[Keita, Louis, Caroline, Elenna]

We are much closer to getting the 3f transition. We have confirmed we can swap PRCL from 1f to 3f while maintaining the same gain (no need for a factor as in 89567).

We have also confirmed what the 27I matrix value for SRCL needs to be to subtract PRCL from the error signal (2.7). We still need to test the 135I input matrix value by putting it into a blank matrix row, but we think it should be roughly -4.

We still have yet to to figure out what the MICH matrix value needs to be, but we think if we follow the same procedure as we did for SRCL, we can get there.

Regarding the DRMI ASC, we have not been successful in putting together a good MICH ASC signal. Unlike PRMI, the AS B RF45 signal is not going to work, but it looks like neither does the AS A RF45 signal. We might need to do a full sensing matrix and then use both sensors to construct a sensible signal. We could also check the AS 36 signals in case they are better.

I checked the air 3f phases and changed them slightly while running a PRM line to maximize PRM in I for both 27 and 135. Attached are screenshots of my measurements and SDF. I first started checking the phases while the SRCL mode hop offset was on, but then I turned it off. With the offset off, the phasing still looks fine.

We have also noticed the SRCL gain seems low by a factor of 2 (with nominal -33 gain from guardian). This is based on the idea that we want SRCL to have a UGF closer to 30 Hz. We don't think this is causing much of a problem right now, but it's something worth checking out and maybe guardianizing.

The MICH OLG still looks very strange, so there must be some cross coupling somewhere, but it's hard to tell what because the air 1f phases look ok, or at least Keita says "it's not wrong".

Unfortunately the day ended a little roughly, because suddenly we went from having very stable long DRMI locks to short locks that ring up quickly. Nothing on our end changed, so we don't understand what happened.

Procedure:

• We can run through the PREP DRMI ASC state in ISC DRMI. After that state completes I manual to ZERO 3F OFFSETS
  • want to clarify that we tried letting the 3f transition state run once, and it failed, so we started working through it carefully loop by loop
• I manually put in the PRCL matrix value of -1.22 into REFLAIR 27I, set REFLAIR 9I to zero, and ramp the LSC input matrix.
• Louis and I checked the PRCL-out-of-SRCL value by measuring an SRM injecting in both REFLAIR 27I and 135I. We calculate that matrix value should be 2.7.
• Based on transfer functions between SRCL on air 1f and 37, we know that there is a sign flip between the 1f and 3f signal. We also think the gain is closely matched, but we aren't sure, and we want to check one more time before trying the switch.

Additional locking notes from the morning:

• Started with initial alignment, trended ITMs top mass osems to make sure there has been no significant shifts (oplevs are out right now due to GVs being closed)
• Locked PRMI, engaged MICH ASC following Keita's steps (91976).
  • MICH ASC for PRMI is now guardianized properly in ISC_DRMI, will run in PRMI ASC
• DRMI locked, I walked through the entire "DRMI locked" state by hand and everything engaged properly!
  • Did not check UGFs of LSC loops
• moved to DRMI WFS centering and started moving the BS around to check the MICH ASC error signal, may have caused a lockloss moving the BS too much in yaw
• [beckoff restart, meetings, etc]
• I rechecked the alignment, and we relocked DRMI. The alignment required a lot of touch up by hand. Howver! I was able to run all the way through to PREP DRMI ASC no problem
  • with touched up alignment, POP18 is 92, PO90 is 2.5
• MICH ASC error signal does not look right
  • both pitch and yaw do not maximize/minimize POP18/90 when crossing zero
  • Keita is checking AS WFS 45 phase
• Elenna checked REFLAIR 3f phases with PRCL line, small changes made it better (10 and 20 deg)
• PRCL 3f transition is fine

TITLE: 09/22 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Oli
SHIFT SUMMARY:
Beckhoff issues were resolved before noon. 

End X's Gatevalve GV 20 is still closed and will remian closed for now.

LOG:
 

Closes FAMIS#62991, last checked 91877

Everything's looking okay. ETMX is obviously very noisy as expected. A few chambers are seeing a bit more noise at 30Hz compared to the last check, but nothing too out of the ordinary. HAM5 H3 is seeing 7-8x more noise at 60Hz for some reason.

 Wanted to compile a table of the whitening changes that we've made to the QOSEM BBSS M1 satamp and how each modification has lowered the time constant. With our current settings, our time constant is 4 seconds, which is much nicer for not saturating compared to the original design, whose time constant was 23 minutes.

