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

NOTE:  The change for ITMx HWS is due to its SLED being swapped on Oct 7 (alog 87353).

TITLE: 11/06 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 148Mpc
INCOMING OPERATOR: Corey
SHIFT SUMMARY: We had 3 lock losses from Close_Beam_Diverters today. The first reminded us that the issue is still present, even though we didn't have a problem getting locked last night. For the second, we tried to delay when the OMC whitening came on, thinking it was getting engaged too soon while the beam diverters were closing. The third we spaced out when the beam diverters closed, so they wouldn't close all three at once. It lost lock just after the first one closed. We then relocked and went to observing with the beam diverters open, but this ended up being a rather short, 1hr, lock. On the final attempt of this shift, we tested out moving the beam diverters and ended up moving the ISC_LOCK state that closes them to just after engaging ASC for full IFO. We have been observing since. See alog87970 for more beam diverter investigations.
LOG:

• 2027 Observing with beam diverters open
• 2121 Lock loss
• 2340 Observing with beam diverters closed           

TITLE: 11/06 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 148Mpc
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
    SEI_ENV state: USEISM
    Wind: 18mph Gusts, 15mph 3min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.57 μm/s 
QUICK SUMMARY:

H1 continues to have a rough time with locking....where the pesky HAM1 Beam Diverters have been a focus.  Additionally, in the background, this all happens with very high µseism!  (peaked 17hrs ago and slowly dropped a tiny amount since then.  Looks like we might have just finished riding through a small wind storm.  At the moment, H1 has been locked for almost 1hr.

Observing at 2340UTC with the beam diverters closed this time. We have moved the ISC_LOCK state the closes the beam diverters to right after Engage_ASC_For_Full_IFO. 

On our way up we did some testing of the beam divereters, see alog87978. Both HAM1 beam diverters show a similar response in the GS13s to the one in HAM6, but the one in HAM6 is 10x smaller in magnitude. 

We are back to Observing at 2027UTC but we have the REFL, AS, and POP beam diverters still open. See alog87970 for more info.

[Alicia Calafat, Joan-Rene Merou, Sheila Dwyer, Robert Schofield, Jenne Driggers]



Scope
We analyze violin harmonics and their intermodulation products in H1:OMC-DCPD_SUM_OUT_DQ, and estimate the quadratic mixing coefficient β for those products. Peak detection and confirmation use an Ansel-inspired adaptive-threshold approach on a stabilized series, combined with simple height floors. We then confirm analytically expected intermodulation frequencies and compute beta from amplitude products of paired parent lines and their intermodulation.



Calibration lines at 15.6, 16.4, 17.1, and 17.6 Hz:







The full-band ASD (about 10 to 1610 Hz) shows violin harmonics near 500 Hz (v), about 1000 Hz (2v), and about 1500 Hz (3v), together with the labeled calibration tones. This context motivates the intermodulation search at violin plus/minus calibration, and at violin-violin sums and differences across the band.







Problem and physical context
Small-signal readout model (mA domain, OUT):

y(t) = α s(t) + β s(t)^2

where s(t) is the photocurrent at DCPD SUM (mA), α is the linear gain, and β is the weak quadratic nonlinearity coefficient (mA-1).

Single violin tone at fv and calibration tone at fcal:

s(t) = X sin(2 π fv t) + Z sin(2 π fcal t)

Square s(t):

s(t)^2 = X^2 sin^2(2 π fv t) + Z^2 sin^2(2 π fcal t) + 2 X Z sin(2 π fv t) sin(2 π fcal t)

Use identities:

sin^2(u) = (1 - cos(2u)) / 2    2 sin(a) sin(b) = cos(a - b) - cos(a + b)

Decomposition

  - Self terms:

    X^2 sin^2(2 π fv t) → DC and a line at 2 fv.

    Z^2 sin^2(2 π fcal t) → DC and a line at 2 fcal.

    - We ignore DC (0 Hz).

    - The 2 fv component is used inside the violin–violin families as the i = j "sum" case (often labeled vv_h2). Estimator: βself(v) = A2v / (Av Av).

    - The 2 fcal component is not used for β (no "cal–cal" family here), though it may be visible.

  - Cross term (interaction):

    2 X Z sin(2 π fv t) sin(2 π fcal t) = X Z [ cos(2 π (fv - fcal) t) - cos(2 π (fv + fcal) t) ] → mixing lines at fv ± fcal with amplitudes ∝ β X Z.

