aLIGO LHO Logbook

H1 General - Friday Ops shift report.

anthony.sanchez@ligo.org — Fri, 24 Apr 2026 16:39:50 -0700

Author: anthony.sanchez@ligo.org

Report ID: 90010

TITLE: 04/24 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

CDS Frame Write restarts @ 15:21 UTC

Lots BSC2 work was done today.
Beam splitter Stays were removed and in between BSC2 and HAM4. Pictures of the Beam Splitter cover and more details can be found here: alog link.
The Beam splitter cartridge is closer than ever to fly out of the BSC2 Chamber.

LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
14:56	FAC	Kim & Nellie	LVEA	N	Technical Cleaning & resupply Nellie out first	15:49
15:45	CDS	Jonathan	Remote	N	FW restarts.	15:50
16:11	FAC	TJ, Randy	LVEA	N	Moving IOT2 table.	16:35
16:24	IAS	Jason & Ryan C	LVEA West bay	N	Faro surveying.	19:24
16:33	EE	Marc	LVEA	N	Pulling sat amps	17:13
16:39	FAC	Randy	LVEA	N	Working on MEGA CleanRoom	21:32
16:53	SEI	Jim	CER	N	Checking AA chassis for inputs	17:08
19:24	SUS	Ibriham & Betsy	LVEA BSC2	N	Putting a sheild around the BS.	20:45
19:31	SPI	Jeff	Optics lab	N	Dropping part off	19:31
20:21	SEI	Jim	LVEA BSC2	N	Helping prep for flying a Beam splitter	22:42
20:33	SUS	Mitch	LVEA	N	Helping Jim/Betsy	21:32
20:43	IAS	Jason & Ryan C	LVEA West bay	N	Faro surveying	22:44
21:32	SUS	Ibrahim	LVEA BSC2	N	Takeing BS stays	22:42
21:58	BHSS	Keita & Disha & Elenna	Optics lab	yes?	Working on Manta Ray	22:44

H1 SPI - Comment to SPI MEDM Screen Initial Release

jeffrey.kissel@ligo.org — Fri, 24 Apr 2026 16:39:19 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90013

ONE-WAY OPTICAL LEVERS Here's the signal chain for the one-way optical levers. There's a good bit of confusing basis changing happening given - the orientation of the QPD segments w.r.t. to vertical being different on HAM2's ISIJ QPDA and HAM3's ISIK QPDB, - The usual conversion from QPD segments to pitch and yaw, as the beam flies, then - Converting from beam pitch and yaw to ISI rotation, given that the HAM2 QPDA measuring HAM3 rotation is on the "front" +X side of HAM2, and the HAM3 QPDB measuring the HAM2 rotation is on the "back" -X side of HAM3. So I had to make custom SPI screens (rather than use the standard ASC QPD screen) that hopefully clears all this up. Also, the QPD2CART matrix is a ramping matrix, and I've never liked the auto-generated MEDM screen for this, so I pioneered a new one that I think has a better user interface. ${USERAPPS}/spi/common/medm/ SPI_CUST_QPD.adl SPI_CUST_QPD_MTRX.adl SPI_CUST_OL_QPD2CART_RAMP.adl SPI_CUST_OL_ISIOUTF.adl all at rev 35103.

Images attached to this report

H1 SPI - Comment to SPI MEDM Screen Initial Release

jeffrey.kissel@ligo.org — Fri, 24 Apr 2026 16:30:04 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90012

INTERFEROMETERS Here're the screens (less commissioned) that cover the digital demodulation and conversion to differential displacement. ${USERAPPS}spi/common/medm SPI_CUST_IFO.adl SPI_CUST_IFO_DEMOD.adl SPI_CUST_IFO_DISP.adl SPI_CUST_DIFFDISP_MTRX_RAMP.adl SPI_CUST_DIFFDISP.adl all commited to rev 35102

Images attached to this report

H1 SPI - Comment to SPI MEDM Screen Initial Release

jeffrey.kissel@ligo.org — Fri, 24 Apr 2026 16:23:25 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90011

LOCAL OSCILLATOR The SPI's longitudinal IFO that measures the differential displacement in the main IFO's X direction release on heterodyne interferometry, with the interference between two beams modulated at 80 MHz and (80 MHz- 4096 Hz) = 79995904 Hz, which creates a beat note at 4096 [Hz]. 80 MHz comes from the site's RF distribution system of 80 MHz. The 4096 Hz is initially digitally generated via CDS, and a copy of that is sent out via DAC to be subtracted from 80 MHz with our homegrown single-sideband mixer, a.k.a "double mixer" (D2400315). This is the screen that controls the parameters of the cds oscillator, as well as some phase rotators and filterbanks to condition the digital LO into an analog signal for the DAC. Nominally, the cds oscillator clock emits a 1 [count] amplitude wave, and the CLKGAIN, SINGAIN and COSGAIN parameters are set arbitrarily high, since its use as the LO for digital demodulation is usually entire internal to CDS. However, because this LO goes somewhere into real electronics, I've set the calibration of the signal condition filters such that the CLK, SIN, and COS gain are in units of [mV/ct] -- and I've set the LO amplitude at 5000 [mV] = 5 [V], mid-range of the DAC. Since we don't yet know the right phasing, all the phase rotators are current set to 0 [deg]. ${USERAPPS}spi/common/medm/SPI_CUST_LO.adl rev 35103

Images attached to this report

H1 SUS - BS stays removed + SEI cables removed and bundled

ibrahim.abouelfettouh@ligo.org — Fri, 24 Apr 2026 16:11:47 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 90009

Ibrahim, Jim, Mitchell

Mitchell and I removed the BS stays from the beamsplitter and placed them in the tube between BSC2 and HAM4. Then, Mitchell and I put the cover over the BS.

Jim and Mitchell were working on removing and bundling SEI cables from inside BSC2 for storage by ISI. Jim (on ISI) and I (in BSC2) then removed cable clamps from the bottom of the ISI/ceiling of BSC2.

Picture provided.

Images attached to this report

H1 TCS - Comment to thermal actuator summary

evan.hall@ligo.org — Fri, 24 Apr 2026 16:11:16 -0700

Author: evan.hall@ligo.org

Report ID: 90007

The measured SR3 RoC change coefficient agrees with the value from 2D axisymmetric finite element simulation in which uniform circular irradiation is applied to the central 6″ diameter of the back of SR3. This code exists as a test function test_back_heat() in finesse-fenicsx. Compare the heater plate design in D1500385. Aidan's Comsol model is T1600096.

Non-image files attached to this report

deformation_HR.pdf

sr3_back_heat_fenicsx.zip

H1 SPI - Comment to SPI MEDM Screen Initial Release

jeffrey.kissel@ligo.org — Fri, 24 Apr 2026 16:08:50 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90008

POWER MONITORING These cover the on-board power monitor SPDs. Eventually, we'll use these filter banks to calibrate the PDs into [mW] as it lands on the ISIK breadboard. ${USERAPPS}/spi/common/medm/SPI_CUST_FBR_PWRIN.adl rev 35102

Images attached to this report

H1 SPI - SPI MEDM Screen Initial Release

jeffrey.kissel@ligo.org — Fri, 24 Apr 2026 16:06:08 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90006

J. Kissel After the install of front-end software (LHO:89777 and LHO:89919) the next step for SPI is MEDM screens -- the UI/UX for the SPI L interferometers and PY one-way optical levers. Here, I post screenshots and corresponding userapps svn file and location. Sub-screens and their future purpose will come in the comments, but make sure to also check out G2402138. In the main entry, I show off the new place that SPI lives on the LHO sitemap and the overview screen. The overview screen, and all subordinate screens use a marco file, which I also attach. All of these files are, of course, properly version controlled in the userapps SVN, here: OVERVIEW SCREEN ${USERAPPS}/spi/common/medm/ SPI_CUST_OVERVIEW.adl rev 35102 MACRO FILE ${USERAPPS}/spi/h1/medm/ h1spih23_overview_macro.txt rev 35106CDS, CSWG, OpsInfo, SEI, SPI

Images attached to this report

Non-image files attached to this report

h1spih23_overview_macro.txt

H1 TCS - thermal actuator summary

sheila.dwyer@ligo.org — Fri, 24 Apr 2026 15:42:33 -0700

Author: sheila.dwyer@ligo.org

Report ID: 90004

With help from Evan and Kevin I've been trying to understand how to make estimates of actuation strength for thermal actuators.

