Since yesterday, we have received an answer from Ali and Keita, that the determination is that the cathode and anode pins are in the correct location. There is a longer explanation about what's going on here and which diagrams are wrong, but I will leave that to them. Therefore, the only cable work that needs to be done is to adjust the pins on our "bad" cable, and then switch the DCPD cables between OMCA and OMCB.

Morning (no cable work):

Oli and I pulled the first contact that we left from yesterday. We just need one 50/50 45 deg AOI mirror for BHSS, and we were able to completely clean two of this type. More of these mirrors will be needed for the greater BHD layout, so Oli and I need to revisit the other three that still are not clean. For now, they are stored on the flow bench in clean single cases.

We went to begin the BHSS alignment, and found that no laser beam was coming out of the fiber. Some time between this alog, when Camilla and Oli aligned the beam into the fiber, and now, the beam was misaligned again. We think one of the mirrors to the fiber coupler was bumped. Correcting this took a little while. Oli had to leave, so Keita and I continued with the alignment. Luckily, our downstream alignment is still good- with the iris alignment template placed on the BHSS, we can see the beam comes down the center of both irises to OMCA.

Most of the beam reflects off the OMC, so Keita and I started turning up the power into the fiber. At some point, we turned up to 20 mW coming out of the fiber. We could see a faint beam transmit from the input coupler and make it to the output coupler. However, we still had a hard time seeing any beam make it to the DCPDs, probably because the power is still very low. We set up a beam block of the OMC REFL path for now, since it just goes right back off the suspension. At this point, we realized it's probably not a good idea to put so much power into the fiber, so we lowered the power again to have about 2 mW coming out of the fiber.

Afternoon (cable work):

Keita and I proceeded to fix the cables. We first checked which cables went to which pins:

Cable D2300119 (for OMCB): longer is on trans PD, goes to pins 4/5, shorter on refl PD, goes to pins 1/2

Travis, Jordan

HAM1 was vented today per M1300464 and E2300169, no pressure change in the corner during the venting. Dewpoint and particle counts collected prior to air admittance (-43C dew point).

Once the laser tables were moved away from the chamber, we vented the annulus system and all but 4 bolts were removed from both +Y and -Y doors in prep for door removal tomorrow. 

Closing WP 13123

TITLE: 03/26 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: HAM1 was vented and the bolts have been broken, doors should come off tomorrow. BHSS work continues, and the LVEA is now in Upgrade Laser Safe.
LOG:

17:00 UTC Jordan went over the VAC checklist and I confirmed the picomoters were off, the JAC PZT scan was disabled and its Driver offset was 0, and that the ISI and HEPI were in their safe states.

17:08 UTC HAM1 pressure starts to rise

17:11 UTC ISI HAM1 wd tripped

20:27 UTC Red alarm Dustmon6 by HAM6, 10.8k and 17.5k counts for the 0.3 and 0.5 um particles

21:58 UTC The SQZ laser was keyed off, The LVEA is now in Upgrade Laser Safe

22:00 UTC The tables by HAM1 were moved

23:05 UTC HAM2 ISI tripped from the HAM1 crew breaking the bolts, and the HAM1 sw watchdog

23:09 UTC RM1 and RM2 wd tripped, the HAM1 CPSs were glitching as well

23:31 UTC HEPI HAM1 watchdog tripped

I reset a PT100 VACSTAT alarm at 10:12 and disabled HAM1.

Thu Mar 26 10:11:54 2026 INFO: Fill completed in 11min 50secs

On Monday, Randy, Jordan and the FAC team craned the HAM3 over into the appropriate place for HAM3 entrance for installation planned next week.  The cleanroom is now up against the BSC2 Platform.  As well, Kim and Nellie have been cleaning the HAM3 cleanroom.

On Tuesday, Randy craned into place and attached the new Installation Platform Sections G and F to the BSC2 platform.  Handrails will be installed next.  These platforms allow access from the eMod cleanroom to the BSC2 cross flow Dome cleanroom and platform, as well as provide added walking space between BSC2 and BSC3.  They also form 2 sides of the BSC3 platform which will be needed in subsequent vents.  Recall, this new LHO BSC2 Installation setup is part of the readiness review for install at https://dcc.ligo.org/E2400329-v1, and is part of a bigger plan to add sections around BSC3 and BSC1 to make a larger platform instead of moving them and encountering interferences other items like racks, trays and equipment.

TITLE: 03/26 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: USEISM
    Wind: 6mph Gusts, 4mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.55 μm/s 
QUICK SUMMARY:

• Zone5_I has been a little warm since the HAM1 CR has been turned on, its just off the plot but it looks stable
• HAM1 vent work continues
• More LVEA craning

"It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife"

- Jane Austen, opening line of Pride and Prejudice

But unfortunately for both us and them, sometimes those men are winged termites in the Optics Lab.

