aLIGO LHO Logbook

H1 SPI - Comment to LIGO-SPI Pathfinder ISIK/ISIJ Picomotor Test: All Motors Operational

sina.koehlenbeck@ligo.org — Fri, 03 Apr 2026 17:12:40 -0700

Author: sina.koehlenbeck@ligo.org

Report ID: 89781

The images show the test equipment used.

Images attached to this report

H1 SUS - Investigating violin mode frequency spacing and amplitude in DARM

georgia.mansell@ligo.org — Fri, 03 Apr 2026 17:01:22 -0700

Author: georgia.mansell@ligo.org

Report ID: 89780

Hi everyone it's been a while since I posted!

Julia Rice and I had a chat with Peter F today about motivating the electrostatic violin mode damper we've been building at Syracuse. We came away with a couple of questions to answer:

1. What's the actual displacement of the fibers when the violin modes are excited, and is our shadow sensor noise low enough to measure the modes.

2. What is the origin of the two violin modes per fiber? Is it fiber ellipticity built into the fibers themselves or asymmetry their attachment points AKA the ear/horn. If it's the former, we'd expect the main oscillation axis of the modes to be randomly oriented. If it's the latter we'd expect 4 modes per test mass to be dominant in DARM, and 4 modes to be much weaker, we'd also perhaps expect to see a regular spacing between pairs of modes.

I still have remote access (thanks Dave for helping me get my ports sorted with NoMachine), so I logged in to grab some plots of violin modes excited vs damped times.

I found an excited time and a quiet time by plotting the ISC_LOCK guardian state and the monitor for ITMY MODE5 which I know is a problematic mode (first plot). I used 5 November 2025 17:59:09 UTC, gps 1447264767 for the modes excited time since this was after many locking attempts with the mode5 monitor was ~20k counts. I used 17 November 2025 20:57:12 UTC, GPS 1447448250 as my quiet time AKA t=0 on the first plot.

Second plot is the money plot! When the modes are excited their amplitudes in DARM range between 1e-16m/rt(Hz) and 1e-14m/rt(Hz), we can roughly convert this to fiber displacement by multiplying by the fiber to test mass mass ratio. We did some back of the envelope calculations with Stefan and there's a factor of 2pi in there somewhere too.

I labelled the plot referencing this handy violin mode spreadsheet from Rahul et al, which set me thinking about the violin mode origin in question 2 above...

I can see the regular spacing with one large mode and one smaller mode in the ETMs for the excited spectrum. BUT it's not like there is 4 modes visible in DARM and 4 that are totally anti-aligned: the smaller modes are still very much visible in the DARM spectrum.

ETMX9 (516.781 Hz) has a small buddy ETMX7 (516.678)
ETMX1 (511.2993 Hz) had a small buddy ETMX6 (511.18)
ETMX3 (508.938 Hz) has a small buddy ETMX4 (508.844)
ETMX8 (507.36) has a small buddy ETMX2 (507.493)

For the first 3 pairs, the bigmode is higher in frequency, not sure if significant. Also, in the damped spectrum the larger modes can become sufficiently damped that the smaller mode is now louder in DARM, I wonder if that might be because we have spent many more hours tuning and damping the settings for the large modes?

There are also some modes that break the trend: ETMY1 and ETMY6 are very close together.

For the ITMs, things are less clear. ITMY1 and ITMY2 are similar height in DARM, same with ITMX8 and ITMX7, and ITMX3 and ITMX5. Things are confusing around the clusters of modes 504 Hz and 508 Hz.

I had previously always assumed that ITMY mode5 and mode6, the extremely close modes, are on the same fiber. But perhaps mode5 is on the same fiber as mode7, and mode6 is on the same fiber as mode8!

To better visualise the data, I made a table of the mode "buddies" and their frequency separations here, check it out if your interested. There is a goofy plot in there with no x-axis and mode spacing on the y-axis. The frequency spacing of pairs of modes is centered around 0.1Hz.

I do think there is scientific value to having a shadow sensor at the fiber: it's clear that the modes are not perfectly aligned or anti-aligned with the DARM axis, I was able to identify all 32 modes. In the egregious case of ITMY, at least 7 of the 8 modes are large in DARM. That being said, the regularity of the spacing means I am quite confident (for most modes!) which two modes are on the same fiber.

Please let me know if I've missed something or if you have any thoughts!

DetChar, SUS

Images attached to this report

LHO General - Comment to Fri Ops DAY Shift Summary

sheila.dwyer@ligo.org — Fri, 03 Apr 2026 16:43:47 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89779

I followed the transition checklist to upgrade phase laser safe to make sure everything is set for venting on Monday. The only thing that I had to change was turning off the squeezer laser, as expected.

LHO General - Fri Ops DAY Shift Summary

corey.gray@ligo.org — Fri, 03 Apr 2026 16:28:56 -0700

Author: corey.gray@ligo.org

Report ID: 89764

TITLE: 04/03 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Final HAM1 checks were made by Keita & Sheila in the morning. ISCT1 was pulled away from HAM1.

There is new anti-slip (yellow) paint on part of the ramp at the OSB door enttrance ramp near the Control Room. This paint should be dry, so it some signs have been removed. (Waiting on more paint to finish job.)
LOG:

1445 optics lab technical cleaning (kim)
1448 X-arm tumbleweed check (randy)
1510-1657 alum-A-lift moved from staging to hi-bay to West Buy (randy)
1541 technical cleaning lvea (kim)
1545-1555 checking mega cleanroom (sheila)
1603 -1828 Opening HAM1 covers + light pipe + moving ISCT1 out of the way (keita.sheila.randy)
- They had to put back up the laser safety barriers for ther South Bay & reconnect isct1
- 1738: Light pipes closed, HAM1 covers closed, taking down laser barriers.
- 1758: Sheila moving over to SQZT7 & going to local laser hazard
  - 1825 SQZT7 work is done & Sheila is out of the LVEA. Laser is still ON, so Sheila can continue SQZ work from Control Room. Sheila will turn this laser off at the end of the day--Will want to turn this laser OFF before venting so we can return to full Laser Safe (Operations Laser Safe?).
- 1801-1828: Moving ISCT1 away from HAM1 (first have to crane a door out of the way and then they can forklift) [randy, keita]
1625-1739 Taking photos of BSC3 for Neil (carlos)
1632-1749 Recon of racks: susR2@ham3, seiC2@cer (jeff)
1634 Anti-Slip coating appliction to OSB door entry near Control Room (tyler)
- Able to paint the sides, but need more coating material for the center portion. This material takes ~4hrs to cure.
2001-2115 Survey work on back-side of the Y-arm (bubba)
2030-2046 Checking susR1 rack check near HAM2 (jeff)
- 2052-2057 returned to rack (jeff)
- 2204-2208 back to susR2
2224 -2233 H2 Bldg walkabout (Josh F)

H1 SPI - h1spih23 SPI Pathfinder's Front-end Software Model Prep and Installation

jeffrey.kissel@ligo.org — Fri, 03 Apr 2026 16:15:56 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 89777

J. Kissel, D. Barker WP 13140 Executive Summary: Dave and I created, compiled, installed, and started running the SPI pathfinder's front-end software model -- h1spih23.mdl -- on the h1seih23 front-end computer. ALL DAC OUTPUTS are 0.0, and saved in the SDF system as such. Details: With all the work done ahead of time in 2024 G2402138, subsequent work on the LHO test stand in 2025, and now armed with the real, final ADC/DAC channel usage (LHO:89775), I've *easily* (1) copied over ${userapps}/spi/x1/models/x1spih23.mdl to a new ${userapps}/spi/h1/models/h1spih23.mdl (2) made sure Matlab had access to the library part directory under ${userapps}/spi/common/models/ (3) updated the ADC inputs and DAC outputs to match the production channels / analog electronics, (4) commited to svn, making sure to turn on the 'Id' and 'HeadURL' properties, and (5) successfull compiled the top level model The model rate is "32k" (2^15 = 32768 [Hz]), in order to comfortably support modulation / demodulation at 4096 [Hz]. We're storing most of data processed from the ADC to frames at 2048 [Hz], tho. Only 8x channels at the full 32768 [Hz] rate -- 60x 2k channels in total. - 4x related to the DAC output, so we can keep track of the digitally requested 4096 [Hz] LO signal (original digital clock, the phase shifted COS and SIN and clock to be sent to the DAC), and - 4x related to the raw demodulated output of the IFO PDs. Dave assigned me DCUID = 187 The model has 5x shared memory (SHMEM) IPC senders: - H1:SPI-H23_DIFF_L :: differential length change between ISIH2 to ISIH3 in IFO X coordinates (in the XY plane, at ISI's Z = 0 coordinates). - H1:SPI-H23_TO_ISIH2_RY :: The rotation of ISIH2 in pitch (+RY follows the right-hand rule; positive RY rotation in the direction of one's fingers with one's right thumb pointed in +Y; the +X side of ISIH2 goes more -Z and the -X side goes more +X) - H1:SPI-H23_TO_ISIH2_RZ :: The rotation of ISIH2 in yaw (+RZ follows the right-hand rule; positive RZ rotation in the direction of one's fingers with one's thumb pointed in +Z; CCW if looking down on the chamber from above.) - H1:SPI-H23_TO_ISIH3_RY :: The rotation of ISIH3 in pitch - H1:SPI-H23_TO_ISIH3_RZ :: The rotation of ISIH3 in yaw Libary parts (and revs) - spi/common/models/SPI_LIBRARY.mdl rev 29747 - isc/common/models/QPD.mdl rev 18653 - cds/common/models/rtdemod.mdl rev 31460 - cal/common/models/CAL_LINE_MONITOR_MASTER.mdl rev 28567 Once Dave installed and turned on the model, I made SDF files for the model softlinks the userapps repo: /opt/rtcds/lho/h1/target/h1spih23/h1spih23epics/burt$ ls -l lrwxrwxrwx 1 controls controls 66 Apr 3 16:08 OBSERVE.snap -> /opt/rtcds/userapps/release/spi/h1/burtfiles/h1spih23_OBSERVE.snap (rev 34930) lrwxrwxrwx 1 controls controls 63 Apr 3 16:08 safe.snap -> /opt/rtcds/userapps/release/spi/h1/burtfiles/h1spih23_safe.snap (rev 34929) and did the same for the filter file: /opt/rtcds/lho/h1/chans$ ls -l H1SPIH23.txt lrwxrwxrwx 1 controls controls 59 Apr 3 16:12 H1SPIH23.txt -> /opt/rtcds/userapps/release/spi/h1/filterfiles/H1SPIH23.txt (rev 34931) Next up MEDM screens!CDS

Images attached to this report

H1 CDS - Running new h1spih23 model on h1seih23

david.barker@ligo.org — Fri, 03 Apr 2026 16:09:13 -0700

Author: david.barker@ligo.org

Report ID: 89778

Jeff, Josh, Erik, Dave:

We started the h1spih23 model for the first time on h1seih23 at 15:51 Fri 03apr2026. It has been allocated dcuid=187.

Erik added this model to CDS puppet. I did a build, rev-update, build-rev-locked and install. Erik then started the model on h1seih23 with no problems.

h1spih23 has not been added to the DAQ, therefore it is missing its DAQ channels and has a bad DAQ status.

h1spih23 runs at 32K. It has 5 SHMEM IPC senders running at that rate. SEI receivers will be added at a later date.

I have added h1spih23 to the CDS Overview (some hand editing was needed since it is not in the DAQ running config yet).

Next week we will add this to the DAQ.

Images attached to this report

H1 ISC - Comment to Peeking down the X arm, Pico-ing HAM3 POP steering mirror, using dichroic to center ASC POP_X, using pico mirror in HAM1 to center LSC POP_A (Camilla, Jennie, Sheila, Jenne, Betsy, Keita)

keita.kawabe@ligo.org — Fri, 03 Apr 2026 15:15:01 -0700

Author: keita.kawabe@ligo.org

Report ID: 89776

FYI, attached is a cartoon of what I think we did in the above alog as far as beam positions go.

Top row represents the top periscope mirror seen from HAM2 and the bottom row the dichroic seen from HAM2. Red,green and green-dotted circles represent the POP, ALSX and ALSY beam respectively, though in reality we didn't open the Y arm so we didn't see ALSY.

Circle radius represents the beam radius (about 2mm or so for POP and 1.4mm or so for ALS).

Beam spacings are according to Mike Smith's calculation (L1200282 section 1 and table 1).

