Thanks to the recovery of the IFO by Yokozawa-san (klog35774), we can perform the nightly measurement today.
So, I ran the nightly measurement script on k1ctr15 with no time constraint (I change the time for commissioning to 00:00 UTC - 23:59 UTC on Friday and Saturday).
So, if you plan to work with IFO before finishing the nightly measurement script, please stop the script by accessing k1ctr15 with remote desctop and send Ctrl+c command from the terminal.

I accepted the following SDFs related to the offload.

I offloaded the BF GAS with the FR.

I took the TCam photos for commissioning at 08:44 ~ 08:50 this morning. The previous work is klog.

The automatic fitting process did't launch just after taking images, even though the issue of the full disc was solved. 
After the relaunching the daemon process of `fit_tcam`, the fitting process started to launch and analyze the images automatically.

The same analysis for K1:MIR-AS_PDA1_RF17_Q_OUT

I evaluated the decay time of the ringdown data. After taking an RMS with 32 Hz sampling and assigning an error bar with a constant and a scaling term, I fitted to the following function:

where A, B, τ, and t0 are constants, and θ(*) is the step function. Please see the plots.

K1:MIR-AS_PDA1_RF17_I_OUT

Spectrograms of the swept sine injection data 1~6

I merged the analysis for 

7. Shake injection to TMSX table EXC1
11/30 04:32:00 - 04:37:00 (JST)
EXC : K1:PEM-EXCITATION_EX0_RACK_1_EXC
REF : K1:PEM-PORTABLE_EXC_RACK_EX0_ADC0_DSUB26_OUT_DQ
Info : White injection 1-50 Hz 3000 count

into the TMSX table EXC1 results on Nov. 29

I deleted Tcam data in /dev/sdd1 after confirming that the data is exactly same as the data in /Tcam_BU_002/.

This work made some space in /dev/sdd1, the Use% became 88% from 100%.

Later, we need to check the status of HDD which was used for /Tcam_BU_001.

I performed the end-to-end test yesterday.
Basically, the script worked well but I found several bugs though they don't affect the finesse measurment.
I will fix the bug and test it at some point.

[Fujimoto, Sugimoto, Michimura, Kawaguchi]

We converted the Xend and Yend data into physical Polarization Rotation (rad) using the calibration factors obtained from the polarization monitor calibration (klog #35743, #35758, #35760).
We evaluated the ASDs of standard DAQ data and High Frequency (HF) 16-bit sampling data and compared them with the shot noise limit.

Methods
 1. Calibration Factors 
We used the factors reported in klog #35743, #35758, #35760  to convert voltage (V) and counts (cnt) into radians (rad). The conversion factors for each channel are as follows:

• Xend:
  • S-pol: 0.516 rad/V (3.19e-4 rad/cnt)
  • P-pol: 0.166 rad/V (1.01e-4 rad/cnt)
• Yend:
  • S-pol: 0.687 rad/V (4.27e-4 rad/cnt)
  • P-pol: 0.0716 rad/V (4.38e-5 rad/cnt)

2. Shot Noise
Similar to the previous report, we calculated the theoretical shot noise level (V/rtHz) from the DC voltage values and converted it to rad/rtHz by multiplying it by the voltage calibration factors (rad/V) listed above.

Result 
The resulting spectra are attached.

Discussion 
For both Xend and Yend, the measured noise floor in the high-frequency band (>10 kHz) agrees well with the calculated shot noise levels (indicated by the dashed lines in the figures). This confirms that the sensitivity of the polarization monitors is limited by shot noise.

## Abstract

There seems to be three resonant modes at 23.756 kHz, 23.878 kHz, and 23.909 kHz in ITMY. However, the larger seismic motion may make the ringdown measurement difficult. 

