TITLE: 09/24 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
INCOMING OPERATOR: Tony
SHIFT SUMMARY:

IFO is in NLN and OBSERVING as of 22:59 UTC (6 hr lock)

We've been locked for the entirety of shift.

LOG:

None

As the other half of Jeff's Side Quest 4 (87102), I took measurements for calculating the absolute calibration of SRM.

Doing this will make the estimator work for SRM easier later on. Like Jeff, I also took two sets of measurements, one with the offsets on (ALIGNED), and one with the offsets off (HEALTH_CHECK). The official measurements that we will be using for getting the OSEM absolute calibration are the ones where the optic is ALIGNED, since that's where it usually is. The set of measurements taken with the alignmet offsets off is to see how much of a difference we see between the two states.
The drive in ISO_{X,Y,Z} correlate with the same optic motion directions as they did when I was taking these same measurements for SR3: ISO_X -> SUS_DAMP_T, ISO_Y -> SUS_DAMP_L, ISO_Z -> SUS_DAMP_V.

These were the settings for the measurements:
- HAM5 in ISI_DAMPED_HEPI_OFFLINE
- SRM in ALIGNED or SRM in HEALTH_CHECK (with damping on)

SRM in ALIGNED (official measurements)
Found in /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/SRM/Common/Data/
2025-09-23-1830_H1ISIHAM5_ST1_SRM_ALIGNED_WhiteNoise_ISO_X_0p05to40Hz_calibration.xml r12666
2025-09-23-1830_H1ISIHAM5_ST1_SRM_ALIGNED_WhiteNoise_ISO_Y_0p05to40Hz_calibration.xml r12666
2025-09-23-1830_H1ISIHAM5_ST1_SRM_ALIGNED_WhiteNoise_ISO_Z_0p05to40Hz_calibration.xml r12666

In ALIGNED, here are the suspension positions according to the OSEMs (in urads*, see Jeff's explanation):
    M1 OPTICALIGN sliders   M1 OSEM    M2 OSEM    M3 OSEM
P          +2520             +1071       +790       +837
Y          -3809              +40        -479       -397
The alignment slider calibrations for SRM are P = 1.875 [DAC ct/"urad"] and Y = 2.681 [DAC ct/"urad"]

SRM in HEALTH_CHECK with damping on (extra measurements for looking at difference)
Found in /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/SRM/Common/Data/
2025-09-23-1810_H1ISIHAM5_ST1_SRM_NoOffsets_WhiteNoise_ISO_X_0p05to40Hz_calibration.xml r12666
2025-09-23-1810_H1ISIHAM5_ST1_SRM_NoOffsets_WhiteNoise_ISO_Y_0p05to40Hz_calibration.xml r12666
2025-09-23-1810_H1ISIHAM5_ST1_SRM_NoOffsets_WhiteNoise_ISO_Z_0p05to40Hz_calibration.xml r12666

Comparing the two sets of measurements, you can see that between both L's and both V's, the M1 OSEMs for the ALIGNED cases are closer to each other than the Offsets Off case, but they still need a calibration factor.

Back in March, I ran a modulation depth test, with several goals in mind related to providing useful calibration information for modeling. That alog is still unfortunately sitting in my drafts. However, I was able to use the results to make a side-by-side comparison with a modulation depth test Sheila ran last Thursday, after the power outage. We are still trying to understand what the overall effect of the power outage was on the IFO. Namely, we have lost 1% of optical gain, 86964.

Some background: the modulation depth test aims to measure the fraction of carrier, 9 MHz and 45 MHz power at each port. This is done by measuring the powers at the nominal settings, and then individiually stepping the 9 and 45 MHz modulation up or down by a known value. Using a measured calibration of V/dBm and rad/V (see alog 62883), and using the bessel functions, the power fraction of each field can be measured at each diode based on how much the total diode power changes at each step. (note: I still have a to do list item to better calibrate the modulation depth in radians using OMC scan data).

Procedure: I stepped both down and up in modulation depth, resulting in 5 different measurements (nominal, 9 down, 9 up, 45 down, 45 up). In March, I stepped down by 3 dBm and up by 2 dBm, but in September we were able to step both down and up by 3 dBm. I measured for 3 minutes at each step in March, and 1 minute at each step in September.

