BSC1&2 locked this morning

Ibrahim and I went to ITMY this morning, I locked HEPI on ITMY while he was setting up the radios and charger. After HEPI was locked, I garbed up and went in with a stool, isopropyl and an allen and locked ITMY and BS ISIs. Mostly went smoothly, some of the lockers need convincing with the allen key. All done now, and ready for IAS.

Current locked status is: HEPI HAM1,2&3 and BSC 1,2&3 are all locked. HAM3 and BSC1&2 ISI are locked. Everything else is unlocked, though we should probably leave all of the SEI guardians in ISI_DAMPED_HEPI_OFFLINE, in the corner.

Mon CP1 Fill, note later time of 10:20

Mon Apr 13 10:30:08 2026 INFO: Fill completed in 10min 5secs

The 10:00 run did not proceed due to urgent security patching. Today's run was rescheduled at 10:20.

Corner station chiller sensor replacement

Evaporator refrigerant pool temperature sensor was replaced this morning on Chiller 1. The old sensor was failing to communicate the temperature of the evaporator during circuit 1 operation, which limited the cooling capacity. 

Ops Monday Morning report

TITLE: 04/13 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: MAINTENANCE
    Wind: 22mph Gusts, 17mph 3min avg
    Primary useism: 0.07 μm/s
    Secondary useism: 0.16 μm/s 
QUICK SUMMARY:
SUS JM3 is still saturating 
SUS BS is also seeing some saturation
BSC2 Dome Not removed yet. 
What work are we thinking will happen today?: 
Faroing Inside the vacuum chamber shooting through HAM3 to BSC2.  
Vac parts removed from BSC2 dome.  

Sun CP1 Fill

Sun Apr 12 10:11:32 2026 INFO: Fill completed in 11min 28secs

 

Sat CP1 Fill

Sat Apr 11 10:09:36 2026 INFO: Fill completed in 9min 32secs

 

BSC1 Door Removed

(Travis S., Randy T., Gerardo M.)
Filter cavity tube work
BSC1 +X door was removed today, to be able to accomplish that first we had close the big gap left on by the cleanroom curtains, and do some work with the filter cavity tube.  At the filter cavity tube next to BSC3 connection we removed one side of the bellows, studs were removed, we opted to do that so as not to stretch the door cover, we used aluminum foil to cover both of the holes on the bellow and gate valve before pulling the C3 cover thru.  No issues to report all worked out good.

Door Removal
We attached the engine hoist to the door and loaded the engine hoist with the door.  After some struggle the door was convinced to detach, the outer O-ring left its groove on two spots, top and bottom about 10 inches for each side, we could not get to the top O-ring very hard to reach, no space, so we just managed to unstick it from the door flange and left it out of the groove.  Door was removed without a problem, O-ring protectors were installed, and door covers were set on chamber and door.

h1hwsey powered up, not running code at this moment

TJ, Dave:

TJ would like to get h1hwsey running again. If memory serves, this did not come back after the 06dec2025 site power outage and at the time it was not needed so we did not investigate it further and instead ran the h1hwsetmy_dummy_ioc.service on cdsioc0 (alog88435) to green the EDC.

At 16:00 this afternoon I went to EY and found that h1hwsey's boot disk caddy was not quite seated fully. This computer is not labeled, but can be verified by: tracing the KVM chan3 cable, checking PCIe camera receiver is installed.

I was able to monitor its reboot using the KVM console. I logged in as user controls and was able to ping the EX HWS machine to verify network operation.

Before I left I labeled the machine.

We are currently not running the IOC on h1hwsey and continue to run the dummy IOC on cdsioc0. We will keep this configuration for the weekend, and on Monday we'll stop the dummy IOC and run the real one.

OPS Day Shift Summary

TITLE: 04/10 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

IFO is in IDLE for PLANNED MAINTENANCE

Main tasks today:

• BSC1 Door Off - Done
• CDS Work - all done
  • Sei H16 restarted
  • ISI Ham6 Updated
  • Timing Card upgraded
  • Susaux H56 restarted
  • Susaux B13 restarted
  • DAC restart to add more STS gnd channels
• CER Chassis Work - Done
• IAS FARO - HAM3 - Done

LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
14:36	FAC	Kim, Nellie	LVEA	N	Technical cleaning	15:21
14:56	FAC	Randy	MY, LVEA	N	Picking up lift	16:41
15:04	IAS	Jason	LVEA	N	Turning on FARO	15:17
15:49	FAC	Kim, Nellie	LVEA	N	Technical cleaning	16:25
16:08	OPS	TJ	LVEA	N	Helping Jim with HAM3 Platforms, looking around	16:58
16:14	SEI	Jim	LVEA	N	HAM3 Platforms	16:31
16:28	EE	Marc	CER	N	PSL Chassis Work	16:58
17:13		Camilla, Gerardo	Optics Lab	N	Inspecting optics	18:32
17:14	IAS	Ryan C, Jason	LVEA	N	FARO	19:40
17:17	FAC	Kim	LVEA	N	Technical Cleaning	17:46
18:33	VAC	Travis, Gerardo	LVEA	N	Checking out FC Tube	19:37
20:06	FAC	Randy	LVEA	N	BSC1 Doors	22:06
20:14	SUS	TJ, Elenna	Optics Lab	N	Manta Ray Cabling (BHSS)	21:08
20:31	IAS	Jason, Ryan C	LVEA	N	FARO	22:31
20:34	VAC	Gerardo, Travis	LVEA	N	Biergarten work	22:45
20:43	EE	Marc, Erik	CER	N	Chassis work	21:08
21:09	TCS	Madi, TJ	EY	Local	Hartmann	22:45
22:48	CDS	Dave	EY	N	Labeling	23:20
23:01	PEM	Robert	EX	N	Grounding studies	00:01

 

Input and BS Pointing Over Last Two Weeks

In an effort to capture the input and BS alignment in different configurations, I trended back some suspensions and their OpLev and Raw OSEM values for P and Y. Table is below and plot of total timespan is attached.

Date	03/23	04/06	04/07	04/10 (before BSC1 work (1500UTC))	04/10
Configuration	HAM 1,2,3 and BSC 1,2 HEPI Unlocked/Nominal, HAM3 ISI Unlocked/Nominal, GV5 Hard Closed	BSC 1,2 HEPI Locked, HAM2 HEPI Unlocked, HAM1/3 HEPI Locked, HAM 3 ISI Locked. GV2 Hard Closed, GV2, GV5 Hard Closed, GV 7 Soft Closed. HAM1 +y Door Still Off	Pre-Vent HAM1,2,3 HEPI Locked, BSC 1/2 HEPI Locked, HAM3 ISI Locked HAM1 +y Door ON	Corner Vented, HAM1,2,3 HEPI Locked, BSC 1/2 HEPI Locked, HAM3 ISI Locked HAM1 +y Door ON	Corner Vented, HAM1,2,3 HEPI Locked, BSC 1/2 HEPI Locked, HAM3 ISI Locked HAM1 +y Door ON, HAM3 Doors Off, BSC1 Door Off
Counts
BS P Oplev	5.59	-2.59	-5.44	-1.10	-1.1
BS Y Oplev	-21.43	-18.84	-18.28	3.52	6.20
MC 1 P	-701.17	-693.12	-645	-165.00	-1894.65
MC 1 Y	-1386.13	-1352.15	-1359.53	-1381.29	-1224.55
MC 2 P	862.00	732.19	712.30	852.70	1200.76
MC 2 Y	-629.41	-405.45	-406.43	-376.60	-998.15
MC 3 P	401.57	372.37	358.45	332.01	-1268.06
MC 3 Y	-154.20	-192.72	-202.2	-270.48	-470.61
IM 4 P	-2442.81	-2364.65	-2257.6	-2332.12	-2329.7
IM 4 Y	-95.51	-73.04	-80.57	-103.24	-105.1
PR 2 P	-435.90	-425.54	-395.4	-418.5	-417.83
PR 2 Y	-1174.28	-1134.31	-1141.43	-1246.12	-1245.86

CDS Maintenance Summary: Friday 10th April

WP13110 IO Chassis Timing Card Upgrade

Marc, Erik, Dave:

Today we upgraded the IO Chassis Timing Card firmware, sync ribbon cable and RCG (where needed) on:

Front End	Timing Card Firmware	Sync Ribbon Cable	RGC5.5.2 update
h1psl0	yes	yes	yes
h1susauxh13	no	yes	no
h1susauxh2	no	yes	yes
h1seih16	yes	yes	yes
h1susauxh56	yes	yes	yes

There were no issues. DCC doc T2600142 was updated.

WP13163 h1isiham6 build against latest blend_switch_library

Jim, Ibrahim, Erik, Dave:

h1isiham6 was updated to use the latest blend switch library, it was the last ISI HAM model to do so.

We combined this with the upgrade of its IO Chassis, and also rebuilt all of h1seih16's models against RCG5.5.2.

A DAQ restart was required.