ETMX is still looking healthy now that we're back in enough vacuum. Here are some transfer functions I took for ETMX M0 and R0 with the OPTICALIGN OFFSET sliders ON

Settings:
- In HEALTH_CHECK
- alignment sliders ON
- DAMP OFF
- SEI in ISI_DAMPED_HEPI_OFFLINE

M0
Data:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGM0/Data/2026-09-21_1745_H1SUSETMX_M0_WhiteNoise_{L,T,V,R,P,Y}_0p02to50Hz.xml
Results:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGM0/Results/2026-09-21_1745_H1SUSETMX_M0_ALL_TFs.pdf
r13155

R0
Data:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGR0/Data/2026-09-21_1830_H1SUSETMX_R0_WhiteNoise_{L,T,V,R,P,Y}_0p02to50Hz.xml
Results:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGR0/Results/2026-09-21_1830_H1SUSETMX_R0_ALL_TFs.pdf
r13156

J. Kissel

Sina has posted some of the first SPI L results in LHO:91794 and subsequent comments in LHO:91861. They conclude, via passive ASD measurement and minimal unit conversion, that "the visual agreement is remarkably good."

Here I post some retrospective results from the driven transfer function set I took on 2026-09-03 (LHO:91798) to get a more quantitative comparison.
Using all channel conversions described in LHO:91809, which are, in summary "just" calibrating the front-end channels into the SI order of magnitude units (i.e. diplacement channels from [nm] to [m], and inertial sensor channels "inertial sensor response asymptoting to 1 [nm/s] at high-frequency" to [m]), I compare the ASDs and transfer functions during the reference time and HAM2 injection times, 
    Reference Time  2026-09-03 17:09:49 UTC 
    HAM2 excitation 2026-09-03 18:34:14 UTC - 18:58:09 UTC

Note -- while I had thought the CRS as blended into the HAM3 sensor array during this time, Jim confirms that it was NOT in play in the HAM3 RY loop (LHO:91866).
Also -- there were questions why "I didn't just use the same excitation that Jim did for the optical lever signals;" the real answer is that I hadn't had the chance to talk to him, couldn't find it easily on my own, and assumed it was some matlab infrastructure that I wouldn't know how to use. I now have talked to him, and he's pointed me to LHO:91754, which points to LHO:91607, which points to the actual path to the file in LHO:91179. But, even if I did find that text file to drive awggui with, it has a low-frequency-focused tilt de-coupling color too it, which is different from what I ended up concocting in DTT. C'est la vie, I think both sets of TFs will be interesting. Certainly this one was.

Attachment 1
Building up an understanding of the front-end-computed HAM3-HAM2 super sensor signal, H1:ISI-DIFF_H23_SS_X_OUT_DQ.

This ASD collection compares the CPS and GS13s of HAM2 and HAM3 against the differential super sensor during the HAM2 excitation (only). Since HAM3 was NOT being driven, we can treat this like the "reference" performance for the HAM2 ISI -- because the HAM2 and HAM3 ISI typically perform similarly in the longitudinal, or ISI and IFO X direction (when the CRS is not engaged into the HAM3 blend). 

- Compare BLUE, DARK GREEN, and HOT PINK traces. We see that the drive on causes displacement on HAM2 is factors of 2x to 50x above the reference level
- Compare THIN DARK PURPLE against CYAN and BRIGHT GREEN traces. We see that the blended input to the super sensor for HAM3 has -- for some reason -- a lot more motion than the "raw" blended CPS and GS13s input. 
- COMPARE BLUE, DARK GREEN, HOT PINK, and BLACK traces. Where the CPS and GS13s are not noise limited (i.e. where're signals are used in the blend to form the super sensor sum), All of the HAM2 and the differential HAM3-HAM2 signal agree, showing the excitation on HAM2.

Conclusion: the front-end computed measure of the differential motion between HAM3 - HAM2 using the onboard CPS and GS13s is functional, comes with a calibration that makes sense, and is measuring the right thing.

Attachment 2
Building up more trust in the HAM3-HAM2 super sensor signal, H1:ISI-DIFF_H23_SS_X_OUT_DQ as a faithful signal for comparison with the SPI L signal H1:SPI-H23_DIFFDISP_MAIN_OUT_DQ.

This ASD collection compares the CPS- and GS13-computed differential X motion (BLACK) and SPI L measured differential X motion (RED) during both the reference quiescient time (DASHED traces) and during the HAM2 excitation (SOLID traces). The excitation is also shown (H1:ISI-HAM2-ISO_X_EXC, calibrated into displacement units [m]).