EDIT: I realized I made an error, and the first results I report below are actually from Feb 2025. The significant difference here is that in my February measurement I only stepped down by 3 dBm for 9 and 45 MHz each, so there is less data to fit. In my March measurement, I stepped up 2 dBm and down 3 dBm, getting 5 total different measurement times. There should be very little difference in the interferometer between February and March 2025, so the differences in the results I believe are due to the fact that more points (5 versus 3) gives you a much better fit to the data. I would compare March and now for a more accurate understanding of the differences.

February results, well before power outage, only fit from 3 data points:

March results, before power outage, fit from 5 data points:

September results, after power outage (and reduction of PSL power, attenuation at IMC REFL), fit from 5 data points:

EDIT: Including the March results (and trusting them more than the February results) changes the conclusion. The input ratios are very similar between all three measurements. This is also true for POP where carrier and 9 ratios are concerned. 45 MHz is the hardest field to measure because the 9 and carrier are so strong at POP. There may be less 45 MHz at POP, or this is just the measurement uncertainty. At REFL, there may be an increase in carrier light now after the power outage, and there may be half as much 9 MHz as in March.

The most dramatic differences are at the AS port. Just comparing the February and March measurements, there may be considerable uncertainty in how much of each field is at AS in general. However, if we choose to believe the March results, this would suggest a significant increase in carrier at AS, and a significant decrease in 9 and 45 MHz. However, comparing February and now, the 9 MHz and carrier are nearly the same, and the 45 seems to have decreased.

S&K Electric onsite. Floor cable tray between SUS racks R4 and R7 installed. Isolated cable tray from supports with teflon. Insulated ground bar installed and tied to rack SUS-R7.

Work in the mechanical room mezzanine (power suppy and cabling for SUS-M2) caused h1sush7 IO chassis to glitch. See alog 87095 for details.

D. Barker, F. Clara, and S&K Electric

Jennie W, Rahul K, Keita K

Executive Summary: The measurements of ISS input beam dither coupling to the PDs need repeated as their may be some settings on the oscilloscope we didn't setup properly.

Measurement Theory:

To get a coupling measurement of the ISS diode array to input beam motion we need:

AC measurement for each of the 8 diodes (ACPD1, ACPD2, etc.).

simultaneous AC measurement for the X and Y channels of the QPD (X, Y).

We have a calibration measured previously that tells us that the QPD calibration [Cal] is 45 V/mm when the input beam is dithered horizontally, and that the direction we dither the beam in is 14.9 degrees from the X axis of the QPD (presumably because the QPD is not quite aligned rotationally in its support).

To work out the movement in the actual horizontal plane on the QPD (R_QPD) we use:

Mag = sqrt(X^2 + Y^2)

theta = atan2(Y, X)

R_QPD = Mag * e^(i*theta)

Average DC voltage for each of the 8 PDs to normalise the coupling measurement (DC1, DC2, etc)

Coupling = (AC PDn / DCn)/ (R_QPD/Cal)

When Mayank and Shiva were here we were doing this measurement using the average and peak to peak values for the voltages of DC and AC signals respectively. This throws away the phase info, so now we are trying to do this using transfer functions between the motion of the input beam on the QPD and the PDs.

On August 18th we re-aligned the input to the ISS in the optics lab to minimise the coupling to each of the PDs by eye on the oscilloscope traces showing the AC coupled time series.

The dither used to measure the coupling is applied on a steering mirror after the mode-matching lens but before the PBS used to fix the polarisation of the beam.

The dither we used initially was 1Vpp, but we made some effort to reduce noise on the signal by tuning the resistance of the laser temperature controller.

The new dither is 40mVpp at 100 Hz, and has an offset of 2.5V to keep the mirror aligned into the ISS array input aperture.

All three oscilloscopes are synced via a square wave from the signal generator used for the dither and can be controlled by USB hookups to the opticslab PC.

The code to trigger them at once is from the ipython notebook saved on C:\Users\opticslab as meas_TF_osc.ipynb:

All this does is trigger the scopes, the channels have to be turned on manually and saved manually. Francisco has worked on a much better bersion of this code but I haven't had time to test it yet.

The data we gathered on the 18th is shown below.

The time series for X and Y is shown here.