In looking at data from the HWS, the values are divided by 2 to account for double passing (the compensation plates, ITM substrate, and SR3 are all double passed by the HWS beam).

	ITMX(uD/W)	ITMY (uD/W)
Ring heater	-10uD/W	-10uD/W	90003 (also close to value Matt's thesis from measurement and model, close to -9.9 uD/W value in finesse). Note that this is per Watt of total ring heater power, not per segment power
central CO2	23.7uD/W	26.5uD/W	89999
annular CO2	-5.4uD/W	-7.3uD/W	89999
SR3 heater	4.75uD/W wavefront change, 2.375 µD/W mirror ROC change		88413, agrees with Evan's simulation, T1600095 has 2.9uD/W

If we are using these values to calculate the focal length of a lens, we would use:

f_new = 1/(1/f_original +diopters)

If we are using it to calculate the ROC of a mirror, we would use :

Rc_new = 2/(2/Rc_original + diopters) For SR3 we would use the 2.375uD/W number multiplied by SR3 requested heater power.

H1 TCS - Comment to Turning on the Ring heaters again!

sheila.dwyer@ligo.org — Fri, 24 Apr 2026 14:59:07 -0700

Author: sheila.dwyer@ligo.org

Report ID: 90003

Here is a screenshot of this test. For ITMX this shows -78 uD of spherical power for 4W of total ring heater power. This means -9.75uD/W of defocus of the substrate lens.

For ITMY this is -82uD of spherical power for 4W, which is -10.25uD/W of defocus. This agrees reasonably well with the -9.9uD/W that is used in finesse.

Images attached to this report

H1 TCS - Comment to Weekend HWS transients

sheila.dwyer@ligo.org — Fri, 24 Apr 2026 14:20:15 -0700

Author: sheila.dwyer@ligo.org

Report ID: 90002

When Matt quotes uD/W for the ring heaters above, he is talking about total ring heater power, while the ndscope screenshot he attaches shows per segment power.

So he arrives at his 21uD/W = (change of 36uD/(2segments*0.44Watts per segment))/(factor of 2 for going from spherical power to defocus).

This is about twice the actuation strength measured in 89038, which agrees with the number and the simulation in Matt's thesis, and the value of -9.9uD/W used in finesse.

For a similar measurement of the CO2 heating, see 89999

H1 TCS - Comment to Long CO2 tests over the break

sheila.dwyer@ligo.org — Fri, 24 Apr 2026 14:17:32 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89999

	ITMX	ITMY
central CO2	23.7uD/W	26.5uD/W
annular CO2	-5.4uD/W	-7.3uD/W

I've read these values off the attached screenshots, and divided by 2 to account for the factor of 2 from double passing the substrate lens, as was done in 88413. The factor of 2 was not included in 71467.

Images attached to this report

LHO VE - Comment to BSC6 AIP is Railed

gerardo.moreno@ligo.org — Fri, 24 Apr 2026 11:46:01 -0700

Author: gerardo.moreno@ligo.org

Report ID: 90001

(Jordan V., Gerardo M.)

Last Tuesday, we did some troubleshooting of the annulus ion pump, we tried to induce for the short internal to the pump to let go by hitting the pump with an object, the pump only flashed once but no good results. Likely the pump is shot, this unit was a salvaged unit that was removed from another chamber, see aLOG 68433 for more info regarding the pump.

H1 SEI - Keel Mass Removal

mitchell.robinson@ligo.org — Fri, 24 Apr 2026 11:37:14 -0700

Author: mitchell.robinson@ligo.org

Report ID: 90000

Yesterday Randy and I removed the 4 Keel mass stacks from BSC2. A swivel lifting eye was used to gently lift until the mass stack seperated from the viton pads. Once seperated the viton was placed in a foil pouch. Each stack was wrapped in foil and craned onto a pallet. The last stack was wrapped with the pouch of viton. The swivel lifting eye was bagged and placed on top of the pallet of masses for use when the masses get added back onto the ISI.

The lifting pads, bumax hardware, and lifting fixture hardware plus SEI tools are staged on the table below the stairs to the garb room.

H1 General - IOT2 moved away from HAM2, cleanroom turned on

thomas.shaffer@ligo.org — Fri, 24 Apr 2026 09:48:05 -0700

Author: thomas.shaffer@ligo.org

Report ID: 89997

WP13189

Camilla removed the bellows yesterday (alog89994), so Randy and I moved the IOT2(ISCT2) table away from HAM2 and over closer to HAM3 on the +X side of the garb room there. This seemed like the most out of the way place while thinking ahead with door moves. The markings on the floor from 3/25 were still relevant, so I didn't mark anything new. Table height is marked with a label on the table, and again still relevant so I didn't change anything.

I then fixed up the curtains and turned the cleanroom on. Counts were below 100 right then, so it's looking good so far.

H1 AOS - WP 13204 EDCU update and daqd restart

jonathan.hanks@ligo.org — Fri, 24 Apr 2026 08:52:10 -0700

Author: jonathan.hanks@ligo.org

Report ID: 89996

Per WP 13204 we added fw2 channels to the edc to save some frame writing information for the review of the new frame writer.

The usuall process was used:

1. regenerate the edc ini file

2. restart daq1 leg

3. restart the edc

4. restart daq0 leg

The daq1 leg was restarted around 8:20am localtime, followed by the edc.

The daq0 leg was restarted around 8:27am localtime.

There have been two restarts of h1daqfw0 since then, at 8:32 and 8:37. Logs show that it was due to missing a input cycle (8:32) and running out of buffers in the circular buffer (8:37). It as come back and appears to be stable now.

H1 General - Friday morning Ops shift report.

anthony.sanchez@ligo.org — Fri, 24 Apr 2026 08:08:58 -0700

Author: anthony.sanchez@ligo.org

Report ID: 89995

TITLE: 04/24 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: 9mph Gusts, 5mph 3min avg
Primary useism: 0.01 μm/s
Secondary useism: 0.14 μm/s
QUICK SUMMARY:
H1's corner station is still still vented for Beam splitter upgrades. Lots of activities in BSC1 & 2 chamber.

Potential work today:
More prep work for flying out the BS cartridge.
SEI - HEPI CS pump station troubelshoot (Jim)?
Reconnect IOT1 (Tony, Camilla, Jennie, Fil cable?) this table is back in place and bellows are in place.
End Station HWS work (Camilla, Maddi, TJ)
CDS/EE - LVEA, MER cabling for HAM6 A+, work at SUS-M2, SEI-M1, and SUS-R7. [HAM7 sus to SAFE]
BSC2 - Drop Elliptical Baffles <-( I think this is done already)
VAC - CP1 Regen, lots of activity at Y-Manifold in LVEA, a few weeks

H1 General - Removed bellows from IOT2L

camilla.compton@ligo.org — Thu, 23 Apr 2026 17:12:13 -0700

Author: camilla.compton@ligo.org

Report ID: 89994

WP13189 Removed bellows from IOT2L. Guillotines and yellow covers are in place.