Move EDC back to h1susauxb13

Erik, Dave:

Back in Dec 2025 at the start of the upgrades we moved the EDC from what was then susauxb123 so it would not be impacted by the BBSS preparation work.

Now that we have completed the BBSS prep, EDC has come home to what is now called h1susauxb13 (sans BS).

This didn't quite go as smoothly as planned and required several restarts of both DAQ legs before it was correct.

The basic squence was:

1. Erik made the puppet changes such that h1edc would not start on h1susauxh56 but would do so on h1susauxb13.

2. Following the upgrade of h1susauxh56's IO Chassis, we powered this up to verify no edc on it.

3. We then hand restarted edc on susauxb13, then started the DAQ 0leg. We had DAQ errors at this point.

4. After a reboot of susauxb13 we found the issue, the daq receiver was not being restarted on DC0, just the daqd service. One DC0 was restarted this way, it had a good edc status. Unfortunately it started not quite in sequence and a clean 0-leg restart later got all the delta-times positive.

5. Restarting the 1leg went a bit better, but NDS1 did not restart cleanly and needed a manual start.

h1susauxh56 is now ready for its BHD upgrade with no impact on EDC trending.

DAQ Restart

Erik, Dave:

As mentioned above this was quite a messy start due to the move of EDC to susauxb13. The EDC INI was also changed to add the non-RGC FEC/SDF channels for the new models started in the past week (spih23, suslo12, susauxh6).

The h1isiham6 ini was also part of this DAQ restart to add the +12 STS GND channels.

 

Fri CP1 Fill

Fri Apr 10 10:08:26 2026 INFO: Fill completed in 8min 23secs

 

ITM only CHETA likely to exacerbate PI issues, particularly for LHO

It dawned on me recently that with the scratched view ports for CHETA, the delay of the CHETA roll out could have a subtle saving grace.
The intended use for IR1 is to heat the ITM with the same power as the absorbed power, so that the ITMs would remain in more or less the same thermal state at all times, making DRMI locking fast and reliable, and removing some of the impact on SRC detuning changing over time as the ITM lenses would evolve less than in O4.
It appears that in the CHETA Design Document, the effects on mode spacing and therefore Parametric Instabilities (PIs) was completely overlooked. Shame, no PI expert in LIGO was consulted, I'm even an author on the cited document in the design document and how we used CHETA like actuators at UWA to mitigate PI.

Very simplistically, rolling out CHETA only for the ITMs (as was the plan for the upcoming IR1) would have two impacts on how the optical mode spacing evolves:

• Mode spacings would start closer to the final, thermalised, frequencies.
• They would evolve with the same time constant (only ETM heating) as in O4, to the thermalised state.
  • But! Because they start closer, the mode spacing would evolve slower.

In O4 LHO's QUAD Radii of curvature's operating point has them stuck between two lock-losing PIs, and they haven't managed to demonstrate reliable damping of either. This lead to several periods in O4 where their lock stretches would be repeatedly cut short at around 4 hours.
The implementation of CHETA on ITMs only would have put them closer to their 10.4 kHz PIs as a starting condition, and because the mode spacing would be changing more slowly over time, they would experience the frequency matched condition of PI for longer periods of time. Thus:

• LHO would lose locks more reliably.
• LHO would have shorted locks.

I could spend time modelling this but its blindingly obvious once you notice.
CHETA on both ETMs and ITMs would theoretically allow you to start with essentially thermalised mode spacing, allowing you to more reliably side-step PIs.

BSC1 +Y Door Bolts Removed + BSC2 Dome Bolts Removed, BUT Had One Galled Dome Bolt!

(Jordan V, Corey G)

In prep for upcoming BBSS Install, "broke" bolts (which is slang for loosened them) on:

• BSC1's +Y Door in the Beer Garden
• BSC2's Dome (to see if giving the Dome's O-Ring some time to "decompress" helps us out at all with removal next week).  

BSC1's +Y Door Bolts (mostly) Removed & Accelerometer Cable Disconnected

BSC1's door had all bolts but (4) removed.  Sadly, I removed the bottom (easy ones) bolts first and then when I got to the top bolts they were very hard to loosen because of some sag.  Additionally, their access is horrible with:  a stiffening plate for the chamber right above the rear access to these bolts, then there are cable trays also in the way, and the C3 fabric cover is draped in your face the whole time.  Jordan helped out and we were able to get the last top bolt removed.  We also loosened the (4) bolts 1-turn which is the typical procedure.

There was an accelerometer still cabled up to this door.  I disconnected the cable (labeled "PEM:BSC1_ACC_X") and stuffed the cable into the cable tray above this door.