Spectral amplitudes from PSD (same convention for all lines)

PSD has units mA2/Hz. Let Δf be the bin width. For a narrow line:

Abin(f) = sqrt(PSD(f) · Δf) = ASD(f) · sqrt(Δf) [mA].

For robustness we integrate ± 1 bin around the peak index:

Abin ≈ sqrt((PSD[i-1] + PSD[i] + PSD[i+1]) · Δf).

Quadratic mixing scaling used for the estimator:

Amix ∝ β · AL · AR.

Per-line β estimators used here:

  - Violin ± calibration:

    β = A(v±cal) / (Av Acal) [mA-1].

  - Violin self-mix (i = j) at 2 fv (vv_h2):

    βself(v) = A2v / (Av Av) [mA-1].

  - General violin–violin (i ≠ j) sums/diffs:

    β = A(f_i±f_j) / (Af_i Af_j) [mA-1].



How the scripts work
  - Intermodulation explorer: input long spectrum (f, PSD); derive ASD; estimate band medians; detect violin peaks with an adaptive threshold on a stabilized series plus simple height floors; propose and confirm intermods at violin ± calibration and violin–violin sums/diffs; export plots and a JSON summary.

  - Beta estimator: read the JSON and the same spectrum; reconstruct A_left, A_right, A_mix via ± 1-bin PSD integration; compute beta_hat = A_mix_bin / (A_left_bin · A_right_bin); summarize by families and produce plots.



Current intermodulation detections
These are the retained detections after applying our thresholds and pairing rules. They are the inputs used downstream to compute and summarize beta by family.

  - Detected violin peaks kept: v = 20, approx 2v = 25, approx 3v = 30.

  - Intermod candidates before pairing: v plus/minus cal total = 154; violin–violin (sums and differences) total = 761.

  - Paired intermods kept for beta: v plus/minus cal = 22; 2v plus/minus cal = 18; 3v plus/minus cal = 18; vv(fund) = 386; vv(2v) = 247; vv(3v) = 128.



Beta results (paired families)

  

    

      
Family
      
Paired count
      
beta median [1/mA]
    
  
  

    
v ± cal
22
0.638
    
2v ± cal
18
0.450
    
3v ± cal
18
0.286
    
vv (fund)
386
10.824
    
vv (2v)
247
1.586
    
vv (3v)
128
13.329
  




Plots

1) Calibration-violin explorer


Calibration tones align as symmetric sidebands around violin harmonics at the predicted offsets (v ± fcal). This validates the pairing rules used for beta estimation and shows that v ± cal families are present at v, 2v, and 3v.

2) Violin-violin explorer


Sums and differences of violin peaks form dense loci at the predicted frequencies. Violin-violin intermods are abundant in all three bands.


Meaning of "violin–violin": all sum/difference pairings between detected harmonics (v, 2v, 3v), both same-harmonic and cross-harmonic, are tested as (fi + fj) and abs(fi - fj) (i.e., v+v and abs(v-v), 2v+2v and abs(2v-2v), 3v+3v and abs(3v-3v), v+2v and abs(v-2v), v+3v and abs(v-3v), 2v+3v and abs(2v-3v)); only those landing in the displayed band are plotted.

3) Violin and intermods (zoom panels with thresholds)


Zooms around about 500, about 1000, and about 1490 Hz show violin peaks, calibration sidebands, and violin-violin intermods. Thresholds used (representative):

  - Band medians (ASD): about 9.29e-08 (v), 8.12e-08 (2v), 8.38e-08 (3v).

  - Violin peak floor (ASD): about 5.3e-06.

  - Intermod minimum height (ASD): about 1.3e-07.

Adaptive selection tracks local noise; loosening/tightening these settings trades recall vs precision. The chosen values recover the strong violins and yield a physically plausible intermod count for stable beta.

4) Beta histograms by family


Violin-violin families peak at larger beta than calibration mixes, as expected for a quadratic mechanism scaling with the product of parent amplitudes. Broader tails appear near thresholds and in crowded regions.

5) Beta by intermodulation family


The hierarchy is clear: vv(fund) and vv(3v) give the largest medians; vv(2v) is smaller but still above all calibration mixes. This is consistent with larger and cleaner A_left x A_right for violin–violin pairs than for violin ± calibration.