H1 TCS - Installed 5mW green laser in EX HWS path

madison.simmonds@ligo.org — Thu, 23 Apr 2026 17:09:12 -0700

Author: madison.simmonds@ligo.org

Report ID: 89993

Madi, Camilla

This week we went down to EX and installed the OzOptics fibre pig-tailed 532nm 5mW laser, and co-aligned it with the HWS 532nm LED beam.
Out-of-fibre the laser power was 4mW, and after the PBS the power was ~1mW (compare to HWS LED at the same location, power was ~1uW)
The green laser return beam was visible at the HWS camera, with ~50uW power. It was also quite large, and the beam shape indicated clipping.
We took an image of the beam spots with the HWS camera, and also briefly installed a CMOS camera to observe the return beam. We cannot fit the entire beam onto the camera sensor, however you can see enough to observe striations in the beam profile (see attached).
Planning to calculate what lens to put in the path to ensure the beam is correctly sized for the entire path to avoid clipping.

Images attached to this report

H1 IOO - Comment to Comparison with IMC WFS before and after JAC installation

jennifer.wright@ligo.org — Thu, 23 Apr 2026 16:54:51 -0700

Author: jennifer.wright@ligo.org

Report ID: 89992

I also plotted the yaw DOFs for each of the sensors I used above and for the same two reference times.

Images attached to this report

H1 SYS - BSC2 Cartridge de-install prep

betsy.weaver@ligo.org — Thu, 23 Apr 2026 16:52:03 -0700

Author: betsy.weaver@ligo.org

Report ID: 89991

Today, with the BS SUS set to SAFE and the SEI chassis turned off at the rack, Tony, Ibrahim and I started unplugging and logging all of the cables in the chamber at the feedthrus. I have a master log going which will be posted as an As-Built to the D1003079 BSC2 Flange Feedthru Layout Drawing for future re-plug-in activities. Pictures of 2 feedthrus prior to unplugging are attached for samples of what I'm talking about. As well, we dropped the ITMX Elliptical Baffle and Down Tube Sub assemblies from Stage 2 and have a good start on the ITMY one but didn't finish since it has mismatched hardware and we need a different tool. (In the event we need to put them back up, we left them off to the sides of the chamber to deal with later - the ITMX one is the one closest into the ITMX chamber.) Also also, we locked the BS SUS, tightened all of the nuts, removed all of the Vibration Absorber Cubes, and put the sock on the full SUS. Tomorrow we need to: Add the BS Face cover Remove a Stay or 4 Finish stowing all of the dangling cables Finish removing the ITMY Elliptical Baffle Get on with the Support Tube and SEI workSUS

Images attached to this report

LHO General - Ops Day Shift Summary

ryan.short@ligo.org — Thu, 23 Apr 2026 16:46:47 -0700

Author: ryan.short@ligo.org

Report ID: 89990

TITLE: 04/23 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: The soon-to-be-removed beamsplitter is now covered in the chamber with cables disconnected, baffles removed, and keel masses off the top of the ISI. The old "meat locker" was also craned over the X-arm and is staged at the LVEA hi-bay door.
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
14:36	FAC	Kim, Nellie	LVEA	-	Technical cleaning	15:52
15:05	FAC	Randy	LVEA	-	BSC2 mass craning	16:53
15:07	FAC	Mitch	LVEA	-	BSC2 mass craning	16:35
16:08	FAC	Nellie	LVEA	-	Technical cleaning	16:46
16:10	FAC	Kim	LVEA	-	Technical cleaning	16:46
16:28	PEM	Ryan C	CER	-	Dropping off dust monitor	16:30
16:46	FAC	Kim, Nellie	EY	-	Dropping off garb	17:26
17:08	PROP	Christina	MY, MX	-	Looking for a crate	17:28
17:26	IAS	Jason	LVEA	-	Staging equipment for FARO	19:15
17:32	IAS	Ryan C	LVEA	-	Staging equipment for FARO	19:15
18:05	SUS	Ibrahim, Tony	LVEA	-	Baffle/cable removal on BS, prep for cartridge	19:39
18:19	SUS	Betsy	LVEA	-	Baffle/cable removal on BS, prep for cartridge	19:39
18:26	TCS	TJ	LVEA	-	Dropping off parts and looking for tubing	18:39
19:54	FAC	Jordan, Randy	LVEA	-	Craning meatlocker	20:46
20:07	SUS	Ibrahim	LVEA	-	Dropping off parts	20:21
20:25	IAS	Jason, Ryan C	LVEA	-	FARO in West bay	Ongoing
20:29	TCS	Camilla, Madi	EX	YES	HWS table alignment	22:54
20:42	SUS	Ibrahim	LVEA	-	BS SUS de-cabling	23:25
20:43	SUS	Tony	LVEA	-	BS SUS de-cabling	23:25
20:49	SUS	Betsy	LVEA	-	BS SUS de-cabling	23:24
21:03	ISC	Keita, Elenna, Disha	OptLab	-	BHD work	22:57
21:28	TCS	TJ	LVEA	-	Measure a tube on TCSX	21:42
22:42	SEI	Patrick	MER	-	Imaging HEPI pump controller computer	23:04
23:32	ISC	Camilla	LVEA	-	IOT2L bellows	Ongoing

H1 ISC - Fixing OMC PZT cable wiring

elenna.capote@ligo.org — Thu, 23 Apr 2026 16:15:28 -0700

Author: elenna.capote@ligo.org

Report ID: 89989

[Disha, Elenna, Keita]

Following FRS ticket 37601, we fixed the incorrect wiring of the OMC PZT cables. We determined that both OMCA and OMCB PZTs were wired incorrectly following this diagram D2200276. We found the black dots on the outside of each PZT to determine the positive lead. Disha and Keita noted that for OMCA, relative to the "head" of the manta ray (short side, this terminology is used in the build document T2100190), the PZT closest to the head has the black dot on towards the center of the manta ray, and the far PZT has the black dot towards the outside of the manta ray. For OMCB it is opposite, the PZT closest to the head has the positive lead on the outside, while the far PZT has it on the inside. I am specifically not naming PZTs 1 or 2, or LV or HV, because it was not clear to us which one is which.

We confirmed that the pins were in the wrong location on the cable, so Keita proceeded to swap the pins around.

The schematic diagram suggests there should be a shielding for the PZT cables wired to pin 1, but there was no such shielding on any pin.

OMCA:

far PZT: had pins on 1-6 (plus-minus), we moved these pins to 5-9 (p-m)

near PZT: had pins on 2-7 (p-m), we moved these pins to 4-8 (p-m)

OMCB:

far PZT: had pins on 1-6 (p-m), we moved to 5-9 (p-m)

near PZT: had pins on 2-7 (p-m), we moved to 4-8 (p-m)

We confirmed with a multimeter that there were no shorts between the pins after the pin swap.

CDS, SUS

H1 IOO - Comparison with IMC WFS before and after JAC installation

jennifer.wright@ligo.org — Thu, 23 Apr 2026 15:48:06 -0700

Author: jennifer.wright@ligo.org

Report ID: 89988

Jennie W, Jeff Kissel,

Summary: Can we see a difference in jitter with JAC in the IMC ASC sensors? Short answer, yes.

