I checked interference between SI and OpLev beams during the SI installation.
The beam pathes for all OpLevs are fine after installation of SI.
Then, I centered MN OpLevs of ITMX as well as ETMX.

Note:

Since beam of MN ROL OpLev was clipped by the beam splitter, I moved BS slightly to -X direction to avoid clopping.

[Yokozawa, Ushiba]

We checked IX payload and found that one of EQ stops from MNR was touched to MN (fig1).
So, we moved EQ stop not to hit MN and then suspension can be aligned state.

Then, we adjusted all EQ stops and take photos for the record.
Photos can be seen from the following link:
https://www.dropbox.com/scl/fo/o4pp1ednlbpmlt8ldzcei/h?rlkey=xwwrpcc8takxpj1ca63jsjor1&dl=0

We haven't finished OpLev path check yet, so we need to do it at some point.

Additional information:

Since all magnets were rebonded, magnets position is not so accurate for ITMX (about 1 mm?).
So, we are not so sure if roll position is good when H3 and H4 magnets are on the horizontal plane.

Also, Roll moving mass is very close to its limit, so it is necessary to move ballast mass for further adjustment (moving mass range is not critical because roll moving mass can be used only at room temperature).

Ushiba, Tamaki, Tanaka

### 

We adjusted the roll alignment of ITMX with MN moving mass. The heights of the magnet's centers on +/- Y side is almost same. 

### What we did

• We placed a laser leveler and adjusted the laser height to align with the magnet center on the -Y side (fig. 1). In this position, the height of the magnet's center on the +Y side was higher than the laser level (fig. 2), indicating a positive movement in the ITMX roll.
• During the R6 Noto earthquake, we observed an increase of +2000 cnts in the value of the MN photosensor in the roll direction (MN_DAMP_R_INMON) (Fig. 3). This direction was consistent with our visual inspection. Consequently, we initiated roll alignment adjustments in the negative direction using the MN moving mass.
• While monitoring the height of the magnet's center on the +Y side and the dynamic range of the moving mass, we adjusted the roll alignment. Figure 4 displays the time series of the MN photosensor's values during the adjustment process (the significant jump at -45 min resulted from the release of TM, as noted by Ushiba-san, which touched the EQ stopper). The MN photosensor's value changed by approximately 1000 cnts. Since the gain of the photosensor at room temperature is half that at cryogenic temperature, the adjustment made during this time appears consistent with the change caused by the earthquake. Figure 5 illustrates the magnitude of the MN moving mass steps.
• Figures 6 and 7 depict the heights of the magnet's centers on the +/-Y sides, respectively. These heights have become nearly identical.

Abstract:

The fourth magnet was found on the recoil mass, and a laser level to be used as a reference during magnet bonding was put on the radiation shield.

Details:

The magnet was found on the recoil mass (see Fig. 1 and 2). It was easy to spot the magnet from the closed flange side. Using a ruler, the magnet was extracted from the open flange side (Fig.3).

After magnet extraction, a laser level was placed on the radiation shield for reference (Fig. 4 and 5). I moved some bundled-up temperature sensor cables to the side since they were in the way (Fig. 6). The vertical axis was aligned with the centre of the residual glue (on the TM). Next, the offset between the horizontal axis of the laser level and center of TM was estimated as:

∼D-M=247 mm.

where,

D is the Design value of the distance from the top of the breadboard to center of TM=285 mm

M is the Measured offset of the laser level horizontal axis from the top of the breadboard= 38 mm (Fig. 7)

Note:

Tomorrow, we will install a tripod or optical stages to adjust the height of the laser level. The laser level was left on the radiation shield.

I prepared to bond magnets on the sapphire spacers.

What I did:
1. Cleaning 4 fallen sapphire bases with aceton.
2. Cleaning 5 used sapphire bases with aceton.
3. Cleaning 3 fallen magnets with aceton.
4. Cleaning 2 used magnets with aceton.

All magnets seem good after cleaning.
Sapphire spacers seem to have some adeasive even after cleaning, so I kept sapphire spacers in aceton and stored inside the draft chamber.

Note:

Used sapphire spacers and magnets are the ones once failed to bond magnets onto the spacers at Toyama university.
I put stuffs for magnet bonding on the tables inside the cleanbooth for draft chamber (fig1).

