aLIGO LHO Logbook

H1 CDS - FMCS Well Pump Monitor EPICS IOC

david.barker@ligo.org — Tue, 12 May 2026 15:55:56 -0700

Author: david.barker@ligo.org

Report ID: 90216

Jonathan, Erik, Dave:

The EY well pump is now being monitored by an EPICS IOC which will report if the pump runs long outside of business hours. The well pump status is available on a MEDM, which can be launched from the FMCS overview MEDM (see attached). If the pump runs for more than 2 hours outside of standard hours (07:00 - 17:00 Mon-Fri) an alarm will be raised.

Images attached to this report

H1 SUS - BSFM lifted off of test stand/ISI

ibrahim.abouelfettouh@ligo.org — Tue, 12 May 2026 15:14:57 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 90214

Ibrahim, Randy, Betsy, Rahul

Today, we:

Prepared the BSFM for test stand removal which involved taking off some wire baffles, loosening dog clamps and wiping down the BSFM platform (LSAT).
Set a perimeter for BBSS to go up (in same position) using dog clamps.
Installed and fit-check the 45 deg. lifting bars - the screws seemed to be too long so we used 2 nuts to back them out.
Brought the aluma lift in to pick up the suspension and lifted it out of the test stand smoothly.
Rested it in the cleanroom on the LSAT with some dunnage blocks.

See pictures

Images attached to this report

H1 SUS - Comment to ZM4 (P-SAMS in HAM7) preload adjusted to change the radius of curvature of the mirror

sheila.dwyer@ligo.org — Tue, 12 May 2026 14:55:35 -0700

Author: sheila.dwyer@ligo.org

Report ID: 90213

Evan and Camille noticed that I flipped a sign here:

The preloading should make the magnitude of the optical power larger, so it should be increased to -106mD - 2.4mD/in lb * 29 in lbs = -175.6 mD with 0 V on the PZT. ROC = 1/-175.6e-3 = -11.4 meters

H1 SPI - Comment to First In-vac Components for SPI Pathfinder Installed!! ISI HAM2 (ISIJ) Reflector Assembly Installed and Cabled up to Feedthrus

jeffrey.kissel@ligo.org — Tue, 12 May 2026 12:08:34 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90212

On the new channel assignment of HAM2's SPI ISIJ picomotor, and why I'm confident it's CH7: Per D1000581-v13, page 13 and then D1900511-v12 page 17, I'm quite confident that the quadrupus cable and up in CH5-8 of the controller on IOT2L, called "PICOMOTOR 5" in D1900511, which I guess becomes "Picomotor B / Slot 2" on page 2 of the ECAT System Diagram D1100683-v11. This is corroborated with opening up the picomotor MEDM screen -- sitemap > LSC > picomotors > "HAM 2 + oplev" button (that has "controller 5" and "PICO B" next to it), and clicking through the channels and seeing that CH8 is called "PSL ISS QPD/PD (PM5)." Here's a labeled picture that makes things more clear.

Images attached to this report

H1 SUS - BBSS SUS medm infrastructure filled in

oli.patane@ligo.org — Tue, 12 May 2026 11:01:58 -0700

Author: oli.patane@ligo.org

Report ID: 90154

I've gone through and filled in most of the infrastructure for the BBSS (found under BS/ITM on sitemap as BBSS temp). Values and filter settings have been saved to sdf and filters added have been committed in H1SUSLO12.txt as r35219. For the majority of the filters banks, I turned any filters that are shown as being on in whatever I referenced them from, but all filter banks have INP and/or OUT OFF, so no signal can pass through.

Infrastucture filled in:

All stages
OSEM2EUL / SENSALIGN / EUL2OSEM Matrices
Filled out according to matrices calculated in /ligo/svncommon/SusSVN/sus/trunk/BBSS/Common/MatlabTools/make_susbbss_projections.m. The Y direction matrix elements for M1 OSEM2EUL have been left blank for now

M1
OSEMINF Filter Banks
- _{F1,F2,F3,LF,RT,SD}_{X_RAW,Y_RAW,SUM} have satamp compensation filter of zpk([0.145],[720e-6],1) installed in FM1, called 0.15:7e-4
- _{F1,F2,F3,LF,RT,SD}_{X,Y} have a conversion from counts to um with a gain(250) in FM5, called to_um. This value was found by using the conversion from Tom of 4000 counts / meter, and then converting meters to um.
- Tom said that we will not need any offsets, and the QOSEMs are calibrated so we don't need any special gains in the filter banks, so I've set the filter banks to gains of 1.
WATCHDOG Filters
BANDLIM Filter Banks
- Same filters as in OSEMINF, plus acBandLimiter
RMSLP Filter Banks
- 10 second LP added into FM1
LOCK Filter Banks
- Copied over from BSFM M1 for now
DAMP Filter Banks
- Copied the damping filters from BSFM M1 over for now
COILOUTF Filter Banks
- Copied over from BSFM M1 for now

M2
OSEMINF Filter Banks
- Satamp precise compensation filters inserted into FM1 according to the installed satamp for M2, plus conversion to_um in FM5
- Offsets and gains need to be re-done for BBSS M2
WATCHDOG Filters
BANDLIM Filter Banks
- Same filters as in OSEMINF, plus acBandLimiter
RMSLP Filter Bank
- 10 second LP added into FM1
LOCK Filter Banks
- Copied over from BSFM M2 for now
OLDAMP Filter Banks
- Copied over from BSFM M2 for now
VRDAMP Filter Banks
- Copied over from BSFM M2 for now
COILOUTF Filter Banks
- Copied over from BSFM M2 for now

M3
OSEMINF Filter Banks
- Satamp precise compensation filters inserted into FM1 according to the installed satamp for M3, plus conversion to_um in FM5
- Offsets and gains need to be done for BBSS M3
WATCHDOG Filters
BANDLIM Filter Banks
- Same filters as in OSEMINF, plus acBandLimiter
RMSLP Filter Bank
- 10 second LP added into FM1
OPLEVINF Filter Banks
- Copied over from BSFM M3 for now
LOCK Filter Banks
- Copied over from BSFM M3 for now
COILOUTF Filter Banks
- Copied over from PR3 M3 since they have the same electronics for M3

H1 IOO - Comment to Restoration of IMC alignment continues (Elenna, Sheila, Jenne, Keita)

keita.kawabe@ligo.org — Tue, 12 May 2026 09:19:44 -0700

Author: keita.kawabe@ligo.org

Report ID: 90210

During the work noted above, I disabled IMC-IM4_TRANS whitening OFF (only one stage was on) because the fringe velocity was big-ish and made flash peaks of some quadrants distorted, which means either the whitening/dewhitening mismatch was a problem (likely) or the ADC was railing (unlikely).

Also, I held the output of H1:IMC-IM4_TRANS_SUM (to avoid dividing P and Y by a tiny number, but of course it was useless). NSUM wasn't changed.

Whitening is still OFF but I turned off the holding of H1:IMC-IM4_TRANS_SUM this morning.

I'll turn one stage of IM4_TRANS whitening back ON after we're done with ISS.

LHO General - Ops Day Shift Start

thomas.shaffer@ligo.org — Tue, 12 May 2026 07:35:18 -0700

Author: thomas.shaffer@ligo.org

Report ID: 90208

TITLE: 05/12 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
CURRENT ENVIRONMENT:
SEI_ENV state: MAINTENANCE
Wind: 4mph Gusts, 1mph 3min avg
Primary useism: 0.01 μm/s
Secondary useism: 0.09 μm/s
QUICK SUMMARY: IPC errors on h1susMC2 and h1seiproc, dackill on h1iopseib2. All sus aligned and damped except PR2 which is in safe (looking into this), SEI in state captured by the whiteboard. Temps look good and dust counts look good in the LVEA. More laser hazard work planned for the day in the LVEA.

H1 CDS - Workstations updated

erik.vonreis@ligo.org — Tue, 12 May 2026 05:08:16 -0700

Author: erik.vonreis@ligo.org

Report ID: 90207

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

H1 IOO - Comment to Restoration of IMC alignment continues (Elenna, Sheila, Jenne, Keita)

jenne.driggers@ligo.org — Mon, 11 May 2026 18:39:08 -0700

Author: jenne.driggers@ligo.org

Report ID: 90206

Once Elenna had the IMC nicely aligned, we moved on to setting the pointing of the beam headed to the IFO. We need this to be roughly correct, so that we can use it to align the ISS array.

