I updated the calibration measurement templates. The update adds zero-amplitude excitations before and after the BPC frequency region.

Previously, frequency points near the BPC were excluded from excitation, but Ushiba-san pointed out that this could still result in unintended excitation near the BPC due to frequency transitions. This update is intended to reduce that possibility. After applying the changes, I performed a DARM OLG measurement and confirmed that the updated template works well.

Since we have several activity inside the mine, I checked the sensitivity (fig1) and OLTF of DARM (fig2), MICH (fig3), and PRCL (fig4).
They seems no significant difference from the reference, so the interferometer after the mine work today seems fine.

Here is a update of the 9 blasting between 5/29 9:30 JST and 6/4 3:10 JST. The pots are available at DAC wiki.

• 1 time: the interferometer survived the blasting at OBSERVATION state (as shown in Figure 1)
  • suvival ratio: 25% = 1/4
  • The amount of the bomb was 10.6, which is a small value. The amplitude of the seismometer was smaller than the typical value at which the lockloss happened.
• 3 times: lockloss occurred from OBSERVATION state (as shown in Figure 2~4)
  • The amplitude of the seismic motion was large enough to make the lockloss.
  • The bomb size were 20.6, 34.0, 20.2.
• 1 time: the interferometer survived the blasting at RF_LOCKED state
  • suvival ratio: 50% = 1/2
• 2 times: lockloss occurred from RF_LOCKED state
• 2 times: interferometer was down or lock acquisition.

I accepted all SDFs when DOWN state was requested to LSC_LOCK guardian from OBSERVATION state.
This will help to know what kind of differences there are for lock acquisition.

Please collect the information on changes of down.snap by wiring log as a comment to this log.

K1:CAL-CS_TDEP_PCAL_LINE{1,2,3}_*, K1:CAL-CS_TDEP_SUS_LINE3_* (Fig.1)

I computed the expected improvement of the inspiral range for the silent run data on 2025/06/03.
Here I assume we could mitigate several bumps or line noise and interpolate linearly the sensitivity. The results and jupyter notebook are available at JGWdoc. The previous works are klog31370, klog32877 and klog33331.

Summary

• I used the data from 2025/06/03 21:00:00 to 21:10:00 UTC. The full calibration was done at 6/3 at 13:25 JST (klog34048).
• By assuming noise improvement across several frequency bands, we can obtain a ~9% improvement in the inspiral range.
  • I selected the frequency bands shown in the attached text file. The first and second columns indicate the frequency bands. The third column indicates the improvement of the range.
  • The largest expected improvements can be seen in 111.5~135 Hz (+4.7%).
  • The plots are available at JGWdoc.

Following updates are acceppted on observation.snap.
 

k1 STEPPER

K1:STEPPER-ITMY_GAS_4_ACTUAL_POSITION

K1:STEPPER-ITMY_GAS_4_TARGET_POSITION

These values are the stepper motor positions changed to offload the BF GAS in IY. I accepted the change before returning to Observing.

I offloaded the BF GAS with the FR.

The temp was recovered. So, the Delonghi heater was on again with the same heater power.

The measured data are stored at "/users/CAL/GitLab/cal-measurements-raw-data-003/pre_o4/common/2025-05-23_HPCD_TF_meas_before_24kricuit_install/"

[Kimura and Yasui]

 At ~ 9:50, we turned on #28 ION pump next to the IXV.  

Before turned on the ION pump, the inside  pressure of IXV was 1.4 x 10^-5 Pa.

After the ION pump was turned on, the pressure and condition of power supply were as follows;

Pressure indiacted on CC-10 between IXV and the ION Pump; 9.2 x 10^-6 Pa

Supply voltage indiacted on the supply; 6.0 kV

Current indiacted on the supply: 925 x 10^-6 A

Pressure indiacted on the supply: 6.2  x 10^-6 Pa 

The IYV temp seemed to increase from Friday by 0.8C. I found the ceiling light is on, which should be off.