The IMC has less angular motion with JAC installed at some frequencies - jitter is being suppressed by the JAC so less input beam motion relative to the cavity axis. The QPD readouts are noisier with JAC but there is one new suspension between JAC and the IMC so maybe the beam pointing to MC1 is noisier? MC2 TRANS QPD looks pretty similar with and without JAC, but this makes sense as cavity axis is still well aligned to this QPD. I need some other figure of merit to look at jitter as it only limits the IFO above 20 Hz, see alog #86555 by Sheila.

Since there was no time for a full IFO lock betwen the HAM1 vent and the current vent of the corner volume, we cannot directly check whether the jitter coupling to DARM is better with the JAC cavity.

We have lots of data of the JAC and IMC locked after the installation of JAC, however.

So I compared two times when we had roughly 2W input from the PSL to HAM1. In both cases H1 and the corner were at vacuum to rule out confounding effects from purge air and other sound noise seen when HAM1 was at air.

In both these cases the IMC was locked.

The two times I used were:

2025/11/17 15:38:54 UTC no JAC, during O4c

2026/03/20 00:26:01 UTC JAC installed, HAM1 at vacuum

Here is the ASD measurements for five sensors in the pitch degree of freedom:

IMC REFL WFS A Roughly the same above 10Hz with and without JAC. Better with JAC between 0.3 and 7Hz.

IMC REFL WFS B Roughly the same above 10Hz with and without JAC. Better with JAC below 7Hz.

IMC REFL QPD A has lower noise now below 5Hz than before JAC installation and much higher noise at frequencies above 10Hz.

IMC REFL QPD B has lower noise now below 3Hz than before JAC installation and much higher noise at frequencies above 10Hz.

MC2 TRANS QPD roughly the same with and without JAC.

Jitter noise is more of a problem in the 20-800 Hz region, which these plots don't tell us much about.

I also need the check YAW

ISC

Images attached to this report

H1 SEI - BSC ISI and T240 Interface Chassis for BSC2 (The BS Chamber) Turned OFF in prep for Cable Disconnection and Cartridge Extraction

jeffrey.kissel@ligo.org — Thu, 23 Apr 2026 14:07:58 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 89987

J. Kissel, M. Pirello, B. Weaver Betsy let us know that she's ready to start disconnecting cables of the ISIBS (the ISI supporting the Beam Splitter) in BSC2. As such, we used D0901301 to guide us, we turned off all three corners of the BSC ISI and T240 Interface Chassis in SEI-C5 U40-38 and U21-19 in the CER. The BSC ISI Interface Chassis are for the on-board capacitive position sensors (both stage 1 and stage 2 CPS), "high" frequency inertial sensors (stage 1 L4Cs and stage 2 GS13s), and the T240 Interface Chassis are for the on-board "low" frequency inertial sensors (stage 1 T240s). All sensors are OFF as of 1:52p PT (2026-04-23 20:52 UTC).CDS, SEI

Images attached to this report

LHO VE - Thu CP1 Fill

david.barker@ligo.org — Thu, 23 Apr 2026 13:56:02 -0700

Author: david.barker@ligo.org

Report ID: 89986

Thu Apr 23 10:11:23 2026 INFO: Fill completed in 11min 20secs

Images attached to this report

H1 PEM - DustMon Monthly Trends FAMIS

ryan.crouch@ligo.org — Thu, 23 Apr 2026 09:53:12 -0700

Author: ryan.crouch@ligo.org

Report ID: 89985

Closes FAMIS37263

No new issues (LAB2 and LVEA5 are not connected currently), or unreasonable/concerning counts at any location.

Images attached to this report

H1 General - JAC table back in place

camilla.compton@ligo.org — Thu, 23 Apr 2026 09:14:52 -0700

Author: camilla.compton@ligo.org

Report ID: 89984

Tony, Mitch and I rolled the JAC table IOT1 back into place next to HAM1 +X yesterday. Feet were put down, though we don't think there's a recorded height for the table ot be set to. Bellows reattached.

H1 SUS - BS OpLev Damping

ryan.short@ligo.org — Thu, 23 Apr 2026 09:02:25 -0700

Author: ryan.short@ligo.org

Report ID: 89983

Since we've found the BS OpLev damping on and causing the suspension to be moving around more than we'd like during prep for the swap to the BBSS, I went through Guardian nodes looking for all the places the OpLev damping is either turned on or off as a learning exercise for myself:

On/Off	Node	State	Method
ON	SUS_BS	ALIGNED	All inputs and outputs on
ON	ISC_DRMI	DOWN	Inputs and outputs on, gains to 300,650 (P,Y)
OFF	ISC_DRMI	ENGAGE_DRMI_ASC	Gains ramp to zero (only if using MICH ASC)
OFF	ALIGN_IFO	MICH_DARK_ALIGN	Gains ramp to zero
ON	ALIGN_IFO	MICH_DARK_OFFLOADED	Gains to 300,650 (P,Y)

Basically, the BS OpLev damping is ON during alignment and lock acquisition, and is turned OFF once MICH ASC is engaged. To keep the OpLev damping off for the time being, I've set their gains to zero since the suspension node doesn't change those and we won't be going through any states that do for a while.

When the BBSS is installed, we should think about how if at all these interactions need to change (although I'm sure someone already has).

OpsInfo

LHO General - Ops Day Shift Start

ryan.short@ligo.org — Thu, 23 Apr 2026 07:38:45 -0700

Author: ryan.short@ligo.org

Report ID: 89982

TITLE: 04/23 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: 10mph Gusts, 6mph 3min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.26 μm/s
QUICK SUMMARY: More prep for BSC2 cartridge removal today, including craning keel masses off and the start of cable unplugging.

LHO VE - Wed CP1 Fill

david.barker@ligo.org — Wed, 22 Apr 2026 17:13:32 -0700

Author: david.barker@ligo.org

Report ID: 89981

Wed Apr 22 10:12:38 2026 INFO: Fill completed in 12min 34secs

Images attached to this report

H1 AOS - Comment to BS OpLev Visual Inspection

oli.patane@ligo.org — Wed, 22 Apr 2026 16:37:31 -0700

Author: oli.patane@ligo.org

Report ID: 89980

While no one was in chamber, I took a couple of transfer functions (red) for the BS in Pitch and Yaw (pdf). I compared them to TFs from a year ago (black), and they look pretty similar. Yaw has a small peak from crosscoupling (from L) at 0.98 Hz, which also matches up with last year's measurements, and no signs of rubbing are seen. Note that these TFs were taken with the OPTICALIGN OFFSETs OFF, as trying to run TFs with them ON would give us poor coherence since we would need to lower the excitations to keep from saturating.

Settings:
- OPTICALIGN OFFSETs OFF
- DAMP OFF
- ISI LOCKED
- HEPI LOCKED

Data:
$sussvn/BSFM/H1/BS/SAGM1/Data/2026-04-22_1700_H1SUSBS_M1_WhiteNoise_P_0p01to50Hz.xml
$sussvn/BSFM/H1/BS/SAGM1/Data/2026-04-22_1700_H1SUSBS_M1_WhiteNoise_Y_0p01to50Hz.xml
r12999

Non-image files attached to this report

BSFM_20260422_PY.pdf

LHO General - Ops Day Shift Summary

ryan.short@ligo.org — Wed, 22 Apr 2026 16:30:52 -0700

Author: ryan.short@ligo.org

Report ID: 89979

TITLE: 04/22 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: More progress towards preparing to remove the BSC2 cartridge, both in-chamber and out, which is now slated to happen on Monday.