Back in March when the IMC was locked, Elenna found the locations of the beam on IM4 Trans and ISS QPD:

IM4 Trans Pit (March 2026): 0.22
IM4 Trans Yaw (March 2026): -0.06
ISS QPD Pit (March 2026): -0.92
ISS QPD Yaw (March 2026): 0.94

We then worked to move IM2 to get to the right spot on IM4 trans, and then IM3 to get to the spot on the ISS QPD. The tricky thing is that, since we can't lock the IMC (IOT2 is away from the chamber, so no IMC REFL PD, so no IMC locking), we're just looking at flashes. So, the spot on the QPDs has to be calculated by looking at peak heights when we get a flash, and doing the matrix math to go from segments to pit and yaw.

.....After 23 different iterations of setting IM2 and IM3 based on an educated guess of where they should go, calculating the QPD spots, finding that we weren't quite right, and then tweaking again, we're leaving the IMs such that we're back to the March location on IM4 trans, but we're less on the edge for the ISS QPD. Current spots (calculated from the peaks of IMC flashes):

IM4 Trans Pit (May 2026): 0.2
IM4 Trans Yaw (May 2026): 0.05
ISS QPD Pit (May 2026): -0.53
ISS QPD Yaw (May 2026): 0.85

This helps assure us that we've got a pretty reasonable beam headed toward the ISS array, and that even if we didn't get the IMC alignment quite right earlier, we should be in a pretty reasonable place and we can use this beam to replace the ISS array.

One final thing we could do as a last check is to calculate the spots on POP A and POP B QPDs (or, at least the one that is used for initial alignment and acquisition), and make sure that we can move IM4 to get to that spot. That would mean that IM4 trans QPD and POP QPDs are both correct, which sets the pointing of the beam into the PRM and into the IFO, so if that line is correct in air and we use it to align the ISS array, then we will certainly be in a good place when we pump down. Again, this would just be a check that the IM1+IM2+IM3 position that we've got right now to give us good pointing to the ISS array is compatible with some IM4 pointing to the POP QPD. The individual segments aren't _DQed, so we'll have to check this tomorrow when the light pipe is open again.

Keita closed the light pipe for the night.

H1 IOO - Comment to Restoration of IMC alignment continues (Elenna, Sheila, Jenne, Keita)

elenna.capote@ligo.org — Mon, 11 May 2026 18:29:51 -0700

Author: elenna.capote@ligo.org

Report ID: 90205

At first, I only moved some combination of MC1, 2 and 3 because we believed that the pointing into the IMC was fine. However, as Keita summarizes above, this was a futile process and veru confusing because it sometimes seemed as if the camera, MC2 trans QPD and IM4 trans QPD all gave differing directions.

However, although Keita said that the beam hit MC2 in a good place, he did clarify this was within mm, so this gave us room to move around JM3 by many microradians. Then, we had this whole realization that JM3 pitch and yaw are flipped relative to IMC pitch and yaw, so some of our other confusion about what we were walking (and why it wasn't really working) started to make sense.

In the end, this is the process that worked: move JM3 a large amount, follow up with MC2 move and some MC1 move in opposite dof (so JM3 pitch goes with MC2/1 yaw). At first, I relied only on IM4 trans, but then the flashes on MC2 trans started to improve, so this became a much more useful signal to follow.

Below, I compare the OSEM readbacks of each suspension from before we started moving to now at the end of the day:

JM3 pitch (IMC yaw): -177 urad

JM3 yaw (IMC pitch): -93 urad

MC1 pitch: -186 urad

MC1 yaw: +83 urad

MC2 pitch: +58 urad

MC2 yaw: -62 urad

MC3 pitch: + 12 urad

MC3 yaw: +21 urad

We should probably put some note next to the JM3 sliders that the pit/yaw dofs are flipped compared to IMC pit/yaw, or I predict that we will recommit this mistake many times over!

Attached is a screenshot of the IMC aligned in air with associated signals (and dog)

Images attached to this report

H1 IOO - Restoration of IMC alignment continues (Elenna, Sheila, Jenne, Keita)

keita.kawabe@ligo.org — Mon, 11 May 2026 18:24:24 -0700

Author: keita.kawabe@ligo.org

Report ID: 90203

I went to HAM3 to see that the MC2 beam position wasn't crazy. See the first photo, the beam is to the left (+Y direction) relative to the baffle on the HR side but the baffle itself is offset in -Y direction relative to the cage. Green lines are extension of the EQ stop screws to guide your eyes.

I also opened the ISCT1 and moved the mirror in front of the REFL BBPD out of the way and directed the beam to IFO REFL camera (because I couldn't see the beam at all without moting the mirror).

While manually aligning the IMC, we found that somehow things are in such a bad state that the MC2 TRANS SUM decreases when IM4 TRANS SUM increases, and vice versa. Improving the IMC alignment using IM4 TRANS as well as IFO REFL camera made the flashes stronger to the point that we can see 00 mode once in a while. I was also able to see the beam in the ISS path. But MC2 TRANS was nowhere near centered. Attempts to resolve this by incremental changes failed.

We wondered if something behind MC2 was bumped and changed the alignment into MC2 trans. I looked at the path and didn't see anything obvious. The beam transmitted through MC2 was visible using a card and a viewer, it was not clipped by the baffle behind MC2 nor the BS for the beam dump. I could not see the transmission of the BS, though, it was too weak, so I cannot confirm if the steering mirror in front of the QPD was bumped or not.

Elenna started making big changes for JM3 in PIT (to make big YAW changes in the beam injected into IMC, remember that YAW and PIT are flipped between JAC and IMC, IMC WFS takes care of this but that won't help when you're manually aligning JM3) and moving MC2 and MC1 so that the IMC follows the input beam. Repeating this in YAW anShe successfully centered the beam on MC2 trans.

At this point I looked at the MC2 beam position again, see the second picture. Apparently the beam moved in YAW by a few mm to the right (i.e. -Y direction).

Elenna will post which optic was moved by how much in which direction.

Jenne is now trying to put IM4_TRANS and ISS QPD beam position back where they used to be using IM2 and 3.

INS, IOO, ISC

Images attached to this report

H1 IOO - Comment to Restoration of IMC alignment continues (Elenna, Sheila, Jenne, Keita)

keita.kawabe@ligo.org — Mon, 11 May 2026 18:14:54 -0700

Author: keita.kawabe@ligo.org

Report ID: 90204

We found that people opening BSC door cover(?) somehow disturbs IMC whether or not HAM3 and HAM2 door covers are on. The IMC fringe becomes super fast and it almost becomes impossible to align anything. Purge air seems to go to strange places to do strange things.

OTOH, when people are out of BSC, we had to put 0.2Hz 150cts excitation to MC2 M1 drive align L2L so the IMC goes across the entire FSR.

H1 COC - 2 of 4 AOSEM Flag Standoffs Glued

ibrahim.abouelfettouh@ligo.org — Mon, 11 May 2026 17:13:19 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 90202

Ibrahim, Betsy, Rahul

Today we glued two of the four AOSEM flag standoffs onto S2 of BBS01.

After gluing, we wanted to make sure we were contacted evenly so an hour and a half later, we used magnets to remove the flags from the glued-on mounts.

We discovered that some glue was touching the bottom of the magnet bushings, so we elected to use some foil as shims to create more space between S2 and the bottom interface of the bushings.

Otherwise, the mounts were flat on the surface. We put the bushings back on for the overnight cure. See pictures below.

Images attached to this report

LHO General - Ops Day Shift End

thomas.shaffer@ligo.org — Mon, 11 May 2026 16:39:18 -0700

Author: thomas.shaffer@ligo.org

Report ID: 90197

TITLE: 05/11 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
SHIFT SUMMARY: The LVEA is still in laser hazard and will be for a few more days. The IMC alignment continues to prove difficult to get right. ITMY IAS finished up today. BBS work continues, CP1 regen, and more!
LOG:

1629 light pipe open

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
19:43	SAF	LVEA IS LASER HAZARD	LVEA	Y	LVEA IS LASER HAZARD	12:03
15:07	VAC	Jordan	LVEA	yes	Checking on pumps and RGAs	15:17
15:27	CC	Ryan C	LVEA	yes	Grab dust monitor	15:42
15:43	FAC	Kim	LVEA	yes	Tech clean	17:13
16:26	ISC	Keita	LVEA	YES	HAM2/3 IMC alignment troubleshooting	18:20
16:27	ISC	Jenne	LVEA	YES	HAM2/3 IMC alignment troubleshooting	17:03
16:27	FAC	Randy	LVEA	yes	Measurements for more platforms around BSC3 area and emod area	16:47
16:29	IAS	Jason, Ryan C, Stephen A	LVEA	yes	ITMY Faroing in beir garten	20:16
17:15	VAC	Jordan	LVEA	yes	CP1 checks	18:25
17:36	FAC	Kim	LVEA	yes	Tech clean	18:19
17:49	VAC	Travis	LVEA	yes	CP1 work	18:31
18:17	SUS	Betsy, Ibrahim	LVEA	yes	BBS first contacting, suspension prep	19:50
20:06	SYS	Betsy	LVEA	yes	Checking that a chassis was turned back on	20:12
20:07	SAF	Ryan S	LVEA	yes	Checking on door	20:17
20:38	TCS	TJ, Madi	EX	Y	HWS table work	23:20
20:40	VAC	Jordan	LVEA	yes	HAM4 RGA	22:48
20:42	SUS	Betsy, Ibrahim, Rahul	LVEA	yes	BBS magnet gluing	23:42
21:13	ISC	Keita	LVEA	YES	HAM2 alignment	21:50
21:21	EE	Fil	LVEA	yes	HAM6 rack cabling	00:21
21:36	CAL	Tony	EX	-	Spinning up NCal	21:36
21:48	SPI	Jeff	Opt Lab	n	SPI work	23:03
22:19	SUS	Oli	CER	n	Taking rack pictures	22:23
22:25	PEM	Robert	EX	n	Grounding studies	00:25
22:49	VAC	Jordan, Gerardo, Travis	LVEA	yes	CP1 regen work	00:49
23:09	SEI	Jim, Michael, Shoshana, Stephen	LVEA	yes	Looking at cartridge and BSC2	01:09

H1 SQZ - Comment to SQZ beam profiles with different psams

sheila.dwyer@ligo.org — Mon, 11 May 2026 16:34:28 -0700

Author: sheila.dwyer@ligo.org

Report ID: 90201

Keita, Ryan Short, Tony, Sheila

In the saved PDFs, the units on "Beam Waist Position" are listed as um, but in the text file (which does contain all the same information), the values are the same but the units are mm. mm must be the correct units.

Looking at T2500077 we believe that to get from the reported Beam Waist position in the text file we need to add (z_stage_min - 4.4 mm= 122.9mm) to the distance from the reference plane as depicted in that diagram to the waist position. We believe that this waist position being positive means that the waist is after the reference plane (on the sensor side of the reference plane), I think a negative number would mean the waist is before the profiler.

I asked Claude to write a script to collect the data from the txt files in the archive above and save it in a yml, the script is attached here in case someone else wants it.

Non-image files attached to this report

thorlabs_to_yml.py

H1 PSL - PSL 10-Day Trends

ryan.short@ligo.org — Mon, 11 May 2026 15:22:20 -0700

Author: ryan.short@ligo.org

Report ID: 90200

FAMIS 63898 (I think. With the new system there are duplicate tickets, so I picked the one that has a schedule assigned.)

No major events of note this week.

Images attached to this report

H1 CAL - Spinning the NCAL with Micheal Ross

anthony.sanchez@ligo.org — Mon, 11 May 2026 14:57:24 -0700

Author: anthony.sanchez@ligo.org

Report ID: 90199

Micheal Ross showed up in the control room, so we spun up the NCAL.

It wouldn't spin at first because there was a current Latch reset button that needed to be pushed. Michael pushed System Reset and Latch Reset in rapid succession.
More documentation can be found here: LIGO iNCal Operating Procedures.pdf T2600149-v1.

We ran it for 4 minutes 30 seconds starting at 21:25 UTC.
H1:CAL-NCALX_MOVE_VELOCITY_VELOCITY_REQ was set to: 104 which translates to ~ 0.991 hz.
H1:CAL-NCALX_VELOCITY_KP_REQ: 0.0100 Mn/rad/s
H1:CAL-NCALX_VELOCITY_FILTER_REQ: 5 ms

NCAL ran.
Beckhoff I/O H1:CAL-NCALX_AXIS_ERROR_ID now has an Error status.

Pressing the system reset button cleared this Beckhoff I/O error status indicator.

Images attached to this report

H1 IOO - IMC_LOCK's OFFLOAD_MCWFS State Updated to Use JM3

ryan.short@ligo.org — Mon, 11 May 2026 11:10:09 -0700

Author: ryan.short@ligo.org

Report ID: 90198

Jenne reminded us that with the installation of the JAC, the process we use to offload the IMC WFS should be updated to use JM3's alignment instead of the PSL PZT since it's now the alignment mirror directly upstream of the IMC. I've done this in the IMC_LOCK Guardian node's code by essentially just doing a "find and replace" for the term "PZT" with "JM3" (and double-checking the result, of course), all of which happened in the OFFLOAD_MCWFS state. We'll test this state's functionality at a later date.

Changes have been committed to svn and loaded.

ISC

H1 AOS - Comment to Two HAM 3 POP-path optics are retroreflecting light scattered from MC1 and PRM

sheila.dwyer@ligo.org — Mon, 11 May 2026 09:03:29 -0700

Author: sheila.dwyer@ligo.org

Report ID: 90196

Here is a layout that may be helpful for understanding some of Robert's photos above: HAM3 IO paths

LHO General - Ops Day Shift Start

thomas.shaffer@ligo.org — Mon, 11 May 2026 07:37:06 -0700

Author: thomas.shaffer@ligo.org

Report ID: 90195

TITLE: 05/11 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: 0.01 μm/s
Secondary useism: 0.12 μm/s
QUICK SUMMARY: IPC errors on h1susMC2 and h1seiproc, dackill on h1iopseib2. All sus aligned and damped, SEI in state captured by the whiteboard. Temps look good and dust counts look good in the LVEA, the ends saw counts up into the 2000s during the last bout of wind 12 hours ago.

Laser hazard work in the LVEA continues today.

H1 SUS - Attempt at QOSEM Test on BSFM

thomas.roocke@ligo.org — Mon, 11 May 2026 02:47:57 -0700

Author: thomas.roocke@ligo.org

Report ID: 90194

[Tom R, Oli]

Summary: QOSEM testing on the BSFM will require the tablecloth to be shifted OR SUSP to be raised, probably not worth the effort to do so given the BBSS will be ready for QOSEMs shortly.

Last Friday Oli and I attempted to install the QOSEMs onto the now removed from chamber and on test stand BSFM suspension, now that the IAS work was completed. The purpose of this test is to run and compare TFs taken with QOSEMs, providing a final functionality test before installation on the BBSS (which is not yet ready to accept QOSEMs). The full test and integration plan for the QOSEMs / BBSS can be found here T2600169.

We began by removing the SD BOSEM from M1 of the BSFM, and swapping the flag out for the QOSEM variety. We installed the QOSEM onto the cage, and used the existing DB25 in vac extensions and in air cables to run the QOSEM to its sat amp in SUS-R2. The QOSEM and its entire signal chain was functional, with readouts from this SD QOSEM appearing as expected in CDS.

Unfortunately upon unlocking the suspension, to align this SD QOSEM, we found that its y axis could not be brought into range with the cams (at its best was ~1mm off). This is a similar issues we faced when setting up the BBSS at LLO. As the SD BOSEM does not have a readout in this 'y' or vertical direction, misplacement of the tablecloth by ~1mm is unnoticeable, and does not impede function of the BOSEMs, but as we are activity trying to readout this axis it does matter for the QOSEM.

As such, to setup the QOSEMs on the BSFM, we would need to raise the tablecloth, or SUSP via the blade spring angle. While this certainly could be done, at the moment this feels like an unnecessary amount of work to do for a quick test of the QOSEMs, given the BBSS will be ready shortly. For now we have abandoned this test, and removed the SD QOSEM from the BSFM, reinstalling the original BOSEM.

SUS

H1 AOS - Two HAM 3 POP-path optics are retroreflecting light scattered from MC1 and PRM

robert.schofield@ligo.org — Sun, 10 May 2026 17:45:44 -0700

Author: robert.schofield@ligo.org

Report ID: 90193

In order to search for retroreflections of scattered light that might recombine and cause scattered light noise, I take pictures from the point of view of the beam spot on important optics. The flash on the camera is right next to its aperture so, when the camera is held close to the location of the beam spot, the path of the light from the flash is similar to that of light scattered from the beam spot during observation, and glints in the photograph are indicative of potentiial retroreflections of scattered light. The distribution of light from the flash is, by design, more uniform than that of most scattered light, so more off-axis retroreflections in the photos tend to be less important.