## What I did

At first, since it was difficult to keep the alignment by manual tuning due to large seismic motion, I fed back WFS signals in the DC region (< 0.1 Hz) to each setpoint of each suspension local control with OPLEV. Thanks to this, IFO alignments was kept for more than 2 hours without any manual tuning even though the seismic motion became larger. 

Moreover, I aligned OSTM in order to send the light to OMC REFL QPDs. This time, I set the threshold value of the OMC protection by misaligning OSTM to 150 cnts in terms of OMMT2 TRANS PD (K1:OMC-OMMT2_TRANS_PDA1_DC_OUTPUT) so that OMC trans DCPD was protected if IFO got down.

In this state, I performed the scan for ITMY with narrower bandwith from 23.74 kHz to 23.84 kHz (100 Hz/1000 points). However, we found only one peak (23.756 kHz), which we already found yesterday, in this region (fig.1).

According to the previous scan performed in 2023 (JGWdoc), they found two peak at 23.87 kHz to 23.90 kHz. So I performed the scan with the same bandwidth from 23.84 kHz to 23.94 kHz. I succeeded in finding two more peaks at  23.878 kHz and at 23.909 kHz (fig.2). However, these peaks could be seen only in OMC REFL QPDs. Unfortunately, we added the DQ channels not for QPDs but for RFPDs... 

Second, I tried to perform the ring down measurement for the 23.756 kHz mode with the QPD signal. However, the QPD signal flucuated largely because the power toward AS fluctuated largely due to large alignment flucuation of main IFO by larger seismic motion. Fig. 3 shows the timeseries of QPD signal during the ringdown measurement. As you can see, it seems to be difficult to see the ringdown behaviour. We need to wait for seismic motion becoming smaller or need other approach to evaluate Q values (by estimating from the linewidth of the peak?).

It become difficult to do Lock acquistion itself. And also, I'm afraid of snow and road frozon. So I gave up today's work.

--

## Note

I (hope) restored the setup related ASC ({D,C}HARD_{P,Y}, {I,E}TM{X,Y}_TM_{LOCK, ISC2OPLEV}_INPUT). 

I modified the filter bank related ASC ({D, C}HARD_{P, Y}) to implemented an integreater labeled "test_int" and gather some gain labeld "oo dB" in one FM.

[Kawaguchi, Sugimoto, Michimura, Fujimoto]

Abstract

On 12/2, we performed a calibration of the polarization monitor system at TMS-Y.
The purpose of this calibration was to obtain the calibration factors for converting the p-pol PD and s-pol PD spectra (V/rtHz measured by DL950, cnt/rtHz measured by CDS) into the polarization rotation spectra (rad/rtHz).
The measurement and analysis procedures are the same as those used for the calibration of TMS-X polarization monitor system (klog #35743, klog #35758).

Preparation: Dark offsets of PDs

We measured the output offsets of each PD in the polarization monitor system at TMS-Y using both the DL950 and CDS.
For CDS, we used the channels K1:TMS-Y_IR_PDA1_OUT_DQ, K1:TMS-Y_IRSPOL_PDA1_OUT_DQ, and K1:TMS-Y_IRPPOL_PDA1_OUT_DQ.
Note that CDS internally adds offsets before the dewhitening filter (after the ADC).

                          DL950            CDS
Y_IR               6(1)e-3 V          0(1) cnt
Y_IRSPOL    18(1)e-3 V    -6.20(3) cnt
Y_IRPPOL    23(1)e-3 V     1.43(2) cnt

HWP dependence of PDs

We rotated the HWP in the polarization monitor system and measured the output voltages of the p-pol PD, s-pol PD and Y_IR PD with the DL950 and CDS.
During the measurement, the average output of the Y_IR PD was 3.77(2) V and 1.473(2)e4 cnt.
Figure 1 and Figure 2 show the measurement results obtained with DL950 and CDS respectively, where the vertical axis is the measured PD output after subtracting the PD offsets, and the horizontal axis is the HWP scale value.