6) β(+cal) versus β(-cal)


v and 2v show near-diagonal symmetry; 3v is imbalanced, consistent with leakage or pairing sensitivity at the third harmonic.

7) Amix versus (AL · AR) - quadratic check


Largest deviations sit near thresholds and in crowded sub-bands.

8) β versus Amix with thresholds


Scatter grows as Amix approaches thresholds.



Next steps
  - Repeat the analysis in the ADC domain (counts) for H1:OMC-DCPD_SUM_IN. Use the OMC_DCPD filter magnitude file (cols: freq, DCPD A mag, DCPD B mag) to convert counts<->mA and recompute beta. Comparing OUT (mA) and IN (counts) will test for any domain-dependent bias in beta.

Bypass will expire:
Thu Nov  6 11:13:32 AM PST 2025
For channel(s):
    H0:VAC-MY_Y1_PT243B_PRESS_TORR
 

Wed Nov 05 10:11:19 2025 INFO: Fill completed in 11min 15secs

TJ had another lockloss around the time of the beam diverters closing this morning, it happened during OMC whitening.  Following up on what Jenne and Elenna saw last night 87962  , I looked at HAM1 GS13s during the lockloss. 

In the attached screenshot the first time cursor shows when the CLOSE_BEAM_DIVERTERS guardian state ends and the guardian moves on to switching the OMC whitening state, the HAM1 ISI is still shaking from the beam diverters when the OMC DCPD gains are changed.  I've saved this template as sheila.dwyer/ndscope/LOCKLOSS/beam_diverter_lockloss_check.yml

I've added a 10 second timer to the close beam diverters state, so that these things will be separated in time.  

TITLE: 11/05 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: USEISM
    Wind: 11mph Gusts, 6mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.60 μm/s 
QUICK SUMMARY: Lost lock about an hour ago, trying to lock DRMI now. Had two lock losses and relocked during the last shift. Looks like the MSR WAP is stuck. Stand down query failure, I'll restart that now. The useism is up again, somehow we locked last night though. Today's plan is to Observe!

TITLE: 11/05 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Preventive Maintenance
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY:

Bit of a rough start to the shift with H1 having issues getting to NLN.  Managed to finally get to Observing after a few hours of work (see earlier alogs).  Violins were high (but not off the DARM FOM), and have steadily been dropping over the 2+hrs of this lock.

Had a LOW SQZ_PMC voltage, but squeezer lockloss and automatic relock brought the voltage back to a better state (70+ volts).
LOG:

• BTE cell phone signal testing (robert, sam)
  • Done around 0100utc (and they regaled stories of seeing a herd of elk, lots of fat black widows, and a kitchen knife (all along the x-arm).
• 0039 Elenna saw 1Hz noise while at ADS TO CAMERAS, so she had me engage "ASC HI GN"....and then continue to INJECT SQUEEZING
• 0040 Lockloss at CLOSING BEAM DIVERTERS (see Elenna's alog)
• Spent a few hours returning to NLN, but it required slowly walking through ISC_LOCK's final states.
• 0501-0540 First Contact three optic faces in the Optics Lab with RyanS as my Buddy (corey)
• 0506-0510 SQZ lockloss due to PMC Voltage being low.  It automatically relocked and it has made the jump from close to 0V up to 72V (see attached pic) and now we no longer have the LOW Voltage notification for SQZ_PMC.

At the beginning of the shift H1 had a lockloss during late stages of ISC_LOCK where we slowly stepped through states and found the lockloss occurred at CLOSING BEAM DIVERTERS (see Elenna's alog 87961).  

Took a couple of locking attempts for H1 to return to this same point of ISC_LOCK locking.  (during this time is when Jenne noticed/addressed the Power Scaling issue (see alog 87965).  

While locking chatted with Oli and they mentioned for some of their locklosses, they would go state by state, but ALSO if there was a 1Hz ring-up during these states, they would go to "ASC HiGn" AND then wait there a few minutes until the 1Hz ring up (seen on the PR_GAIN channel on PRMI.sb of nuc30  +  ASC-INP1_P_INMON on nuc29).