An old photo taken from near the beam spot on PR3 showed a glint from an optic on the POP path so I re-took beam spot photos last week since we are baffling HAM3. The figure shows that I did not find a retroreflection in beam spot photos from PR3, but I did in photos from MC1 and from close to the center of PRM. I took beam spot photos with both my IR camera and cell phone – the figure shows cell phone photos as they are eaisier to interpret, but photos from both cameras show the same issues. I could verify these retroreflections and track them to their source by eye using a head lamp near my eyes. The PRM retroreflection is from the last optic on the POP path and the MC1 retroreflection is from the second to the last optic on the POP path (see diagram on the second page of the figure).

Im a little surprised that there are two of these random alignments, but I guess it is due to how small the angular differences between the paths from HAM3 to HAM2 are and the number of mirrors on the tables. I am also concerned that my beam spot photo technique only picks up retroreflections and not reflections of scattered light from one optic to a different optic. I would also like to make us more aware of these cross talk issues in planning optic paths and suggest that it might be worthwhile to develop code that checked for this.

I don’t know how bad these retroreflections are, but, in my photos, they are brighter than the reflections from ballast masses and the table that we are trying to baffle, so I may try to baffle the PRM retroreflection when we return to baffling. Im not sure how I could baffle the MC1 retroreflection without blocking the POP path.

Non-image files attached to this report

Beam-Spot-Photos-and-Diagram.pdf

H1 CDS - MSR UPS momentarily went onto battery power due to power glitch 17:39:23 Friday 8 May 2026 PDT

david.barker@ligo.org — Sat, 09 May 2026 08:18:39 -0700

Author: david.barker@ligo.org

Report ID: 90192

No issues seen on CDS.

Images attached to this report

H1 IOO - Commissioning JAC WFS

jennifer.wright@ligo.org — Fri, 08 May 2026 19:13:17 -0700

Author: jennifer.wright@ligo.org

Report ID: 90188

Jennie W, Madi S, Sheila D,

Summary: JAC REFL A PD and WFS A and B are well-aligned and the beam is centred on the steering mirrors, but still some sign confusion on the readout for the WFS A quadrants and the WFS B DC readout (the QPD).

Earlier Madi and I went and re-centred the beam on the IOT1 steering mirrors JACR-BS3, BS4, M8, M9, M10. We then re-aligned the REFL PD and both WFS QPDs.

While centering we realised the degrees of freedom were switched.

After checking in the QPD input matrix for both WFS A and B, I found these were the wrong sign.

These matrix parts were copied from the IMC model and I didn't realise the IMC QPDs have a switch between pitch and yaw due to the periscopes that carry IMC REFL beam from MC1 to the in-air IOT2L.

I have switched both JAC QPD input matrixes to the values shown here.

I also checked the WFS I input matrix vales for A and B and these appear the have the correct signs for each quadrant.

Then I went to the table to do some sign checks on the QPD RF readouts to confirm these are hooked up correctly.

First I locked the JAC and then detuned it so the WFS signals are dominated by length noise. An offset of 0.4 in JAC-L_SERVO_OFFSET can be used to detune the cavity without unlocking.

Then I checked that the motion of the across the QPDs matches what we measure.

Moving anti-clockwise on pitch adustment knob for WFS A is down on QPD and on JAC-WFS_A_DC_PIT.

Moving left on QPD is down on JAC-WFS_A_DC_YAW.

QPD A seems to have the correct matrix.

As I was doing these adjustments I looked at the four demodulated I-quadrature signals for WFS A.

Whent the beam moves down in pitch quadrant 2 and 4 go down and quadrant 1 and 3 go up - this is confusing as 1 and 3 should be diagonal from each other. See ndscope.

When the beam goes down in yaw quadrant 1 and 4 go up and quadrant 2 and 3 go down - the opposite way to what we expect from the motion on the QPD. See ndscope.

I did the same series of checks for WFS B

Moving anti-clockwise with the pico mirror pitch adjustment knob is up on the QPD itself but down on the WFS-B_DC_PIT channel, this is wrong.

Moving anti-clockwise with the pico mirror yaw adjustment knob moves right on the QPD itself and up on WFS_B_DC_YAW channel - this makes sense.

So maybe we need to change the input matrix for this or fix some wiring.

Still need to check the four demodulated I-quadrature signals for WFS B.

NB: Two months ago we started commissioning the JAC WFS and discovered that the X and Y on the A picomotor are swapped somewhere in the chain, see alog #89437. This probably needs the control wires swapped at the pico signal distribution box on the table itself but the picos are not hooked up at the moment as the controlled is shared with IOT2L which is unplugged for vent work in HAM2.

Images attached to this report

H1 ISC - Restoring IMC alignment (Jennie, Rahul, Jenne, Keita)

keita.kawabe@ligo.org — Fri, 08 May 2026 18:16:11 -0700

Author: keita.kawabe@ligo.org

Report ID: 90191

PSL power into JAC 200mW. Jennie was able to lock JAC without much problem.

Jenne put MC2 back to march 2026 (in-lock) alignment in PIT and YAW using osem (not the slider) taking into account ISI (HAM3) Rz.

To see the fringes, we injected 600 counts 0.2Hz into H1:SUS-MC2_M1_DRIVEALIGN_L2L_EXC. IMC flashed right away but the transmisison fringe looked like a weak horizontal line. Moving MC2 alone did not make the fringe converge.

Jenne moved MC3 and MC2 (and MC3). Improved some but not drastic. Tried JM3, again improved, but not drastic. Jenne was able to see the MC2 TRANS SUM but it was awkward and slow. At this point, at least the beam was not a straight horizontal line any more, we saw HOMs both in PIT and YAW, sometimes even 10 and 01 and what might have been a dim 00 spot. According to Jenne, the maximum MC2_TRANS number observed (about 3 after subtracting DC offset with 200mW input) is about 10% of what we expect with a good alignment (300 counts with nominal 2W).

We need a better alignment to be able to see the beam in the ISS path, though, I couldn't see anything.

I wanted to see the PRM reflection on the ISCT1 REFL camera as it will make the alignment easier (because we can see the IMC transmission beam shape).

Inside ISCT1, the beam was making it to the BS for the 1F diode but was hitting the mirror holder of the mirror for the BBPD. I touched up the common steering mirror for 1F and BB (just downstream of the shutter) so the beam goes to the direction of BBPD (and of course 1F PD) but could not see the transmission of the mirror for the BBPD using a card and a viewer, probably because the power was too small. (We're injecting 200mW, MC2 transmission is a small fraction of that as of now, and the REFL path is supposed to handle 60W.) No beam was seen on the camera either.

On Monday we might temporarilly move the BS for the BBPD out of the way so we can see the beam on the camera.

INS

H1 SQZ - looking at SQZ beam profile data from last summer

sheila.dwyer@ligo.org — Fri, 08 May 2026 17:19:17 -0700

Author: sheila.dwyer@ligo.org

Report ID: 90186

I had a look at some of the data from Leo Schrader's SURF project, in particular the measured overlaps of the sqz beam with the OMC posted 86485 and the measured q parameters on SQZT7 posted in 86365.

I first took the measured q parameters, and using finesse propagated them to the OMC and calculated overlaps, which are plotted as sqrt(vertical overlap * horizontal overlap). The attached scatter plot shows the predicted overlaps compared to the measured overlaps as the ZM4 + ZM5 strain guage voltages vary. You can see that for the nominal O4 settings of -0.4V ZM5, 6.2V ZM4, the measured q agrees pretty well with the measured overlap. Moving away from the nominal values, some of the measured qs do not seem very compatible with nearby measured overlaps. (note, these measurements cover the whole PZT range of 0-200V for both psams, the strain gauges just have different ranges.)

I then tried to use the overlap data to take a gues at what this means for the actuation range of ZM4 + ZM5 psams. I used the following information from Camille to estimate the ROC of ZM4 and ZM5.

ZM4 is SN1, characterization data in E2100289 indicates that before the preloading was changed in chamber, with 0V on the PZT the optical power was -106mD. In 75677 the pre-load was increased by 29 in lbs, T2300426 says the preload should increase the optical power by 2.4 mD/ in lb of preloading, so after preloading the optical power with 0 V on the PZT should have been -36mD, or an ROC of -55.5 meters. 0V on the PZT now corresponds to 2V on the strain guage.
ZM5 is SN4, E2100291 says with 0V on the PZT the optical power was 667mD with 20 in lbs of preload. 75709 says the preload was increased to 47 in lbs, so 27 in lbs of preload was added. I assumed that the optical power change with pre-load is the same for ZM4 as ZM5, and estimate that the optical power after the pre-load change the optical power with 0V on the PZT should be 729 mD, or an ROC of 2.737 meters. 0V on the PZT now corresponds to -5.2V.