Walking platforms around the BSC2 ISI were installed: alog89977
BS OpLev positioning was determined to be good: alog89978
IOT2L was de-cabled to prepare for its move away from the HAM2 +Y door: alog89975
More water lines on the TCSX table were replaced: alog89976

LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
14:39	FAC	Kim, Nellie	LVEA	-	Technical cleaning	16:00
14:39	FAC	Randy	LVEA	-	Craning walk platforms at E-mod	15:36
15:29	SUS	Betsy	LVEA	-	Staging for BSC2	16:26
15:46	SUS	Ibrahim	LVEA	-	Staging for BSC2	16:26
15:48	EE	Fil	LVEA	-	De-cabling IOT2L	16:51
16:00	FAC	Nellie	EY	-	Technical cleaning	16:47
16:07	TCS	Camilla, TJ	LVEA	-	CO2X table water pipe swap	16:58
16:08	FAC	Kim	MX	-	Technical cleaning	16:45
16:52	EE	Fil	MER	-	HAM6 SUS cabling	19:37
17:09	AOS	Jennie, Tony	LVEA	-	Scouting IOT1 table position	17:15
17:12	EE	Marc	LVEA	-	Grabbing a chassis	17:20
17:25	SUS	Ibrahim, Betsy, Oli	LVEA	-	Inspecting BS and OpLev in-chamber	18:57
18:14	TCS	TJ, Camilla	LVEA	-	CO2X table water pipe swap	19:44
18:26	CAL	Tony	EY	-	Checking PCal interlock	18:50
18:31	SUS	Mitchell	LVEA	-	Dropping off parts	18:52
18:33	FAC	Randy	LVEA	-	Walkabout	18:57
19:50	FAC	Randy, Mitch, Travis	LVEA	-	Installing BSC2 walk platforms (Travis out @ 20:47, Mitch out @ 21:38)	21:50
20:04	FAC	Tyler	EX	-	Checking chiller	20:51
20:33	AOS	Betsy	LVEA	-	Staging for BSC2	21:12
20:50	AOS	Ibrahim	LVEA	-	Staging for BSC2	21:50
21:13	ISC	Camilla, Tony	LVEA	-	Rolling up IOT1	21:46
21:22	SUS	Jason	LVEA	-	Checking BS OpLev pointing	22:11
21:32	SUS	Betsy	LVEA	-	Checking BS OpLev pointing, other checks	22:29
21:41	ISC	Jennie, Madi	LVEA	-	Rolling up IOT1	21:46
22:59	EE	Marc	LVEA	-	Installing chassis	23:30

Images attached to this report

H1 AOS - BS OpLev Visual Inspection

jason.oberling@ligo.org — Wed, 22 Apr 2026 15:43:08 -0700

Author: jason.oberling@ligo.org

Report ID: 89978

B. Weaver, J. Oberling

With trends of the BS OpLev posted here and here, Betsy and I decided to also go out and physically look at where the beam is on the OpLev QPD. The beam itself sits a little bit low and about half-way to one edge of the QPD. I've attached a couple of pictures, but they aren't the best quality due to low light and difficult access (the BS OpLev sits on the +X/-Y BSC2 HEPI pier, between the pier and the chamber, roughly 7 feet above the floor). The 2nd picture is viewing the QPD using an inspection mirror, hence why it is flipped w.r.t. the 1st picture. My phone camera couldn't really pick out the actual OpLev beam, it instead registered it as a "blob" on the QPD (pointed to by the yellow arrows in each picture); the beam itself is roughly in the center of the blob and looks by my eye to be approximately 1.5mm to 2mm in diameter. The bright spot seen off to the side in each picture is NOT the beam, it is scatter that is reflecting off of a component on the QPD amplifier board.

Based on this, we decided to NOT recenter the BS OpLev before cartridge removal, as the beam is not near the edge of the QPD.

Images attached to this report

H1 SYS - BSC2 Cartidge preps

betsy.weaver@ligo.org — Wed, 22 Apr 2026 14:31:16 -0700

Author: betsy.weaver@ligo.org

Report ID: 89977

PARTICLE COUNTS in Cleanroom Tent on top of BSC2: All zeros (or puffs of 10) across from the HEPA flow bank on the opposite side of the ISI pillow, see pix attached. Counted just after crew left area doing walking plates. The Tent is working as planned. PEM BNCs wandering across the West bay was coiled up out of the way of all of the heavy foot traffic. PEM WEST BAY WALL COIL cables across floor has been disconnected and also coiled up and now out of the way of heavy foot traffic. Travis/Mitchell/Randy installed the Walking Plates for better access to the ISI up at the platform level. Note, after some deliberation and re-reviewing of the drawings (which are actually incorrect), it turns out that you cannot attach the bolts to the underside of the flanges anyways due to in-accessibility of the area. LLO doesn't recall using them recently either. (Last picture)

Images attached to this report

H1 TCS - Majority of TCSX on-table water lines swapped

camilla.compton@ligo.org — Wed, 22 Apr 2026 14:01:56 -0700

Author: camilla.compton@ligo.org

Report ID: 89976

TJ, Camilla

We have almost finished swapping all TCSX on table water lines to new ones as started in alog 89974, photo attached. The new beamdump lines didn't fit the connectors tightly so the old lines have been left for now. The table has not yet been tested for leaks.

Images attached to this report

H1 CDS - ISCT2 Cabling Disconnected

filiberto.clara@ligo.org — Wed, 22 Apr 2026 10:01:47 -0700

Author: filiberto.clara@ligo.org

Report ID: 89975

WP 13189

In preparation for HAM2 door removal, the ISCT2 table enclosure cables have been disconnected.

ISC

H1 TCS - Comment to TCSX supply line expansion joint OK

thomas.shaffer@ligo.org — Wed, 22 Apr 2026 08:42:26 -0700

Author: thomas.shaffer@ligo.org

Report ID: 89974

Yesterday Camilla and I changed out the largest of the flex tubes (3/4" OD) on the X table. There is a stark difference seen between the new, clean tubes and the old, very dirty ones. We noticed that the stickers indicating flow on the lines were somehow switched when going from the lines feeding into the table to the lines on the table. We have no idea when this happened, but we are going to stick with this convention until after all tubes are swapped so we stay consistent. We can decide if the lines feeding into the table need to be switched after or not.

Images attached to this report

LHO General - Comment to Ops Day Shift Start

ryan.short@ligo.org — Wed, 22 Apr 2026 08:36:15 -0700

Author: ryan.short@ligo.org

Report ID: 89973

CS HEPI pump stations are still down, so many chamber HEPIs are tripped.

Images attached to this report

H1 CDS - Comment to End Station DC Power Supply Photographs

david.barker@ligo.org — Wed, 22 Apr 2026 08:04:17 -0700

Author: david.barker@ligo.org

Report ID: 89972

Note that the EY photos were taken with h1iscey not on SEI-YC1, so it was at 3A, now at 5A. Conversely h1iscey at this time was on ISC-YC1,TCS-YC1 so it was at 9A, now 6A.

H1 CDS - End Station DC Power Supply Photographs

david.barker@ligo.org — Wed, 22 Apr 2026 08:00:48 -0700

Author: david.barker@ligo.org

Report ID: 89971

While at the end stations yesterday I took photos of the DC power supplies. I've included them here for future reference.

left-rack/right-rack is as viewed standing in front of the racks. Note that the end stations are mirror images of each other.