The time series for ACPD1-8 is shown here.

One can not really see a coherence, this could mean the array is perfectly aligned, but this is not likely as we have not done very fine adjustments.

This is more obvious if one looks at the ASD of each of the PDs, I have just attached one of these but none of them show a signal above the surrounding noise at 100 Hz where the injection was.

We are seeing this signal on the X and Y ASDs.

The csv files I saved for AC, DC and QPD all had different time steps, but the same span meaning they were all different lengths. We might need to retake this data and mess around with the display and save settings to fix this - Keita investigated earlier today and it is possible to change the save resolution to be larger and also to reduce the number of samples the oscilloscope saves via the trigger menu.

I might also try to increase the dither amplitude if this still doesn't help us do the measurement.

Once we have this measurement working we will need to iterate this measurement a few times while making small adjustments to the alignment into the array and possibly moving one or more of the PDs in their mounts.

The next steps are to repeat this measurement for vertical dither and then to do beam scans across each PD to see how well centred they are with respect to the beam.

TITLE: 09/23 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: Busy maintenance day that we've just recovered from. Maintenance activities ran slightly long, and relocking took longer than expected due to a lockloss during INJECT_SQUEEZING from an unknown source. The AIP is still running at HAM6. H1 has been locked for about 30 minutes.
LOG:

TITLE: 09/23 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Preventive Maintenance
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 11mph Gusts, 4mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.14 μm/s 
QUICK SUMMARY:

IFO is NLN and OBSERVING as of 22:56 UTC

Maintenance went slightly long after IOT2L Beam Profiling, requiring us to pico to get bacvk onto IMC WFs.

Additionally, there were SQZ issues relating to the filter cavity not being able to lock potentially due to reset HAM7 FC1 slider values.

Note: Annulus pump running near HAM6 (alog 87101).

Hoping to stay in Observing!

Fil swapped out the satamps for ETMY (L1), ITMX (L1), ITMY (L1), BS (M2), PRM (M2, M3), SRM (M2, M3) today (87103), so the 10:0.4 filters compensation filter in the OSEMINF bank for these SUS's named stages needed to be updated to their new precise compensation filters. Jeff measured the response for each satamp's channels before they were installed, and I used my script python3 /ligo/svncommon/SusSVN/sus/trunk/Common/PythonTools/satampswap_bestpossible_filterupdate_ECR_E2400330.py -o ITMX_L1 ITMY_L1 BS_M2 PRM_M2_M3 SRM_M2_M3 to mass update these compensation filters. I've attached a txt file of the output of this script, along with the filter diffs for each suspension before I loaded them all in.

PS Jeff had done ETMY L1 by hand earlier, so I didn't need to update it with my script.

Elenna, Camilla, Ryan. WP#12806 . IOT2L layout D1300357

Followup from the beam measurements taken last week 86962, while we still had the nominal ~115W through the PSL EOM. Elenna and I repeated these measurements today, now that the power through the EOM has been reduced to ~90W, see 86966, which appeared to improve the mode matching to the IMC. We see the beam has changed shape (now larger on IOT2L) since the power reduction.  

We took the PSL input power down to ~100mW, locked out the rotation stage and then used the nano scan to take some beam profiles in the IMC REFL path on IOT2L.

For positions B and C, we added a temporary steering mirror between IO_MCR_M7 and IO_MCR_L2. Distance between IO_MCR_BS1 and IO_MCR_M7 = 7"; Distance bewtween IO_MCR_M7 and temporary steering mirror = 1 1/2". 

J. Kissel

We're beginning the process of completing all the side quests for suspensions beyond SR3 and PR3. For a summary of what these side quests are, check out the first half of G2501621. 
Today, after 
 - LHO:87103 Fil upgraded satamps the lower, M2 and M3, stages of H1 SUS PRM (ECR E2400330; Side Quest 1), and
 - LHO:87105 Oli updated the OSEMINF filter banks to precisely compensate the new sat amp frequency response (Side Quest 3),
I report on measurements taken for Side Quest 4 -- to measure the absolute, overall scale of the individual OSEMs response to suspension point motion (as predicted from the ISI GS13s projected into that basis) in the presence of ISI drive. This will eventually be processed in a way similar to LHO:86222 for PR3 top mass and LHO:84531 for SR3 top mass.

