Filters updated to best possible for this new satamp: 86071

Jennie, Elenna,

The other day Elenna noticed some coherence between DARM and the light reflected from the OMC (OMC-REFL_A_LF_OUT_DQ) and wondered if this implies our mode-matching or OMC alignment is bad.

So I took some times from above when one of the offsets was non-nominal and we compared the coherence between these times, since it shows some small change maybe there is still some tuning we could do of these offsets to recover some optical gain.

The measurement is saved in /ligo/home/jennifer.wright/git/2025/OMC_Alignment/Jennie_OMC_offsets.xml

Each was around 3 minutes long apart from the starting measurement which we took from a quiet time before the measurements.

The measurement times are:

nominal settings: 16:29:21 UTC

PITCH A: 17:54:11:UTC

PITCH B: 18:39:57 UTC

YAW A :18:58:10 UTC

YAW B :19:23:20 UTC

Here's a visual look at all locklosses versus ETMX glitch locklosses throughout the run

I (with help and input from Sheila and Joe B) pushed a new calibration today before this report was run.

First, we tried pushing the 20250628T190643Z report, but again that "failed" because the broadband showed a higher uncertainty than expected, again. The kappa C value also dropped from 0.993 before the push to 0.985 after the push and TDCF burn in. We puzzled over this for a bit, until I brought up that maybe this report is too out of date to be useful. We also had to make minor ring heater changes to avoid PIs just after this report had been generated. Sheila trended the optical gain and saw that it did decrease by about 1% after we changed the ring heater.

So, I took a look at the report from 20250719T225835Z, and it looked very promising. The sensing function fit residual showed it was much more flat than the 6/28 report. I pushed this report next, and after burn in kappa C returned to be about 0.993. The broadband also showed this was a better calibration. We think this is improved, and we will stick with this calibration!

Open questions: why is the error still at 2% at 20 Hz? Can we improve the optical gain further?

The lockloss that Ryan S. reports as being from a sitewide power glitch in this alog had a similar behavior in the suspension channels and yaw loops. Apparently the power glitch that caused the lockloss also tripped the HEPI pumps, but I'm not sure how that relates to the control loop behavior. I'm not sure if this is useful to link with these other locklosses or not.

Generally, every yaw ASC loops sees this behavior, but it's hard to tell what is moving first, or the most, since the channels are not calibrated into useful units. As a note, the soft loops are not DC coupled, so I imagine they are just following the other loops. Our lockloss scopes plot the very slow ASC channels, so here is a faster plot of some of the ASC channels before one of these locklosses. The centering loop signals are moving away from zero, but not large enough that the beam is at the edge of the WFS.

I broke out my old TMS servo scope to see if we are being pulled off the TMS QPDs. Clearly the X TR B yaw signal is increasing, but it may be because it's trying to follow a large movement in the hard loops. TMS X yaw moves about 1 urad before the lockloss as well.

In the first yaw excursion lockloss Camilla notes above, the ETMX HEPI RZ appears to oscillate in the two seconds before lockloss. I don't see that in the other yaw excursion lockloss though.

Both of these YAW ASC locklosses saw TMSX_Y start oscillating a few seconds before the lockloss.

• 07/23 03:50UTC: YAW ASC excursion
• 07/23 10:49UTC: YAW ASC excursion

Follow up to add that although the lockloss that Ryan S noted on 7/13 had an ASC excursion, the TMSX yaw suspension did not have the similar strange behavior that these other few locklosses have (ndscope). It's possible that this TMSX yaw behavior is linked to the sat amp change on 7/15, 85770.

Looking into past alogs, I noticed that I reported this same issue last summer in alog 79948. Additional discussion about this line can be found in the detchar-requests repository (requires authentication). In this case, the line appeared in late spring and disappeared in early autumn of 2024. No source was identified before the line disappeared. 

Going back further, I also see the same feature appearing in late spring and disappearing in early autumn of 2023. The presence of the line is hence correlated with the outside temperature, likely related to some aspect of the air conditioning system that is only needed when it is (roughly) hotter outside than inside. This also means that we can expect this line to remain present in the data until autumn unless mitigation measures are taken.

I looked briefly into the 20 Hz Noise without much success. Comparing the floor accelerometers, the noise is louder in the EBAY than the LVEA (although the signal of the EBAY accelerometer doesn't look good since the vent). The next closest is HAM1 followed by BS. So the noise is around the -X-Y corner of the LVEA, likely in the EBAY, Transition Area or Optics Lab because HAM6 sees less motion than HAM1 and EBAY sees the most.