Images attached to this report

H1 SPI - H1-SUS-R2 Rack Re-labeled with From-the-Bottom Convention and Prepped for SPI Electronics

jeffrey.kissel@ligo.org — Fri, 03 Apr 2026 15:11:02 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 89774

J. Kissel Now that we have a better handle on how much rack space the SPI pathfinder will take from making it fully functional in the optics lab (see LHO:89269) I've uploaded a new version of the rack layout design to G2401479-v3 -- a copy of which is attached here for convenience. Then, with this in hand, I went out to SUS-R2 and: - Finally removed all evidence of the iLIGO style U-height labeling, - Re-labeled the rack in the standard 42U rack convention with super large font for ease of reading, and - installed rack screws in all locations where the SPI chassis will need them. The first two pics show BEFORE (labeled with counting starting at the top) vs. AFTER (labeled with counting starting at the bottom). In this modern convention, forced on this old rack, u-height "1" is missing; true for all of these racks (e.g. true SUS-R1 as well; see LHO:83156). The last pic shows U18 thru U2 with all the rack screws and sockets prepped. I'm in the process of feeding this info back to Dean so he can update the Altium version of the SPI wiring diagram D2400111.CDS

Images attached to this report

Non-image files attached to this report

G2401479-v3_SPI_AnalogRackLayout_Design.pdf

H1 AOS - Comment to HAM1 almost done, but we still need to check the POP beam dump and take a few pictures. (Camilla, Elenna, Betsy, Sheila, Keita)

keita.kawabe@ligo.org — Fri, 03 Apr 2026 14:48:54 -0700

Author: keita.kawabe@ligo.org

Report ID: 89770

Friday update: We're done with HAM1. (Randy, Sheila, Keita)

For component names see layout_truer.png which should be better than HAM1 layout on DCC as of now (D1000313-v20) as POP AIR and REFL AIR paths are both incorrect on DCC.

Anyway, I looked at the REFL_AIR and POP_AIR beam when the beam diverters were closed and both landed on the beam dump.

REFL_AIR:

See REFLAIR_beamdump.jpg. Also, REFLAIR_BDV.jpg shows the BDV1 seen from the top. Horizontal alignment seems to be decent.

POP_AIR:

POPAIR_beamdump.jpg shows the beam position of BDV2 reflection on the beamdump.

POPAIR_BDV.jpg shows that the beam is rather low on the BDV2 optic. It's hard to say how much lower than in the middle due to parallax but it's low. I used an IR viewer to see the edge of the optic and couldn't see any scattering/clipping.

Note that POP_AIR beam itself is supposed to be lower than green beam by 13.3mm at the HAM1-HAM2 septum according to L1200282 table 1. Due to this, and since the green beam is somewhat higher than the middle of M10 dichroic in PIT, it's not surprising that the POP_AIR is low. See POPAIR_dichroic_IR.jpg, which was shot today, and POP_ALS_dichroic_green.jpg which was shot yesterday.

However, when Sheila opened the POP beam diverter, the IR beam was reasonably centered in PIT on the last steering mirror M16. It seems that the beam is shot up probably from the dichroic, and was made level by M16 in the POP_AIR path and by PM1 and L2 in the POP path.

Tables were moved out:

We closed the PSL light pipe, closed the door cover (Sheila removed the lower cover for the +Y door as there were small rips, so that door is now covered by a single fabric), disconnected cables from IOT1, closed the bellows opening of that cable, and removed the laser barriers.

Randy temporarily craned one of the doors so he can drive fork lift to move ISCT1 by HAM2-HAM3 tube, and put the craned door back on the same spot on the floor as before.

Randy and I marked the feet of the IOT1 on the floor and rolled that table to its temporary parking position.

Images attached to this report

H1 SPI - ADC / DAC Channel Usage for SPI

jeffrey.kissel@ligo.org — Fri, 03 Apr 2026 14:25:16 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 89775

J. Kissel More experience with the SPI in the optics lab yields an explicit ADC / DAC channel usage list for the SPI pathfinder. I've uploaded it as a part of G2401479-v2, but attached here for convenience. This kind of critical info / easy look-up table should be a part of the Altium wiring diagram, D2400111, but sometimes given there saturation of information it's nice to just have a look-up table especially when building front-end models. Enjoy, future us!CDS, SEI

Non-image files attached to this report

G2401479-v2_SPI_ADC_and_DAC_ChannelUsage_Design.pdf

H1 SPI - Comment to Installed SPI ISIJ QPDA TIA

jeffrey.kissel@ligo.org — Fri, 03 Apr 2026 14:04:06 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 89773

EDIT (2026-04-03) Per my own wiring diagram, and for the consideration of extensibility of the SUS-R1 rack, I've edited the above installation -- I've moved this S2500711 SPI TIA chassis for HAM2's ISIJ QPDA from SUS-R1 U6 to SUS-R1 U3. See D2400111 and G2401479-v2. Two "EDIT" pictures attached. I've updated the S1301885 e-traveler as well.

Images attached to this report

H1 PSL - PSL Status Report (FAMIS #39758)

corey.gray@ligo.org — Fri, 03 Apr 2026 12:35:07 -0700

Author: corey.gray@ligo.org

Report ID: 89772

This is for FAMIS #39758.
Laser Status:
NPRO output power is 1.841W
AMP1 output power is 70.55W
AMP2 output power is 138.4W
NPRO watchdog is GREEN
AMP1 watchdog is GREEN
AMP2 watchdog is GREEN
PDWD watchdog is GREEN

PMC:
It has been locked 27 days, 19 hr 55 minutes
Reflected power = 27.29W
Transmitted power = 103.6W
PowerSum = 130.9W

FSS:
It has been locked for 0 days 2 hr and 22 min
TPD[V] = 0.484V

ISS:
The diffracted power is around 4.3%
Last saturation event was 0 days 21 hours and 25 minutes ago
Possible Issues:
PMC reflected power is high

PSL

H1 SQZ - FC1 aligned to irises on FCGS refl, works well

sheila.dwyer@ligo.org — Fri, 03 Apr 2026 12:32:16 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89771

Yesterday Camilla and I put two irises on the FCGS refl path, 89751, to use as a reference for FC1 alignment, and turned on the cleanroom to test how well this would work. The temperature swing in zone 4 G was not as large this time as other times that the cleanroom was turned on or off, but it is large enough for us to see. Around 11:30 this morning I went to the table to check the iris, the beam was off as shown in the photo. I walked it towards being centered on the iris, and this recovered the green flashes to 40 counts, with CLF locked IR flashes are up to 0.4-0.6, infrequently, and frequently around 0.2 counts.

While I was doing this, I saw that when FC1 was badly misaligned, looking at the green here is a nice way to see where the filter cavity flashes are, movie attached.

This screenshot shows what this looked like on the osems and sliders: I moved FC1 +10 urad in pitch on the slider by looking at the iris, which restored the flahes. The top mass osem suggests that after this adjustment FC1 pitch is undercorrected by -43urad, M2 wit would suggest that I overcorrected by +4urad, M3 wit says I overcorrected by +10urad.

Here's a screenshot of all osems earlier in the week with Camilla had nice flashes in IR and green, and here's a screenshot of all the osems now.

Images attached to this report

Non-image files attached to this report

IMG_1553.mov

H1 SUS - Accepting SUS Slider Slider Values On SDF Before Next Vent

corey.gray@ligo.org — Fri, 03 Apr 2026 12:31:06 -0700

Author: corey.gray@ligo.org

Report ID: 89766

After all the alignment tweaks (from recent Round 2 of HAM1-JAC & SQZ work), this morning Betsy requested we record how our H1 alignment looks. Sheila mentioned noting the SUS sliders is the best way to do this, and using SDF can take care of this for us. Guardian does not touch SUS slider values and they (for the most part) are Not Monitored by SDF. So Accepting these SUS slider values is a good for maintaining this prefered alignment.

To capture where we are "slider-wise", went through the exercise of ACCEPTING all SUS Slider Values for H1. Will go through SDF_OVERVIEW.adl, and open each SUS SDF Table to ACCEPT the slider values.

The Process: For each SUS SDF table, I will:

Open a SUS SDF Table (I started by chamber by chamber starting with HAM1 and went down the line ending with ETMy....pecked away at this from roughly 1600-1745utc/9-1045ampdt)
Change "TABLE SELECTION" to "CHANS NOT MON"
If there is a long list of Not-Monitored channels, switch from "SHOW ALL" to "SORT ON SUBSTRING", and enter part of the slider channel name in the "String Box" to narrow the list down to the slider channels
- slider channels: H1:SUS-[SUS]_M[1 or 0]_OPTICALIGN_[P or Y]_OFFSET
Click ACCEPT for slider channels in the table list
Click CONFIRM
Return "TABLE SELECTION" to "SETTINGS DIFFS"
- Return to "SHOW ALL" & clear substring field, if you did a "SORT ON SUBSTRING"

List of All SUS SDF Tables This Was Done For:

HAM2: SUSMC1, SUSMC3, SUSPRM, SUSPR3, SUSIM (for IMs 1,2,3,4), SUSHAM1 (for JMs [1,3], PM1, and RMs [1,2])
HAM3: SUSMC2, SUSPR2
HAM4: SUSSR2
HAM5: SUSSR3*, SUSSRM
- * SUSSR3: (looking like sliders are MONITORED (pointed this out to Sheila--noted this optic is rarely moved). Will keep monitoring, but ACCEPTING the pitch slider which did come up as having a diff)
HAM6: SUSIFOOUT (OFI*, OMS [for OMs 1,2,3], OMC), SUSSQZOUT (for ZMs [4,5,6])
- *OFI only has the one Yaw slider (which is 0).
HAM7: SUSFC1**, SUSSQZIN (for ZMs [1,2,3])
HAM8: SUSFC2
BSC1: SUSITMY
BSC2: SUSBS
BSC3: SUSITMX
BSC9: SUSETMX, SUSTMSX
BSC10: SUSETMY, SUSTMSY

NOTES:

Attaching a screenshot of IFO_ALIGN_COMPACTEST.adl from earlier this morning. (Note: MC2, ETMy, & SRM are listed as MISALIGN from Guardian [I pointed this out to Sheila, but this is when Sheila said it's fine since Guardian doesn't change these slider channels]).

**Sheila will probably touch some Squeezer-related sliders this afternoon---This would be for FC1 (see her alog 89771).

GRD, SUS

Images attached to this report

H1 CDS - Comment to SPI added as a userapps subsystem to CDS workstations and front ends

erik.vonreis@ligo.org — Fri, 03 Apr 2026 11:36:50 -0700

Author: erik.vonreis@ligo.org

Report ID: 89769

The change needs to be made in two places. In CDS puppet there's an array at the top of cds-env.pp and also add to the array in /opt/rtcds/userapps/release/etc/SUBSYS.ini

H1 CDS - SPI added as a userapps subsystem to CDS workstations and front ends

erik.vonreis@ligo.org — Fri, 03 Apr 2026 11:30:19 -0700

Author: erik.vonreis@ligo.org

Report ID: 89768

SPI has been added added as a subsytem in the userapps directory tree. MATLAB can open SPI models by name and h1build should build spi models (not tested yet as there are no models to build).

You'll need to wait an hour after this post for puppet changes to propagate and log out and back into a workstation for the MATLAB path update to take effect.

SPI

LHO VE - Fri CP1 Fill

david.barker@ligo.org — Fri, 03 Apr 2026 10:21:03 -0700

Author: david.barker@ligo.org

Report ID: 89767

Fri Apr 03 10:12:27 2026 INFO: Fill completed in 12min 23secs

Images attached to this report

H1 AOS - Comment to HAM1 almost done, but we still need to check the POP beam dump and take a few pictures. (Camilla, Elenna, Betsy, Sheila, Keita)

sheila.dwyer@ligo.org — Fri, 03 Apr 2026 08:33:02 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89765

HAM1 was under vacuum May 23rd, 84334, which is why we did not adjust the in vac alignment at that time.

LHO General - Fri Ops Day Transition

corey.gray@ligo.org — Fri, 03 Apr 2026 07:54:40 -0700

Author: corey.gray@ligo.org

Report ID: 89763

TITLE: 04/03 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, 3mph 3min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.17 μm/s
QUICK SUMMARY:

GV7 was closed last night (~530pm)--still only soft closed to the X-arm (Y-arm has been [hard] closed ~2weeks).

Closeout work in HAM1 will need to continue today and then move tables away from HAM1 in prep for a Monday vent.

LHO VE - GV7 is Soft Closed

gerardo.moreno@ligo.org — Thu, 02 Apr 2026 23:17:45 -0700

Author: gerardo.moreno@ligo.org

Report ID: 89762

Betsy informed me that the commissioners were done with the peek along the X-arm and I closed GV7, once again it does not want to hard close, currently sitting at "soft close" with 50 psi of instrument air in an attempt to close it.
I tried increments of 10 psi with the new regulator, I took the pressure up to 90 psi, and it sat there for about 30 minutes, no luck closing. Probably the gate valve is not "hard closing" due to the leaks within the gate valve's piston system.
I've set the pressure down to 50 psi and left it and maybe it will hard close, with the leaks present lots of air is wasted. Also, this configuration allows for crane usage along the XBM from now on.

Images attached to this report

H1 AOS - HAM1 almost done, but we still need to check the POP beam dump and take a few pictures. (Camilla, Elenna, Betsy, Sheila, Keita)

keita.kawabe@ligo.org — Thu, 02 Apr 2026 23:10:41 -0700

Author: keita.kawabe@ligo.org

Report ID: 89761

Following yesterday's work (alog 89745), ISCT1 was moved in place (but not landed, so the table is much higher than usual for now) to check the in-air beams.