Images attached to this report

LHO General - Ops Day Shift Start

ryan.short@ligo.org — Wed, 22 Apr 2026 07:42:43 -0700

Author: ryan.short@ligo.org

Report ID: 89970

TITLE: 04/22 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: 26mph Gusts, 17mph 3min avg
Primary useism: 0.07 μm/s
Secondary useism: 0.18 μm/s
QUICK SUMMARY: Activities today mainly to continue prep for BSC2 cartridge removal. Some more TCS water line work and cabling happening today as well. It's raining.

H1 CDS - Comment to CDS Maintenance Summary: Tuesday 21st April 2026

david.barker@ligo.org — Wed, 22 Apr 2026 07:34:37 -0700

Author: david.barker@ligo.org

Report ID: 89969

Tue21Apr2026
LOC TIME HOSTNAME MODEL/REBOOT
09:55:51 h1lsc0 h1ioplsc0 <<< LSC IOP restart for timing glitches
09:56:05 h1lsc0 h1lsc
09:56:19 h1lsc0 h1lscaux
09:56:33 h1lsc0 h1sqz
09:56:47 h1lsc0 h1ascsqzfc

11:29:26 h1seih23 h1spih23 <<< NEW SPI MODEL
11:30:10 h1susauxb2h34 h1susauxb2h34 <<< NEW SUSAUX B2H34 MODEL

11:32:08 h1daqgds0 [DAQ] <<< 0-LEG RESTART
11:32:16 h1daqfw0 [DAQ]
11:32:16 h1daqtw0 [DAQ]
11:32:17 h1daqnds0 [DAQ]
11:36:11 h1daqdc1 [DAQ] <<< 1-LEG RESTART
11:36:20 h1daqfw1 [DAQ]
11:36:22 h1daqnds1 [DAQ]
11:36:22 h1daqtw1 [DAQ]
11:36:30 h1daqgds1 [DAQ]
11:38:50 h1daqfw0 [DAQ] <<< SPONTANEOUS FW0 RESTART
11:44:18 h1daqnds1 [DAQ] <<< NDS1 RESTART (GRD STARTED)

14:56:24 h1iscey ***REBOOT*** <<< ISCEY IO CHASSIS POWER RECONFIG
14:58:06 h1iscey h1iopiscey
14:58:19 h1iscey h1pemey
14:58:32 h1iscey h1iscey
14:58:45 h1iscey h1caley
14:58:58 h1iscey h1alsey

H1 General - EY Safety Interlock System

filiberto.clara@ligo.org — Tue, 21 Apr 2026 17:33:48 -0700

Author: filiberto.clara@ligo.org

Report ID: 89968

WP 13194

The EY interlock system was found with both the ALS and PCAL laser enable outputs disabled. Trending the laser enable channels shows channels went offline during upgrades to the H1SEIEY IO Chassis. Both the EK1501-0010 coupler and EL2904 binary output terminals were replaced. The 24V DC power to the Safety Interlock Chassis was moved to a dedicated 24V power supply.

CDS

LHO General - Ops Afternoon Shift Summary

ryan.short@ligo.org — Tue, 21 Apr 2026 16:55:52 -0700

Author: ryan.short@ligo.org

Report ID: 89966

TITLE: 04/21 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: Busy day after taking over from Corey. End-of-day optic alignment trends are attached; only things of note are that MC2 is now MISaligned after the Guardian restart today.

Work on BSC2 continued with HEPI actuators and walking plates
TCSX water lines on the optical table started to be replaced
Guardian computer upgraded to Debian 13
- When nodes came back online, this turned BS OpLev damping on, so the suspension was erroneously moving a bit for the afternoon (outputs turned off @ 23:18 to fix)
Laser interlock chassis at EY was worked on, see alog89965 for some details
- This brought the site interlock down for a while; I've recovered the PSL but other lasers remain off until they're needed again
Turbopump on CP1 installed, see alog89967

LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
17:38	CAL	Tony, Marc	PCal Lab	-	Looking for parts	17:52
17:38	TCS	TJ	LVEA	-	TCSX expansion joint	18:05
18:10	IAS	Ryan C	LVEA	-	FARO in West bay	19:11
18:20	IAS	Jason	LVEA	-	FARO in West bay	19:11
18:28	CAL	Tony, Fil, Marc	EY	-	PCal chassis troubleshooting	18:51
18:35	FAC	Randy	LVEA	-	Pictures in mega cleanroom	18:43
19:26	FAC	Randy	LVEA	-	Prep for BSC2 platform craning	19:47
19:29	PEM	Ryan C	CER	-	Testing dust monitor	19:39
19:52	EE	Fil, Marc	EY	-	PCal chassis/interlock work	23:11
20:03	SEI	Jim, Randy	LVEA	-	Craning BSC2 walking plates	21:30
20:05	PEM	Ryan C	CER	-	Swapping dust monitors	20:12
20:41	IAS	Jason, Ryan C	LVEA	-	FARO in West bay	22:41
20:43	TCS	TJ	LVEA	-	Prep for TCSX table line swaps	20:58
20:58	CDS	Dave	EY	-	Chassis power supply swap	22:08
21:04	VAC	Travis, Jordan	LVEA	-	Craning BSC2 walking plates	21:23
21:21	CDS	Erik	CR	-	Powering off h1iopiscey	21:21
21:59	TCS	TJ	LVEA	-	TCSX table water line replacements	23:44
22:09	SEI	Jim, Mitch	LVEA	-	BSC2 HEPI actuators	23:26
22:14	TCS	Camilla	LVEA	-	TCSX table water line replacements	23:51
22:35	CDS	Dave	EX	-	Checking power supplies	23:08
22:51	IAS	Jason, Ryan C	FCES	-	Grabbing equipment	23:24
23:11	EE	Fil, Marc	LVEA/OptLab	-	Inventory	00:11
23:32	PEM	Ryan C	CER	-	Dropping off dust monitors	23:33
23:34	VAC	Jordan	LVEA	-	Pictures of CP1	23:40
23:42	CAL	Tony	EY	-	Bringing PCal back up	01:42

Images attached to this report

LHO VE - Installation of Turbopump on CP1

jordan.vanosky@ligo.org — Tue, 21 Apr 2026 16:47:38 -0700

Author: jordan.vanosky@ligo.org

Report ID: 89967

In prep for the C1 regen, we installed the SS500 turbopump on the +X port of CP1, along with a full range gauge and roughing port. This replaced an old Edwards turbopump assembly with the new pump which is compatible with the SS500 cart.

Additionally, since we will not be venting the cryopump to atmosphere during the regen, we can not remove the old CETEC valve and replace with a new VAT valve. So we added a 12" spool on the CETEC valve and then the new redundant 10" VAT gate valve. Once the regen procedure is complete the CETEC valve will remain open and isolation will occur using the new VAT valve.

All new joints were helium leak checked, and no leaks found above the leak detector background of ~4.7E-10 Torr-l/s.

Images attached to this report

H1 CDS - CDS Maintenance Summary: Tuesday 21st April 2026

david.barker@ligo.org — Tue, 21 Apr 2026 16:15:40 -0700

Author: david.barker@ligo.org

Report ID: 89965

WP13187 restart h1ioplsc0 to fix timing issue.

Dave:

At 09:55 h1ioplsc0 (and therefore all models on h1lsc0) was restarted to see if this would clear up the recent spate of IOP timing glitches seen in the past week. So far, so good.

WP13180 h1susauxb2h34 model, add LO1,2 voltage monitors

Jeff, Oli, Erik, Dave:

A new h1susuaxb2h34 model was installed which reads the newly installed 9th ADC for LO1,2 voltage monitor signals. A DAQ restart was required.

