I found the output of Tx temperature sensor is providing strange value "-100" now.
The value before the power outage was about 24 dgree.
We need to check it later.

Because the Pcal-X was turned OFF from 9/14 JST, this is not caused by the laser related phenomenon, but might by electrical noise duo to the power outage?

Oshino-san, DanChen-san, Washimi-san, Ikeda

Related to K-Log#37506 

Below is a summary of the recovery work following the power outage on September 21.

DC Power Supplies

* All central DC power supplies for both the 24 V and 18 V systems had tripped.
* The DC power supplies at both end stations and on the second floor had not tripped and had recovered to a state in which power was being supplied.
* The front-panel power buttons on the V2 I/O chassis were OFF after power was restored. This is the expected behavior following a power outage.

FEPCs

* k1ix1, k1iy0, k1asc0, and k1test0 had restarted but stopped during the boot process because k1boot was unavailable and the required file systems could not be mounted.
* All other FEPCs were powered off.

The following recovery work was performed on the real-time systems:

1. After waiting for the air-conditioning system and k1boot to recover, we switched off the 18 V and 24 V power supplies. On the rack side, we also switched off the circuit breakers, chassis power supplies, and power strips.

2. We placed the control panels in operation mode.

3. For both the 24 V and 18 V systems, we performed the following sequence:

   * Switched on the power supply
   * Measured the voltage at the circuit breaker
   * Switched on the circuit breaker
   * Measured the voltage at the power strip
   * Switched on the power strip
   * Switched on the chassis power supply

4. After powering on all equipment in the central area, we followed the same procedure for the second floor of the central area and the first and second floors of both the X- and Y-end stations. We also powered on the workstations.

Some equipment, including the OMC PZT drivers, POS-related equipment, and several other devices, remains powered off.

The DC power supplies on the second floor of the central area and on the first and second floors of both end stations had remained on. However, all real-time PCs and I/O chassis had their power switches set to OFF, so we switched them on.

5. We restored the real-time computers in the central area.

Recovered:

* Without Dolphin:
  k1mcf0, k1ix1, k1iy1, k1ex1, k1ey1, k1ex0, k1ey0, k1test0, k1iy0

* With Dolphin:
  k1lsc0, k1asc0, k1als0, k1ioo, k1ioo1, k1imc0

Although some systems show drift in IRIGB_TIME, we confirmed that they have otherwise recovered and are operating normally.

Remaining systems:

* Without Dolphin:
  k1px1 — The electronics power supply has not yet been checked.

* With Dolphin:
  k1pr2, k1pr0, k1prm, k1bs, k1sr2, k1sr3, k1srm, k1omc0, k1omc1

The cards on k1pr2 are not being recognized. Due to time constraints, we will investigate the issue in detail tomorrow.
 

As part of the power outage response, we shut down cal-gst1.

Once the power outage response is complete and the systems are back up, we plan to start cal-gst1 again.

Note: cal-gst2 and k1bcst0 were OFF when we checked. We have not turned ON them.

Data from the Hokuriku power line company.

[Power outage]

According to the auto mail system for the electrical system trouble,

The power outage happened at 2026/09/21 18:08:16,  and its recovery was at 2026/09/21 18:09:18.

Almost a 1-minute power outage. This is consistent with the report from an IPMU member via e-mail about the power outage at the IPMU building and the Kamioka Complex Building.

[Electricity Recovery Situation]

Atotsu Koguchi: still no electricity. According to Nakai-denki-san, Only the cubicle at the Atotsu entrance has no automatic recovery function, while other cubicles at EY end and the corner have it. It is quite strange design. Anyway, Uchiyama-kun, Oshino-kun, and Nakai-denki-san will go to the Atotsu entrance around 8:00 for recovery. Also Fukumura-san will be at the DAB.

Actually, no network and no webcam images, no warning system, no PHS, and no dry air are available at the Atotsu entrance after some of them were alive because of a battery.

Other places (Corner XY ends): recovered.