ALS beam from the PSL table as well as green ALSX beam:

Was already good. See ALS_beampos.jpg.

Note that ALSY beam is supposed to be at the same height as ALSX but shifted horizontally by 10mm or so in -X direction on the periscope mirror. According to Mike Smith's L1200282 Table 1 (which is the table we should use though there are other similar tables in that document) ALSY is shifted by 8.5mm in +Y direction relative to ALSX on the septum window (and the two beams are diverging after 3" mirror in HAM3).

REFL air and POP air:

REFL was already hitting the ISCT1 top peri mirror but was close to the +X edge (REFL_before.jpg). POP air beam was coming to the same mirror mount as was described back in May/25/2025 in alog 84558 (especially this picture in that alog) though I didn't know/remember. (Turns out that I was away for a week when that was done, my recollection only included my May/09/2025 alog 84334.)

I didn't like that POP and REFL beam are both at the edge of the mirror and "fixed" it, i.e. I undid the work people did on May/25/2025 (sorry). I adjusted 90:10 air-vac splitter (M12 in layout.png) to make sure that the beam is not close to the edge of the last steering mirror for the POP air path (M16), and used M16 to steer the POP beam back to the top POP periscope mirror in ISCT1.

I found that the beam was too much in +X direction at the bottom and didn't hit the bottom periscope mirror even when I maxed out the YAW adjustment range of the top peri mirror. (My guess was that people found that back then and decided to shift the POP beam onto the REFL top peri mirror, but Sheila didn't think so even though neither she nor Camilla remembered exactly why.)

Anyway, since I still didn't like that the beams are both close to the edge of the mirror, I decided to keep the "new" configuration where REFL hits REFL periscope and POP hits POP periscope.

I shifted the REFL top periscope mirror by ~1" in +X direction so the REFL beam is not close to the edge of the mirror. Betsy took the picture of the REFL beam on the top periscope mirror.

The REFL beam hits the bottom periscope mirror. Further adjustment is necessary downstream.

For POP, since the only thing lacking was the adjustment range of the top peri mirror, at first I wanted to swap the mirror mount (ultima with 2 actuators) with a 3-actuators variation to gain more adjustment range, but it turns out that the adjustment knob on the "third" actuator would interfere with the bracket on which the mirror mount is bolted. As a quick fix, I merely "pushed in" the fixed pivot pin to tilt the mirror in a disired direction, which worked. See top_POP_peri_mechanical_tweak.jpg.

I also steered down the beam by M16 a bit, shifted the top POP peri mirror in +X direction by ~1" like I did for the top REFL peri mirror, used M16 to steer the beam again, and ended up with an OK position on the top peri mirror. See POP_top_peri_beamPos.jpg.

The beam hit the bottom peri mirror, it's not centered but is OK. Further downstream alignment should be done in the future.

Finally, POP_REFL_at_VP_position.jpg shows the REFL and POP air beam when the card was held very roughly at the location of the viewport. This more or less agrees with one of the pictures (https://alog.ligo-wa.caltech.edu/aLOG/uploads/84344_20250509211310_PXL_20250509_231320536.jpg) in my May/09/2025 alog and I'm positive that the POP won't be clipped by the VP.

REFL_AIR and POP_AIR Beam dumps:

REFL air goes to beam dump when the REFL beam diverter closes (forgot to take picture but not surprising as REFL air path wasn't touched).
Unfortunately I forgot to check if the POP air beam goes to the beam dump when the POP beam diverter closes. This needs to be checked the first thing tomorrow.

Images attached to this report

LHO General - Comment to OPS Thursday Day shift summary

ryan.crouch@ligo.org — Thu, 02 Apr 2026 17:05:16 -0700

Author: ryan.crouch@ligo.org

Report ID: 89760

Keita, Betsy, and Elenna out at 00:00 UTC

LHO General - OPS Thursday Day shift summary

ryan.crouch@ligo.org — Thu, 02 Apr 2026 16:34:51 -0700

Author: ryan.crouch@ligo.org

Report ID: 89753

TITLE: 04/02 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: The HAM1 work continues, ISCT1 was moved back into place.
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
14:32	FAC	Randy	LVEA	N	Prep for ISCT1 move, then help with HAM3 cleaning	15:49
14:44	FAC	Betsy	LVEA	N	Help Randy move table	15:24
15:04	FAC	Kim, Nellie	LVEA	N	Tech clean, HAM3	16:05
15:04	SEI	Sina	Optics lab	LOCAL	SPI work	17:07
15:25	SEI	Jeff	Optics lab	LOCAL	SPI	17:07
16:41	ISC	Keita, Betsy	LVEA	LOCAL	ISCT1 work, Betsy out at 17:55	19:03
16:41	FAC	Randy	LVEA	N	West bay work	17:28
16:47	FAC	Mitch	LVEA	N	Checks	16:52
17:09	SQZ	Camilla, Sheila	LVEA	LOCAL	SQZT work, LOCAL hazard	17:49
17:18	TCS	Sophie, Georgia	Prep lab	LOCAL	CHETA work	18:54
17:25	FAC	Tyler+Contractor	Optics lab, LVEA walls	N	Termite inspection/ sprays - ACME	17:44
17:29	CC	Oli	Optics lab	N	Talk to Tyler+contractor	17:38
17:55	ISC	Elenna	LVEA	LOCAL	HAM1 work	19:03
17:57	ISC	Jennie	LVEA	LOCAL	See if HAM1 crew needs help	18:05
20:21	EE	Fil	LVEA then CER	N	HAM6 electronics, then cabling in the CER	23:04
21:49	BHD	Oli	Optics lab	N	Magnet checks	22:35
21:53	ISC	Keita	LVEA	LOCAL	HAM1 work	Ongoing
21:53	FAC	Richard	LVEA / CER	N	Check on Fil	22:03
21:54	ISC	Betsy, Elenna	LVEA	LOCAL	Join HAM1 work	Ongoing
22:02	ISC	Camilla, Georgia	Optics lab	N	Look at mounts	23:18

The megaclean room around HAM6/7 was turned on in the morning and will be left on for ~24 hours as a test. ZONE4's temperature has risen due to this.

Images attached to this report

H1 CDS - Comment to GigE cameras on Debian 13 investigations.

anthony.sanchez@ligo.org — Thu, 02 Apr 2026 15:38:31 -0700

Author: anthony.sanchez@ligo.org

Report ID: 89759

Interesting note.
Opening 2 PRM and 2 PR3 cameras makes them start working for some reason?

H1 CDS - Comment to GigE cameras on Debian 13 investigations.

erik.vonreis@ligo.org — Thu, 02 Apr 2026 15:28:06 -0700

Author: erik.vonreis@ligo.org

Report ID: 89758

Rebooting h1digivideo2 and h1digivideo4 did not help. Streams from only those servers are still corrupted.

Here's a list of some other changes that didn't help:

Update to 6.19 kernel

Update all packages including mesa drivers in Debian13 backports

Switching to the xe driver

Adding some linux commandline switches to turn off Intel driver power-state switching.

H1 CDS - GigE cameras on Debian 13 investigations.

anthony.sanchez@ligo.org — Thu, 02 Apr 2026 15:21:58 -0700

Author: anthony.sanchez@ligo.org

Report ID: 89757

Opslogin can still run 4 Different cameras at the same time.

I logged into CDSWS25 as myself and opened 6 FC_TRANS_GR camera feeds, because it currently has good fast flashes. No issues at all. all 6 show perfectly.
I then closed all but one, then opened PRM and i get stuttered screen tearing and artifacting. infact any 2 different cameras will cause this to happen.

Graphics issue?:
putting them on different screens did not help.
Reducing number of physical hardware monitors from 2 asus screens to 1 did not sold the issue. nor did reducing the resolution. So Perhaps this is not a graphics issue. Because I can also display youtube videos as well.

Network Bandwidth limitation? :
I pulled up htop and noted the bandwith use.
For just FC_TRANS_GR alone the RX bandwith is around ~420KiB/s.
For just PR3 alone the RX bandwith is ~110KiB/s
and PRM is about ~120 KiB/s
but if I open PRM and PR3 at the same time I get stuttered screen tearing and artifacting, even thought the RX bandwidth is only 230 KiB/s.
And if that was the limit od the bandwidth then why would FC_TRANS_GR perform so well since it's RX bandwidth is at 400+ KiB/s. So perhaps this rules out a network bandwidth limitation.

I then installed VLC on this workstation and played a random video that I downloaded from the CDS_DEV Mattermost chat and played that on loop with no issues.

Then I ran a Gstreamer test command: gst-launch-1.0 videotestsrc ! autovideosink
And that seemed to work well. then I ran 2 with out issue.

I suggested to Erik that we reboot the server, to see if it might help.

H1 ISC - Comment to FC1 shifts during the vent, likely explanation for our alignment difficulties.

camilla.compton@ligo.org — Thu, 02 Apr 2026 14:57:36 -0700

Author: camilla.compton@ligo.org

Report ID: 89756

This morning to get flashes maximized for time that the CR is now off, I moved ZM1 and ZM2 <10urad but moved FC1 P 30 urad, FC2 25urad and ZM3 70urad, plot.

Simular story from Wednesday AM once the CR was turned on, 65urad on FC1 but also 70urad on ZM3, plot.

This might complicate the 89751 plan of just using FC1 to gert flashes back.

Images attached to this report

H1 SQZ - Comment to SQZ SUS not-repeatable alignment into FC

camilla.compton@ligo.org — Thu, 02 Apr 2026 11:32:38 -0700

Author: camilla.compton@ligo.org

Report ID: 89749

As the temperature returned to normal with the mega clean room being turned off, our flashes degraded again. I again tried going back to the FC1 osems and the FC flashes disappeared, first attached t-cursor. I then tried going to the bottom mass WIT channels, which went the opposite direction to the osems, here the flashes were lower than when we started, second attached t-cursor. This makes us think that the best flashes are for the same slider values.

Images attached to this report

H1 ISC - FC1 shifts during the vent, likely explanation for our alignment difficulties.

sheila.dwyer@ligo.org — Thu, 02 Apr 2026 11:31:39 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89751

Oli, Camilla, Sheila

Yesterday Camilla noted that she could not restore filter cavity flashes by restoring FC1 pitch top mass osems when the temperature shifted because the HAM5/6 cleanroom was on 89729.

Because we can't look at filter cavity flashes while HAM7 is vented, we rely on retro reflecting the beam off FC1 to point it down the filter cavity.

During this last vent, the cleanroom was turned on Dec 4th, where you can see the tempature rise, the top mass osem shows a shift of -205urad, the bottom mass osem shows a shift of +44 urad. The chamber was vented December 8th, top mass osem shows a shift of +300 urad, bottom mass -77urad. There was another shift in the osems on Decmember 23rd, Oli tracked down that Travis turned on the purge air at this time, top mass osems shift +167 urad, bottom mass osems shift -29 urad. (The top and bottom masses always show different directions, top mass is 4-5 times larger shift than the bottom mass).

We left the FC1 slider at the setting it had in O4, and aligned the new OPO to retro reflect off this alignment. On Jan 20th, 88806, we noticed that the osems said FC1 pointing was different from O4, so we moved FC1 sliders by -175 urad to bring the top mass osems back to where they were in O4. Looking at the bottom osems, this was a shift of -200 urad in the wrong direction, so this attempt to correct for the shifts seen by the top mass actually introduced a larger alignment shift than all of the other changes.

This morning, Camilla and I placed two irises on SQZT7 in the FGCS reflection path. We hope that we can restore FC1 pointing using those irises, and then use that as a reference to check FC1 alingment once we vent. We moved FC1 by 60 urad in either direction and can clearly see the beam clipping on the irises. We turned the cleanroom back on, and will try to see if this can restore the alignment tomorow.

Camilla put FC1 back to it's PIT slider position during the vent, ~50urad, gave us light on SQZT7 IR and the HAM7 WFS, so this is close to reproducing the FC1 alignment that we used during the vent.

So, the conclusion is that my mistake during the vent was to try to use top mass osems to correct for the changes in FC1 alignment.