However, for PRM, which is a globally controlled suspension where we drive the M2 and M3 stages (unlike PR3/SR3), the lower stages also need all of these side quests and absolute calibration. So, here I gather the data or the M2 and M3 as well since we can get them "for free," just adding the channels to the response list.

Here's the position of the suspension according to the medium trustworthy "urad" while the suspension is ALIGNED -- 
          M1 Drive request    M1 OSEM      M2 OSEM      M3 OSEM [all "urad"]
    P ::      -1628           -1231          -982         -1520 
    Y ::        -60             -45          +645          -344
where I put "urad" in quotes because that's what these OSEMs are all calibrated to, nominally, but they've never been validated with anything -- until the future results from the data in this aLOG. That includes -- to the best of my aLOG searching, even the alignment sliders (which are sometimes calibrated with using the IFO beam and a distant geometrically known shape as an optical lever; see e.g. for BS and PR2 LHO:25650 or PR3 LHO:70197). Indeed, the alignment slider calibrations for PRM are still P = 1.875 [DAC ct/"urad"] and Y = 2.681 [DAC ct/"urad"] that were derived from the modeled electronics chain and actuation strength from LHO:4563.

Anyways -- Here's the data with the alignment offsets ON.
/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/PRM/Common/Data
2025-09-23_1810_H1ISIHAM2_ST1_PRM_WhiteNoise_ISO_X_0p05to40Hz_calibration.xml
2025-09-23_1810_H1ISIHAM2_ST1_PRM_WhiteNoise_ISO_Y_0p05to40Hz_calibration.xml
2025-09-23_1810_H1ISIHAM2_ST1_PRM_WhiteNoise_ISO_Z_0p05to40Hz_calibration.xml
and I attach screenshots of these templates' results.

The top mass, M1 data show similar levels of calibration adjustment needed as PR3/SR3; corrections in the range of 1/0.78 = 1.28 [urad/"mrad"] and 1/0.64 = 1.56 [urad/"urad"] are needed.
Perhaps unsurprisingly, the lower stage OSEMs need similar levels of correction. 
PRM's M3 LL OSEM needs the most correction, needing a factor of 1/0.0915 = 10.9 [urad / "urad"]. Yikes! Note, with the suspension ALIGNED, the ADC counts for the M3 LL are still at 18660 [ct], and MISALIGNED they're 18740 [ct], both out of 2^15 = 32768 [ct], so it's not like it's at the edge of it's range, either with the flag fully or not occulting light. Nor is it like the LED emitted power dropped substantially low... huh.

Welp, it'll be good to get all of these OSEMs calibrated!

WP 12802
ECR E2400330
Modified List T2500232

The following SUS SAT Amps were upgraded per ECR E2400330. Modification improves the whitening stage to reduce ADC noise from 0.05 to 10 Hz.

F. Clara, J. Kissel, O. Patane

This is an alog I started before the power outage, because we were worried that the filter cavity backscatter was the reason for our intermittent squeezer noise.  (We now realize that the noise we are looking for is not from the filter cavity 87071.)

The overall message is that the filter cavity backscatter seems low compared to DARM, but there is a source of scattered light upstream of SFI2.

Filter cavity length

I've constructed a model of the filter cavity length loop using the foton filters for PRM in the CAL-CS model.  As noted in 78728 we need to modify the analog gains for M3 for FC2.  I've used a filter cavity pole of 34 Hz, and adjusted the sensor gain to get the model to match the measured open loop gain (plot).  The measurement used in that plot has poor coherence below 5 Hz, which explains why the model doesn't seem to fit there. This model also matches the cross over measured by injected at M1 LOCK L well (plot). 

The next plot shows the uncalibrated error signal (measured at LSC DOF2 IN1), with the loop correction applied (error_spectrum * (1-G)), and a line which I've added as a crude estimate of sensor noise.  You can see that there seems to be a bump in sensor noise around 100 Hz that isn't included in my rough estimate, I am not sure what that is.  

The next plot shows calibrated length noise. 