As Elenna and I were cleaning up our work in the back optics table this afternoon, we noticed a few winged termites, and ended up finding maybe almost 10 in total walking around on the floor in the back area of the optics lab near the wall mounted cabinets between the two cleanrooms. We got rid of them but couldn't find where they had come from. I'm wondering if they're maybe coming from an opening under one of those cabinets? Last year this happened but those came out from under the flow benches along the wall - not sure if this is part of that same colony that survived or a different colony.

To summarize the ongoing issues from yesterday:

• we determined that the cables (DCPD and PZT) attached to each OMC are mixed up
• one cable has incorrect wiring, because the ground pins are not where they should be (pin 2 and 5 are ground instead of 6 and 9)
• we're not sure if the polarity is correct on the diode

Keita and I have decided that swapping cables can possibly be done without removing the DCPDs. We're going to determine OMC A and OMC B based off of the PZT cable, and then swap the DCPD cables. We're waiting to hear the final verdict on the diode polarity to do pin adjustments and cable swapping.

In the meantime, Oli and I installed OMCB on the suspension and bolted it down using the OMC alignment template. We have placed the butterdishes over OMCA and B, but we haven't secured them yet with viton clamps while we continue to do work on the OMCs. The cables are only loosely clamped.

Next, Oli and I worked first contacting the remaining optics for BHSS- two HRs and one 50/50 splitter. The HRs were finished today, installed in their mounts, and placed randomly on the platform. The 50/50 splitter is still being FCed and should be ready in the morning. Once that optic is installed, we will proceed with the alignment of the OMCs and optics.

One vertical clamp is still missing from OMCB, but we should be able to install it once the helicoils and such arrive.

Sheila, Camilla.

We decided to pause on looking for the FC alignment and look at SQZ alignment into the IFO. To check our irises and possibly look for scattering shelves. 

Locked SEED_DITHER with 75mW into fiber. Moved ZM3 to get OPO_IR PD up to max 0.9mW. Opened BeamDiv and after aligning SRM, mis-aligning SR2, could see beams on AS_A,B and C. AS_A and B had a similar size ~60 to reported before (e.g. 86965), but there was less power on AS_C: 4e-4 rather than the previous 7e-4.

We used Ryan's DRMI time from 89573 to put OM1, OM2 and SRM back. The with the SQZ SEED injected, we tried to use SQZ centering loops to center on AS_A and AS_B, this didn't work quite as expected. ZM4 kept saturating although these loops had worked Janaury 19th, before moves were done on the VOPO to help with clipping e.g. 88966.

Then went back to alignment on Jan 31st with 88976 with ZM1,2,3, 4,5,6 FC1. And took OM1,2,SRM to the January 19th positions. However here we saw no light on SQZT7 OPO IR PD, HAM7 WFs or in HAM6 on the AS_A,B,C diodes. This was done at 23:10 UTC. Comparisons of osems attached. The sliders to get these osems values are fairly different, see attached, so I also tried going to these slider values, that gave me some light on SQZT7 IR PD, HAM7 WFS and FCES with SEED injected, see attached. HAM6 AS diodes saw nothing. 

TITLE: 03/25 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: GV7 is still broken and will not hard close, HAM1 vent prep work, the PSL incursion was completed, and the BHSS work continues in the Optics lab.
LOG:

• 19:19 UTC Tony keyed off TCSY

J. Kissel, M. Pirello

While in SUS-R2 and thinking SPI, and looking at the proposed rack layout from G2401479, and accounting for all the SUS (BBSS, LO1, LO2) that's incoming for O5 -- I found that SPI can have a bit more space if we just move the SUS-PR3 optical lever whitening chassis up 5 U-heights from "32" to "27." I put the u-height in quotes because this is an old style rack with the u-heights labeled from top down, rather than the bottom up per industry convention. I would have and could have gone higher, but the 27 slot already had mounting clips in it, so I went there. We can go as high as "25" if need be in the future.

Pics of before vs. after are attached.

F. Clara, J. Kissel, S. Koehlenbeck, J. Oberling, M. Pirello
D2400110

Today we picked up where we left off with the install of SPI into H1. 
Where we last left things, we'd installed a new SPI pick-off of ALS/SQZ beam in Apr 2025 (see ECR E2400083 and results in LHO aLOGs 83989, 83996, 83978). Back then, we had ended the work with the input to the fiber collimator within the PSL dumped.

With Jason and Sina in the PSL, we confirmed that the SPI path was still blocked. 

However, we also realized/remembered/confirmed that the entire ALS/SQZ/SPI path had 25% less power -- We've been running the PSL at lower power allocation downstream of the PMC since Sep 2025 to prevent issues we'd found with the currently installed EOM after a power outage triggered a dust monitor to spew out dust into the PSL (see that saga in e.g. LHO:87109 LHO:86966). They found the power at the SPI pick-off was 140 [mW] instead of the 188 [mW] we left in Apr 2025 (see LHO:83996).

(Using labels in the half-up-to-date drawing D1300348)
Jason and Sina rotated ALS-HWP2 upstream of ALSPBS01 to restore the nominal 50 [mW] into the ALS/SQZ pick-off and ~200 [mW] (190 [mW] measured). This means there's ~50 [mW] less out to ALS / ISCT1 than before today.