H1 SPI - Installed SPI ISIJ QPDA TIA

jeffrey.kissel@ligo.org — Thu, 02 Apr 2026 11:05:30 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 89752

J. Kissel, S. Koehlenbeck H1 SUS-R1 D0902810, S1301885 TIA D1002481-v3, S2500711 Finished with all required assembly and testing of the SPI pathfinder's in-vac ISIJ Reflector assembly (D2400102), we packed it up such that it's install ready. That means it's supporting QPD photodiode transimpedance amplifier, whose [V/A] impedance has been measured and tailored to suit a 10 [V_p] differential ADC input (see 89739) is no longer needed in the optics lab. As such -- we moved it from the optics lab to its final location in the LVEA -- in the U6 position of SUS-R1 by HAM2. Pictures: BEFORE installation AFTER installation S-NUMBER and U-Height zoom for confirmation. We have not cabled up any of its inputs or outputs, but will do -- per D2400111 -- so in the fullness of time.CDS, SPI, SUS

Images attached to this report

LHO VE - Thu CP1 fill

david.barker@ligo.org — Thu, 02 Apr 2026 10:35:39 -0700

Author: david.barker@ligo.org

Report ID: 89750

Thu Apr 02 10:16:29 2026 INFO: Fill completed in 16min 25secs

Images attached to this report

H1 General - Comment to OPS Thursday day shift start

ryan.crouch@ligo.org — Thu, 02 Apr 2026 07:49:16 -0700

Author: ryan.crouch@ligo.org

Report ID: 89748

JAC has been trying and failing to lock overnight (since 5pm PST // 00 UTC yesterday), the SCAN keeps timing out "Check trigger level or Laser power". Bringing it to DOWN for now.

LHO General - OPS Thursday day shift start

ryan.crouch@ligo.org — Thu, 02 Apr 2026 07:32:02 -0700

Author: ryan.crouch@ligo.org

Report ID: 89747

TITLE: 04/02 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: 0.21 μm/s
QUICK SUMMARY:

HAM1 and SPI work continues
ISCT1 to be moved back into place today
LVEA temps look nice and stable

H1 TCS - CHETA 0922 unit installed

sophie.muusse@ligo.org — Wed, 01 Apr 2026 18:06:38 -0700

Author: sophie.muusse@ligo.org

Report ID: 89746

S. Muusse, G. Bolingbroke, C. Compton

The new QCL laser 0922 was installed in the setup to replace the broken 0920 unit and has been turned on and its working. Thermal paste got on the output lens during storage/transport and but we cleaned off using tissue and isopropanol. The main path alignment has been completed but the pickoff paths havent been checked and lenses havent been replaced. The new unit requires a slightly different lens position described in the yaml file which will hopefully be installed tomorrow.

H1 ISC - Peeking down the X arm, Pico-ing HAM3 POP steering mirror, using dichroic to center ASC POP_X, using pico mirror in HAM1 to center LSC POP_A (Camilla, Jennie, Sheila, Jenne, Betsy, Keita)

keita.kawabe@ligo.org — Wed, 01 Apr 2026 17:38:36 -0700

Author: keita.kawabe@ligo.org

Report ID: 89745

After opening the X arm, Jenne used the baffle PD script to roughly align the X arm.

We've found that the green beam was too high, hitting the aluminum part of the top periscope mirror mount. But it was off in YAW, too. We moved the PR3 to see what happens, but we ended up reverting it and moved pico steering mirror for POP path in HAM3.

In PIT, green beam was brought to a place where it's higher than the middle of the top periscope mirror because centering that beam in PIT the IR beam will be clipped.

The IR beam was still very close to the +X-Y edge of the dichroic and also the 90:10 to split in-air and in-vac beams, so pico-ed in YAW too.

At this point there was a HUGE pit offset on POP-X, the beam was hitting the top of the QPD case, and large (but not huge) yaw offset. We couldn't center the beam using PM1, so we used the dichroic.

We had to set the DC gain of the WFS DC interface on the front panel to HIGH to be able to see any meaningful DC signal from POPX, but anyway we managed to roughly center the beam in that H1:ASC-POP_X_DC_PIT_OUT and H1:ASC-POP_X_DC_YAW_OUT go both positive and negative as the beam fluctuates.

We didn't see anything on LSC POP_A at this point. We scanned PM1 and found that the beam is not that far and off mostly in PIT. We used a pico-ed splitter to split ASC and LSC POP to steer the beam on POP_A. We scanned the PICO to roughly put the beam at the center of the plateau. I say "roughly" because we used PRX beam which was freely flashing, so it was hard to go precise, but we can always do it after pumping down.

I say that the in-vac alignment is done (in that we can fine-tune after pumping down using picos and suspensions in HAM1 and also using pico in HAM3 if necessary).

Since we changed the HAM3 pico and made a large adjustment of the dichroic, the in-air POP beam as well as the green beam should have been affected. We'll put the table by HAM1 and see how they land on the periscope, and will adjust the steering mirrors in HAM1 if needed.

INS, ISC

H1 CDS - WP 13137 Testing running the MX weather station IOC in a container

jonathan.hanks@ligo.org — Wed, 01 Apr 2026 17:24:01 -0700

Author: jonathan.hanks@ligo.org

Report ID: 89744

To test out new infrastructure for running IOCs and other services in CDS I put the MX weather station into a podman container and started it on our new service-host cluster (a high availbility cluster for services).

As part of this I created a generic container that should work for the other weather stations and the dust monitors (until those are migrated to beckhoff).

This work is part of an effort to improve our infrastructure, including how we track, monitor, and manage our IOCs. There should not be any user visible change with this, other than the IP address that the IOC responds from is different.

Notes:

* We run these older IOCs in the background with screen as they are iocsh shells and want a terminal. For this setup I no longer need to run with screen, we just tell the container system (podman) to run the container with a tty in interactive mode in the background.

PEM

LHO FMCS - Comment to Wed DAY Ops Summary

ryan.crouch@ligo.org — Wed, 01 Apr 2026 17:03:00 -0700

Author: ryan.crouch@ligo.org

Report ID: 89743

Zone4s' temperature has dropped rapidly over the past half hour. Minute trends look like it may be rebounding but I can't tell yet.

Images attached to this report

LHO VE - Comment to GV7 Pneumatic Pressure System

gerardo.moreno@ligo.org — Wed, 01 Apr 2026 16:54:25 -0700

Author: gerardo.moreno@ligo.org

Report ID: 89742

(Travis, Jordan, Dave, Gerardo)

We finally got a chance to actuate GV7, but to the open position, and it took about 40 psi to start moving, it opened without any issues, current pressure to keep it open is 55 psi. Opening the gate valve generated a few alarms, nothing out of what we expected, Dave took care of them.
GV7 will remain open until work at HAM1 is done, then we can attempt to hard close this gate valve, then after a start a vent of the corner.
A very smooth working pressure regulator, it did its job with ease.

H1 ISC - Beam aligned to both OMCs!

elenna.capote@ligo.org — Wed, 01 Apr 2026 16:43:13 -0700

Author: elenna.capote@ligo.org

Report ID: 89741

[Georgia B, Elenna, Oli]

Last Friday I reported that the alignment to OMCA was decent, 89674. However, I had aligned OMCA with an HR and then removed it to align OMCB. On Monday, I tried placing a beamsplitter at the same location so I could simultaneously align OMCA and OMCB, but then I didn't have enough power for both. I then tried to fix the upstream fiber, which at first went horribly, but now we are getting 50 mW to align with, so overall things have improved.

Today, Oli and I began to realign the beams to the OMCs, since so much changed upstream. Georgia then later tagged in to help me. For alignment, we have about 33 mW to align OMCB and about 17 mW to align OMCA. This enough to see flashes on the card at the DCPDs.

Summary: we see flashes at the DCPDs of OMCA and OMCB. These flashes look pretty good overall. The beam is not modematched to the OMCs, so the flashes look mostly like mode mismatch.

We used the IR sensitive camera to take long exposure shots of the DCPDs to capture a long average of the flashes.

Here is a picture of both DCPDs of OMCA. There are some blobs that indicate the alignment could be a bit better, but overall it looks pretty good.

Here is a picture of DCPDA of OMCB. This mostly looks like mode mismatch, so again, decent alignment overall.

I have also attached videes of the OMCs flashes on an IR card.

SUS

Images attached to this report

Non-image files attached to this report

OMCA_flashes.mov

OMCB_flashes.mov

LHO General - Wed DAY Ops Summary

corey.gray@ligo.org — Wed, 01 Apr 2026 16:30:33 -0700

Author: corey.gray@ligo.org

Report ID: 89726

TITLE: 04/01 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

HAM1 & SQZ alignment work continued with focus on HAM1 GV7 was opened for a check down the X-arm for HAM1 work. Team is still out at HAM1 and GV7 will be open overnight. Would like to have ISCT1 rolled into place in the morning.

LOG:

1406- lvea technical cleaning (nellie.kim)
- 1526 nellie out
- 1600-1634 MY technical cleaning (nellie)
1420-1520 craning handrails up to the eMod (randy)
- 1550-1740 clean-up in lvea
1511-1645 HEPA Fan swap at h1psl (tyler,eric)
- 1645-1655 Move to optics lab for termites? (tyler)
1529-1657 SPI in optics lab (sina)
- 1626-1657 SPI in optics lab...but only for about 30min before a meeting (jeffK)
- restart after meeting - 1915 More SPI before lunch (sina, jeff)
1614-1638 lvea walkabout around h1psl (richard)
1702-1708 turning off mega cleanroom fans (richard)
1703-1717 Opening lightpipe & HAM1 door cloth cover for alignment work (sheila)
1706-1714 checking h1psl hvac (post new fan install) [jason]
1725-1731 Turning down HAM1 purge (keita)
1728 cheta lab (sophie,georgia)
1745-1905 susR2 rack near HAM3 + upstairs of CER (fil)
- 2000-2320 Continue rack & CER work (fil)
1757 OPEN GV7 (gerardo.travis)
- 1808 jordan joining
- 1825 GV7 OPENED
1940-2038 Cleanroom lowering a few inches in West Bay (randy,eric,tyler,mitchell)
1953-2148 BHSS laser HAZARD work (elenna,oli)
- 2049 Oli out
1959 Checking green beam at HAM1 (keita)
- 2013 jenne & sheila joining
- 2249 Jenne out
- 2259 sheila out---
2007-2148 CHeTA laser set-up (sophie, georgia)
- 2022-2142 Camilla joining
2013 MX weather station work (jonathan)
2018 checking on cleanroom team (richard)
2053 SPI assy & alignment (jeff, sina)
2054-2113 RGA search (gerardo)
2104-2110 Running cleanroom roof sock to lvea (randy)
2118-2122 fiber feedthru check at HAM7 (travis)
2120-2143 EX cleanroom accessory search (randy)
2130 PM1 @HAM1 had software WD tripped noticed, and he is bypassing (since there is lots of shaking out there) [dave]
2143-2200 Going to PCal Lab for dustmonitors (ryanC)
- 2226 now going to swap out a cable--heading to CER & then back to PCal lab (ryanC)
2155 Betsy & Camilla joining HAM1 team on the floor
2216-2316 BHSS alighnment (elenna,georgia)
2236 Artemis launch!
2256 M7.8 EQ in the south Pacific with S&P waves hitting at 2300 (R-waves due around 2350-0000)
2302 Checking on HAM1 team (richard)
2307 CHeTA laser HAZARD work (sophie)

H1 SPI - LIGO-SPI Photodetector Chassis: CDS Range Maximization and TIA Output Settings

sina.koehlenbeck@ligo.org — Wed, 01 Apr 2026 16:19:46 -0700

Author: sina.koehlenbeck@ligo.org

Report ID: 89739

Sina, Jeff

The photodetector chassis of the LIGO-SPI pathfinder has been modified to maximize the CDS range. The TIA is designed to put out 0V - 10V on the positive leg of the differential output. The power monitoring PDs are set to get close to 5V, the interferometer PDs a mean of 2.5V, and the QPD quadrants 3.5V each. The whitening filters for the heterodyne-interferometer photodiodes are bypassed. The details of the installed capacitor and resistors are listed in the following table:

Detector	R4 Resistor value now (kohm)	Design value of pole frequency (Hz)	C5 capacitor value calculated (F)	C5 capacitor value now (pF)	Resulting pole frequency (Hz)	Chassis Variant	Channel	Mean power at PD (mW) measured with S121C	Mean voltage at PD positive leg (V)	Sum of mean voltage of TIA positive leg (mV)	PD calibration (mW/V)
PD POW: FBR_PWRIN_MEAS (SIG)	53	1.00E+04	3.00E-10	220	13,650	3	1	0.9	3.9	3.9	0.23
PD POW: FBR_PWRIN_REF (LO)	53	1.00E+04	3.00E-10	220	13,650	3	2	1	4.25	4.25	0.24

QPDB								9.9	13.5	13.5	0.73
QPDB Q1	3	1.00E+04	5.31E-09	1,000	53,052	2	5		2.9	2.9
QPDB Q2	3	1.00E+04	5.31E-09	1,000	53,052	2	6		3	3
QPDB Q3	3	1.00E+04	5.31E-09	1,000	53,052	2	7		3.9	3.9
QPDB Q4	3	1.00E+04	5.31E-09	1,000	53,052	2	8		3.7	3.7

PD IFO: IFO_MEAS_A (LO)								3.3	0.9
PD IFO: IFO_MEAS_A (SIG)	3	5.00E+04	1.06E-09	1,000	53,052	2	3	4.8	1.29	2.19	3.7
PD IFO: IFO_MEAS_B (LO)								3.1	0.9
PD IFO: IFO_MEAS_B (SIG)	3	5.00E+04	1.06E-09	1,000	53,052	2	4	4.8	1.36	2.26	3.5

PD IFO: IFO_REF_A (LO)								2.6	1.16
PD IFO: IFO_REF_A (SIG)	4.99	5.00E+04	6.38E-10	560	56,955	2	1	2.9	1.24	2.4	2.29
PD IFO: IFO_REF_B (LO)								2.6	1.08
PD IFO: IFO_REF_B (SIG)	4.99	5.00E+04	6.38E-10	560	56,955	2	2	2.9	1.22	2.3	2.39

QPDA	1.5	10000	1.06E-08					18.5	9	9	2.06
QPDA Q1	1.5	10000	1.06E-08	2000	53,052	1	1		1.9	1.9
QPDA Q2	1.5	10000	1.06E-08	2000	53,052	1	2		2.6	2.6
QPDA Q3	1.5	10000	1.06E-08	2000	53,052	1	3		2.2	2.2
QPDA Q4	1.5	10000	1.06E-08	2000	53,052	1	4		2.3	2.3

The capacitor for the QPDs might be changed to result in a low-pass frequency of 10 kHz at a later date.