I used these estimates for optical power with 0V on the PZT and varied a linear slope of optical power per strain guage voltage. Assuming a slope of mD/V for each psams, I estimated the ROCs of each mirror. For any set of psams slopes, I estimated the q before ZM4 by using the measured q for the nominal strain guage values of 6.2 and -0.4V. I flipped the sign of the real part and propagated it back to before reflection off ZM4 using the estimated ROCs for that slope, then flipped the sign of the real part again to reverse propagation direction. (Thanks Keita and Disha for help understanding how to flip the qs). I then propagated that estimated q back through the ZMs allowing the strain gauge voltage to vary and calculated overlap with the OMC. This approach garantees that the nominal strain gage of 6.2V -0.4V the contour will match the 2.3% mismatch estimated from the measured q there. It would be nice to do an actual fit, and also allow the ROCs at 0V on the PZTs to vary, to see if we can get a better match to the dataset that way.

In the example contour plot I've put ZM4 at -10mD/V strain gage, which means -0.36mD/V PZT, and the O4 nominal ROC would be -25.6meters. ZM5 is at -13mD/V strain gage, which means -.47 mD/V pzt and nominal ROC of 2.99 during O4.

Lastly, I made a plot of propagation of the measured qs to the output of the AR side of SRM, that we can compare to Evan Hall's much nicer plots of SEC and arm cavity modes at SRM.

The script used to make these plots can be found in the commissoning-modeling-repo here.

Images attached to this report

H1 SUS - Comment to Troubleshooting SUS MC2 (HSTS) in HAM3 - found M1 (BOSEM) and M2 (AOSEM) feedthrough cable connection switched

oli.patane@ligo.org — Fri, 08 May 2026 17:08:09 -0700

Author: oli.patane@ligo.org

Report ID: 90190

Here is MC2 looking good after the find. I also took TFs of PR2 to check that it was also fine since we had been messing with it during the troubleshooting.

Non-image files attached to this report

20260508_MC2_TFs.pdf

20260508_PR2_TFs.pdf

LHO General - Fri Ops DAY Shift Summary

corey.gray@ligo.org — Fri, 08 May 2026 16:34:26 -0700

Author: corey.gray@ligo.org

Report ID: 90167

TITLE: 05/08 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

MC2 was fixed (cabling issue---see their alog). ISS team went out to HAM2 late this afternoon.
LOG:

1513-1542 LVEA garb checks (kim.dawn)
1528-1536 MC2 work fixes continue w/ work at racks (Rahul)
1549-1558 restoring mc2/pr2 cables (rahul)
1622-1628 reboot coil driver for mc2 (rahul.marc)
1655-1704 Dust monitor being power cycled, since it's been down (ryanC)
1645-1800 LVEA technical cleaning (kim)
1700-1830 Back to HAM3 for more checks (rahul.marc)
1703-1818 open light pipe, working on iot1, no locking for jac (jennie, madi)
1711-1945 BS/BBSS OSEM swaps (thomas.oli)
1745-2001 SQZT7 back panel off for table work (sheila)
1834-1852 Back to HAM3 area for another round of checks (rahul.marc)
1851-2000 Continuing JAC work at IOT7 & closed light pipe when out(madi.jennie)
1900-1947 EX grounding studies (robert)
2016-2110 Going into HAM3 for cable checks (rahul.marc)
2036-2300 FARO-ing ITMy @BSC1 (jasaon.ryanC.)
- 2054-2300 Stephen joining
2110 Fixed MC2! Mix up in the cable due to install and/or drawing (rahul, marc)
2125-2150 Woodland High School (Maggie)
2110 Continue ISS Array work at HAM2 (kieta,elenna,jennie)
- 2255 elenna out
- 2300 jennie out
- 2305 jenne in
2110-2300 Checking IOT1 JAC stuff (jennie)
- 2311 back out
2234-2305 PCal checks at EX (marc)
- 2250 Marc plugged in cables and we have data for channels he was looking at
2239 EX grounding checks (robert)
2245 Checking on ISS work (rahul)
2315-2323 TCS chiller famis check (corey)
2327 Grabbing headsets for ISS array group (oli)

H1 TCS - TCS Chiller Water Level Top-Off (Bi-Weekly, FAMIS #28640)

corey.gray@ligo.org — Fri, 08 May 2026 16:31:16 -0700

Author: corey.gray@ligo.org

Report ID: 90189

Addressed TCS Chillers (Fri [May8] 413-423pm local time) & CLOSED FAMIS #28640.

For measurements below, measuring from "top" of the red floaty ball.

TCSx Chiller: Had level of 29.7 cm. Added 50mL for 30.5cm.
TCSy Chiller: Had level of 10.8 cm. Added 0mL for 10.8cm.
There was no water in the small cup under the slow leak.

TCS

LHO General - Comment to Ops Day Shift End

gerardo.moreno@ligo.org — Fri, 08 May 2026 15:37:47 -0700

Author: gerardo.moreno@ligo.org

Report ID: 90187

(Randy T., Chris S., Eric O.)

Facilities set the scaffolding at GV7, the temporary work platform is set about 1 foot above the gate valve's bonnet, leaving clearance for all annulus pipes and other accessories.

Images attached to this report

H1 SUS - Troubleshooting SUS MC2 (HSTS) in HAM3 - found M1 (BOSEM) and M2 (AOSEM) feedthrough cable connection switched

rahul.kumar@ligo.org — Fri, 08 May 2026 15:35:31 -0700

Author: rahul.kumar@ligo.org

Report ID: 90185

Marc, Oli, Jeff, Jenne, Richard, Betsy, Fil, Keita, Rahul

Yesterday afternoon, Jenne pointed it to us that she was struggling to point (move in pitch or yaw) MC2 suspension in HAM3 chamber - she was applying bias on Pitch dof and was not seeing optic move accordingly (this was to get the beam in HAM2 for ISS PD work). We then started troubleshooting MC2. We started with the usual health checks (trying to damp the sus, TF measurements, M1 osem spectra) and it clearly looked that something was off - though we were not able to pin point on anything. Fil and I then swapped the cable 01 with cable 02 (basically trying to run MC2 using PR2 electronic chain for T1, T2, T2 and LF bosem - for ref. see wiring diagram D2300383, page 01 for MC2). When we (Oli and I) tried controlling MC2 using this, the results were all the more confusing.

This morning I restored the MC2 and PR2 cables back to its nominal state. Marc and I then started looking into the electronics chain of MC2 - poking each stage one by one. We started at Satamps (in the LVEA near HAM3 chamber) where I applied some offset at the CD on the medm screen and Marc measured the output voltage. For bosems T1, T2, T3, LF we measured 230mV and for RT and SD (these two bosems on MC2 share the electronics chain with PR2) we measured 350mV. We then moved to CER and repeated the same measurement at the MC2 coil driver and the result was no different. To check the DAC card and AI chassis we routed MC2 through another Coil driver (used by PR2) and yet there was no change in the output voltage. We swapped out the satamps and coil drivers to look for any change - found none. This meant that the electronics chain for MC2 was healthy, hence we restored everything.

Richard then suggested to measure the resistance of the coils on the BOSEMs at the satamps. For T1, T2, T3 and LF it was found to be around 16 ohms (much lower than what we expect) and for RT and SD 40ohms (which is the correct value). Around lunch time Marc and I talked to Jeff kissel and everything at this point was pointing towards the suspension (either the bosems or their connection at the new feed through) in Ham3 chamber. After lunch time Marc and I headed to HAM3 chamber. After looking at the dust count (measured in lower 10s), I opened the curtains on the +Y side near MC2. I then identified the M1, M2 and M3 stage cable on MC2 and followed it to the connector on the ISI table. I then followed the table cable to the feedthrough connection (in vacuum side). Marc was standing outside the chamber near the feedthrough side (in air). I then started unplugging the cables on each stage one by one and initially it was very confusing but very quickly we realized (to cut the long story short) that - the M1 and M2 stage cables were not correctly connected at the feedthrough (in vacuum side - see D1002874). To confirm this we measured the resistance of the bosem coils at the D6 feedthrough in HAM3 chamber. The top F1 and Bottom F3 connection were showing out 16 ohms and the middle F2 was showing 40ohms. This told us that the middle F2 connection belongs to the M1 stage and the top F2 belongs to M2 stage - see below for clarity.