After removing EQ events which happend during the locklosses, the probability of surviving lock during an EQ in O2 winter was found to be 54%, O3b winter was 64%, O4a winter was 73% and O4b winter was 41%. 

Some corrections have been done in the script after getting Derek's feedback and have attached the updated scatter plot between peak horizontal ground motion and peak vertical ground motion of Earthquake events, also data table including total number of EQs and lock probability in each observing runs' winters. Although, the number of surviving EQ events are still lower in O4 than O3. 

As of 2025/07/25 00:00 UTC, the TMSX satamp box for F1/F2/F3/LF has been swapped from S1100150 to S1100122

See 85980 for more info

Here's the characterization data and fit results for  S1100075 , assigned to ETMX M0's F1F2F3SD OSEMs (Fil refers to this as ETMX MO F1F2F3SD).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100075_ETMX_M0_F1F2F3SD_20250710.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
ETMX     M0       S1100075         CH1                F1           0.0971:5.31     120           zpk([5.31],[0.0971],1,"n")
                                   CH2                F2           0.0973:5.33     120           zpk([5.33],[0.0973],1,"n")
                                   CH3                F3           0.0979:5.36     120           zpk([5.36],[0.0979],1,"n")
                                   CH4                SD           0.0953:5.21     120           zpk([5.21],[0.0953],1,"n")
  
The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

As LHO:85626 discusses, I'm intentionally excluding the fit of transimpedance gain from the foton design string, and so I've stopped using the R_TIA_kOhm as a knob in my by-hand fitting of the zeros and poles. Hence, you'll find that from here on, R_TIA_kOhm will almost always be the default 120 kOhm value I've found that works with the measured data and changing only the zero:pole frequency.

Here's the characterization data and fit results for  S1100163 , assigned to ETMX M0/R0's LFRT/LFRT OSEMs (Fil refers to this as ETMX MO/RO RTLF/RTLF above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100163_ETMX_M0R0_LFRTLFRT_20250710.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
ETMX     M0R0      S1100163        CH1                LF           0.0948:5.18     120           zpk([5.18],[0.0948],1,"n")
                                   CH2                RT           0.0954:5.21     120           zpk([5.21],[0.0954],1,"n")
                                   CH3                LF           0.0969:5.30     120           zpk([5.30],[0.0969],1,"n")
                                   CH4                RT           0.0947:5.17     120           zpk([5.17],[0.0947],1,"n")
  
The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

As LHO:85626 and the above LHO:86028 discusses, R_TIA_kOhm is the default 120 kOhm.

Here's the characterization data and fit results for  S1100132 , assigned to ETMX R0's F1F2F3SD OSEMs (Fil refers to this as ETMX RO F1F2F3SD above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100132_ETMX_R0_F1F2F3SD_20250710.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
ETMX     R0        S1100132        CH1                F1           0.0943:5.17     120.75        zpk([5.17],[0.0943],1,"n")
                                   CH2                F2           0.0960:5.25     121.00        zpk([5.25],[0.0960],1,"n")
                                   CH3                F3           0.0963:5.28     121.25        zpk([5.28],[0.0963],1,"n")
                                   CH4                SD           0.0970:5.33     120.75        zpk([5.33],[0.0970],1,"n")
  
The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

This sat amp actually needed some fit transimpedance gain, so I report it here. But, again, it's not used in the compensation filter.

Here's the characterization data and fit results for  S1100140 , assigned to ETMX L1's ULLLURLR OSEMs (Fil refers to this as ETMX UIM ULLLURLR above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100140_ETMX_L1_ULLLURLR_20250715.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
ETMX     L1       S1100140         CH1                UL           0.0943:5.14     120.5         zpk([5.14],[0.0943],1,"n")
                                   CH2                LL           0.0965:5.26     120.5         zpk([5.26],[0.0965],1,"n")
                                   CH3                UR           0.0943:5.14     120.5         zpk([5.14],[0.0943],1,"n")
                                   CH4                LR           0.0961:5.24     120.5         zpk([5.24],[0.0961],1,"n")
  
The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

Similar to S1100132, I found I needed to slightly adjust the transimpedance to get a good phase fit of the zero frequency while getting magnitude scale to the ~1.000 +/- 0.005 level. Again, this won't be used in the compensation filter.