• The blue trace is the measured error signal calibrated using the sensing function found by fitting the open loop gain error_spectrum/sensing function
• The purple trace shows how the estimated sensor noise would be expected to contribute to that: sensor_noise_estimate * 1/(sensing function *(1-G)).  This is fairly close to the error signal above 8 Hz, so I've made an assumption that above 8 Hz the error spectrum is dominated by sensor noise, and that below 8 Hz the error spectum reflects the suppressed length noise that is not from this control loop (ie, ground motion, osems).  We could check the osem noise by doing injections.  
• The orange trace shows the loop corrected error signal, an estimate of what the noise would be if there were no loop: error_spectrum * (1-G)/ sensing function
• The green and red traces are the control signals for M1 and M3, calibrated by the plant models used in modeling the open loop gain and cross over measurements.  Plotting these was usefull for debugging the loop model and gaining confidence in the modeled sensing function, because they now roughly agree with the loop corrected error signal. (but they won't be used again here).
• The chartruse trace is an estimate of the sensor noise imposed on the filter cavity by the control loop, sensor noise * G/(sensing function *(1-G)).  This is roughly along the 
• The brown trace is the awnser, an estimate of the filter cavity length noise with this loop running.  This is the quadrature sum of the blue calibrated error signal below 8 Hz (asumming that is residual length noise where the loop is gain limited), and the chartruse estimated sensor noise imposed. 
• The pink shows the estimated RMS length noise of the filter cavity, 0.13 pm, dominated by the imposed sensor noise.  Page 21 of T1800447 states that 2.5 pm of RMS length noise would limit the squeezing at 50 Hz to 3dB, if we had 6 dB of squeezing and 12 dB of anti squeezing.  This level of rms length noise is probably OK.  
• section 8.2 of T1800447  estimates that the VCO noise is 1e-16 m/ rt Hz, small enough that we don't need to include it in this estimate. The sensing noise that I am estimating from looking at the error signal is nearly two orders of magnitude higher than the VCO noise which was used as the sensing noise in the loop modeling done in the design document. 

Backscattered power

Using the measurement of excitations on ZM2 in 86778,we can estimate the amount of backscattered light that is reaching the filter cavity.  The DCPD spectra, calibrated into RIN and with the DARM loop removed are plotted here and here with different FFT lengths.  Next time if we do this measurement with a lower frequency and higher amplitude excitation we will be able to use a longer FFT length for the plot and still se

I've made a model of the noise caused by backscattered light using equation 4 (and 5) from P1200155.  The excitation was a 1Hz 100 count excitation into test L, in the osems this showed a peak to peak amplitude of 0.37 um, and to go from optic motion to path length change we need roughly a factor of 4 since ZM2 is at a low angle of incidence and it is double passed.  To match the shelf frequency in the measurement I had to increase the amplitude used in the model by a factor of 3.4.  Using a QE of 100% gives a PD responsivity of 0.858 A/W, and 46.6mW of power on the OMC PDs.  This model doesn't include any phase modulation from any other elements in the optical path, but the real measurement does, which is why the measurements shows a nice shelf but the model shows a series of peaks when I use a longer FFT. I think would be less apparent if we make the measurement with a lower frequency higher amplitude excitation next time. 

The result of this shows that we have 12 pW of scattered light passing ZM2, since backscatter that reaches the filter cavity should all be reflected back towards the IFO along with the squeezing this means that we have 12 pW of scattered carrier from the OFI reaching the filter cavity.  Comparing this to table 1 of T1800447 this is a lower scattered light power reaching the diodes than expected, for a similar level of carrier light reaching the DC PDs, which suggests that all three Faradays are providing the isolation level expected or slightly better.  When driving ZM5, we get 12 nW of power scattered back to the interfometer, suggesting that there is a scattering source where we would not expect one to be.  This seems most likely to be upstream of SFI2, since we only expect nW of total scattered light downstream of SFI2.  If you are interested in looking at a diagram of possible scatters there is a VIP layout here, the beam which leaves B:M5 goes to a PD mounted on the ISI which is called B:PD1 and is intended to monitor light scattered from the OFI towards the squeezer.  

Coupling and noise projection

The last two plots here show the results of a filter cavity noise injection, similar to what Naoki did in 78579.  This suggests that this noise is large enough to include in our noise budget, but not nearly large enough to explain the excess noise we see in DARM when the filter cavity error signal is seeing extra noise. 