New h1spih23 model

Jeff, Dave:

We installed a new h1spih23 model which added 4 slow channels, REF/MEAS CONSCALE for A/B. A DAQ restart was required.

WP13186 h1guardian1 upgrade to Debian 13

TJ, Erik:

h1guardian1 was upgraded to Debian13. This was a from-scratch install using new boot drives. Puppet did a lot of the configuration but some hand editing was also needed.

DAQ Restart:

Erik, Dave:

The DAQ was restarted for the two model changes above.

FW0 spontaneously restarted when FW1 had just got going.

NDS1 restarted at the time h1guadian1 was coming up, we assume that this was caused by a guardian NDS query storm.

FW2 has been down since 02:34 this morning and stopped updating around 05:02. At the time of the DAQ restart we found FW2 running again without no intervention. Following the DAQ restart FW2 died completely. I restarted rts-daqd_rs by hand, it kinda worked but seemed to be a whole full frame behind. So I stopped it for now.

WP13190 EY +24V Power Work. WP13181 PCALY recovery

Erik, Marc, Fil, Tony, Dripta, Richard, Dave:

The cause of the PCALY trip during IO Chassis upgrades Thursday 9th April was tracked to a shared +24VDC power supply between h1seiey and the laser-interlock-chassis.

Fil and Marc moved the interlock power from this shared power supply to a safety-system PS.

This left two remaining issues with EY +24VDC power: h1iscey was not on the correct PS and the SEI-C1 was still supplying the BRS beckhoff mini-terminals.

We took care of the first item. Marc ran a long 24V power cable from the back of h1iscey IO Chassis to the SEI-C1 power strip (mirroring what was done at EX).

We recorded the current draw on all the power supplies before and after the change, and attempted to measure the current surge when h1iscey was powered up.

Here are the +24VDC currents recorded

+24VDC Power Supply	Powers:	Current Before	Current After	Power-On Current Surge
SUS-TC1,2	SUSEY, SUSAUXEY	5.0A	-	-
ISC-YC1, TCS-YC1	Beckhoff -[ISCEY]	9.0A	6.0A	-
SEI-YC1	SEIEY +[ISCEY]	3.2A	5.0A	6.0A (+1 A)

Note that the interlock had already been removed from SEI-YC1 at this time.

This just leaves the BRS Beckhoff terminals incorrectly attached to SEI-YC1, but their current draw sould be negligible.

Here are the EX current values for completeness.

+24VDC Power Supply	Powers:	Current
SUS-C2	SUSEX, SUSAUXEX	5.5A
ISC-C1	Beckhoff	5.0A
SEI-C1	SEIEX, ISCEX	6.0A

H1 CDS - Comment to h1guardian1 machine down for OS upgrade

erik.vonreis@ligo.org — Tue, 21 Apr 2026 13:00:07 -0700

Author: erik.vonreis@ligo.org

Report ID: 89964

Upgrade to debian 13 is completed. Nodes are running, communicating via epics and NDS and controllable from the workstations. Some more testing is needed of git archiving etc.

H1 TCS - TCSX supply line expansion joint OK

thomas.shaffer@ligo.org — Tue, 21 Apr 2026 11:37:45 -0700

Author: thomas.shaffer@ligo.org

Report ID: 89963

Randy T., Camilla C., TJ S.

After the chiller was found tripped off and water was found in the plastic "leak containment apparatus" last week (alog89931), we expected to have to replace the expansion joint as we did in January 2024 (alog75657). Turns out, the expansion joint is okay but the fittings have loosened themselves overtime not just on this line but some of the others as well. More details below.

Today when Randy went to go swap the joint out for a used spare, he noticed that the fittings were very loose, not only on the TCSX supply line, but on a few others. He re-tightened all fittings and we decided to test it out slowly with water. Camilla tried to turn on the chiller, but it would shut itself off saying "low flow". She and I then closed the 3way valve in back which makes the chiller run in a closed loop within the chiller. This worked to get it to run. We then slowly opened that valve to slowly allow water to start flowing down the supply line. Randy was waiting and watching at the joint and never saw any water leaking out during the ~5 min test.

At this point we think that the water just leaked out of the loose fittings when the quick connect was disconnected last week. The updated chiller settings most likely helped and turned off the chiller before the pressure reached levels that could cause damage to the system. We will add checking the tightness to the quarterly pipe check FAMIS task.

Next steps - start on replacing the TCSX table flex lines, and work on making a unistrut cage around the quick connects to avoid bumps in the future.

LHO General - Tues DAY Ops Summary

corey.gray@ligo.org — Tue, 21 Apr 2026 10:39:24 -0700

Author: corey.gray@ligo.org

Report ID: 89958

TITLE: 04/21 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Covering the morning Ops shift & handing off to RyanS.
LOG:

1431-1553 Technical cleaning @lvea (nellie.kim)
- 1553-1703 kim will head to @ex
- 1553-1630 nellie @my
1500-1604 Property inventory checks in livea & optics lab (christina)
1547-1552 Checking to see if FARO did an auto-power-up this morning (ryanc)
1557-1629 cp1 turbo (new) leak checking (jordan, gerardo)
1615-1645 3ifo checks in lvea & then out-bldgs (tyler)
1615 FAMIS checks (chris)
1619 FARO procedure tests in northbay (jason.ryanC)
1628-1645 pipe bridge, tcsx (tj.randy)
- 1645 TCSy chiller turned OFF (tj)
- 1645 randy swapping out tcsx expansion joint on piping platform
1628 Pcal lab grabbing parts for EY (tony)
- Went to EY after and was done at EY at 1735.
1629-1703 EY annulus pump check (jordan.gerardo)
1645 Guardian server work (WP13186) begins with TJ having me taking SEI nodes to desired states (mainly ISI DAMPED HEPI OFFLINE)
- Eric & TJ beginning guardian server work.
- 1708 Connection error for many/all guardian nodes
1655 h1ioplsc0 restart to try and fix timing errors (dave, W13187); will do a daq restart around 1130.
1703 hepi actuator stuff @bsc2 (mitch,jim)
1717-1733 return to cp1 turbo (new) leak checking (jordan, gerardo)
1720 EY property inventory (fil)
1724 Flushing TCSx system test (camilla, randy)
1729 Ibrahim looking for randy
1739 handing off to RyanS.

LHO VE - Tue CP1 Fill

david.barker@ligo.org — Tue, 21 Apr 2026 10:14:26 -0700

Author: david.barker@ligo.org

Report ID: 89962

Tue Apr 21 10:10:27 2026 INFO: Fill completed in 10min 24secs

Images attached to this report

LHO VE - Comment to HAM1 -Y Door Report

gerardo.moreno@ligo.org — Tue, 21 Apr 2026 10:13:16 -0700

Author: gerardo.moreno@ligo.org

Report ID: 89960

Both aux carts are now removed from the annulus system for HAM1/HAM2. The annulus system is back to nominal, at vacuum and under ion pump management, the main volume for HAM1 is at atmosphere and ready to pump down as soon as it is requested.

Images attached to this report

H1 CDS - h1guardian1 machine down for OS upgrade

david.barker@ligo.org — Tue, 21 Apr 2026 10:12:43 -0700

Author: david.barker@ligo.org

Report ID: 89961

WP13186 TJ, Dave, Erik:

10:07 h1guardian1 powered down for OS upgrade to Debian13.