Calibration: p-pol PD to polarization rotation (V/rtHz → rad/rtHz)

Model: $V_\mathrm{p} = A(1-\cos (4(\theta_\mathrm{HWP}-B)))+C$

Fitting parameters: A[V], B[deg], C[V]

Result:
A = 11.71(5) V
B = 71.35(4) deg
C = 1.808(7) V

Calibration factor:
$\frac{d\phi}{dV_{p}} = \frac{1}{2A\sin(4(\theta_\mathrm{HWP}-B))}\times\frac{3.77(2)\,\mathrm{V} - 6(1)\times10^{-3} \mathrm{V}}{V_\mathrm{IR}- 6(1)\times10^{-3} \mathrm{V}}$
$=0.072(3) \,\mathrm{rad/V}\quad (\mathrm{at}\, \theta_\mathrm{HWP} = 80.5(5)\,\mathrm{deg}, V_\mathrm{IR}=3.77(2)\,\mathrm{V})$

Calibration: p-pol PD to polarization rotation (cnt/rtHz → rad/rtHz)

Model: $C_\mathrm{p} = A(1-\cos (4(\theta_\mathrm{HWP}-B)))+C$

Fitting parameters: A[cnt], B[deg], C[cnt]

Result:
A = 1.910(7)e4 cnt
B = 71.32(3) deg
C = 2940(7) cnt

Calibration factor:
$\frac{d\phi}{dC_{p}} = \frac{1}{2A\sin(4(\theta_\mathrm{HWP}-B))}\times\frac{1.473(2)\times10^4 \mathrm{cnt} - 0(1)\,\mathrm{cnt}}{C_\mathrm{IR}- 0(1)\,\mathrm{cnt}}$
$=4.4(2) \times 10^{-5}\,\mathrm{rad/cnt}\quad (\mathrm{at}\, \theta_\mathrm{HWP} = 80.5(5)\,\mathrm{deg}, C_\mathrm{IR}=1.473(2)\times10^4 \mathrm{cnt})$

Calibration: s-pol PD to polarization rotation (V/rtHz →rad/rtHz)

Model: $V_\mathrm{s} = A(1+\cos (4(\theta_\mathrm{HWP}-B)))+C$

Fitting parameters: A[V], B[deg], C[V]

Result:
A = 1.224(3) V
B = 71.39(8) deg
C = 0.182(2) V

Calibration factor:
$\frac{d\phi}{dV_{s}} = -\frac{1}{2A\sin(4(\theta_\mathrm{HWP}-B))}\times\frac{3.77(2)\,\mathrm{V} - 6(1)\times10^{-3} \mathrm{V}}{V_\mathrm{IR}- 6(1)\times10^{-3} \mathrm{V}}$
$=-0.69(3) \,\mathrm{rad/V}\quad (\mathrm{at}\, \theta_\mathrm{HWP} = 80.5(5)\,\mathrm{deg}, V_\mathrm{IR}=3.77(2)\,\mathrm{V})$

Calibration: s-pol PD to polarization rotation (cnt/rtHz → rad/rtHz)

Model: $C_\mathrm{s} = A(1+\cos (4(\theta_\mathrm{HWP}-B)))+C$

Fitting parameters: A[cnt], B[deg], C[cnt]

Result:
A = 1.988(3)e3 cnt
B = 71.48(6) deg
C = 297(2) cnt

Calibration factor:
$\frac{d\phi}{dC_{s}} = -\frac{1}{2A\sin(4(\theta_\mathrm{HWP}-B))}\times\frac{1.473(2)\times10^4 \mathrm{cnt} - 0(1)\,\mathrm{cnt}}{C_\mathrm{IR}- 0(1)\,\mathrm{cnt}}$
$=-4.3(2) \times 10^{-4}\,\mathrm{rad/cnt}\quad (\mathrm{at}\, \theta_\mathrm{HWP} = 80.5(5)\,\mathrm{deg}, C_\mathrm{IR}=1.473(2)\times10^4 \mathrm{cnt})$

Polarization ellipticity

For reference, the ellipticity (semi-minor/semi-major axis) of the polarization incident to the polarization monitor system at TMS-Y can be estimated as

Ellipticity = sqrt(V_p_min/V_p_max)=sqrt(C/(2*A+C))=0.2677(7)

using A = 11.71(5) V and C = 1.808(7) V.
The above value gives an upper limit on the ellipticity of the cavity transmitted light.