The code and data to produce this are in sheila.dwyer/SQZ/FilterCavity/fc_lsc_model.py

Dripta & I went down to EY with PS4 to do a standard ES measurement following T1500016-v19. Using the new es-measure script to fetch the GPS times and write them to config.py in real time was simple and worked well. Thank you Miriam for your work on this.

PCAL beams status: 
I took pictures of the Beam spot on the RX sphere before we touched anything. The beam spot looks well centered but enlongated in the vertical. 

Generating measurement data:
python generate_measurement_data.py --WS PS4 --date 2025-09-22
Reading in config file from python file in scripts
../../../Common/O4PSparams.yaml
PS4 rho, kappa, u_rel on 2025-09-22 corrected to ES temperature 299.6 K :
-4.700378053418811 -0.0002694340454223 2.9106526570958727e-05
Copying the scripts into tD directory...
Connected to nds.ligo-wa.caltech.edu
martel run
reading data at start_time:  1442680123
reading data at start_time:  1442680556
reading data at start_time:  1442680888
reading data at start_time:  1442681222
reading data at start_time:  1442681647
reading data at start_time:  1442682007
reading data at start_time:  1442682196
reading data at start_time:  1442682767
reading data at start_time:  1442683111
Ratios: -0.5345899840068289 -0.5432499955076983
writing nds2 data to files
finishing writing
Background Values:
bg1 =        18.446477; Background of TX when WS is at TX
bg2 =        4.880811; Background of WS when WS is at TX
bg3 =        18.451540; Background of TX when WS is at RX
bg4 =        4.973802; Background of WS when WS is at RX
bg5 =        18.448515; Background of TX
bg6 =        -0.547938; Background of RX

The uncertainty reported below are Relative Standard Deviation in percent 

Intermediate Ratios
RatioWS_TX_it      = -0.534590;
RatioWS_TX_ot      = -0.543250;
RatioWS_TX_ir      = -0.526799;
RatioWS_TX_or      = -0.534601;
RatioWS_TX_it_unc  = 0.056427;
RatioWS_TX_ot_unc  = 0.050625;
RatioWS_TX_ir_unc  = 0.054770;
RatioWS_TX_or_unc  = 0.060578;
Optical Efficiency
OE_Inner_beam                      = 0.985385;
OE_Outer_beam                      = 0.983858;
Weighted_Optical_Efficiency        = 0.984621;

OE_Inner_beam_unc                  = 0.042178;
OE_Outer_beam_unc                  = 0.043242;
Weighted_Optical_Efficiency_unc    = 0.060406;

Martel Voltage fit:
Gradient      = 1637.943418;
Intercept     = 0.261280;

 Power Imbalance = 0.984059;

Endstation Power sensors to WS ratios::
Ratio_WS_TX                        = -0.927782;
Ratio_WS_RX                        = -1.382883;

Ratio_WS_TX_unc                    = 0.043998;
Ratio_WS_RX_unc                    = 0.042386;

=============================================================
============= Values for Force Coefficients =================
=============================================================

Key Pcal Values :
GS           =      -5.135100; Gold Standard Value in (V/W)             
WS           =      -4.700378; Working Standard Value             

costheta     =      0.988362; Angle of incidence
c            =      299792458.000000; Speed of Light
             
End Station Values : 
TXWS         =        -0.927782; Tx to WS Rel responsivity (V/V)
sigma_TXWS   =        0.000408; Uncertainity of Tx to WS Rel responsivity (V/V)
RXWS         =        -1.382883; Rx to WS Rel responsivity (V/V)
sigma_RXWS   =        0.000586; Uncertainity of Rx to WS Rel responsivity (V/V)

e            =        0.984621; Optical Efficiency
sigma_e      =        0.000595; Uncertainity in Optical Efficiency

Martel Voltage fit : 
Martel_gradient         =        1637.943418; Martel to output channel (C/V)
Martel_intercept   =        0.261280; Intercept of fit of     Martel to output (C/V)

Power Loss Apportion : 
beta          =        0.998844; Ratio between input and output (Beta)  
E_T          =        0.991707; TX Optical efficiency 
sigma_E_T          =        0.000300; Uncertainity in TX Optical efficiency 
E_R          =        0.992855; RX Optical Efficiency 
sigma_E_R          =        0.000300; Uncertainity in RX Optical efficiency 

