 2%

Many of these are issues are documented in Ryan's shift alog here: 87485.

We dropped out of observing and I set the EY camera offsets to their proper value. This immediately began increasing the PRG and arm power. Then, I loaded the camera servo guardian so that when we relock these values are set properly. Then, I proceeded to monitor all the camera offsets and A2L gains and accept their new values in OBSERVE. This will cause SDF differences if these values change. However, I think these are important enough settings that we should be monitoring them for observing.

Kappa C has increased and the calibration monitoring lines are now back to 2% or less.

TITLE: 10/15 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 0mph Gusts, 0mph 3min avg
    Primary useism: 0.08 μm/s
    Secondary useism: 0.13 μm/s 
QUICK SUMMARY:

• 14:00 UTC Observing
  • DCPD window shows something ringup then damp back down in the past 15 minutes, Transient PI? It was smaller than we saw yesterday (added plot at 18:39)
• 14:17 UTC GRD-Short E610359
• Secondary microseism continues to decrease, low winds
• Lockloss doesn't seem to be updating, the most recent one isn't showing up
  • The web site says: online last update: 1076.1 min ago (2025-10-14 13:42:18.164546)

Wed Oct 15 10:05:11 2025 INFO: Fill completed in 5min 8secs

Gerardo confirmed a good fill curbside.

The chilled water plants at the Mid stations have been shut down for the Winter. 

TITLE: 10/15 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 156Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: Observing at 155 Mpc and have been Locked for about 8.5 hours. Nothing happened during my shift besides a couple of ITMX saturations.
LOG:

23:00UTC Observing and Locked for almost 3 hours
    23:34 Left Observing to close beam diverter
    23:34 Back into Observing

Still Observing and have been Locked for almost 7 hours. Secondary microseism has continued to drop. Our range has been a bit better than it has been the last couple of days, so that's cool. 

First attachment is a screenshot of D1300130 ISS array PD assembly (which is somehow called "PSL PDD MODULE").

Each PD (part #8) is entirely retained in an aluminum cylinder called the PDD main photodiode mount (part #9) and therefore the can of the PD is conductive to the cylinder. However, the cylinder is supposed to be isolated from the ISS array plate (and therefore the entire ISS array structure) by two pieces of kapton insulators (part #10). PCB assembly, which is connected to the PD, is sandwiched between two aluminum clamps (part #2 "PDD clamp" and part #11 "Clamping plate", which I refer to the bottom and the top clamp respectively), but the PCB ground is isolated from the clamps by an insulator ring (part "7?").

This way ground loop is broken even though the can of the PD is connected to the shield of two SMP coax cables on the PCB board (part #1).

Rahul and I checked the continuity between the cylinder and the ISS array cage. (Note that this check could not be done without disconnecting all SMP cables from the preamp first, because the preamp's ground is somehow connected to the optics table, which is connected to the ISS array cage.)

Issues found on the installation spare:

Unfortunately two of the PDs on the first floor (PD 5 and 6 in our notation in the lab, see the 2nd picture for the notation even though that is the picture of the 3IFO unit) didn't pass the check.

We also checked the grounding of the QPD and it was good.

Inspecting 3IFO, finding the same issue, and fixing it:

We quickly checked the 3IFO unit too and found that it also had a grounding issue for one of the PDs (PD 2). In the 2nd attachment, you can see that the space between the top and the bottom clamp of PD2 is smaller than the others.

We removed the top clamp and found no insulator (3rd attachment). We disconnected the PCB from the PD and learned that:

1. Disconnecting the PCB won't change the PD position. PD is somehow firmly attached to the main photodiode mount, and it won't shift unless we loosen the bottom clamp. 
2. The insulator was found on the other side of the PCB, between the PCB assy and the PEEK pin guide (part #4).
3. Installing the insulator on the correct side (4th attachment) and reinstalling the top clamp, the grounding was broken.

Fixing the issue on the installation spare:

With the new knowledge about the insulator, we looked at the gap between the top and the bottom clamps of the PDs for the installation spare unit and it looked like PD5, 6, 7 had the insulator on the wrong side of the PCB even though PD7 didn't have the grounding issue.

Sure enough, we removed the top clamp for these problematic PDs, found no insulator for any of these (5th attachment), removed the PCB and found the insulator on the wrong side (6th attachment shows you one example), installed them correctly and the grounding problem was gone.

Electrical test:

Since we have disconnected the PCB and reconnected to the PDs, we reconnected all of the PDs to the preamp again and confirmed that all PDs still respond to the light as they used to.

We haven't measured if any one of these are much noisier than the others, which we'll check later.

Closes FAMIS#28427, last checked 87380

ITMX had too low of coherence again this week so it didn't run. Everyone else is looking normal.

ETMX

ETMY

ITMX

ITMY

Jennie W, Keita, Rahul

On Friday, Keita and Rahul and I tried moving PDs 2 and 6 to align them better with the others. As can be seen from the scans we did of the DC voltage of the diodes as we moved the input alignemnt in horizontal translation and yaw from alog #87290, 2 and 6 have a range of alignment that is shifted relative to the other 6.

We also checked this with a IR sensitive camera with a zoom lens.

One person used the camera with a zoom lens to check the spot on the PDs as another person loosened the screws from behind the array and the third person held the barrel of the PD assembly to stop it moving or rotating in an undesired direction.

There is not a lot of space as 2 and 6 are in a column and are very close to diodes 1 and 5 on the right.

The horizontal scan we took after these moves showed we had made things worse, see this image.

Later that afternoon, Keita moved the PD 2 back and checked the alignment and it looks better.

The alignment as of yesterday (Monday) was 143mm in pitch (as read out by the allen key in the PZT mirror pitch actuator wheel) and 0.4145 inches in horizontal translation as read out by the translation stage the PZT mirror sits on.

Keita measured the coupling (after finding an error in my code from the previous coupling measurement I plotted last Thursday (alog #87400)).

The coupling in both vertical and horizontal is below 10, so this should be good enough for install if all else checks out.

Yesterday afternoon, Rahul and I did the vertical scan (slightly off from the horizontal reference position of 0.4145 inches that Keita had aligned to). The data in this graph was collected at a horizontal translation stage reading of 0.4162 inches.

We had to redo the horizontal scan today as I missed out some scan values yesterday. The data was collected with the pitch indicator at 143mm (the allen key on the pitch wheel actuator).

WP 12836
ECR E2400330
Modified List T2500232

The following SUS SAT Amps were upgraded per ECR E2400330. Modification improves the whitening stage to reduce ADC noise from 0.05 to 10 Hz.

F. Clara, J. Kissel, O. Patane