So for this 2nd attempt of getting through CLOSE BEAM DIVERTERS this shift, went through the states:

• 0323 LASER NOISE SUPPRESSION --no issues observed
• 0325 ADS TO CAMERAS--this is where the 1Hz ring up occurred.
• 0327 ASC HiGn engaged!
  • note:  have to enter "y" (not "Y")
  • Waited about 4min---basically watched the ring up noise disappear and return to quiet levels
• 0331 ASC Low Noise engaged!
• 0333 INJECT SQUEEZING
• 0332 - 0337 Closed the Beam Diverters by hand per Jenne's suggestion---> Able to close all of them (even HAM1's POP shutter which we feared would cause the lockloss). 
• Then continued through the remaining ISC_LOCK states.

Made it to NLN, but could not go to Observing for (2) (I believe) separate reasons. 

1)  SQZ_OPO_LR:   "CMB EXC is ON" and SDF Diffs (see attachement #1).  For the SDF Diffs, I reverted these with no problems. 

At this point, I tried to go to OBSERVING, but could not.

2) Then noticed for SQZ_PMC, we had the notification:  "PMC PZT volts low".  Thought I would address this, but then I was able to take H1 to OBSERVING, so I kicked the can and went to OBSERVING instead of addressing the low voltage.  See attachement #2 for PMC Voltage over the last week.  Still have the notification for the low pmc voltage.

We have had multiple locklosses right near the end of the locking sequence around CLOSE BEAM DIVERTERS and OMC WHITENING. Today, we held at different states while locking. First, we pasued at MAX POWER while we waited for the R waves of a few different earthquakes to pass. Then, we proceeded successfully through to LASER NOISE SUPPRESSION. There are large glitches in this state, probably because of the CARM loop, so we stayed in the state to wait for the glitches to die down. Then, Corey selected ADS TO CAMERAS. This state proceeded fine, but we saw the 1 Hz starting to ring up. Corey selected the ASC Hi Gain script button on the seismic page to damp the 1 Hz back down. It damped down. We next went to INJECT SQUEEZING, which was fine. We waiting again about a minute after the state finished. Finally, Corey selected CLOSE BEAM DIVERTERS and we lost lock. Here is the guardian log so we can see the timestamps of each step.

We had the same lockloss earlier, it's logged at being from "omc whitening" but usually the beam diverters state is very fast so we are in omc whitening by the time the lockloss happens. Attached is the suspension signals from both locklosses. It looks like something rings up in DARM.