Force Coefficients : 
FC_TxPD          =        9.154426e-13; TxPD Force Coefficient 
FC_RxPD          =        6.237665e-13; RxPD Force Coefficient 
sigma_FC_TxPD          =        4.917409e-16; TxPD Force Coefficient 
sigma_FC_RxPD          =        3.268808e-16; RxPD Force Coefficient 
data written to ../../measurements/LHO_EndY/tD20250923/

Martel_Voltage_test.png
WS_at_TX.png
WS_at_RX.png
WS_at_RX_BOTH_BEAMS.png

Analysis:
Generated the LHO_EndY_PD_ReportV5.pdf with out issue.
Rho_R Prime[page 13] seems to be near 5 hops of the statistical uncertainty.
 

During Tuesday maintenance, we swapped the HAM6 AIP (Starcell). Note this annulus system is connected to HAM5 via the septum plate. We vented the lines with dry nitrogen and left a continuous nitrogen purge(~.3 psi) of the line during the pump swap. Nitrogen attached to HAM5 pump out port while HAM6 pump out port was left open to atmosphere.

No issues during the swap, annulus system is now pumping at both HAM5 & 6 ports with an aux cart and turbo pair. As of end of maintenance, the HAM6 cart was at ~3E-5 Torr, HAM5 cart at ~1E-4 Torr. These pumps will continue running until pressure is <1E-5 Torr at which point the ion pumps will be powered on.

Carts are placed on foam for isolation, and a piece of foam between the flex hose running up to HAM6 pump out port and HAM6 chamber. See attached pictures. 

Work permit will be closed once pumps are disconnected from chambers.

I swpet the LVEA and the only thing I noticed was one unused extension cord that I unplugged. The vacuum pump at HAM5/6 can definitely be heard, but this is known.

TJ, Fil, Jonathan, Erik, Dave:

In preparation for Fil's Mech Room Mezanine rack work, TJ safed the HAM7 systems and I fenced h1sush7 and h1seih7 from the Dolphin fabric.

I also bypassed h1iopseih7's SWWD.

Today I rephased the AS WFS 45 segments.

To avoid lockloss, I transitioned the DHARD input matrix to AS WFS 45 A only so I could phase WFS B. Then, I switched DHARD to WFS B and phased WFS A. I switched by using the DHARD blend filters. Set the DHARD_P_B and DHARD_Y_B input matrix values to the desired value, then make sure the DHARD A and B blend filters have the same ramp time. Then, ramp the gain of one blend to zero and the gain of the other to one. I used a similar process here: 85774.

To get the phasing, I drove a DARM line at 255 Hz in DARM2 EXC, after engaging the EBS255 filter in DARM2 FM10. I was able to get good SNR with an excitation of 3000 counts.

I adjusted each segment to reduce the signal in I (red trace) and maximize in Q.  I was able to reduce the line height by between a factor of 2 to a factor of 5 on each segment. The phase changes were between 3-6 degrees on each segment. The light pink and blue traces show the phasing before I started.

This change was SFDed in both safe and observe, shown in attachments below. For some reason, AS A RF45 is in the ASCIMC model but AS B RF45 is in the ASC model.

I attached a comparison of the before and after for each segment. (Note, seg2 on WFS 45A had a strange behavior where it appears the line in Q reduced with the phase change, but that reduction was present before I started changing the phase.)

We have now been locked for over 16 hours.

IMC REFL DC power is steady at 18.5 mW

IMC WFS A is at 0.95 mW and IMC WFS B is at 0.75 mW

The IMC power in is 62 W and the power at IM4 trans is 56.7 W

MC2 trans is about 9670 [mystery units]

This is reasonable power for IMC refl, but the WFS power is very low. These are the jitter witnesses, and jitter subtraction is not performing as well as it was before the power outage. I can think of several possible reasons for this, but I'm sure that having less than a mW of power isn't helping.

We may want to consider either a) increasing the power on the IMC refl path b) changing the splitter between IMC refl and IMC WFS to be a 50/50 instead of a 90/10, or c) some combination of the first two options that gets us reasonable power on both IMC refl and IMC WFS.