- During the reference time (DASHED), the SPI L and the on-board sensors only agree above 5 [Hz]. *very interesting* We know the low-frequency-end -- below ~2 [Hz] -- is dominated by the SPI seed laser's frequency noise -- which is dominated by the IMC's displacement. Remember, at the time of measurement, only the IMC is locked (but now with the JAC locked between the PSL and IMC). It looks like -- at least during this measurement -- that's larger or different or incoherent with the HAM3-HAM2 motion. So... maybe this is all suspension noise (or ISI tilt)? Needs more study / noise budgeting.

- During the excitation time (SOLID), the SPI L and the on-board sensors agree across a much broader frequency-band, only disagreeing between 1.5 and 10 [Hz]. *very interesting*. *great* that the excitation i.e. this amount of differential motion *makes* the SPI L and on-board sensors agree for the most part. I have even less of a guess at an explanation for the frequency region where they're not, tho.

Conclusion: Under large differential displacement, the SPI L agrees with the on-board sensors over a very broad range of frequencies, from 0.005 - 2 [Hz] and 10 - 60 [Hz] Lots still to investigate, tho.

Attachment 3
Linear transfer function between the HAM3-HAM2 super sensor signal, H1:ISI-DIFF_H23_SS_X_OUT_DQ and the SPI L signal H1:SPI-H23_DIFFDISP_MAIN_OUT_DQ, as well as the length/frequency control channel for the input mode cleaner (H1:IMC-F_OUT_DQ. 

I show the driven transfer function magnitude for these signals on a log-log plot. Coherence shown separately below.

- Where the SPI noise didn't match the ISI-DIFF noise between ~2 - 10 [Hz], the TF is incoherent (coherence shown separately below), so ignore that.
- At other frequencies, where the ASD "visually agree" the transfer function is NOT exactly 1.0 -- see more discussion of the values of the TF magnitude in the semilogx version of the plot below. *very interesting* 
- I don't understand the magnitude of the IMC-F transfer function at all below 1 [Hz]. The next plot shows it's coherent... *very interesting* or *I'm missing something obvious*

The IMC-F channel has the following calibration into [m]:
    Gain: 1.1683e-06
    Poles: 0
    Zeros: (none)
I don't remember how I calculated this, or where I got it from. To be (re)investigated... but I would have guessed -- since IMC-F_OUT_DQ is already calibrated into [kHz], that it *should* be something like a factor of (2 * L_IMC * lambda / c) = 1.1724e-13 [m/Hz] or 1.1724e-13 [m/kHz] with no poles at 0 [Hz], from df / f0 = dL / L_rt math, but that doesn't seem to be it at all. I probably just need to go back to the code used to produce plots in the SPI final design doc ... just haven't had time.

Also -- side note -- looked into the IMC_X calibration infrastructure that uses the length drive to MC2 to calibrate the control signal into displacement units and that doesn't work.

Attachment 4

Coherence between SPI L and the ISI-DIFF channel and the IMC-F channel for the two TFs shown above.
I also show the coherence between the SPI L channel and the individual ISI CPS and GS13s to understand from where the coherence comes (expecting more from HAM2 since this is during the HAM2 drive.)
I also show the coherence between the ISI-DIFF channel and the IMC just to see how that's different.

Conclusion: Lots to see here, but I haven't really digested it or tried to make sense of it.

Attachment 5
Same transfer function as in Attachment 3, just shown in semi-log x so we can read off what the magnitude of the TF is at coherent frequencies.

- The TF is indeed almost a flat 1.0 [m/m] above 10 Hz; but not quite. *very interesting*
- Between 0.1 and 1 [Hz], where the SPI and ISI-DIFF are *definitely* coherent, the TF magnitude is *not* 1.0, not is it flat. It's got bumps and wiggles between 1.0 and 0.7. Best first guess it that this has something to do with gain peaking in the blend filters. *very interesting*

Conclusion: this TF is going to be very interesting, and we won't be able to "just" blend the SPI "right in" with a simple filter. And, I need to try to get more coherence below 0.1 [Hz].

Very interesting! 

FAMIS81871, last checked in alog91654.

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

• TCSx Chiller:  Had level of 28.3 cm.  Added 770mL to reach 30.5cm.
  • This was almost at the level noted in the procedure of < 28.0cm, but it has been almost a month since the last time these were topped off.
• TCSy Chiller:  Had level of 9.3 cm.  Added 400mL to reach 10.7cm.
  • When I first started to add water, the level quickly dropped by ~half a cm, I had checked beforehand to make sure the filter was off level so that there was no seal. After a few hundred mL it shot back up by that half a cm, which led me to overfill by 0.2 cm.  
• There was no water in the small cup under the slow leak, just some spots of leftover glycol.