Given below the flange layout in HAM3 chamber (D1002874)- D6 F1 and F2 were incorrectly connected. Marc and I changed that on in-air side.
Old connection - D6-F1 F DB25 SUS MC2 M1 T1T2T3LF OSEMs. New connection D6-F1 F DB25 SUS MC2 M2 OSEMs
Old connection - D6-F2 F DB25 SUS MC2 M2 OSEMs. New connection D6-F2 F DB25 SUS MC2 M1 T1T2T3LF OSEMs
Did not touch - D6-F3 F DB25 SUS MC2 M3 OSEMs

Oli took transfer function measurements and will post the results below. In the meanwhile we can say that MC2 is healthy and back in action.

SUS

H1 SQZ - SQZ beam profiles with different psams

sheila.dwyer@ligo.org — Fri, 08 May 2026 15:07:32 -0700

Author: sheila.dwyer@ligo.org

Report ID: 90181

Ryan Short, Tony Sanchez, Sheila

We took beam profiles of the sqz beam in the homodyne path using the Thorlabs M2Ms beamprofiler extension. It made collecting data for a variety of psams settings much faster than using a scanning slit profiler alone.

Tips for using this very nice extender kit:

The visible alignment laser made alignment easy.
We used the lens LA1461-C for 1064nm, the list of lenses and wavelengths is here: lens list
make sure that the unit is plugged in, powered on with the power button, and connected to the laptop before you start the software. Close and re-open the software if "translation stage control" and "M2 set" don't show up for you at the bottom of the "beam settings" window. Once they show up you just have to go to the M^2 button and hit play to make a measurement.
You can get the fit beam parameters by saving a pdf by clicking the button that says "Save test Protokol", you have to hit save twice on the screen where you type a file name and again on the next screen. "Save Measurement Data and results" gives you all the data, but not the fit beam parameters. You again have to hit save twice.
Sivananda Reddy contacted Thorlabs and posted a diagram of where the reference plane is in the dcc: T2500077

We spent some time refinding the IR beam on the SQZT7 IR PD, documented this in it's own alog so it's easy to search: 90183

We set the profiler as shown in the attached photo. The flipper mirror is 50.75" from the bottom persicope mirror, a steering mirror is 225mm from that, and the reference plane is 260mm from the steering mirror, so the reference plane is 1.774 meters from the bottom periscope mirror. Leo Schrader has a helpful list of distances in the google document linked to T2500228.

In 85282 Leo measured the beam distance from the top to bottom periscope mirrors to be 574mm.
The distance from the top of the persicope to the beam diverter was measured to be 84.5" in 61755.
In 75749 the distance from the beam diverter to ZM5 is listed as 1183.54mm based on a CAD drawing from Don Griffith.
This means the total distance from the reference plane to ZM5 is 5.678 meters. We have left the profiler and temporary mirrors in place so that we can use them during the upcoming HAM7 vent.

Images attached to this report

Non-image files attached to this report

May72026.zip

H1 SPI - Comment to SPI Breadboard Arrives; Quick Fit Checks

jeffrey.kissel@ligo.org — Fri, 08 May 2026 14:29:18 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90184

Obligatory "Mitch for Scale" picture, and evidence that this plate has been blessed by the whole Kissel nuclear family, so it'll *definitely* work this time.

Images attached to this report

H1 SPI - SPI Breadboard Arrives; Quick Fit Checks

jeffrey.kissel@ligo.org — Fri, 08 May 2026 14:28:22 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90182

J. Kissel, M. Robinson ECR: E2600106 Drawing: D2400143-v6 Assembly: D2400107-v5 I'm delighted to share that the new version of the SPI Pathfinder's ISIK Transceiver's custom breadboard (D2400143-v6) has arrived on site today! Big thanks to Greg and Levi at RDL Machine for rushing this thru their shop, and then hand-delivering it to me at a meet-up in Pasco this morning. Mitch and I did a quick inspection and crude fit-checks of the plate prior to handing off to Chris who's hard at clean-n-bake work in the VPW, and here're some pictures. The things that were keeping me up at night: - Will the new alignment peg system for the IXM mounts work? YES! I used a broken-but-good-enough Newport U100A mirror mount I had on my desk, which is close enough in dimension to the in-vac Siskiyou IXM100 mounts (D2400208 and D2400209), and it seats up against the pegs really well, and the mounting hole lines up. - Will our fingers fit around the knobs given the size of the new slots for the IXMs? YES! There's plenty enough room. And just to nip the "that looks different, why?" questions in the bud: - The Fiber collimator IXM mount positions for R_F1 and M_F1 *don't* have an alignment knob slot. That's intentional, because we still need those "utility" holes behind that mounts as mounting spots for the SLIC Shroud that goes over the SPI transceiver when fully integrated into the detector. - There is one slot, for the M_M3 mount that is *not* entirely thru the plate. That's because on the *back* side, that slot would have routed through the shoulder relief around the mounting hole. As such, I tested that we still have finger room with alignment knobs and that also works fine. Off to clean-n-bake!

Images attached to this report

H1 SQZ - slider settings to get SQZ beam onto SQZT7 IR PD

sheila.dwyer@ligo.org — Fri, 08 May 2026 14:20:10 -0700

Author: sheila.dwyer@ligo.org

Report ID: 90183

Sheila, Ryan Short, Tony

Just adding this screenshot to document that we found the SQZ seed beam on the SQZT7 OPO IR PD with seed dither locked and these slider settings.

Images attached to this report

H1 General - Dead fly taken out of HAM2 chamber

rahul.kumar@ligo.org — Fri, 08 May 2026 12:53:41 -0700

Author: rahul.kumar@ligo.org

Report ID: 90180

Keita, Elenna, Rahul

Yesterday, when we opened the curtain in HAM2 chamber (for ISS PD installation work), we found a dead fly in the chamber (not sure how long it was dead inside but the body felt very fragile, but fortunately it didn't break apart while it was taken out of the chamber) - please see two pictures attached.

The fly did not wear any laser goggles, nor it had any clean garbs on, but most probably it endured UHV and IR laser during its stay inside the chamber.

Images attached to this report

X1 SPI - Revision to LHO:88873

joshua.freed@ligo.org — Fri, 08 May 2026 12:30:54 -0700

Author: joshua.freed@ligo.org

Report ID: 90179

J. Freed

An error was found in the plot of Keyrad4r.png from 88873. The SPI budget was overestimated by a magnitude of 3. It is corrected here.

The code for this plot is being stored at https://svn.ligo.caltech.edu/svn/seismic/Common/SPI/PhaseNoise/python/

Images attached to this report

H1 AOS - Comment to aLIGO BS Test Stand Surveying Complete (WP 13210)

ryan.crouch@ligo.org — Fri, 08 May 2026 10:55:28 -0700

Author: ryan.crouch@ligo.org

Report ID: 90174

Adding some photos I took throughout the test stand measurements Tagging EPO.

EPO

Images attached to this report

H1 SYS - Comment to BSC2 Cartridge on the Test Stand

corey.gray@ligo.org — Fri, 08 May 2026 10:38:26 -0700

Author: corey.gray@ligo.org

Report ID: 90177

tagging for photos.

EPO

H1 SUS - Comment to BSC2 Cartridge pictures and time lapse movie

corey.gray@ligo.org — Fri, 08 May 2026 10:35:31 -0700

Author: corey.gray@ligo.org

Report ID: 90176

tagging for photos.

EPO

H1 SPI - Comment to First In-vac Components for SPI Pathfinder Installed!! ISI HAM2 (ISIJ) Reflector Assembly Installed and Cabled up to Feedthrus

corey.gray@ligo.org — Fri, 08 May 2026 10:28:19 -0700

Author: corey.gray@ligo.org

Report ID: 90175

tagging for photos.

EPO

H1 COC - Comment to BBS01: Mystery spots on AR Side + Cleaning

corey.gray@ligo.org — Fri, 08 May 2026 10:21:51 -0700

Author: corey.gray@ligo.org

Report ID: 90173

tagging for photos

EPO

H1 COC - Comment to BBS01 First Contact on AR Side

corey.gray@ligo.org — Fri, 08 May 2026 10:08:01 -0700

Author: corey.gray@ligo.org

Report ID: 90172

tagging for photos.