H1 SQZ - Comment to HAM7 BL2 clipping model

camilla.compton@ligo.org — Tue, 21 Apr 2026 08:48:11 -0700

Author: camilla.compton@ligo.org

Report ID: 89959

The aperture stop installed is D2000339: 0.2" (5mm) diameter.

LHO General - Tues DAY Ops Transition

corey.gray@ligo.org — Tue, 21 Apr 2026 07:27:15 -0700

Author: corey.gray@ligo.org

Report ID: 89957

TITLE: 04/21 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: 4mph Gusts, 2mph 3min avg
Primary useism: 0.01 μm/s
Secondary useism: 0.29 μm/s
QUICK SUMMARY:

BSC2 work continues, CDS work. HAM5 & 6 HEPI has been down overnight due to HEPI pump system issues noted yesterday.

H1 CDS - Workstations updated

erik.vonreis@ligo.org — Tue, 21 Apr 2026 07:20:34 -0700

Author: erik.vonreis@ligo.org

Report ID: 89956

Workstations were updated and rebooted. This was an OS packages update. Conda packages were not updated.

H1 ISC - Comment to SRC Gouy Phase measurement (without even locking SRMI)

sheila.dwyer@ligo.org — Mon, 20 Apr 2026 17:13:15 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89955

At the time of this measurement, CO2 heating was central. The CO2 FLIP1MON was 0 and FLIP2MON was 1. Comparing this to the current values and the MEDM that says we are currently using annular heating, I believe this means that these measurements were done with central CO2.

Images attached to this report

H1 TCS - ETMX Ring Heater test, turned up from 1W/segment to 2W/segment.

camilla.compton@ligo.org — Mon, 20 Apr 2026 17:03:51 -0700

Author: camilla.compton@ligo.org

Report ID: 89954

Madi, Camilla

Started ETMX Ring Heater test for HWS testing, turned up from 1W/segment to 2W/segment. Plan to leave until tomorrow.

H1 General - Ops DAY Shift End

oli.patane@ligo.org — Mon, 20 Apr 2026 16:33:53 -0700

Author: oli.patane@ligo.org

Report ID: 89953

TITLE: 04/20 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: Some BSC2 and cabling work done today. HAM5 and HAM6 HEPI are going to be down overnight since the HEPI pump is having issues.
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
14:40	FAC	Kim, Nellie	LVEA	n	Tech clean	15:32
15:09	FAC	Randy	MidY	n	Rock cleanup on aisle MY	16:10
15:51	FAC	Nellie	HAM Shack	n	Tech clean	16:34
16:01	VAC	Jordan	LVEA	n	CP1 RGA work	16:29
16:44	SEI	Jim	LVEA	n	BSC2 work	17:49
16:57	IAS	Jason	LVEA	n	FARO scoping	17:28
17:20	FAC	Randy	LVEA	n	Just looking at HAM6 cleanroom	18:07
17:21	VAC	Jordan, Gerardo, Travis	LVEA	n	CP1 pump work	18:44
17:34	SEI	Mitchell	LVEA	n	BSC2 work	17:49
19:10	EPO	Jeff, +1	LVEA	n	Tour	20:17
19:47	EE	Fil	MER	n	HAM6 cabling	00:20
20:18	VAC	Travis, Jordan, Gerardo	LVEA	n	CP1 pump work	23:29
20:23	CDS	Dave	EX	n	Reboot BRSX	21:30
20:25	FAC	Randy	LVEA	n	Looking at HAM6 some more	21:43
20:29		Jennie	Optics Lab	n	Looking for laptop	20:40
20:37		Betsy	LVEA	n	Looking at HAM6 with Randy	21:46
20:44	IAS	Jason	LVEA	n	Grabbing FARO parts	20:57
21:10	SEI	Jim	LVEA	n	Talking with Betsy / SEI work	23:28
21:19	TCS	Madi, Camilla, Maya	OpticsLab, LVEA	n	Grabbing parts	21:51
21:30	CDS	Dave	EY	n	Verifying 24V power supply	22:02
21:44	SEI	Mitchell	LVEA	n	BSC2 work	23:28
21:52	TCS	Camilla, Madi, Maya	EX	y(local)	HWS work	23:06
22:12	IAS	Jason, RyanC	LVEA	n	Setting up FARO for tomorrow	22:40
22:22	TCS	TJ	LVEA	n	Draining TCS chiller line	23:19
23:15	SUS	Ibrahim	LVEA	n	BBSS ExpreSS	23:33

H1 TCS - TCSX table drained and most of supply line

thomas.shaffer@ligo.org — Mon, 20 Apr 2026 16:25:21 -0700

Author: thomas.shaffer@ligo.org

Report ID: 89952

In prep for WP13185 to replace the flex lines on the table and the expansion joint, I've drained and vacuumed the TCSX table and then I just used gravity to drain most of the water in the supply line, enough so that the expansion joint is free of water.

H1 CDS - BRS EX computer running again

david.barker@ligo.org — Mon, 20 Apr 2026 16:24:35 -0700

Author: david.barker@ligo.org

Report ID: 89951

WP13182 BRS-EX recovery

Jim, Patrick, Dave

I tried to reboot, but ended up power cycling, h1brsex. Patrick started the code and IOC. Since then it has been attempting to damp over the past few hours.

H1 PSL - PSL 10-Day Trends

ryan.short@ligo.org — Mon, 20 Apr 2026 12:01:08 -0700

Author: ryan.short@ligo.org

Report ID: 89950

FAMIS 31134

The ISS diffracted power has drifted down a bit over the past few days, so I'll bring that back up towards 4%. No other major events of note.

Images attached to this report

H1 TCS - Comment to TCS Chiller Water Level Top-Off - BiWeekly FAMIS 28639

camilla.compton@ligo.org — Mon, 20 Apr 2026 11:07:35 -0700

Author: camilla.compton@ligo.org

Report ID: 89949

TJ, Camilla. Trending the pressure values doesn't tell us much. The chiller appears to go to the high pressure fault and trip off before the pressure channels register a high pressure, see attached. ANALOG1 PSI starts at 65 PSI and ANOLOG2 started at 26 PSI, after the chiller trips off, these increase to 6500 PSI (unphysicial) and 44 PSI. The chiller must have an additional pressure sensor it uses to trip off. Current settings are to trip off at 80 PSI, see FRS 30283.

Images attached to this report

LHO VE - Mon CP1 Fill

david.barker@ligo.org — Mon, 20 Apr 2026 10:18:59 -0700

Author: david.barker@ligo.org

Report ID: 89948

Mon Apr 20 10:09:19 2026 INFO: Fill completed in 9min 16secs

Images attached to this report

H1 General - Ops DAY Shift Start

oli.patane@ligo.org — Mon, 20 Apr 2026 07:39:22 -0700

Author: oli.patane@ligo.org

Report ID: 89947

TITLE: 04/20 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: 9mph Gusts, 5mph 3min avg
Primary useism: 0.03 μm/s
Secondary useism: 0.19 μm/s
QUICK SUMMARY:

BSC2 work today

H1 CDS - ETMY SWWD trip due to Earthquake

david.barker@ligo.org — Mon, 20 Apr 2026 07:36:31 -0700

Author: david.barker@ligo.org

Report ID: 89946

ETMY SWWD tripped at 01:17 PDT this morning due to an EQ. I have reset the DAC drives.

Images attached to this report

LHO VE - Sun CP1 Fill

david.barker@ligo.org — Sun, 19 Apr 2026 10:41:58 -0700

Author: david.barker@ligo.org

Report ID: 89945

Sun Apr 19 10:06:23 2026 INFO: Fill completed in 6min 19secs

Images attached to this report