Here's the characterization data and fit results for  S1100122 , which -- per LHO:85981, LHO:85980 and after 2025-07-25, has been assigned to TMSX M1's F1F2F3LF OSEMs (Fil refers to this as just TMSX F1F2F3LF above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100122_TMSX_M1_F1F2F3LF_20250724.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
TMSX     M1       S1100122         CH1                F1           0.0962:5.26     120           zpk([5.26],[0.0962],1,"n")
                                   CH2                F2           0.0971:5.31     120           zpk([5.31],[0.0971],1,"n")
                                   CH3                F3           0.0957:5.24     120           zpk([5.24],[0.0957],1,"n")
                                   CH4                LF           0.0951:5.20     120           zpk([5.20],[0.0951],1,"n")
  
The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

As LHO:85626 and the above LHO:86028 discusses, R_TIA_kOhm is the default 120 kOhm.

Here's the characterization data and fit results for  S1100058 , assigned to TMSX M1's RTSD OSEMs and CH3CH4 are not connected to any OSEM in-vacuum, hence the "xxxx" place holders (Fil refers to this as just TMSX RTSD above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100058_TMSX_M1_RTSDxxxx_20250708.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
TMSX     M1       S1100058         CH1                RT           0.0939:5.11     121           zpk([5.11],[0.0939],1,"n")
                                   CH2                SD           0.0960:5.25     120           zpk([5.25],[0.0960],1,"n")
                                   CH3                xx           0.0955:5.23     120           zpk([5.23],[0.0955],1,"n")
                                   CH4                xx           0.0961:5.25     120           zpk([5.25],[0.0961],1,"n")
  
The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

As LHO:85626 and the above LHO:86028 discusses, R_TIA_kOhm is (mostly) the default 120 kOhm, save for CH1.

Here's the characterization data and fit results for  S1100071 , assigned to MC2 M1's T1T2T3LF OSEMs (Fil refers to this as just MC2 T1T2T3LF above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100071_MC2_M1_T1T2T3LF_20250710.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
MC2      M1       S1100071         CH1                T1           0.0977:5.34     120           zpk([5.34],[0.0977],1,"n")
                                   CH2                T2           0.0956:5.23     120           zpk([5.23],[0.0956],1,"n")
                                   CH3                T3           0.0948:5.18     120           zpk([5.18],[0.0948],1,"n")
                                   CH4                LF           0.0958:5.22     120           zpk([5.22],[0.0958],1,"n")
  
The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

As LHO:85626 and the above LHO:86028 discusses, R_TIA_kOhm is the default 120 kOhm.

Here's the characterization data and fit results for  S1100147 , assigned to MC2/PR2 M1's RTSD/T1T2 OSEMs (Fil refers to this as just MC2/PR2 RTSD/T1T2 above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100147_MC2PR2_M1_RTSDT1T2_20250710.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
MC2      M1       S1100147         CH1                RT           0.0975:5.33     120           zpk([5.33],[0.0975],1,"n")
MC2      M1                        CH2                SD           0.0947:5.18     120           zpk([5.18],[0.0947],1,"n")
PR2      M1                        CH3                T1           0.0969:5.29     120           zpk([5.29],[0.0969],1,"n")
PR2      M1                        CH4                T2           0.0962:5.25     120           zpk([5.25],[0.0962],1,"n")
  
The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

As LHO:85626 and the above LHO:86028 discusses, R_TIA_kOhm is the default 120 kOhm.

Here's the characterization data and fit results for  S1100121 , assigned to PR2 M1's T3LFRTSD OSEMs (Fil refers to this as just PR2 T3LFRTSD above).
The data was taken per methods described in T080062-v3.
The data was processed and fit using 
    ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
         plotresponse_S1100121_PR2_M1_T3LFRTSD_20250710.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are
Optic    Stage    Serial_Number    Channel_Number     OSEM_Name    Zero_Pole_Hz    R_TIA_kOhm    Foton_Design
PR2      M1       S1100121         CH1                T3           0.0979:5.37     120           zpk([5.37],[0.0979],1,"n")
                                   CH2                LF           0.0967:5.29     120           zpk([5.29],[0.0967],1,"n")
                                   CH3                RT           0.0958:5.24     120           zpk([5.24],[0.0958],1,"n")
                                   CH4                SD           0.0969:5.31     120           zpk([5.31],[0.0969],1,"n")
  
The attached plot and machine readable .txt file version of the above table are also found in
${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/

As LHO:85626 and the above LHO:86028 discusses, R_TIA_kOhm is the default 120 kOhm.

Well, it appears as if the pump still has some life, just a few minutes ago started to pump the annulus system, for now.

(Jordan V., Gerardo M.)

Late entry, activity took place last Tuesday 07/22/2025.

The annulus ion pump signal railed again, so this time we decided to replace the controller.  It does not seem like the controller improved the ion pump behavior, since the current signal is swinging more than before, see attached plot.  We are keeping an eye on this system.