EPO

H1 IOO - Comment to ISS replacement work - day 1

corey.gray@ligo.org — Fri, 08 May 2026 10:01:41 -0700

Author: corey.gray@ligo.org

Report ID: 90171

tagging for photos

EPO

H1 AOS - aLIGO BS Test Stand Surveying Complete (WP 13210)

jason.oberling@ligo.org — Fri, 08 May 2026 09:43:03 -0700

Author: jason.oberling@ligo.org

Report ID: 90170

R. Crouch, J. Oberling, B. Weaver, S. Appert

We are done with the surveying of the aLIGO BS on the mechanical test stand. I'm still working on processing the data but can give a quick overview of where things stand:

With respect to the ISI, the BS is within the aLIGO install specifications (lateral/vertical +/- 1.0 mm; longitudinal +/- 3.0 mm)
- Position deviations when looking normal to the AR surface
  - Lateral: -0.7 mm (left)
  - Vertical: -0.8 mm (low)
  - Longitudinal: +1.8 mm (in the +X/+Y direction)
- Will rotate these to the IFO coordinate system at a later date, once all data has been processed
BS Pointing is NOT within the aLIGO install specification (Pitch +/- 55 µrad; Yaw +/- 190 µrad)
- Signs reported using the standard SUS sign convention (positive pitch is down, positive yaw is CCW when looking top-down)
- Pointing deviations from nominal (Pitch: -446 µrad; Yaw: +0.7849 rad (44.9699°) from the +Y axis)
  - Pitch: -200 µrad
  - Yaw: -710 µrad
- The yaw deviation appears to have been counteracted by a CCW yaw shift done via HEPI once the BS was installed in WBSC2 back in 2013; no explanation for the pitch deviation, but I do recall that pitch did not hold very well on the journey from the test stand to the chamber back in 2013, so there's no guarantee that our measured pitch here is fully representative of the BS optic pitch from in-chamber
- We have a suspiscion there is an error in the test stand monument used to do the pointing alignment back in 2013, and potentially an error in the LVEA monument used to the in-chamber pointing alignment; working out a way to test that with the FARO
The BS SUS cage mostly hangs around the aLIGO position tolerances, but we never measured it during the 2013 install (as our target was to place the optic, and the cage ended up wherever it ended up), so this is the first data we have on its position

I'm working on a larger alog tying together all of our BS and WBSC2 measurements (WBSC2 support tube ends, BS in-chamber, and BS on the test stand) to provide a more complete picture of the BS alignment as we have measured it these last couple of weeks (it's going to be a long one); this alog will have the full set of data from the various test stand measurements. In addition, the SUS and IAS teams met yesterday to discuss our path forward. We decided that, despite the error seen in pointing on the test stand, we will align the BBS to its nominal position and pointing w.r.t. the ISI on the test stand. Once back in-chamber we will use the BBS SUS cage position as the metric for adjusting HEPI to once again place the BBS in its nominal in-chamber position; pointing will be restored with the BS optical lever, as originally planned. I'll write up a RODA documenting this decision and upload it to the DCC ASAP.

This completes LHO WP 13210.

Edit: Some spelling and grammar clean up.

SYS

H1 COC - Comment to BBS01: Mystery spots on AR Side Imaged

corey.gray@ligo.org — Fri, 08 May 2026 09:27:45 -0700

Author: corey.gray@ligo.org

Report ID: 90168

tagging for photos

EPO

LHO General - Fri Ops Day Transition

corey.gray@ligo.org — Fri, 08 May 2026 07:48:38 -0700

Author: corey.gray@ligo.org

Report ID: 90166

TITLE: 05/08 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: 0.02 μm/s
Secondary useism: 0.09 μm/s
QUICK SUMMARY:

ISS Array work continues...MC2 troubleshooting continues.

H1 COC - Comment to BBS01: Mystery spots on AR Side Imaged

betsy.weaver@ligo.org — Thu, 07 May 2026 22:45:12 -0700

Author: betsy.weaver@ligo.org

Report ID: 90165

All of the spot pictures are un-cropped since the dino-lite was jigged to be roughly the same picture size and therefore show the relative spot sizes from one picture to the next. The last picture has a 2mm disc shown for scale (a banana was way too big, thankfully). The attached shows roughly where the 4 spots are. From some estimating on the pictures, spot sizes are roughly:

1: 0.5mm diam, bottom of the optic

2: 0.3mm diam, bottom of the optic

3: 0.6mm diam, centerline, but left a few inches

4: No pictures, almost dead center of optic so riskier to photograph, but much smaller like 0.1-0.2mm diam when visually comapred to the other spots

Images attached to this report

H1 AOS - Comment to Particulate levels in BSC2

betsy.weaver@ligo.org — Thu, 07 May 2026 22:14:10 -0700

Author: betsy.weaver@ligo.org

Report ID: 90164

Note for the casual reader regarding motivation of this line of alog: I asked Robert to re-invent some of the contamination control metric checks he had done years ago since we have newer staff which maybe have not seen alot of his past good work on dust mobility in chambers. Now is a good time to evaluate and clean an "empty" chamber since BSC2 detector hardware is currently gutted and in the West Bay. We observed oxidation somewhere around the feedthrus in BSC2, or possibly on the support tubes so wanted Roberts keen eye to give us guidance on things like "how bad is it and will it move with XX activity".

H1 AOS - Particulate levels in BSC2

robert.schofield@ligo.org — Thu, 07 May 2026 18:03:30 -0700

Author: robert.schofield@ligo.org

Report ID: 90161

I took a Met One GT-521S laser particle counter into BSC2 to answer a few questions.

Q: What is the reading while standing still in the chamber? About zero

Q: How much dust will be suspended by reconnection of BS cables on the inside feedthroughs of BSC2? A: I simulated reconnection of cables by tapping and wiping continuously in one of the nozzles for a minute and the 0.3um size value averaged about 200 particles/ cubic foot while the 0.5um size value averaged about 70 particles/ cubic foot.

Q: What are the levels for walking around (gently) on the aluminum floor of BSC2? A: 0.3 um - about 150, B: 0.5 um - about 80

Q: Does bumping the cloth cover over the top of the chamber increase dust levels? A: Less than walking on the floor

Q: What level is reached while wiping the floor? A: About the same as for walking on the floor.

Q: How long before the dust levels are difficult to distinguish from zero? A: For all of the above experiments, the readings were back to about zero after a minute or so.

H1 AOS - Status of baffle installation in HAM3

robert.schofield@ligo.org — Thu, 07 May 2026 18:02:38 -0700

Author: robert.schofield@ligo.org

Report ID: 90162

Mitchell & Robert

Mitchell and I installed baffles on the +X side of HAM3 and we installed the scraper baffle extension on the -Y side of the scraper baffle. We also removed the lower central piece of the MC baffle near HAM3. Pictures of all of these are in the attached pdf. We are stopping now for a couple of weeks until the SPI baffles have been installed to avoid interference. When we get back to this, we will install the baffles on the -X side of the table, install the central scraper baffle extension, replace dog clamps on PR2 with shorter clamps so they dont glint, install a POP path baffle, and make final adjustments of the baffles using beam-spot photos.

Non-image files attached to this report

Status-HAM3-Baffle-Install.pdf

H1 IOO - Comment to ISS replacement work - day 1

keita.kawabe@ligo.org — Thu, 07 May 2026 17:30:55 -0700

Author: keita.kawabe@ligo.org

Report ID: 90158

About the installed unit.

New ISS unit is SN1202965 with a base D1101073 (ALIGO IO PSL ISS PD L1 BASE).

Our plan was/is to reuse the base that is already in chamber, D1101074 (ALIGO IO PSL ISS PD H1 BASE), together with the strain relief assemby. (FYI, there's also supposed to be an obsolete base D1101075, ALIGO IO PSL ISS PD H2 BASE.) In other words, in the first attachment, the parts outlined in red will stay in chamber, only the blue part will be replaced.

One complication is to make sure that the SMP cables are connected to the PDs in correct polarity, otherwise the PDs will be forward-biased and damaged. However, it turns out that array PDs in the new one we're installing and the old one in chamber are all angled in a consistent manner that, seen from the back of the PDs, cathode is to the left and anode is to the right. See the 2nd (new unit) and the 3rd/4th picture (old one). This means that we don't have to use tags or anything to ID SMP cables, all we need to do is to make sure that the cables won't fall out of the strain relief. Once the main body of the array (PD array and QPD) is swapped, we can just connect cables based on the position of the strain relief holes they're in.

A note about misalignment of the IMC seen from inside HAM2.

We did not see "flashes" because it didn't flash at all. We were able to see the MC1 transmission and the return beam after one round trip inside the IMC, and the latter was more than 1" higher than the former. There was also YAW difference. All in all two beams were about 1.5" apart. MC1 transmission beam position looked OK.

This was eventually traced back to the problem of MC2 top OSEMs, which will be alog-ed by somebody else.

Images attached to this report

H1 COC - BBS01: Mystery spots on AR Side Imaged

ibrahim.abouelfettouh@ligo.org — Thu, 07 May 2026 17:25:38 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 90159

Ibrahim, Betsy

Today, Betsy and I set up a Dino-Lite to image the spots we found yesterday (alog 90147).