Then with the SPI pickoff still dumped, we installed a 30 [m] patch cord*** from the PSL optical table, out the mouse hole between the +X wall of the PSL enclosure and HAM1, then up running along the upper racks to waterfall down at SUS-H2. The fiber sits within the typical orange tubing. Per D2400110, this is SPI_PSL_001, and it's labeled as such on both ends.

After install, I connected the SUS-R2 end to a Thorlabs S121C power meter with S120-APC2 fiber adapter. 
With this installed (making the system laser safe at SUS-R2 end), Jason/Sina unblocked the SPI pickoff input. 
With 190 [mW] in, we measure 187 [mW] out on the other end. 98% transmission, pretty excellent. Almost unbelievably excellent but we weren't rigorous with our uncertainty and systematics.

Happy with this result, we then blocked the SPI path again, and re-capped the SUS-R2 end for final dressing in the racks.
We'll unblock again when we're read to connect it to the Laser Prep Chassis.

***Patch cord details:
Manufacturer DIAMOND
DIAMOND Part Number: ENS/1094388
Customer Part Number: 9711228
Patchcord SM L=30 PM
2xFC 2mm APC (i.e. 2mm narrow key FC/APC on both ends)
tran 6,6/125/245 PAND 980nm



 

WP 13105
WP 13113

During the last two days CDS EE has completed the following:

1. SPI Optical Fiber pulled from the PSL enclosure to SUS-R2
2. Heliax cable pulled from ISC-C3 to SUS-R2, part of SPI
3. Two Heliax cables pulled from ISC-C4 to ISC-R2, part of JAC
4. Cabling disconnected to IOT1 and ISCT1

This completes dirty work over HAM1 and HAM2. In the next two weeks, will close out work in SUS-R2 before HAM3 is vented.

List of items needed for SUS-R2:

1. Install power supplies in CER Mezzanine
2. Terminate power cables and install junction box
3. Terminate Heliax cable
4. Test and install two SAT Amp Chassis
5. Installation of DC sequencer
6. Install QOSEM Sat Amp
7. Pull cabling from SUS-R2 to HAM3
8. Installation of SPI electronics

F. Clara, J. Kissel, J. Oberling, M. Pirello, T. Sanchez, and R. Thompson

Elenna, Oli

Summary: OMCB has its DCPDs installed and most of its stoppers (barring one that needs to be retapped + helicoiled). OMCA has been aligned according to the OMCA / OMCB install template and is ready for laser alignment. Cabling for both OMCs should be good to go.

After last week's issue of the OMCB DCPD A (TRANS) missing a diode hole (89583), we were able to clear up the issue and fix it (89606). Elenna then installed the DCPD B (REFL) diode. Note that once again there were tiny metal shavings below where the DCPD's were installed, which we picked up with a qtip that we wet with iso. Once we had both installed (pic), we installed the rest of the stoppers around OMCB. The only one we didn't install is one of the vertical stops. This is because there was an issue with the helicoil last week, and we ended up having to remove it. We think this might be due to an issue with the threads, so we are waiting on a 3/8"-24 tap to retap the hole before installing a new helicoil. Because we don't have this stop yet, it doesn't really make sense to fasten on the butter dish, but we might just sit it on today to hinder dust accumulation.

We also realized that the PZT cables were going to be way too short to reach the cable pylons for both OMCA and OMCB, so we very carefully opened the peak cable wraps on the OMCs and took out what we think should be enough. On OMCB we noticed that the little copper wrap for one of the PZTs was not right above the PZT as it should be, but instead was on the other side of the peak cable wrap and was only wrapped loosly around one of the cables. Because of this we just removed the wrap. The cables right above the PZT are looking fine and don't look like they need anything to hold them together.

I had been confused about the OMCA / OMCB install template for the past few days, since installing it was putting OMCB further back in its slot than OMCA, but I was able to confirm yesterday in eDrawings that OMCB is actually supposed to be an extra 1 mm away from the front of its slot as compared to OMCA, so we moved OMCA into position and bolted it down.

I also went in and installed the magnet mounts for the OSEM magnets (without the magnets), as well as the big mass on the back of the BHSS.

Installed serial numbers:

OMCB (SN 105)

• DCPD A (TRANS)
  • DCPD: 1C-14
  • Housing: SN 002
• DCPD B (REFL)
  • DCPD: 1C-10
  • Housing: SN 008

Hepi Pump Trends (Monthly) Famis 39954:
 

On Jan 26th the HPI-PUMP_EX_PRESS1_PSI started rising in maximum pressure. and on  maybe feb 2nd it started getting worse. Seems like it has plateau-ed on Feb 16th, but the Pressure still remains elevated.

That channel back in Oct was between 92.4-92.6 PSI. 
And now it's between 91.9 - 93.5 PSI. I'm not sure if this is out of bounds for HEPI.