Next

We will use the obtained calibration factor above to convert the PD spectra into the polarization spectra.
After that, we are planning to search for the axion dark matter signal in the polarization spectra.

As an additional data analysis for the TMS-X polarization monitor calibration, we have also determined the calibration factor that converts the s-pol PD spectrum (V/rtHz measured by DL950) into the polarization rotation spectrum (rad/rtHz).
The analysis procedure follows the same steps as in (klog #35743), but since the HWP dependence of the s-pol PD signal is opposite in phase to that of the p-pol PD signal, the sign of the model function has been modified accordingly.
Also, because the output of the X_IR PD was not plotted in Figures 1 and 2 of (klog #35743), we have added those plots and attached the modified figures in this post.

Calibration: s-pol PD to Polarization rotation (V/rtHz → rad/rtHz)

Model: $V_\mathrm{s} = A(1+\cos (4(\theta_\mathrm{HWP}-B)))+C$

Fitting parameters: A[V], B[deg], C[V]

Result:
A = 1.311(9) V
B = 8.1(2) deg
C = 0.22(1) V

Calibration factor:
$\frac{d\phi}{dV_{s}} = -\frac{1}{2A\sin(4(\theta_\mathrm{HWP}-B))}\times\frac{3.79(3)\,\mathrm{V} + 5(1)\times10^{-3} \mathrm{V}}{V_\mathrm{IR}+ 5(1)\times10^{-3} \mathrm{V}}$
$=-0.52(2) \,\mathrm{rad/V}\quad (\mathrm{at}\, \theta_\mathrm{HWP} = 20.0(5)\,\mathrm{deg}, V_\mathrm{IR}=3.79(3)\,\mathrm{V})$

Calibration: s-pol PD to Polarization rotation (cnt/rtHz → rad/rtHz)

Model: $C_\mathrm{s} = A(1+\cos (4(\theta_\mathrm{HWP}-B)))+C$

Fitting parameters: A[cnt], B[deg], C[cnt]

Result:
A = 2.16(7)e3 cnt
B = 8.4(5) deg
C = 3(2)e2 cnt

Calibration factor:
$\frac{d\phi}{dC_{s}} = -\frac{1}{2A\sin(4(\theta_\mathrm{HWP}-B))}\times\frac{3.17(2)\times10^3 \mathrm{cnt} + 0.3(2)\,\mathrm{cnt}}{C_\mathrm{IR}+ 0.3(2)\,\mathrm{cnt}}$
$=-3.2(2) \times 10^{-4}\,\mathrm{rad/cnt}\quad (\mathrm{at}\, \theta_\mathrm{HWP} = 20.0(5)\,\mathrm{deg}, C_\mathrm{IR}=3.17(2)\times10^3 \mathrm{cnt})$​​​​​​​

Spectrograms for

8. Shake injection to TMSX table EXC3
11/30 04:39:00 - 04:49:00 (JST)
EXC : K1:PEM-EXCITATION_EX0_RACK_3_EXC
REF : K1:PEM-PORTABLE_EXC_RACK_EX0_ADC0_DSUB27_OUT_DQ
Info : Sweep sine injection 1-600 Hz 100 count with 600s

9. Shake injection to TMSX table EXC4
11/30 04:50:00 - 04500:00 (JST)
EXC : K1:PEM-EXCITATION_EX0_RACK_4_EXC
REF : K1:PEM-PORTABLE_EXC_RACK_EX0_ADC0_DSUB28_OUT_DQ
Info : Sweep sine injection 1-600 Hz 100 count with 600s

Analysis for the "1. ~ 7. Shake injection to TMSX table EXC2" on Nov. 30

In the strain channel, some excess appeared in the ASDs. However, they are recognized to be accidentally overlapped glitches, judged by the spectrogram plot. 