Below are photos including before and after cleaning - according to the names of the files. None of the spots seemed to change after cleaning.

We also cleaned the spot that's in the center (not imaged with dino-lite) but it also did not go away.

Current most likely hypothesis is a coating defect due to circular nature of the spots and the resistance to cleaning.

Images attached to this report

H1 COC - Comment to BBS01: Mystery spots on AR Side + Cleaning

ibrahim.abouelfettouh@ligo.org — Thu, 07 May 2026 17:19:30 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 90160

Check alog 90159 for continuation of this story.

LHO VE - Corner RGA Rebuild

jordan.vanosky@ligo.org — Thu, 07 May 2026 17:06:15 -0700

Author: jordan.vanosky@ligo.org

Report ID: 90157

The corner RGA tree was rebuilt in order to match the standardized trees on other HAM chambers. This included reducing the amount of elbows and piping, removing calibrated leaks, installing a 10 l/s ion pump, and installing a full range gauge that can be read by the new PrismaPro RGA head. This volume will pump down over the weekend, and we will confirm the connection/functionality of the new RGA to the control room RGA computer. Once confirmed, the entire RGA tree will be baked at high temperature to clean the volume for use. The small area around the RGA tree (output tube on +X side) has been sectioned off with caution tape, please avoid the area.

Images attached to this report

H1 General - OPS Thursday Day shift summary

ryan.crouch@ligo.org — Thu, 07 May 2026 16:33:43 -0700

Author: ryan.crouch@ligo.org

Report ID: 90153

TITLE: 05/07 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: The LVEA is now is laser hazard, HAM2 ISS swap and HAM3 cabling was started today.
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
13:55	FAC	Kim	LVEA	N	Tech clean	14:49
14:36	VAC	Jordan	LVEA	N	Check on CP1 and HAM6 RGA	15:25
15:37	FAC	Kim	LVEA	YES	Tech clean	17:12
15:50	FAC	Ibrahim	Optics lab	N	Grab mounts	16:37
16:11	EPO	Mike, Mira	LVEA	N	Tour the LVEA	16:55
16:23	CAL	Tony	PCAL lab	N	Grab equipment	16:38
16:24	SUS	Rahul	LVEA	N	Look for tool pan at HAM2	16:29
16:32	VAC	Jordan	LVEA	YES	Corner RGA work	18:35
16:35	FAC	Eric	Mezz	N	FAN1 work	18:15
16:36	ISS	Keita, Elenna	Optics Lab / LVEA	n / YES	ISS work	19:11
16:38	SQZ	Sheila	LVEA	N	SQZT7 work	16:42
16:42	SQZ	Tony	LVEA	N	Help Sheila, beam profiler	19:24
16:44	SQZ	Sheila	LVEA	YES	LazHaz transition then beam profiling	19:24
16:59	ISS	Rahul, Jennie	Opt Lab / LVEA	n / YES	ISS work	19:09
17:02	SQZ	Ryan S	LVEA	YES	Beam profiling	19:24
17:17	FAC	Kim	EX	n	Tech clean	18:02
18:02	FAC	Kim	EY	n	Tech clean	19:23
18:18	ContCont	Robert	LVEA	YES	BSC2 contamination control	20:37
18:32	EPO	Anna + film crew	LVEA	YES	Filming	20:07
18:35	ISS	Jenne	LVEA	YES	Locking JAC	19:06
19:09	EPO	Ibrahim	LVEA	YES	LVEA tour	19:49
19:43	SAF	LVEA IS LASER HAZARD	LVEA	Y	LVEA IS LASER HAZARD	04:03
19:49	SEI	Jim	EndY	N	Check out BRS-Y heater and wind fence	21:01
20:34	SUS	Betsy, Ibrahim	LVEA	Y	BBS cleaning cont. done at 22:25	22:56
20:38	VAC	Jordan, Anna + film crew	LVEA	Y	X1 beamtube enclosure	21:13
20:46	ISC	Rahul, Elenna, Madi, Disha, Keita	LVEA	Y	ISS work HAM2, Disha Madi out @ 21:41, everyone except Keita 22:56	23:33
20:51	EE	Fil	LVEA	Y	Cables by HAM3	22:17
20:53	SAF	Richard	LVEA	Y	Check work by HAM2	21:04
21:12	SQZ	Sheila, RyanS, Tony	LVEA	Y	SQZT7 beam profiling, Tony Ryan out at 22:30	22:55
21:13	VAC	Jordan	LVEA	Y	RGA work by HAM6	22:45
21:22	ISC	Jenne	LVEA	Y	Join/assist HAM2 crew	21:49
21:31	ISC	Jennie	LVEA	Y	HAM3 work	22:30
22:25	ISC	Jenne	LVEA	Y	HAM3 work	23:30
22:43	SUS	Betsy, Ibrahim	LVEA	Y	ITM cover	23:43
22:51	OPS	Corey	CER	Y	Grab a vacuum	22:56
23:30	IAS	Jason	LVEA	Y	FARO auto power off/on	22:45

H1 IOO - ISS replacement work - day 1

jennifer.wright@ligo.org — Thu, 07 May 2026 16:02:58 -0700

Author: jennifer.wright@ligo.org

Report ID: 90155

Jennie W, Jenne D, Keita K, Elenna C, Rahul K, Fil C, Jim W,

Summary: Today we started the replacement of the ISS array with its spare. JAC REFL PD was aligned and JAC locked but some problems encountered with MC2 which we need to fix so we can check the current ISS array alignment before removing it.

First part of day - JAC locking

We had a bit of trouble locking the JAC till Keita reminded me to check the error signals. The beam needed aligned on the IOT1 table. Jenne and I did this with the two mirrors before REFL PD that are not common to the WFS path.
After this we could lock JAC.

Checking beam in HAM2.

Checking the beam coming towards MC3 with the flashes transmitted back through the IMC, Keita and co realised that the IMC and input beam from the JAC were not well aligned.

Jenne and I consulted with Jim and isolated the HAM1 chamber, plus reset the set points for the HAM2 CPS. This means that the residuals for HAM1 were low but both HAM2 and 3 which have their ISIs locked, are out of nominal alignment, ie. higher in pitch and lower in yaw than their nominal.

The positions we want for MC2 to put compensate for the ISI relative alignment change are M1-OPTICALIGN_OFFSEt_P = 864/858

M1-OPTICALIGN_OFFSET_Y = -451.5/-354.5

The positions we want for MC3 are M1-OPTICALIGN_OFFSEt_P = 417

M1-OPTICALIGN_OFFSET_Y = -185.4/-190.6

The positions we want for MC1 are M1-OPTICALIGN_OFFSEt_P = -686

M1-OPTICALIGN_OFFSET_Y = 1352/1358

Unfonrtunately while trying to align MC2 we encountered some problems with the suspension so that is in the process of being debugged. Possible culprit is the D6 feedthrough swap last Thursday on HAM3 as MC2 top mass osems changed a lot that day. Left record of values we need to align osems to above so we can come back to this when we have fixed MC2 problems.

ISS Array

In the meantime Keita, Rahul and Elenna opened the box with the new ISS unit in the clean room and prepared to swap out the base with the one in chamber (our new unit is set for L1 beam height). To do this thye had to removed the blue glass beam dumps to reach the 1/4-20 screws at the four corners of the middle ISS mounting plate.

ISC

LHO VE - CP1 Soft Regeneration Update

gerardo.moreno@ligo.org — Thu, 07 May 2026 08:34:11 -0700

Author: gerardo.moreno@ligo.org

Report ID: 90152

(Jordan V., Dave B., Gerardo M.)

The internal pressure to CP1 turned around overnight signaling that the process of emptying the trap is complete, now we'll continue to monitor and pump on the cryotrap volume.until good pressure is achieved.

A side note, I manually turned off the CC for PT114B last night at 9:44 pm (local time) as the pressure was rising a bit high, then turned it back on this morning at 5:33 am local time.

Attached is a snapshot of one day trend data of pressure behavior regarding the soft regeneration for CP1.

Process started here.

Images attached to this report

Non-image files attached to this report

20260507-CP1_Soft_Regen.pdf

H1 General - OPS Thursday Day shift start

ryan.crouch@ligo.org — Thu, 07 May 2026 07:32:09 -0700

Author: ryan.crouch@ligo.org

Report ID: 90151

TITLE: 05/07 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: 5mph Gusts, 2mph 3min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.26 μm/s
QUICK SUMMARY:

Temps looks good, no dust alarms
Potential LVEA laser hazard transition today to allow
- ISS swap
- JAC locking and WFS work
- SQZT7 table beam profiling