[Auto action after the power outage and to dos]

• All GVs were closed.
• All pumps seemed to stop. All TMPs except for SRM had an interlock system. The TMP/DRY for SRM has no interlock system, but the GV between the TMP and dry pump is expected to close due to its fail-safe system.
• Ion pumps are also expected to stop because of a 1-minute power outage. 
• Cryocoolers and their water-supplying system seem to have stopped. We can verify this with webcam images. Vacuum level in each cryostat (IXC, IYC, EYC) is expected to worsen because of the temperature increase of the duct shields.
• The precision coolers for the PSL room and BS area seem to be automatically recovered, and we verified their operation by web cameras. However, the target temperature seems to be changing from the set values. ~21C is expected for the PSL room, but 23.7C at present. 18C for BS, but 22 at present. 23.7C for the PSL room should be set back at ~ 21:00 again before restarting the IR laser.
• Green lasers seem to be operating due to the batteries. The IR laser seems to have stopped. The water chiller also stopped, according to the image of webcamers. The water chiller system for beam dumpers are also expected to stop. So we need to restart it when the IR laser is recovered.
• The water supply system seemed to have recovered automatically by webcam, and the fact that the precission coolers are working well.
• Dehumidifiers (Corner station and TMP area): All seemed to stop. We need to restart manually.
• Coolers
  • Corner
    • Daikin coolers at MCF, BS, SRM, and the Corner Machine room seemed to stop. They can be restarted by switching to be off, then to the cooling mode again. 
    • Daikin cooler at IYC stopped originally.
    • Hitachi cooler at IYV: I guess it stopped. We need to restart it.
    • Hitachi cooler at IYX: It originally stopped.
  • Ends
    • EXC:  I guess it stopped. We need to restart one, not two.
    • EXV: It originally stopped.
    • EYC: It originally stopped.
    • EYV: It originally stopped.
• Heaters in each area
  • Corner
    • MCF(Delonghi): stopped. We need to turn it on manually.
    • PR2(Sunrise): stopped. I checked its response and turned it off again.
    • IXV, IYV (Delonghi): stopped. We need to turn it on manually.
    • Others (PR3, BS, SR3) stopped originally.
  • Ends
    • EYV (Sunrise): stopped. I recovered it at level 1
    • EYC (2 x Sunrise): stopped. I recovered it at level 2
    • EYC (Delonghi): stopped. We need to turn it on manually.
    • EXV (Delonghi): stopped. We need to turn it on manually.
    • EXC (Sunrise) : stopped originally
• DGS/DMG system
  • Coolers in the control room in DAB: stopped and 40C dgrees before turning on coolers by Ohino-kun and Washimi-kun.
  • Coolers in the computer room in KAGRA: They seemed to stop. Some of the DAQ and DMG systems kept working. So the temperature is now gradually increasing. Ikeda-san tried to stop several systems. DMG system kept working.

I summarized the results of the PRCL/SRCL measurements performed so far.
 

• When data were acquired at 160 MHz, 140 MHz, -140 MHz, and -160 MHz, and the uncertainties of the resonance frequencies were estimated visually:

  klog:37184, klog:37185
  PRX: 68.267(13) m

  klog:37191
  PRY: 64.921(12) m
  SRY: 64.941(13) m
  SRX: 68.284(16) m
   

• When data were acquired at 190 MHz, 160 MHz, 140 MHz, -140 MHz, -160 MHz, and -190 MHz, and the resonance frequencies were determined by fitting:

  klog:37209
  PRY: 64.9280(33) m
  SRY: 64.9422(82) m

  klog:37223
  PRX: 68.2688(46) m
  SRX: 68.2818(45) m

  klog:37248
  PRC: 66.5984(28) m
  SRC: 66.6120(47) m
  Schnupp asymmetry: 3.3405(48) m
   

• When data were acquired at 1.6 GHz, 0.8 GHz, -0.8 GHz, and -1.6 GHz, and the resonance frequencies were determined by fitting:

  klog:37250
  SRY: 64.94397(50) m

  klog:37260
  SRX: 68.2842(13) m
  PRX: 68.26307(11) m
  PRY: 64.92543(46) m
  SRC: 66.61409(70) m
  PRC: 66.59425(24) m
  Schnupp asymmetry: 3.33791(45) m
   