SPI

H1 SPI - LIGO-SPI Pathfinder ISIK/ISIJ Picomotor Test: All Motors Operational

sina.koehlenbeck@ligo.org — Wed, 01 Apr 2026 13:47:31 -0700

Author: sina.koehlenbeck@ligo.org

Report ID: 89740

Sina, Jim

We tested the functioning of the picomotors in the LIGO-SPI Pathfinder ISIK and ISIJ assemblies. All motors are working (see attached video).

SPI

Non-image files attached to this report

20260331_172250.mp4

H1 ISC - ITMX alignment set with green baffle PD script

jenne.driggers@ligo.org — Wed, 01 Apr 2026 12:27:59 -0700

Author: jenne.driggers@ligo.org

Report ID: 89737

After the vacuum team opened up GV7 so that we can have a peek down the arm, I ran the green baffle PD scripts for the Xarm.

I did the usual misalign ITMX and ETMX, and ran the script for TMSX. I then realigned ITMX, and ran the script for ITMX. I then realigned ETMX and ran the script for ETMX.

I looked at H1:ALS-X_REFL_A_DC_POWER and moved ETMX a bit to try to get some refl dips, which indicate that there are some flashes in the Xarm. ETMX is not at all optimized, and I haven't touched TMSX since running the baffle align script on it.

The baffle align script moved ITMX 5 or 6 urad "down" in yaw, and very little in pitch. The attached screenshots shows times before, during, and after the baffle align script, for the ITMX sliders, top mass osems, and oplev. The only difference between screenshots is whether cursors are included for convenience.

Images attached to this report

H1 IOO - Comment to Two PRX alignments

sheila.dwyer@ligo.org — Wed, 01 Apr 2026 12:27:53 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89738

Redoing these screenshots after Jenne Driggers ran the baffle PD script to point ITMX down the X arm.

O4 PR3 pointing here

yesterday's PR3 pointing that put beam close to POP X here

Images attached to this report

H1 SQZ - ZM3 moves for FC alignment

camilla.compton@ligo.org — Wed, 01 Apr 2026 12:08:22 -0700

Author: camilla.compton@ligo.org

Report ID: 89736

Sheila, Camilla

Yesterday, Sheila moved ZM3 in steps of +10urad in PIT on the sliders (towards the diorection we know we need to be for SQZT7 light). She then compensated with FC1 and FC2 to maximize FC green flashes each time. And then measured the amount ZM3 needed to be moved to get light on SQZT7, ZM3 needed to be moved less each time to get light on SQZT7 IR PD (good) however, the flashes could not be brought back to thier maximum (bad). Plot attached.

Today, I moved ZM3 in steps of -10urad in PIT on the sliders (away from the diorection we know we need to be for SQZT7 light). Then compensated with FC1 and FC2 to maximize FC green flashes each time. And then measured the amount ZM3 needed to be moved to get light on SQZT7, ZM3 needed to be moved slightly more each time to get light on SQZT7 IR PD (bad), but the flashes could be brought back to thier maximum and mayeb even got slighly better (good). Plot attached

Images attached to this report

H1 SUS - Comment to JM3 overdamped for HAM1 work

keita.kawabe@ligo.org — Wed, 01 Apr 2026 11:47:47 -0700

Author: keita.kawabe@ligo.org

Report ID: 89734

Tried the same thing for JM1, but the LL and UR coils rail once in a while because the alignment slider offsets are larger for JM1. Even without any damping/feedback, the DAC output for JM1 LL and UR are ~96 million counts (they rail at 134 million).

I decreased the gain by a factor of 2 for JM1.

[H1:SUS-JM1_M1_DAMP_P_GAIN, H1:SUS-JM1_M1_DAMP_Y_GAIN]=[-10, -20], [H1:SUS-JM3_M1_DAMP_P_GAIN, H1:SUS-JM3_M1_DAMP_Y_GAIN]=[-20, -40].

Elliptic lowpass as well as YAW "boost" were disabled for both.

Images attached to this report

H1 IOO - Comment to JAC refl shutter trigger level, can lock JAC (and sometimes IMC) at 20W input power

jenne.driggers@ligo.org — Wed, 01 Apr 2026 11:40:45 -0700

Author: jenne.driggers@ligo.org

Report ID: 89735

At Elennas' good suggestion, I added the IMC_power_adjust_func() to the IMC_LOCK's ACQUIRE state, so that it will adjust the IMC's FASTGAIN, so that the fast gain won't be wildly high when trying to acquire at higher powers.

I did modify the function, so that if we're in ACQUIRE, it uses a FASTGAIN 5dB lower than the operating nominal gain. This makes it match the 2W acquisition situation, where the fastgain was always acquiring at 0dB, and then for a 2W IMC lock would increase during the BOOST state to 5 dB.

The IMC will lock at 10W, but it takes a long time. It's a little happier at 8W. It's still perfectly happy at 2W (which makes sense, since none of the 2W settings have changed).

I'm pausing any further testing, since the Xarm is open for our green peek.

H1 IOO - Two PRX alignments

sheila.dwyer@ligo.org — Wed, 01 Apr 2026 10:57:34 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89733

For the HAM1 work today, here are two screenshots showing PRX alignments with two different PR3 values.

PR3 yaw slider at -233.7 urad is here, since HAM2 HEPI is locked 3.7 urad positive RY compared to it's usual location (89701), this corresponds to -230 urad our yaw alignment from O4 (and from the March 14th PRMI/DRMI locking).

PR3 yaw slider at -240, here, is the alignment for which in the in chamber crew found the beam on the edge of the ASC POP X diode.

Images attached to this report

H1 SUS - JM3 overdamped for HAM1 work

jenne.driggers@ligo.org — Wed, 01 Apr 2026 10:37:36 -0700

Author: jenne.driggers@ligo.org

Report ID: 89732

[Keita, Oli, Jenne]

To make relocking the IMC easier during the HAM1 work, JM3's damping has been significantly increased. Oli did mention that the JM3 damping loops haven't seen much real tuning yet, so even when we discontinue this overdamping, we may want to spend some time on them.

Attached are screenshots of JM3's damping loops before we tuned anything, as well as how we're leaving JM3 overdamping for now.

The spectra show JM3 damping, but with gains of -2 in each of the Pit and Yaw loops as the references (so, a little more damped than they were yesterday), and then the live traces are with the overdamped situation.

As a comparison, Oli pointed me to this old alog 62672 with a similar suspension's damping loops measured.

Images attached to this report

LHO VE - Wed CP1 Fill

david.barker@ligo.org — Wed, 01 Apr 2026 10:24:14 -0700

Author: david.barker@ligo.org

Report ID: 89731

Wed Apr 01 10:14:14 2026 INFO: Fill completed in 14min 11secs

Images attached to this report

H1 SQZ - Comment to SQZ SUS not-repeatable alignment into FC

camilla.compton@ligo.org — Wed, 01 Apr 2026 10:04:40 -0700

Author: camilla.compton@ligo.org

Report ID: 89730

Rahul found that this was because the LVEA temp around HAM7 had increased ~3degF. Betsy , Geradro noticed this was as the Megacleanroom had been turned on. Richard is now turning it off.

H1 SQZ - SQZ SUS not-repeatable alignment into FC

camilla.compton@ligo.org — Wed, 01 Apr 2026 09:46:43 -0700

Author: camilla.compton@ligo.org

Report ID: 89729

On Monday I had a good alignment for the FC, see 89694 and that alog's attached screenshot. Yesterday we went there and had to touch up FCs a little to get flashes. Today for the same sliders was even worse witha very PIT misalinged FC Green beam, see attached, in the same FC1 PIT slider potion, the osems were 150urad off, attached. When I brought us back to the top mass osem positions for all optics (ZM1,2,3,FC1,2 and ZM2 PSAMS) we have no green flashes in the FC, just a single pass green beam, attached.

Since the good FC flashes time on Monday, the FC has moved as attached, ~100urad in Pit and ~200urad in yaw during aligned/misaligned transitions.

I see two issues here:

Why is the FC1 top mass osems drifting 150urd in 24 hours
We don't seem to be able to trust the osems as going back to them gives us no FC flashes.

Rahul did in-air TF's 75830

SUS

Images attached to this report

LHO FMCS - HVAC Fan Vibrometers FAMIS Check (FAMIS 39861)

corey.gray@ligo.org — Wed, 01 Apr 2026 09:11:04 -0700

Author: corey.gray@ligo.org

Report ID: 89728

For FAMIS #39861: Fans look mostly flat (Corner's FAN5 looks faintly noisier the last 1.5 days).

PEM

Images attached to this report

H1 TCS - TCS Monthly Trends (FAMIS #38839)

corey.gray@ligo.org — Wed, 01 Apr 2026 08:07:04 -0700

Author: corey.gray@ligo.org

Report ID: 89727

Attached are monthly TCS trends for HWS & CO2 lasers. (FAMIS link)

TCS

Images attached to this report

LHO General - Wed DAY Ops Transition

corey.gray@ligo.org — Wed, 01 Apr 2026 07:40:32 -0700

Author: corey.gray@ligo.org

Report ID: 89725

TITLE: 04/01 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: 0.19 μm/s
QUICK SUMMARY:

HAM1 JAC alignment work continues (I pressume similar for SQZ alignment.) There is a plan to swap out a ceiling HEPA Fan for the anteroom of the H1 PSL enclosure this morning. Also prep for HAM3 venting is on the docket when HAM1 work completes (i.e. lock HEPI, chamber cleaning, etc.)....and also venting the corner as well.

LVEA is still Operations laser SAFE (or bifurcated for HAM1 + SQZ work and laser goggles required at height). Warmer this morning April Fool's Day and rainy.

H1 IOO - Debugging POP in-vac path

jennifer.wright@ligo.org — Tue, 31 Mar 2026 18:57:54 -0700

Author: jennifer.wright@ligo.org

Report ID: 89724

Jennie W, Keita K, Jason O, Jenne D,

Once we got the locking of JAC and IMC working at 20W this morning, Keita went into the chamber while we had PRMI aligned to check the POP beam alignment in HAM1.

We had trouble keeping the IMC locked when Keita was moving next to the chamber, JAC occasionally unlocks but is staying locked for long periods. I hypothesise that JM3 moving around is more of a problem than JM1 because of this. Eventually we managed to stay locked with 4W while Keita was in chamber. Over this period Keita realised the beam was mis-aligned coming out of the POP periscope and so we used PR2 and PR3 yaw to walk the beam back till it was well centred on AS AIR camera and we still saw flashes. Eventually we mis-aligned ITMY and just used PRX flashes. We had to move 10 microradians on PR2 and then correct with 1 microradian on PR3 to maintain the alignment.

I put the power up to 10W from 4 W and we saw a power change on ASC-POP_X.

To see if we could recover alignment onto POP-X with PM1 we put the PM1 yaw up to a high value so it was railing and we did see some counts on ASC-POP_X QPD SUM but we cannot point the beam onto the diode before PM1 rails so we undid this.

The day ended with a total move of -120 on PR2 yaw, -12 on PR3 yaw, -8.1 mircoradians on PR3 pitch, and +81 microradians on PR2 pitch. Keita can now see the beam on the side of the ASC POP X QPD.

The pitch changes we did at the end of the day were to try and improve the steering to ASC POP X but we didn't get time to optimise this so we can undo them tomorrow if necessary.

Summary: Checking POP is hard as the IMC will unlock very easily if someone is in HAM1, probably due to shaking of JM3. We need to work out if we trust the PRC alignment axis or if we want to cross-check it with something else (like the ALS beam from the X-arm) before we continue debugging.

ISC

Images attached to this report

LHO VE - GV7 Pneumatic Pressure System

gerardo.moreno@ligo.org — Tue, 31 Mar 2026 18:32:36 -0700

Author: gerardo.moreno@ligo.org

Report ID: 89723

(Jordan V., Travis S., Gerardo M.)