2025-11-05_00:36:48.787114Z ISC_LOCK [LASER_NOISE_SUPPRESSION.run] ezca: H1:IMC-REFL_SERVO_IN2GAIN => -29
2025-11-05_00:36:48.787719Z ISC_LOCK [LASER_NOISE_SUPPRESSION.run] ezca: H1:IMC-REFL_SERVO_FASTGAIN => -16
2025-11-05_00:37:24.445085Z ISC_LOCK REQUEST: ADS_TO_CAMERAS
2025-11-05_00:37:24.445085Z ISC_LOCK calculating path: LASER_NOISE_SUPPRESSION->ADS_TO_CAMERAS
2025-11-05_00:37:24.446434Z ISC_LOCK new target: ADS_TO_CAMERAS
2025-11-05_00:37:24.501243Z ISC_LOCK EDGE: LASER_NOISE_SUPPRESSION->ADS_TO_CAMERAS
2025-11-05_00:37:24.501532Z ISC_LOCK calculating path: ADS_TO_CAMERAS->ADS_TO_CAMERAS
2025-11-05_00:37:24.505287Z ISC_LOCK executing state: ADS_TO_CAMERAS (578)
2025-11-05_00:37:24.506308Z ISC_LOCK [ADS_TO_CAMERAS.enter]
2025-11-05_00:37:24.532550Z ISC_LOCK [ADS_TO_CAMERAS.main] ezca: H1:GRD-CAMERA_SERVO_REQUEST => CAMERA_SERVO_ON
2025-11-05_00:37:24.533290Z ISC_LOCK [ADS_TO_CAMERAS.main] camera servo guardian state
2025-11-05_00:37:24.533992Z ISC_LOCK [ADS_TO_CAMERAS.main] ezca: H1:ASC-AS_A_RF36_Q_YAW_SW1 => 8
2025-11-05_00:37:24.785056Z ISC_LOCK [ADS_TO_CAMERAS.main] ezca: H1:ASC-AS_A_RF36_Q_YAW => ON: OFFSET
2025-11-05_00:38:24.227696Z ISC_LOCK [ADS_TO_CAMERAS.run] ezca: H1:SUS-ETMX_L2_DRIVEALIGN_P2L_SPOT_GAIN => 3.13
2025-11-05_00:38:24.228345Z ISC_LOCK [ADS_TO_CAMERAS.run] ezca: H1:SUS-ETMY_L2_DRIVEALIGN_P2L_SPOT_GAIN => 4.89
2025-11-05_00:38:24.230162Z ISC_LOCK [ADS_TO_CAMERAS.run] ezca: H1:SUS-ETMX_L2_DRIVEALIGN_Y2L_SPOT_GAIN => 4.85
2025-11-05_00:38:24.230577Z ISC_LOCK [ADS_TO_CAMERAS.run] ezca: H1:SUS-ETMY_L2_DRIVEALIGN_Y2L_SPOT_GAIN => 0.78
2025-11-05_00:39:40.380293Z ISC_LOCK REQUEST: INJECT_SQUEEZING
2025-11-05_00:39:40.383415Z ISC_LOCK calculating path: ADS_TO_CAMERAS->INJECT_SQUEEZING
2025-11-05_00:39:40.386240Z ISC_LOCK new target: INJECT_SQUEEZING
2025-11-05_00:39:40.448133Z ISC_LOCK EDGE: ADS_TO_CAMERAS->INJECT_SQUEEZING
2025-11-05_00:39:40.448133Z ISC_LOCK calculating path: INJECT_SQUEEZING->INJECT_SQUEEZING
2025-11-05_00:39:40.453186Z ISC_LOCK executing state: INJECT_SQUEEZING (580)
2025-11-05_00:39:40.453467Z ISC_LOCK [INJECT_SQUEEZING.enter]
2025-11-05_00:39:40.471153Z ISC_LOCK [INJECT_SQUEEZING.main] ezca: H1:GRD-SQZ_MANAGER_REQUEST => FREQ_DEP_SQZ
2025-11-05_00:39:40.472228Z ISC_LOCK [INJECT_SQUEEZING.main] timer['CheckSqz'] = 90
2025-11-05_00:39:40.473316Z ISC_LOCK [INJECT_SQUEEZING.main] ezca: H1:GRD-SUS_PI_REQUEST => PI_DAMPING
2025-11-05_00:39:40.720211Z ISC_LOCK [INJECT_SQUEEZING.run] USERMSG 0: SQZ_MANAGER: has notification
2025-11-05_00:39:45.281174Z ISC_LOCK [INJECT_SQUEEZING.run] USERMSG 0: SQZ_MANAGER: has notification
2025-11-05_00:40:51.377382Z ISC_LOCK REQUEST: CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.378087Z ISC_LOCK calculating path: INJECT_SQUEEZING->CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.378087Z ISC_LOCK new target: CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.459548Z ISC_LOCK EDGE: INJECT_SQUEEZING->CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.459721Z ISC_LOCK calculating path: CLOSE_BEAM_DIVERTERS->CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.464167Z ISC_LOCK executing state: CLOSE_BEAM_DIVERTERS (590)
2025-11-05_00:40:51.465760Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.enter]
2025-11-05_00:40:51.475467Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] Closing REFL beam diverter
2025-11-05_00:40:51.476845Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:SYS-MOTION_C_BDIV_A_CLOSE => 1
2025-11-05_00:40:51.476939Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] Closing AS beam diverter
2025-11-05_00:40:51.478119Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:SYS-MOTION_C_BDIV_D_CLOSE => 1
2025-11-05_00:40:51.478494Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:VID-CAM16_EXP_REQ => 36000
2025-11-05_00:40:51.579758Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:VID-CAM16_EXP_SET => 1
2025-11-05_00:40:51.579758Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] Closing POP beam diverter
2025-11-05_00:40:51.580545Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:SYS-MOTION_C_BDIV_B_CLOSE => 1
2025-11-05_00:40:53.156310Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.run] Unstalling IMC_LOCK
2025-11-05_00:40:53.347649Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.run] Unstalling VIOLIN_DAMPING
2025-11-05_00:40:53.521338Z ISC_LOCK JUMP target: LOCKLOSS
2025-11-05_00:40:53.521845Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.exit]
2025-11-05_00:40:53.582367Z ISC_LOCK JUMP: CLOSE_BEAM_DIVERTERS->LOCKLOSS
2025-11-05_00:40:53.582367Z ISC_LOCK calculating path: LOCKLOSS->CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:53.585523Z ISC_LOCK new target: DOWN
2025-11-05_00:40:53.590140Z ISC_LOCK executing state: LOCKLOSS (2)