I asked Hayakawa-kun to turn it off. Temporarily, I also turned off the Delonghi heater. Please wait a day for the recovery.

Modified IFO guardian
We raised CFC check latch for testing READY state.
IFO guardian might speak repeatedly for a while, so sound notification in READY state of IFO guardian was disabled.
It will be enabled again later.

Missed DARM related filters in actuation path
Because some actuation filters hadn't copied from VIS model to CAL model (see Fig.1) when optical gain and actuator efficiency were updated, I copied them. Copied filters are shown in Fig.2. Fortunately, they are not engaged in the observation state, so there is no impact on calibration even if they are not copied. But remaining non-copied filters may hides important changes, they should be copied even if they are not used in the observation state.

By copying filters, CAL_PROC guardian dropped CFC_LATCH because filter updates were detected and then IFO guardian backed to CALIB_NOT_READY (Fig.3 -> Fig.4). In this time, we knew this was not a impact on calibration and observation, I loaded filter coefficients on k1calcs.

Update of MICH/PRCL calibration
MICH and PRCL calibration parameters were also update as values in klog#34033. Detailed changes in foton filters as shown in Fig.5.
Finally, I raised CFC_LATCH flag and keep IFO guardian in READY state.

> Please switch the state to WORKING_WITH_OBSERVATION*. We don't want to waste times for the unnecessary check.
Sorry for inconvenience. CAL measurements are now intentionally done in OBSERVATION_WITHOUT_LINES instead of WORKING_WITH_OBSERVATION for the reliability of measurements. We may be able to avoid using OBSERVATION_WITHOUT_LINES if there is some DQ flag which ensures no activity except calibration measurement at the same time...

As I reported in klog34027, SR2 yaw motion is currently very large.
To evaluate the effect of SR2 angular fluctuation, I checked the spectrum and coherence of SR2 OpLev and AS_17Q error signals (fig1).

AS RF17 Q signals have a peak at 0.188Hz, which is the same frequency of the peak in SR2 yaw.
In addition, AS RF17 Q signals and SR2 TM yaw signals have a coherence at the peak.
Since AS RF17 Q signals are monitored DARM fluctuation well at low frequency, current SR2 motion seems to coupled to DARM thorugh misalignment to OMC.

This results in the optical gain variation in time, so it should be fixed for stabilizing IFO control and sensitivity.

[Sunil, Yuzurihara]
We performed the lockloss investigation for the recent lockloss from the OBSERVATION state of the LSC_LOCK guardian, between 2025-06-02 02:33:35.062500 UTC and 2025-06-03 00:07:31.062500 UTC. The previous lockloss investigation was posted in klog34025. During this period, there were 14 lockloss. Note that this number included the lockloss from the 'WORKING_WITH_OBSERVATION_WITHOUT_LINES', so some of the lockloss might be related to the commissioning work.

EXCITATION under OBSERVATION_WITHOUT_LINES

Even though the state of the LSC_LOCK guardian was the OBSERVATION_WITHOUT_LINES, the excitation was done during 5 lockloss. Please switch the state to WORKING_WITH_OBSERVATION*. We don't want to waste times for the unnecessary check.

• 2025-06-02 04:38:37.562500 UTC
• 2025-06-02 05:05:22.062500 UTC
• 2025-06-02 05:59:09.187500 UTC
• 2025-06-02 06:47:16.937500 UTC
• 2025-06-02 08:15:36.312500 UTC
   

1~10Hz seismic motion made the IMC lockloss

For 3 lockloss, we saw the excess of the seismic motion with 1~10 Hz, which made the oscillation of the IMC length control and caused the IMC lockloss. The plots are listed in DAC wiki.

• 2025-06-02 02:33:35.062500 UTC
• 2025-06-02 06:47:16.937500 UTC
• 2025-06-02 08:15:36.312500 UTC

One new finding about one lockloss (2025-06-02 02:33:35.062500 UTC) is that the excess of the seismic motion continued over 2 minutes, as shown in Figure 1. This is quite longer than the typical time of the earthquake or the blasting and the shape is different. This might be different source. As a result of excess of the seismic motion, mirrors started to oscillate (Figure 2) and lockloss happened.
This is different from the blasting, because I didn't receive the announcement.