We removed and replaced the broken pressure regulator for GV7, we haven't tested the new regulator yet (open or try to hard close GV7), but hope to do so soon. During the regulator replacement we installed an isolation valve on the line that feeds GV7, this for upcoming work on this system.
While doing the replacement of the regulator for GV7, we discovered that the pressure regulator for GV8 pneumatic system is broken too, currently it is reporting a max pressure of 100 psi and a low pressure of 80 psi, it rides the instrument air compressor behavior (high and lows). We tried to lower the pressure but the regulator is non-responsive. We'll replace the pressure regulator at the next opportunity. Also, it turns out that the pressure regulators attached to the different pneumatic gate valves are not the same model.

Images attached to this report

H1 CDS - SWWD code verification and MEDM updates

david.barker@ligo.org — Tue, 31 Mar 2026 17:27:56 -0700

Author: david.barker@ligo.org

Report ID: 89722

Following the B13, B2H34 and H12 upgrades in Dec 2025 and Jan 2026 today I did a second round of verification that the IOP models were reading the correct ADC channels and that the MEDMs were correct. The IOP models are correct and no changes were needed.

Some MEDMs had white-boxes for the raw ADC counts, which was addressed. The SWWD MEDMs use macro file substitution for the detailed screens, and the differences that now exist between the sites means it is no longer feasible to maintain these files in the cds/common/medm/ area. Today I moved them to cds/h1/medm before making the final updates.

At this time all the MEDMs are correct with the exception of the BS IPC channel for SUS-BS to SEI-BSC2. h1iopsusb2h34 has a simulink copy-paste error, the channel which should be BS_WD_SND but is actually BS_WD_SND1, hence the white-box.

I'm also reminded that during these upgrades we decided to not change the IPC channel names in order to minimize the scope of work, so IPC names containing B123, H2A, H34 still exist. During the next RCG upgrade we will correct the names.

An overview of the SWWDs at both sites can be found in the DCC T2600106

LHO General - Tues DAY Ops Summary

corey.gray@ligo.org — Tue, 31 Mar 2026 16:30:04 -0700

Author: corey.gray@ligo.org

Report ID: 89712

TITLE: 03/31 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Lots of subsystem work going on today. The JAC team continued their alignment work at HAM1. SQZ team continued alignment work at SQZT7 and then in the Control Room. SPI team was in the Optics Lab most of the day.

Tomorrow morning a new HEPA fan will be installed for the h1psl room's anteroom....so it shouldn't affect HAM1 work.
LOG:

1411-1500 LVEA technical cleaning (nellie.kim)
- Held off cleaning top of HAM3, since HAM3 was unlocked (they noticed the signs saying so at HAM3), AND bifurcated Laser Safe requires goggles at-height, but that makes it unsafe to see things when climbing on top of a chamber.
- 1515-1635 EY & returned to get keys! (nellie)
  - 1635-1648 FCES (nellie)
- 1629 Kim out of lvea
  - 1718 EX cleaning
1445-1535 handrails on eMod platform (randy)
1516 Opening light pipe (sheila)
- 1519 NOTE: Sheila noticed a small puddle around the entry to the LVEA (under chiller piping?). She wiped it up, but would like spot to be checked later. There was cleaning in lvea earlier.
  - This is most likely just from cleaning/mopping earlier (richard & kim checked)
1535-1540 Optics Lab pop-in (camilla)
1540-1618 climbing HAM3 for LO1 (fil)---->PR2, MC2 to SAFE
- 1618-1730 susR2 work near HAM3 (fil)
1544-1606 Opening -Y cloth cover for in-air JAC & locking (jenne)
1547-1620 Monthly fire pumps run (eric)
1548-1614 both mids for inventory (jordan)
- 1614-1618 PCal Lab room inventory (jordan)
1613-1800 LN2 truck MX
- ~1645-1811 LN2 truck at Corner's CP1
1615-1620 Taking First Contact to flamable cabinet (ibrahim)
1616 BHSS work (elenna.camilla)
- 1623 oli joining
- 1857 Out for lunch, laser SAFE!
1627-1645 Checking on fil (richard)
1634-1725 lvea Receiving and then to MX to grab a BS container (ibrahim)
- 1725 continue BS container search in optics lab (ibrahim)
1658-1912 GV7 regulator (gerardo.travis.jordan)
1703 Grabbing nd filter in optics lab & taking to IOT1/JAC table (jennie)
- 1809-1920 Grabbing another nd filter to use at IOT1 (jennie.sheila)
1721 turning down purge air down at HAM1, checking rack (keita)
1804-1814 PCal (tony)
1808-1816 Rosalind Franklin Elementary in Control Room Group1 (amber)
- 1830--1842 Rosalind Franklin Elementary in Control Room Group2 (cassidy)
1914-1932 TCS Chiller maintenance check (corey)
LUNCH Note: IMC locking, JAC locking---> next check on beam
1958 BHSS Work continues in laser hazard (elenna.oli)
1958-2001 quick trip to CER for dustmonitor (ryanC)
- 2056-2100 Another dust monitor trip (ryanC)
2006-2259 SPI work in (jim, sina)
- 2020 Jeff joining
- 2124 Jeff returning again
- 2255 Jim & Sina out for assistance with the in-vac picomotors
- 2319 Jeff out for the day
2006 JAC work at HAM1 (keita, jennie)
- 2037 jason joining
2007 HAM1 photo & then optics lab (josh.georgia.michele)
2031-2200 Grabbing HEPA Ceiling Fans from the H2 PSL room in the LVEA (tyler.eric)
- 2138 eric out
- Plan to install one in H1PSL tomorrow (Wed) morning
2105 Back to susR2 rack near HAM3 (fil)
2114-2232 SQZT7 work (sheila.georgia.sophie.camilla)
- 2233 sheila and camilla continue sqz work in control room
2153-2203 Touching base with JAC crew at HAM1 about a possible guardian change (jenne)
2225 Elenna checking to see if she can help the HAM1 crew on Betsy's request
2259 SPI crew (jim.sina) asking keita (at HAM1) about picomotors

H1 TCS - TCS Chiller Water Level Top-Off (Bi-Weekly, FAMIS #28559)

corey.gray@ligo.org — Tue, 31 Mar 2026 13:41:11 -0700

Author: corey.gray@ligo.org

Report ID: 89720

Addressed TCS Chillers (Wed [Mar4] 1242-0105pm local time) & CLOSED FAMIS #28559. (Last checked 28558).

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

TCSx Chiller: Had level of 30.4 cm. Added 0mL for 30.4cm.
TCSy Chiller: Had level of 9.5 cm. Added 325mL for 10.5cm.
There was no water in the small cup under the slow leak.

TCS

H1 TCS - CHETA: Fixing Beam astigmatism

sophie.muusse@ligo.org — Tue, 31 Mar 2026 12:28:17 -0700

Author: sophie.muusse@ligo.org

Report ID: 89719

Due to a mistake in past CHETA models there is more astigmatism then expected on the tables and a change in beam size at the ITM. The astigmatism can be fixed by rotating L1 around the vertical axis and the beam size can be changed by movind L2 using the translation stage in each setup. Using a modified Fintrace model the required rotation angle and translation for each table as they are currently populated at LHO (0922, 0918) and LLO (0919, 0851) have been calculated and are shown below.
The tables below give the current astigmatism and then the angles and translations such that the x and y beamsize on the ITM is 52.7mm with no astigmatism.

This code is avaliable in the CHETA modelling repository.

Unit	Current astig [mm]	Rotation angle of L1 [deg]	Translation [mm]	ITM wx [mm]	ITM wy [mm]
0922	-7.69	10.17	-0.12	52.7	52.7
0918	-4.02	11.84	-12.89	52.7	52.7
0919	-7.55	12.17	3.81	52.7	52.7
0851	-5.76	11.13	3.73	52.7	52.7

Without translating of L2 astigmatism can be removed but the beam size is still unoptimised.

Unit	Current atig [mm]	Angle [deg]	ITM wx [mm]	ITM wy [mm]
0922	-7.69	10.17	52.75	52.75
0918	-4.02	11.18	55.39	55.39
0919	-7.55	12.03	50.95	50.95
0851	-5.76	11.24	51.80	51.80

H1 IOO - JAC refl shutter trigger level, can lock JAC (and sometimes IMC) at 20W input power

sheila.dwyer@ligo.org — Tue, 31 Mar 2026 12:27:44 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89718

Sheila, Keita, Jennie W, Jenne D, Georgia B.

We want to be able to power up to 20W in JAC to check the POP beam.

We were loosing lock with about 8W into JAC because the REFL shutter was closing. Jennie Wright measured 6mW on the REFL diode with 2W input to HAM1 and JAC unlocked yesterday. This corresponds to 0.58V on the shutter trigger diode. The threshold cannot be set above 2V, which means we would unlock when 21mW hit the diode. Jennie Wright added a ND05A into the path before the refl diode, and another ND05A in front of the shutter diode.

Now, with 2W input to HAM1 and JAC unlocked, we should have 2mW on the REFL diode, and the shutter diode votlage is 0.18V. The threshold of 2V now will shut the shutter with 22mW on it.

Gaurdian changes:

The JAC error signals are normalized by the PSL input power if we use the laser power guardian to change the input power, so we shouldn't need a power scaling like 89708. People have been using the rotation stage instead of the guardian to adjust the power because the laser power guardian would go into fault if the power was below 1W (people have been going below 1W while HAM1 is vented.) Jenne Driggers adjusted the fault in LASER_POWER and added a 200mW state to the laser power guardian, so now we should use this guardian whenever we want to change powers, even below 1W.

We also hard coded the gain used for locking JAC in the down state, although this could be reverted to allow the power normalization to work again, once that has been updated to take into account the new ND filters. Once this was done, we could lock JAC at a variety of powers and also change the requested power after it was locked.

Georgia B and I also had a look at the IMC guardian, which has not generally been able to lock the IMC except at 2W. There was some code in the down state of IMC LOCK that was supposed to adjsut settings for lcokign at different power levels, these were unused except for the IN1 gain setting used for acquisition. Georgia and I adjusted some of these numbers and watched if the IMC would lock, we didn't take much time to test it but we did ~~once~~ twice see the IMC lock with 10W + input power, so that is promising.

IOO, OpsInfo

H1 IOO - Reduced whitening for JAC-REFL_A_LF

keita.kawabe@ligo.org — Tue, 31 Mar 2026 11:11:21 -0700

Author: keita.kawabe@ligo.org

Report ID: 89716

Locked with 2W input, JAC REFL A LF signal was constantly railing regardless of the purge air level. Turns out that we were using two stages of 1:10 whitening.

I went to the floor and turned one stage off on the front panel of the RFPD DC interface D1102079 (circuit diagram D1102060) in ISC R1 rack and disabled the corresponding dewhitening filter. I could have disabled both, but with an ND0.5 filter JennieW was installing, this will do the job for now.

I always forget this but gray switch up=1 stage active, middle=2stages, down=0. I put two labels on the front panel so I don't have to remember.

IOO, ISC

Images attached to this report

LHO VE - Tue CP1 Fill

david.barker@ligo.org — Tue, 31 Mar 2026 10:40:18 -0700

Author: david.barker@ligo.org

Report ID: 89715

Tue Mar 31 10:10:46 2026 INFO: Fill completed in 10min 42secs

Images attached to this report

H1 SEI - H1 ISI CPS Noise Spectra Check - Weekly (FAMIS #39344)

corey.gray@ligo.org — Tue, 31 Mar 2026 10:39:35 -0700

Author: corey.gray@ligo.org

Report ID: 89714

FAMIS Link: 39344

Only CPS channels which look higher at high frequencies (see attached) would be the following:

ITMy_ST1 H3
ETMy_ST1 H2

In the bash window we get this note:

"BSC high freq noise is elevated for these sensor(s)!!!: BSITMy_ST1_CPSINF_H3 "

SEI

Non-image files attached to this report

CPS_spectra_10:15-03_31_2026.pdf

LHO General - Comment to Tues DAY Ops Transition

corey.gray@ligo.org — Tue, 31 Mar 2026 08:07:47 -0700

Author: corey.gray@ligo.org

Report ID: 89713

Cleaning Top Of HAM3 Deferred This Morning

kim/nellie/randy noticed that HAM3 was UNLOCKED, so they did NOT clean of HAM3. LVEA is also "bifurcated safe", which would require goggles and that's not safe when climbing on top of chambers when it's hard to see with goggles on. So top-of-HAM3 cleaning will need to wait (gave betsy a heads up on this).

LHO General - Tues DAY Ops Transition

corey.gray@ligo.org — Tue, 31 Mar 2026 07:46:13 -0700

Author: corey.gray@ligo.org

Report ID: 89711

TITLE: 03/31 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: 2mph Gusts, 1mph 3min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.11 μm/s
QUICK SUMMARY:

From the alog, it sounds like HAM1 checks will continue; when this is done the move will be venting the corner and prepping for opening HAM2+3 (and dome next week...but no need to get ahead of ourselves); also when HAM1 work is done, hard close GV2 (x-arm). SQZ work also continues.

