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:
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.
Richard noticed we the PSL was at 10W, so it was taken down to 0W. TJ noticed MC2 was saturating (nuc23); so IMC was taken to OFFLINE.
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!
Please quote all numbers for fiber motion and put all plots in 'meters' (either rms or pk), not meters/sqrt(Hz). It is the former that has physical meaning, can be compared to calculation, and is not dependent on the resolution bandwidth one might choose for a spectrum.
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:
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.
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.
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!
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.
HAM1 was under vacuum May 23rd, 84334, which is why we did not adjust the in vac alignment at that time.
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.
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.
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.
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.
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.
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.
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).
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).
The images show the test equipment used.