• After adjusting the height of the lens on the POS table, when data were acquired at 1.6 GHz, 0.8 GHz, -0.8 GHz, and -1.6 GHz, and the resonance frequencies were determined by fitting:

  klog:37393
  SRX: 68.2863(18) m
  SRY: 64.95025(42) m
  SRC: 66.61828(92) m
   

• When data were acquired from the reflection signal of OMMT2 at 1.6 GHz, 0.8 GHz, -0.8 GHz, and -1.6 GHz, and the resonance frequencies were determined by fitting:

  klog:37450
  SRX: 68.28747(42) m

  klog:37455
  SRY (HWP 14, polarizer 295): 64.94808(80) m
  SRY (HWP 59, polarizer 250): 64.94959(71) m
  SRC (SRY: HWP 14, polarizer 295): 66.61778(45) m
  SRC (SRY: HWP 59, polarizer 250): 66.61853(41) m

  klog:37458
  PRX: 68.26556(22) m
  PRY: 64.92693(52) m
  PRC: 66.59625(28) m
  Schnupp asymmetry (SRY: HWP 14, polarizer 295): 3.33884(48) m
  Schnupp asymmetry (SRY: HWP 59, polarizer 250): 3.33839(47) m

  klog:37466
  SRY: 64.94972(93) m
  SRC: 66.61860(51) m
  Schnupp asymmetry: 3.33842(49) m
   

• The results for PRX are summarized in Fig. 1, those for PRY in Fig. 2, those for SRX in Fig. 3, those for SRY in Fig. 4, those for PRC in Fig. 5, those for SRC in Fig. 6, and those for the Schnupp asymmetry in Fig. 7.

I offloaded the F1 GAS with the FR.

In the last test (klog), I tried to feed forward the low-pass-filtered ACC signals to the original ACC signals in order to compensate the cradle effects. In this time, I tried to feed forward the LVDT signals to the original ACC signals using the same offline data. Assuming that the tilt of the IP table is proportional to the deviation of the IP, the acceleration α due to the tilt φ is expressed as α = g·φ = C·δx.  Here, g is the gravity acceleration, C is the coupling efficiency, and δx is the deviation to be obtained from the LVDT signal.

The plot shows the ratio of the measured transfer functions from the actuator L to the LVDT L and the ACC L. The blue line shows the original TF ratio (C = 0 m/s^2 /m). The red line shows a smaller gain deviation (C = -0.03 m/s^2 /m).

[Kimura, Yasui, Talada (NIFS) and JECC Torisya members]
　From September 14 through September 17, we replaced the cold head on the transmission-side cryoduct shield of the EXC.
The newly installed cold head is a unit that underwent performance testing at the Kashiwa Campus.
Photos taken during the replacement are attached for reference.
　We plan to conduct performance testing on the removed cold head at the Kashiwa Campus to investigate the cause of its malfunction.
Once the cause is identified, we plan to have the cold head overhauled by the manufacturer.

[Kimura and Yasui]
  At 9:30 on Sep. 14, we re-started air injection to EXC up to atmospheric pressure.
The inner presusure of EXC was reached  9.7 x 10^4 Pa at 10:42.
Then the pressurization work was compleated.
To reach this pressure, we used one high-pressure gas cylinder filled with 7 m³ of air.    
A total of ten high-pressure gas cylinders were used for this operation.

The transfer functions of the TM were measured again. The H2 OSEM position has moved within the sensing range (~7900 cnt). The transfer functions to the H2 OSEM still have low S/N, but have improved.

The transfer functions of the TM were measured after the evacuation. The transfer functions to the H2 OSEM were very noisy. The H2 OSEM position was completely out of the sensing range.

The transfer functions of the TM were measured after the evacuation. They look healthy.

The transfer functions of the TM were measured after the evacuation. They look healthy.

I monitored the OMMT1, OMMT2, and OSTM suspensions during the evacuation of the OMMT-OMC chamber.

The OSEM positions changed by 100~400 counts. The H2 OSEM in the OMMT1 has gone out of the sensing range. The H2 magnet may be deviated in the transverse (off-axis) direction.