Chilly sub-32degF out. LVEA door says "laser safe", but from Ibrahim's emails yesterday & alog activity, it is the LVEA is in LASER HAZARD BIFURCATED at HAM1.

H1 CDS - Workstations updated

erik.vonreis@ligo.org — Tue, 31 Mar 2026 06:52:44 -0700

Author: erik.vonreis@ligo.org

Report ID: 89710

Highlights include ndscope combined file and DAQ channel completion on the command line. Timeout to lock screen should be fixed so that the workstation won't lock you out after a few minutes. You may need to go into Settings->Power Manager->Display and Settings->Screensaver to turn them off.

This was an OS packages update. Conda packages were not updated.

H1 SQZ - Comment to ZM2 PSAMS adjustment improved FC flashes to 60+ in green and 1+ in IR

keita.kawabe@ligo.org — Mon, 30 Mar 2026 22:33:13 -0700

Author: keita.kawabe@ligo.org

Report ID: 89709

Looking at flashes in chamber

When JAC and thus IMC were both locked with 2W, it was possible to see PRMI flashes on a card. It was like a flash per 30 sec or so and it was quite frustrating, but I was able to see that the beam was off-centered into -Y direction significantly.

In the attached, the edge of the card is right in front of the +X-Y edge of the POP red-green dichroic (I'm inserting the card from +Y door). You would think that the beam is clipped but it is not quite, maybe it is clipped a bit on the +X+Y edge of the air-vac splitter downstream, but the transmission of that splitter hits the PM, goes through the lens and toward LSC and LSC POP sensors. It's funny that the centering on the lens looked better than on the dichroic but I might have been tricked by 0 deg AOI VS 45 deg.

See the second attachment for the layout. What I thought was the actual PRMI flash path is drawin in cyan.

Images attached to this report

H1 IOO - Power Adjust function added to JAC

jennifer.wright@ligo.org — Mon, 30 Mar 2026 19:13:27 -0700

Author: jennifer.wright@ligo.org

Report ID: 89708

Jennie W, Keita K, Betsy W, Camilla C

At the end of the day (for the day's activities to get to this point see Sheila's alog #89701) we were in chamber trying to see PRMI flashes in the POP in-vac path on -Y side of HAM1. We tried to lock JAC at 20W input so the flashses would be clearer on the card but it turns out anything over about 5W input puts the trigger PD above its threshold so the shutter in front of the JAC REFL PD and JAC WFS QPDS closes. Keita had Camill and I measure the power and for 2W input we get 5-6mW on this REFL PD and around 3mW on each QPD. This means that we shouldn't try and raise the trigger threshold (currently at 1.2V) as at 20W we will have 50mW on the REFL PD. I thought we had more of a margin than this.

What this means is we want to lock the JAC every time at 2W and then scale the gain in lock so only a low level of power goes to the REFL PD.

I copied some code from the ISC_library to do this. The new function is the state decorator JAC_pwr_adjust_function. It should scale the gain in JAC-L_SERVO by the requested input power as measured at IMC-PWR_IN_OUTMON while the JAC-LOCK guardian is in the 'LOCKED' state. It compiles now but I haven't tested it on the IFO yet as we left IMC and JAC in down, the input power at 100mW and the lightpipe closed at the end of the day.

ISC

LHO VE - Kobelco Oil Temp Issue

jordan.vanosky@ligo.org — Mon, 30 Mar 2026 17:29:49 -0700

Author: jordan.vanosky@ligo.org

Report ID: 89707

This morning I noticed that the oil temp for the Kobelco was high at ~150F (nominal is around 110-115F). Looking at the sight glass for the oil level, it was high compared to it's usual level during operation. (see attached, off line is when compressor is off, RUN is the level during operation)

Gerardo and I confirmed the oil pump was running and the oil line pressure was ok through the control panel. We then opened the ball valve for the coolant line which goes to the oil cooler. This very quickly dropped the oil temp back to nominal, and there was some tuning done to keep it at ~115F.

Gerardo then contacted the rep who replaced the oil pump on this unit a couple of weeks ago, and confirmed it was just a matter of adding more coolant flow to the oil cooler. The oil level at the sight glass then returned to it's nominal level.

No issues since, but we will continue to monitor.

Images attached to this report

H1 SQZ - ZM2 PSAMS adjustment improved FC flashes to 60+ in green and 1+ in IR

camilla.compton@ligo.org — Mon, 30 Mar 2026 16:38:04 -0700

Author: camilla.compton@ligo.org

Report ID: 89694

Sheila, Camilla, Sophie

Following Sheila's finding last week that the nominal ZM2 PSAMS settings of 3.15 V is giving us an oval beam, 89675, we set ZM2 PSAMs to 4.5V and immediately got better flashes in green and IR on FCES. Moved ZM2 to increase flashes to be ~55 on green PD C and occasionally up to 1.2 on IR PD D with CLF injected.

Sheila could lock green FC for ~10 seconds. With the SEED injected it did not seem to be co-resonant and she needed to turn off SUS feedback to help green FC locking.

We then locked FC servo (wouldn't stay locked for long, but was able to move FC1, FC2 and ZM2 PSAMS to maximize the maximum locked values. Got to 58 on PD FC_TRANS_C for 4.8V or 4.9V. Leaving at 4.85V. Could further increase to 66 on PD FC_TRANS_C iteratively with FC1 and FC2, see attached. Locked for ~20 s max.

To get light (100e-6) on SQZT7 OPO_IR PD, we needed to move ZM3 +100urad in PIT on the sliders.

I then thought that we could go to the location we have SQZT7 IR light and light on the HAM7 WFS and movve ZM3 towards the place where we have known FC flashes and bring back the alignment on the HAM7WFS with ZM2 and FC1. I did this but it maybe unsurprisingly didn't;t work. In hindsight maybe I could have used a different combination of mirrors.

To get light (100e-6) on SQZT7 OPO_IR PD, still needed to move ZM3 +100urad in PIT on the sliders. At which point there is no flashes on FCES green or IR. to get max light on the SQZT7 PD (0.0018) I had to change ZM3 from P,Y (-474, -367) for FC flashes to (-334, -309) for SQZT7 light OR move ZM2 from P,Y (429,132) for FC flashes to (-747,1) for SQZT7 light and centered WFs (not inc. WFS A PIT). In going from SQZT7 light to towards FC light, the beam on HAM7 WFS moves positive in PITCH and positive in YAW. This corresponds to

	From SQZT7 light to FC light
DOF	PIT	YAW
WFS A and B	Positive	Positive
ZM1	Positive sliders	Positive sliders
ZM2	Positive sliders	Negative Sliders
ZM3	Negative Sliders	Negative Sliders
FC1 (?)	Positive sliders	Positive sliders

I changed H1:SQZ-RLF_QPD_A_SEG_3_VOLTS from 1.31087 to 10 to stop this broken WFS A QPD segment from effecting the position on the WFs so much. Didn't make much of a difference though.

Images attached to this report

LHO General - OPS Day Shift Summary

ibrahim.abouelfettouh@ligo.org — Mon, 30 Mar 2026 16:30:12 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 89706

TITLE: 03/30 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

IFO is in IDLE for PLANNED MAINTENANCE

HAM 1 team has been working on JAC from the bifurcated HAM1 area and the control room throughout the day. SPI and BHSS work continued in the optics lab.

IX has been a bit finicky and tripped the SW WDs. They didn't seem like they were untripping and we were seeing the counts get worse with the damping loops. Additionally, the rocker switch death flashed a few times. Jim fixed this by turning off SUS damping, then letting the ISI damp until counts visibly went down before turning on damping everywhere.

BSC2 platform work and HAM3 cabling continued.

LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
14:49	FAC	Kim, Nellie	LVEA	Y	Technical Cleaning	16:48
15:14	SUS	Randy	LVEA	Y	Handrails, BSC2	17:46
16:03	SUS	Elenna	Optics Lab	Y	BHSS	18:30
16:04	SQZ	Sheila, Camilla	LVEA	Y	Detransitioning LVEA Hazard to Bifurcated Hazard	16:33
16:07	SUS	Jeff	Optics Lab	Y	Extracting chassis part	16:16
16:16	JAC	Keita	LVEA	Y	JAC	18:30
16:30	EE	Fil	LVEA	LOCAL (bifurcated)	HAM3 Cabling	18:30
16:52	SUS	Mitchell	LVEA	LOCAL (bifurcated)	Parts	17:43
16:53	JAC	Jennie	LVEA	LOCAL (bifurcated)	Helping keita with JAC	17:25
16:55	OPS	Ryan C	CER	N	Testing out dust monitors	17:42
17:00	SUS	Oli	Optics Lab	Y	BHSS	18:30
17:13	SUS	Betsy	LVEA	LOCAL (bifurcated)	Walkabout	18:00
17:21	OPS	Jenne	LVEA	Y	Talk to crew on floor	17:25
17:25	SUS	Sina, Jeff	Optics Lab	Y	SPI	18:30
17:34	FAC	Kim	EX	N	Technical Cleaning	18:18
18:24		Jennie	LVEA	LOCAL (bifurcated)	Signage	18:29
19:05	SUS	Oli, Elenna	Optics lab	Y	BHSS work	20:18
19:30	FAC	Randy	LVEA	Y	Emod. work	21:08
20:01	EE	Fil	LVEA	Y (bifurcated)	HAM3 Cabling	23:59
20:14	FAC	Chris	LVEA	Y (bifurcated)	grabbing wipes	20:27
20:25	CER	Ryan C	CER	N	Dust monitor work	21:40
20:29	SUS	Jeff	Optics Lab	Y	SPI	22:19
20:30	SUS	Sina	Optics Lab	Y	SPI	00:29
20:48	SEI	Jim	LVEA	Y(bifurcated)	Check on IX	21:02
21:03	SUS	Elenna	Optics Lab	Y (bifurcated)	BHSS	22:19
21:52	VAC	Gerardo	EX, EY, MX, MY, LVEA	Y (bifurcated lvea)	inventory check	08:52
21:59	VAC	Jordan	LVEA	Y (bifurcated)	inventory check	23:08
22:19	SUS	Jim	Optic Lab	Y	SPI	23:08
22:32	SUS	Keita, Betsy	LVEA	Y(bifurcated)	HAM1	01:32
22:43	SUS	Jennie	LVEA	Y(bifurcated)	HAM1	23:43
23:13	SUS	Jim	Optics Lab	Y	SPI	01:13
23:16	OPS	Camilla	Optics Lab, LVEA	Y	Device delivery	23:28
23:18	AUS	Thomas, Georgia	LVEA	Y(bifurcated)	Walkabout	00:18

H1 ISC - PRC alignment

sheila.dwyer@ligo.org — Mon, 30 Mar 2026 16:28:20 -0700

Author: sheila.dwyer@ligo.org

Report ID: 89701

Jenne Driggers, Sheila, Keita, Camilla, Jennie Wright, Rahul

We are searching for PRX flashes to use for the POP path work in HAM1.

We are using a DRMI locked time from March 14th (1:30-2 UTC) as a reference. Since that time HAM2 hepi has been locked, causing a +3.7urad shift in RZ, which means that PR3 and PRM osems need to be -3.7urad yawed compared to how they where before HEPI was locked to reproduce the alignment (this shift is small compared to the misalignments that we are looking for).

While trying to restore to this reference time, we see that restoring ITMX sliders restults in optical levers similar to the reference time, and PRM sliders results in PRM osems similar to the reference times. However, restoring PR3 sliders to the reference time gives top mass osem pitch -20 urad in pitch, and PR2 sliders restored gives a +30 urad shift according to the top mass osems.

HAM2 CPS RY shows a +1.3 urad shift at the same time as the PR3 osem shift show -24urad (these are opposite directions), HEPI shows -1.5urad RY, at 11 am pacific time Friday, there is no change in the DAC drive at this time.

PR2's shift seems to have happened right after the DACKill from Friday. Ibrahim and Oli are running top mass to top mass TFs for health checks on both of those.

Keita walked aligments to get PRX flashes back. In the end, PRM and ITMX are back to where they were when DRMI was locked March 14th, as well as PR3 yaw. PR3 pitch osem is back to where it was on the 14th, but the slider is +11urad. PR2 pitch slider is -47urad, osem says -29 urad, yaw +45 slider, +55 urad osems.

We dedicded it was time to move on with the in chamber work, because while these alignment shifts are strange, they probably can't explain the misalingment between the in air and the in vacuum pop paths.

H1 SUS - Comment to PR3 / PR2 TFs look good

ibrahim.abouelfettouh@ligo.org — Mon, 30 Mar 2026 15:31:34 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 89705

PR2 TFs

Non-image files attached to this report

2026-03-30_1600_H1SUSPR2_M1_ALL_TFs.pdf

H1 SUS - PR3 / PR2 TFs look good

oli.patane@ligo.org — Mon, 30 Mar 2026 15:30:59 -0700

Author: oli.patane@ligo.org

Report ID: 89703

Commissioners wanted health checks run for PR3 and PR2 to check for any suspension issues. I ran TFs for PR3 and Ibrahim ran them for PR2. Results for both suspensions look good. Results for PR3 are below, and then Ibrahim will be commenting on the info for the PR2 measurements.