I monitored the new OLDAMP matrix values on the BBSS (these are not guardianized).

TITLE: 09/21 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 7mph Gusts, 4mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.17 μm/s 
QUICK SUMMARY:

Slow controls and Beckhoff are currently Down. -Fil is currently troubleshooting this.
EX has been pumping down all weekend and now down to 3.68e-7 Torr according to H0:VAC-EX_X4_PT525_MOD1_PRESS_TORR. 
Gate valve 20 Is still closed.

The EY Slow controls issue escalated overnight, DEV5 now has no communication with EY.

The link deteriorated over the course of 5 hours, starting at 23:24 Sat 19sep2026 and was completely lost by 04:23 Sun 20sep2026.

Trending the slave_count_actual for DEV5 shows it erratically drops from 127 to 1 over this time period.

I turned off the JAC heater servo at 23:45:00 UTC today to do a longer step response test over the weekend.

[Elenna, Louis]

After the HAM2 work (91959) finished today, we decided to double check AS port powers in a couple states. I trended back about a week to September 10, long before the RCG upgrade (91936). We are seeing a ~20% drop in counts on AS_A and AS_C in PRX_LOCKED and SRY. Also, our PRMI buildup right now is about 56. Last time we locked PRMI without ALS it was 52.

* Not sure how comparable this number is since we don't know much about the centering on the LSC POP diode at the reference time. POPX pit & yaw are ~ -1 during this reference time stretch.

After closing up BSC9 yesterday we started pumpdown of the EX volume this morning using the two mobile ISP1000 scroll pumps.

There was minimal overpressure in the system, so I could not get a good dewpoint measurement of the blow down air.

It took ~6 hours to rough the system down from atmosphere to ~500 mtorr, where we start the turbopump.

The cooling water was adjusted on the turbopump stand so that the pump and controller pressures were <= 40C. Once the turbo was at full speed and the inlet pressure ~5e-5 Torr, I switched the backing pump to the dedicated ISP250 on the turbo stand.

Setpoints were adjusted to 5E-2 Torr on Channel 1 (Foreline) and 5E-5 Torr on Channel 2 (Turbo inlet).

We will need to leak check the TMDS port gate valve since it was removed to verify the gate o-ring was in place.

Also, the EX cleanroom was powered off at ~3:10 pm local time.

After various ETMX transfer functions and offset tests, it looks like ETMX isn't rubbing anymore!

I did these tests this morning and wasn't able to get any rubbing. For everthing I did, L1 LL (and everyone else) moved as expected and no one got stuck anywhere. The offset tests that I did involved putting offsets in the L1 COILOUTF banks, M0 TEST banks, and R0 TEST banks and making sure L1 osems were all responding how we expected them to.

We noticed that L1 UL has been a little more jaggedly compared to the other L1 osems since we went to air, but the osem spectra looked good (comparing to its brethren) and putting a drive in M0 to move L1 around shows that UL is moving and behaving normally. We think it's probably just related to its current flag vs osem position as we put air in the chamber.

Transfer Functions
Settings:
- HEALTH_CHECK
- OPTICALIGN OFFSETS ON
- DAMP OFF
- ISI in ISI_DAMPED_HEPI_OFFLINE

M0
Data:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGM0/Data/2026-09-15_1540_H1SUSETMX_M0_WhiteNoise_{L,P,Y}_0p02to50Hz.xml
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGM0/Data/2026-09-15_1540_H1SUSETMX_M0_WhiteNoise_{T,V,R}_0p03to50Hz.xml
r13152
Results:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGM0/Results/SAGM0/Results/2026-09-15_1540_H1SUSETMX_M0_ALL_TFs.pdf
r13153

R0
Data:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGR0/Data/2026-09-15_1615_H1SUSETMX_R0_WhiteNoise_{L,T,V,R,P,Y}_0p03to50Hz.xml
r13148
Results:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGR0/Results/2026-09-15_1615_H1SUSETMX_R0_ALL_TFs.pdf
r13150

Spectra:
L1
Data:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGL1/Data/2026-09-15_H1SUSETMX_L1_OSEMINF_spectra_invac_vs_inair.xml
r13149

WP13410

Replaced multiple signal path resistors to reduce gain and adjust the filter to match work done at Caltech linked here.