In the QPDs signal, some overestimations were found at 250-450Hz

[Fujimoto, Sugimoto, Michimura, Kawaguchi]

We plotted the ASD of the Xend and Yend TMS transmitted light using both High Frequency (HF) sampling data (200 kHz - 1 MHz) from DL950 and standard DAQ data. We compared HF measurements in 12-bit resolution (taken on November 23, 2025; klog #35639) with 16-bit resolution measurements. The analysis indicates that the 16-bit resolution provides a slightly better noise floor, confirming the shot noise limitation.

Analysis Methods
Channels: IR_PDA1 (Total), IRSPOL (S-pol), and IRPPOL (P-pol).
Voltage Conversion (for DAQ data): Counts were converted to voltage using the factor 40/2^16 [V/count] divided by the Filter Gain (accounting for the gain of filters inserted in the signal path).
Shot Noise Calculation: Calculated using V_{shot} = \sqrt{2 e V_{avg} R}, where V_{avg} is the mean voltage calibrated from the DAQ data measured in GPS time 1448688900 and R is the resistance derived from the PD Gain settings (0/10/20 dB of PDA100A2).

Parameters and Results
The settings, measured DC voltage averages, and calculated shot noise levels for each channel are as follows. We have also compared the spectra with data taken with the standard DAQ from GPS times.

1. Xend

• IR_PDA1
  • Filter Gain = 0.510091, PD Gain = 0 dB
  • DC Avg: 3.86 V
  • Shot Noise: 4.32e-8 V/rtHz
• IRSPOL
  • Filter Gain = 1, PD Gain = 0 dB
  • DC Avg: 2.43 V
  • Shot Noise: 3.43e-8 V/rtHz
• IRPPOL
  • Filter Gain = 1, PD Gain = 10 dB
  • DC Avg: 2.05 V
  • Shot Noise: 5.61e-8 V/rtHz

2. Yend

• IR_PDA1
  • Filter Gain = 2.39184, PD Gain = 0 dB
  • DC Avg: 3.91 V
  • Shot Noise: 4.35e-8 V/rtHz
• IRSPOL
  • Filter Gain = 1.00, PD Gain = 0 dB
  • DC Avg: 2.53 V
  • Shot Noise: 3.50e-8 V/rtHz
• IRPPOL
  • Filter Gain = 1.00, PD Gain = 20 dB
  • DC Avg: 3.80 V
  • Shot Noise: 1.36e-7 V/rtHz

Discussion
 - 16 bit measurements with DL950 gives the best noise floor, and is mostly shot noise limited above 10^4 Hz.
 - Unknown bump at around 10^5 Hz.
 - Excess noise at around 20 Hz in measurement from yesterday. But the excess noise at higher frequencies in Nov 23 measurements compared with July measurements, reported in klog #35639, is gone now. Temporal variations (from beam spot motions?)?
 - Spectra shapes seems similar between IR_PDA1, IRSPOL_PDA1 and IRPPOL_PDA1. We might be able to subtract common noises.
​​​​​​
Next plans
 - Calibrate into radians using the calibration factor reported in klog #35743
 - Subtract common noises.

[Kawaguchi, Sugimoto, Michimura, Fujimoto]

We have finished some measurements for the calibration of the polarization monitor system at TMS-Y.
This procedure was the same as the one we recently carried out at TMS-X (klog #35743).

We will analyze the obtained data in the same way, and share the results on the klog tomorrow.
Also, we are planning to analyze the short-term polarization rotation data and search for the axion dark matter signal.