Settings:
- PR3 in HEALTH_CHECK
- DAMP OFF (including estimator damping)

Data:
/ligo/svncommon/SusSVN/sus/trunk/HLTS/PR3/SAGM1/Data/2026-03-30_2115_H1SUSPR3_M1_WhiteNoise_{L,T,V,R,P,Y}_0p02to50Hz.xml
r12986
Results:
/ligo/svncommon/SusSVN/sus/trunk/HLTS/PR3/SAGM1/Results/2026-03-30_2115_H1SUSPR3_M1_ALL_TFs.pdf
/ligo/svncommon/SusSVN/sus/trunk/HLTS/PR3/SAGM1/Results/2026-03-30_2115_H1SUSPR3_M1.mat
r12987

Non-image files attached to this report

2026-03-30_2115_H1SUSPR3_M1_ALL_TFs.pdf

H1 SUS - Comment to OSEM spectra for SUS PR2 and PR3 - looks healthy

rahul.kumar@ligo.org — Mon, 30 Mar 2026 15:28:28 -0700

Author: rahul.kumar@ligo.org

Report ID: 89704

spectra for PR2 and PR3 from last week (25 March 2026).

Images attached to this report

H1 SUS - OSEM spectra for SUS PR2 and PR3 - looks healthy

rahul.kumar@ligo.org — Mon, 30 Mar 2026 15:26:32 -0700

Author: rahul.kumar@ligo.org

Report ID: 89702

Sheila, Rahul

This morning I took top mass osem spectra for both PR2 and PR3 suspension and they looks healthy (the noise level for all bosems are similar and the magnitude is to below 10^-4 above 10Hz - un-calibrated) - plot attached below. There is a 15Hz peak seen on PR3, which is also seen (in both PR2 and PR3) if we go back in time (7 days) compare the spectra results.

I also looked at the medm screen of both the suspensions (input filters, flag position, damping loops and coil driver settings) and trended bosem channels and did not find anything unusual.

SUS

Images attached to this report

H1 TCS - CHETA QCL Fused Silica beam dump

sophie.muusse@ligo.org — Mon, 30 Mar 2026 12:13:05 -0700

Author: sophie.muusse@ligo.org

Report ID: 89698

Summary: A thermal lens resulting from using 2 Fused Silica windows as attenuators in the CHETA system should not effect the profiled beamsize.

We are considering using 2 Fused Silica windows at 45 degrees as absorping attenuators at the outputs of the QCL during beam profiling to stop back reflections which we believe are currently damaging the units. We plan on using 2 windows to prevent a beam displacement so the path doesnt have to be altered. During this process we require atleast 7mW on the thermal profiler to accurately profile the beam.

The attenuation through each 1mm window assuming using a loss factor of -28e6dB/km at 4.6um would be as follows:
Power after first window: 0.398W
Power after second window: 0.158W
Power reflected back through both windows: 0.0251W

This shows there will be non-neglible absorption so some quick modelling has been completed to demonstrate that this thermal lens would not have a significant effect on the system.

I have used the finesse Hello Vinet implementation to model both the thermo-refrative and thermal expansion induced thermal lenses, assuming 2W of QCL power is absorbed in the substrate. This will be an over estimate as HV assumes that Pin ≈ Pout and that the absorbed power is much smaller than Pin.
A radius of curvature was found from the HV OPD by completing an overlap interval with 2,0 and 0,2 modes.

Assuming worst case scenario of 2W of absorbed power and an beamsize of 300um (approximately the waist of a nominal QCL unit) there is an induced thermal lens of f =30.5273 m Rc = -0.0451 m. To determine the effect on the q-parameter of the beam I have assumed both glass windows act as a lenses with this focal length and use ABCD matrics determine the change in q. This change in q is similar to the measurement error of these q factors and when propagated through to the ITM changes the beam size by less than 1%. This calculation for every unit is given in the table below using these yaml files.

Condition	q (x)	q (y)	w at ITM x (m)	w at ITM y (m)	q at ITM x	q at ITM y
0918
current system	−0.234 + 0.113j	−0.295 + 0.098j	0.05346	0.05747	35.977 + 0.663j	35.634 + 0.563j
with lens	−0.231 + 0.110j	−0.290 + 0.094j	0.05426	0.05854	35.994 + 0.644j	35.664 + 0.543j
0920
current system	−0.129 + 0.071j	−0.155 + 0.059j	0.04794	0.05408	36.818 + 0.866j	36.576 + 0.671j
with lens	−0.128 + 0.069j	−0.15367 + 0.05782j	0.04828	0.05451	36.830 + 0.854j	36.594 + 0.662j
0919
current system	−0.186 + 0.096j	−0.227 + 0.072j	0.04737	0.05492	37.546+0.920j	37.221 +0.673j
with lens	−0.184+ 0.094j	−0.224 + 0.070j	0.04791	0.05566	37.564 + 0.900j	37.251+ 0.656j
0851
current system	−0.180 + 0.069j	−0.224 + 0.063j	0.04887	0.05462	36.143 + 0.670j	35.772 + 0.545j
with lens	−0.178 + 0.067j	−0.221 + 0.061j	0.04928	0.05515	36.316 + 0.795j	35.896 + 0.620j

edit: fixed LLO numbers with updated parameters

Images attached to this report

Non-image files attached to this report

Thermal_lens_in_SiO2_QCL.py

H1 SPI - SPI Amplifier Modification

thomas.roocke@ligo.org — Mon, 30 Mar 2026 12:02:11 -0700

Author: thomas.roocke@ligo.org

Report ID: 89700

[Tom, Jeff]

The SPI amplifier chassis' (S2500712, S2500713) were modified to increase their transimpedance gain, based upon testing in the optics lab from Jeff. Resistors R4 were changed to modify the gain, and capacitors C5 were changed to maintain circuit stability and bandwidth. Exact component changes summarised below:

S2500711

CH1: R4 = 1.5kohm, C5 = 2.2nF
CH2: R4 = 1.5kohm, C5 = 2.2nF
CH3: R4 = 1.5kohm, C5 = 2.2nF
CH4: R4 = 1.5kohm, C5 = 2.2nF

S2500712
CH1: R4 = 5kohm, C5 = 560pF
CH2: R4 = 5kohm, C5 = 560pF
CH3: R4 = 3.3kohm, C5 = 1nF
CH4: R4 = 3.3kohm, C5 = 1nF

CH5: R4 = 3.3kohm, C5 = 1nF
CH6: R4 = 3.3kohm, C5 = 1nF
CH7: R4 = 3.3kohm, C5 = 1nF
CH8: R4 = 3.3kohm, C5 = 1nF

S2500713
CH1: R4 = 54kohm, C5 = 56pF
CH2: R4 = 54kohm, C5 = 56pF

LHO FMCS - HVAC Fan Vibrometers FAMIS Check (FAMIS 39860)

ryan.crouch@ligo.org — Mon, 30 Mar 2026 12:01:54 -0700

Author: ryan.crouch@ligo.org

Report ID: 89699

Closes FAMIS39860, last checked in alog89375

Everything looks as it did during the last check, except MR_FAN4_170_1 looks noisier than during the last check.

PEM

Images attached to this report

H1 SEI - BRS Drift Trends - Monthly FAMIS

ryan.crouch@ligo.org — Mon, 30 Mar 2026 11:48:57 -0700

Author: ryan.crouch@ligo.org

Report ID: 89695

Closes FAMIS38815, last checked in alog89298

BRS_Y looks to be drifting down, over the past two months at least. The aux channels look just as they did before.

Images attached to this report

LHO VE - Mon CP1 Fill

david.barker@ligo.org — Mon, 30 Mar 2026 11:47:53 -0700

Author: david.barker@ligo.org

Report ID: 89697

Mon Mar 30 10:08:08 2026 INFO: Fill completed in 8min 5secs

Images attached to this report

H1 General - Omicron glitch rate comparisons for O4

jane.glanzer@ligo.org — Mon, 30 Mar 2026 11:35:25 -0700

Author: jane.glanzer@ligo.org

Report ID: 89696

Attached to this alog are the Omicron glitch rate compariosns between O4a, O4b, and O4c. I am posting just for the record, but this was also presented at the LVK in Pisa (see here). For the comparisons, I used roughly about ~3240 hours of observing time (denoted by the H1:DMT-ANALYSIS_READY:1 flag). The exact GPS times used for the analysis were:

O4a: 1372611618 - 1389484818

O4b: 1397692818 - 1422118818

O4c: 1422118818 - 1447502418

The first attached plot shows the glitch rate across each observing period, which includes glitches with an SNR > 7.5, and frequency between 10 Hz - 1024 Hz. The rate was the highest in O4a, at around ~38 glitches per hour. The subsequent glitch rates for O4b/c were lower and similar levels, coming in at around ~11 glitcher per hour and ~10 glitches per hour. In O4a, the glitch rate was high due to increased non-stationary noise from ~10 Hz - 50 Hz (see alogs 71005 & 71092). The following two plots show the glitch rates as a function of SNR and frequency. Most glitches had an SNR below 50, and frequency below 50 Hz.

DetChar

Images attached to this report

H1 SPI - Comment to SPI Fiber Patch Cable from PSL to SUS-R2 Installed; Verified Excellent Transmission

jeffrey.kissel@ligo.org — Mon, 30 Mar 2026 10:15:55 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 89693

J. Oberling, S. Koehlenbeck 2026-03-27 #BelatedaLOG During this power measurement, I made the rookie mistake of overlooking the PM100D power meter console's laser wavelength setting -- and not taking a picture of the display during the measurement. Today, we both (a) retook the measurement at 1064 [nm] with 189.3 [mW] input, and found 173 [mW] output. (b) confirmed that at 532 [nm] the output read as 188 [mW]. For now we set the nominal power into the laser prep chassis as 173 [mW]. After this measurement, we took this same power meter (S121C) and fiber adapter (S120-APC2) into the optics lab and instead used the fiber-coupled NPRO we'd been using to test ISIK in there. We measured the power out of the fiber (i) with it fiber-coupled in the same way as the SPI_PSL_001 measurement, and (ii) using an addition PAF2-5C collimator to project the beam into free space on to the power meter. We set the FC-NPRO's power to 177 [mW] in the (i) configuration, but then measured 140 [mW] in the (ii) configuration. This leads us to suspect that the S120-APC2 + S121C system -- a reflective Si diode, with a shiny metal adapter -- is errantly reporting more power than there really is. We'll repeat the measurement of SPI_PSL_001 another day with a thermal power meter to arrive at our final number. SPI

Images attached to this report

H1 SUS - QOSEM In-Vac Cable Assembly

thomas.roocke@ligo.org — Mon, 30 Mar 2026 09:53:49 -0700

Author: thomas.roocke@ligo.org

Report ID: 89692

[Tom, Sophie, Ibrahim, Betsy] Thursday, Friday and Saturday of last week we assembled a batch of 4 QOSEM In-Vac cables (D2500311) for use at LLO on the BBSS. All cables have passed electrical testing. On Sunday, Betsy cleaned and began an airbake on the cables, and they have now begun there vacuum bake, which should finish Wednesday evening.

Images attached to this report

H1 CDS - Comment to alarm handler is beeping about H1:PEM-CS_DUST_LAB2_300NM

ryan.crouch@ligo.org — Mon, 30 Mar 2026 09:21:34 -0700

Author: ryan.crouch@ligo.org

Report ID: 89691

This station (PCAL lab/LAB2) doesn't even have a device connected currently. There have been connections issues here for the past few months that I haven't tracked down yet. I'm not sure why it would have restarted to alarm, but I'll comment this station out of the ioc startup for now.

H1 ISC - Comment to Saturday morning: pico holder on the WFS sled for 50:50 splitter was loose (JennieW, Jason, Keita)

keita.kawabe@ligo.org — Mon, 30 Mar 2026 09:08:44 -0700

Author: keita.kawabe@ligo.org

Report ID: 89690

Correction: In the above alog text, "LSC_REFL_B_ghost.jpg" points to the picture for REFL_A ghost beam. This is the correct one: LSC_REFL_B_ghost.jpg.

LHO General - OPS Day Shift Start

ibrahim.abouelfettouh@ligo.org — Mon, 30 Mar 2026 07:39:01 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 89689

TITLE: 03/30 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: 14mph Gusts, 10mph 3min avg
Primary useism: 0.03 μm/s
Secondary useism: 0.13 μm/s
QUICK SUMMARY:

IFO is in IDLE for PLANNED MAINTENANCE

An earthquake tripped some watchdogs - untripped now.

Plans this week prep BHSS and SPI in Optics lab and continue BSC2 platform install.