Randy has been hard at work adding temp handrails and the eMod garbing cleanroom to the BSC2 platform access area.  Its pretty workable now.  The temp handrails have a pretty large footprint so I might make changes to those in the next incarnation of this, so the walkway from the eMod to the BSC2 platform is pretty narrow.  This platform and eMod placement will service BSC1 and BSC3 as well however, so we will rework or remove some handrails as we add those sections.  The tent is easy to pull back when we need the dome and cartridge to be craned away.

Now that HAM1 is closing again (doors going on with VAC team now), we are turning attentions back to the CDS and BBSS work slated in line next.  Attached is the snapshot of the Trello with the next vent actions queued up.  We anticipate venting the corner chamber volume and also opening HAM3 this week.

FAMIS 31132

The broken anteroom fan was swapped last Wednesday, so there are changes seen on several trends at that time. The ISS diffracted power increased, so I've just adjusted the RefSignal slightly to bring the diffracted power back down to around 4% and the PMC transmission back up to what it was before the fan swap.

Mon Apr 06 10:07:21 2026 INFO: Fill completed in 7min 18secs

Monthly FAMIS Check (#39345)

T240 Centering Script Output:

Averaging Mass Centering channels for 10 [sec] ...
2026-04-06 09:03:52.267253
There are 11 T240 proof masses out of range ( > 0.3 [V] )!
ETMX T240 2 DOF X/U = -1.862 [V]
ETMX T240 2 DOF Y/V = -1.903 [V]
ETMX T240 2 DOF Z/W = -1.191 [V]
ITMX T240 1 DOF X/U = -2.423 [V]
ITMX T240 1 DOF Z/W = 0.37 [V]
ITMX T240 3 DOF X/U = -2.723 [V]
ITMY T240 3 DOF X/U = -1.215 [V]
ITMY T240 3 DOF Z/W = -3.11 [V]
BS T240 3 DOF X/U = -0.38 [V]
HAM8 1 DOF Y/V = -0.456 [V]
HAM8 1 DOF Z/W = -0.766 [V]
   All other proof masses are within range ( < 0.3 [V] ):
ETMX T240 1 DOF X/U = -0.079 [V]
ETMX T240 1 DOF Y/V = -0.076 [V]
ETMX T240 1 DOF Z/W = -0.114 [V]
ETMX T240 3 DOF X/U = -0.097 [V]
ETMX T240 3 DOF Y/V = -0.159 [V]
ETMX T240 3 DOF Z/W = -0.087 [V]
ETMY T240 1 DOF X/U = 0.027 [V]
ETMY T240 1 DOF Y/V = 0.07 [V]
ETMY T240 1 DOF Z/W = 0.259 [V]
ETMY T240 2 DOF X/U = -0.204 [V]
ETMY T240 2 DOF Y/V = 0.238 [V]
ETMY T240 2 DOF Z/W = 0.042 [V]
ETMY T240 3 DOF X/U = 0.267 [V]
ETMY T240 3 DOF Y/V = 0.048 [V]
ETMY T240 3 DOF Z/W = 0.007 [V]
ITMX T240 1 DOF Y/V = 0.28 [V]
ITMX T240 2 DOF X/U = 0.119 [V]
ITMX T240 2 DOF Y/V = 0.163 [V]
ITMX T240 2 DOF Z/W = 0.263 [V]
ITMX T240 3 DOF Y/V = 0.143 [V]
ITMX T240 3 DOF Z/W = 0.057 [V]
ITMY T240 1 DOF X/U = -0.045 [V]
ITMY T240 1 DOF Y/V = 0.16 [V]
ITMY T240 1 DOF Z/W = -0.038 [V]
ITMY T240 2 DOF X/U = 0.052 [V]
ITMY T240 2 DOF Y/V = 0.2 [V]
ITMY T240 2 DOF Z/W = 0.036 [V]
ITMY T240 3 DOF Y/V = -0.021 [V]
BS T240 1 DOF X/U = 0.043 [V]
BS T240 1 DOF Y/V = -0.119 [V]
BS T240 1 DOF Z/W = -0.038 [V]
BS T240 2 DOF X/U = 0.235 [V]
BS T240 2 DOF Y/V = -0.134 [V]
BS T240 2 DOF Z/W = 0.132 [V]
BS T240 3 DOF Y/V = -0.158 [V]
BS T240 3 DOF Z/W = -0.169 [V]
HAM8 1 DOF X/U = -0.297 [V]
Assessment complete.

STS Centering Script Output:
Averaging Mass Centering channels for 10 [sec] ...
 
2026-04-06 09:04:04.266410
There are 2 STS proof masses out of range ( > 2.0 [V] )!
STS EY DOF X/U = -4.57 [V]
STS EY DOF Z/W = 2.369 [V]
   All other proof masses are within range ( < 2.0 [V] ):
STS A DOF X/U = -0.496 [V]
STS A DOF Y/V = -0.768 [V]
STS A DOF Z/W = -0.628 [V]
STS B DOF X/U = 0.152 [V]
STS B DOF Y/V = 0.942 [V]
STS B DOF Z/W = -0.444 [V]
STS C DOF X/U = -0.995 [V]
STS C DOF Y/V = 0.908 [V]
STS C DOF Z/W = 0.636 [V]
STS EX DOF X/U = 0.606 [V]
STS EX DOF Y/V = -0.511 [V]
STS EX DOF Z/W = -0.372 [V]
STS EY DOF Y/V = 1.135 [V]
STS FC DOF X/U = 0.153 [V]
STS FC DOF Y/V = -1.192 [V]
STS FC DOF Z/W = 0.629 [V] 
Assessment complete.

FAMIS Link:  39345 

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

1. ITMx_ST1 V1
2. ETMy_ST1 H2

In the bash window got ZERO notes.

TITLE: 04/06 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 4mph Gusts, 2mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.14 μm/s 
QUICK SUMMARY:

Lots of activities on the docket for today.  HAM1 is set for door re-install, but could wait until after corner vent + HAM3 door removal.  Lots of staging for HAM3 opening and BBSS@BSC2.  Also a list of various CDS activities.  

Sun Apr 05 10:05:09 2026 INFO: Fill completed in 5min 6secs

Sat Apr 04 10:06:55 2026 INFO: Fill completed in 6min 52secs

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!

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)

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!

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.

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.

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.

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).