I checked the whitened timeseries of the PEM channels (ACC, MIC, MAG, and SEIS). But, there was no coincident transient.

Following updates are acceppted on observation.snap.
 

k1calcs

K1:CAL-CS_TDEP_{SUS,PCAL}_LINE?_REF_* (Fig.1)

They are reference transfer function at line frequencies for tracking calibration lines. They had been accepted once as tentative values for some test. In this time, they updated again with finalized calibration parameters.
 

K1:CAL-CS_TDEP_PCAL_LINE?_CORRECTION_{REAL,IMAG}, K1:CAL-CS_TDEP_PCAL_LINE?_PCAL_DEMOD_SIG (Fig.2)

These values are the pcal correction factors for line tracking. For simple management of line tracking parameters, I merged gain in filterbank was merged to EPICS records.

The online parameters were updated and the SDFs on Pcal-X and Pcal-Y were accepted.

Line tracking parameters are updated with finalized reconstruction parameters in klog#34048.

Updated channels are K1:CAL-CS_TDEP_{SUS,PCAL}_LINE?_REF_* which are available on MEDM screen for reference model records (see Fig.1).

After then, corrections in pcal beam position in klog#34039 were also taken into account for line tracking parameters. Pcal correction had been done by two component one was in filterbank module for compensating XPcal and Ypcal, and another one was residual functions of Pcal in order to switch used pcal easily. But residual function also depends on Xpcal or Ypcal now. So there was no longer working to make management easy. So I merged a correction factor in the filterbank module to one in reference TF on the EPICS records (see Fig.2)

There is no change that we need to re-calculate reference TF at line frequencies if we switch used pcal (X or Y). On the other hand, pcal correction factor which we need to manage becomes only one (K1:CAL-CS_TDEP_PCAL_LINE?_CORRECTION_{REAL,IMAG}) for each line.

(EY)

• Finally, the TEMPERATURE_EY_50K_FERARM_HEAD seemed to start decreasing. After losing cooling power, it took ~ 7 days to recover its cooling performance, compared to only 2 days in the previous case. So, a more nasty situation in the cold head is expected, such as an increase in the frozen material in it.
• Also, the temperature of REFARM1/2/3/4 started decreasing.
• As reported before, the vacuum level did not change a lot during the enhancement of TEMPERATURE_EY_50K_FERARM_HEAD, but rather reduced because of all the TMPs operations.

I estimated calibration parameters including pcal beam spot effect (klog#34039).
All DARM-related parameters were updated as of 6/3 at 13:25.

1. Parameters in sensing

Optical_gain = 2.1994e12 (-6 from % klog#33643)
Cavity_pole = 18.078 (+0.43 %)

2. Actuator efficiencies
H_etmxtm = 3.8756e-14 at 10Hz (-0.85 from % klog#33944)
H_etmxim  = 1.6451e-14 at 10Hz (-1.95 from % klog#33609)

The difference in the results is considered to arise from the PCAL correction and the frequency range used for fitting. After discussing with Yamamoto-san, we decided to update the values.

I identified the occurance time of the PRCL transient and check the timeseries data by ndscope. If you made the whitened timeseries plot, you can find the transient time easily.

Figure 1 shows the channels related to PRCL and RFPD on the POP table. You can see clearly the transient behavior on POP error / feedback signals and K1:LSC-POP_PDA1_RF45_{I, Q}_IN1_DQ. We can't see the coincident transient in oplev for the PRM and other oplevs.
Figure 2 shows the channels related to the LSC control. we can't see the transient behavior, except for the PRCL and K1:LSC-POP_PDA1_RF45_I_ERR_DQ.
I and Ushiba-san checked the other channels, such as POP90, IMMT1 oplev, ASC for IMMT2, ASC for PR3, and ASC for BS. We can't ses the coincident transient. Some plots are summarized on DAC wiki.