Time lapse of me removing half the bolts in this LINK (since we only files allowed in alog have to be smaller than 15Mb.)  :(

BSC2's Dome Bolts (mostly) Removed, But Have A Galled Bolt!

BSC2's dome bolts were removed.  4-bolts were left in place (they were loosened and then tightened up a little).  One notable, is there is 1-galled dome bolt.  Jordan and I used the long wrenches to see if we could use more force to help it break loose, but no luck.  We did not try pouring some alcohol on the bolt to help as a lubricant.  The bolt is loose and has about 1-2mm of a gap on it.  So, the pros could try use even longer cheater bars, a saw cutter, or they were also chatting about a tool to cut the nut off.  At any rate, 

BHSS optics aligned, beam dumps placed

[Oli, Elenna]

Summary: Oli and I finished the alignment of all the optics on the BHSS. We were able to place beamdumps to capture the reflected beams off of the four QPDs.

Oli wrote up a summary of the work from yesterday, 89836, and they noted a mistake in the alignment of the B path. We were able to correct that alignment, so the reflected beam from QPD-T-B-R2 goes to QPD B 1 and the transmitted beam reflects off QPD-T-B-R3 to the QPD B 2. Keep in mind that we are following the naming convention that's currently in D2000405 and the BHSS build document T2100190. We found that we had placed B-R2 one hole wrong yesterday, and once we had corrected this, it was much easier to center the beams on the mirrors and get them to the correct QPDs.

Oli briefly described this issue yesterday, but I want to emphasize again: we struggled to use the D2400130 alignment template to align the mirror called "36-R1". This mirror is a high reflector that steers the beam to a splitter that splits to the on-platform OMCB REFL path, and then off-platform to the LO WFS. Because this mirror is a high reflector, it has black glass clipped to the back, and the screw to hold the clip in place protrudes and interferes with the place the optic is supposed to press against the alignment template. This means we have to slightly rethink the HAM6 table alignment plan slightly. I think, since we have aligned the subsequent beamsplitter to the OMCB REFL path, we can follow these steps:

• use the OMC iris alignment template to align the input beams to each OMC, remove when finished
  • placing this alignment template requires removing the three optics at the head of the manta ray (A-R1, B-R1 and 36-1)
• use D2400130 to align A-R1 and D2400129 to align B-R1
• Use the reflected beam from OMCB and the placement of B-R1 and all downstream optics to find the correct placement of 36-R1

These steps will vary slightly depending if we only do the phase A install, or we do phase A and B together. If we only do phase A, we will just have to guess the 36-R1 placement for now, because there will be no beam to check it.

We are ready to go for cable routing and butterdish clamping on the BHSS!

IO Chassis Firmware and Sync Cable Upgrade

Per WP13110 we have upgraded the IO chassis listed below.
This link contains the asbuilt for all of the H1 IO Chassis: https://dcc.ligo.org/LIGO-D1301004
This link contains the ECR for the IO Chassis sync cable upgrade: https://dcc.ligo.org/LIGO-E2600069

This link is to the work in progress spreadsheet LHO Front Ends Upgrade Status

Corner:
SUSB2H34 has upgraded firmware and sync
SUSAUXB2H34 has upgraded firmware and sync
SEIH7 has upgraded firmware and sync
OMC0 has upgraded firmware and sync
OAF0 has upgraded firmware and sync
ASC0 has upgraded firmware and sync
LSC0 has upgraded firmware and sync

OPLEV charge measurements, ETMX, ETMY

We ran the OPLEV charge measurements this afternoon. We had a env / package issue trying to start the script, it was complaining about the scipy sin function, I ended up changing from the default cds env to the aligoNB using "conda activate aligoNB" after doing a pip env search to find which environment had the needed packages, I still had scipy sin issues but they were depreciation warnings. To fix this script we may be to rewrite the scipy parts with numpy. The End Stations SEI configuration was ISI_DAMPED_HEPI_OFFLINE. This was a pretty good measurement unlike a few of the previous ones, I didn't get any saturations on either QUAD and the coherence was pretty good.

ETMY's charge is a little high (above 50 on half of the plots) but it is trending to zero or is mostly static near zero (UR P).

ETMX's charge is high (above 50 on all but 2/8 plots but not quite at 100) and is trending away from zero, increasing. The ETMX_L3_LOCK_BIAS_OFFSET value has been at its "unlocked" value of -8.9 during the break, it flips to ~+6 when we are in full lock.

We are still fully processing and thinking about the results, more to come.