The attached picture shows where we found the 3 magnets.

[Kimura and M. Takahashi]
 We presuurized IXC up to 1.0 x 10^5 Pa by the compressued air which dew point was < -40 ℃ on 14th/Feb..
And we opened four flanges which were IXC φ800 flange, flanges on both sides of the cross tube, and IXA flange on the aisle side of the IXA.
Please see attached photos.
Air supplied from an air compressor for work inside the IXC.

[Akutsu, Chen, Hirata, Ushiba]

Abstract:

All four magnet bases (sapphire spacers) are fallen off from the mirror and all four magnets are fallen off from the spacers.
We found four spacers and three magnets.
One magnet should be somewhere inside the cryostat, so we will look for it next time.

Detail:

We found that all four magnets are fallen off from the mirror (fig1-4) though we thought one magnet was survived when performing health check (klog28395).
We are not so sure when magnet drop happened but this fact implies that even magnets were survived during health check, the magnets might be damaged and easy to fall off.
So, it would be necessary to check ITMY even though ITMY seemed healthy at this moment (we need to discuss if it is necessary or not).

After confirming all magnets were fallen, we look for sapphire spacers and found two of them on the optical table (fig5-6) and two of them on the recoil mass (fig7).
Also, we found three of four magnets (fig8).
All sapphire mirror do not have magnets (fig9), so one magnet should be still inside the cryostat.

Since magnets are fallen off from the spacer, we need two days for magnet recovery: one day for bonding magnet on the spacer and the other for conding spacer with magnet on the mirror.

 "16:12 5.2 x 10^4 Pa. Stopped injection. "
This statement is incorrect.
The correct statement is  "16:12 5.5 x 10^4 Pa. Stopped injection. ". 

[Kimura and M. Takahashi]
 We presuurized IXC up to 5.2 x 10^4 Pa by the compressued air which dew point was < -40 ℃ on 13th/Feb..
Detailes are as followes;
1. Start injection the compressued air into IXC
 10:15 Start injection
 10:31 1.2 x 10^3 Pa
 10:55 2.8 x 10^3 Pa
 11:00 Flow rate adjustment is performed. Slight opening of supply valve
 11:03 3.5 x 10^3 Pa
 11:14 5.0 x 10^3 Pa
 11:30 7.2 x 10^3 Pa. 
           Flow rate adjustment is performed.  
 11:46 8.4 x 10^3 Pa
 13:04 2.1 x 10^4 Pa
 14:03 3.1 x 10^4 Pa 
 14:20 Flow rate adjustment is performed.  
 14:56 4.1 x 10^4 Pa
 15:28 4.6 x 10^4 Pa
 15:47 5.2 x 10^4 Pa
 16:12 5.2 x 10^4 Pa. Stopped injection. 
2. We will re-start injection on on 14th/Feb. morning.
3. The following related work was performed;
   (1) Removal of the claw clamps securing the flange to be opened, leaving a few pieces in place
   (2) Removed claw clamps from four flanges: IXC φ800 flange, flanges on both sides of the cross tube, and IXA flange on the aisle side of the IXA
   (3) Installation of chain blocks to suspend the φ800 flange of IXC
 4. The blower for the work inside the IXC was inspected and found to be out of order.
Therefore, it was decided to use air supplied from an air compressor for work inside the IXC.

I turned off ITMX IM heater.

The warming-up status.

[Kimura and M. Takahashi]

 We presuurized IXC up to 1 x 10^3 Pa by N2 gas on 6th/Feb..

Detailes are as followes;

1. Turned off Q-mass connected to IXC.

  The graphs of Q-mass during refrigerator and heater heating are shown for reference.
     Fig. 1 Before and after IXC radiation shield cooling was stopped
     Fig. 2 Before and after heater heating of duct shield cryo-coolers
     Fig. 3 Before and after duct shield ooling was stopped

2. Closed GVs infront of TMPs connected to IXC, and turned off the TMPs.

3. Turned off warm up heaters installed to innerradiation shield in IXC and duct shield coolers.

4. Start injection N2 gas into IXC

 14:10 1.4 x 10^-1 Pa

 14:21 5.9 x 10^1 Pa

 14:23 1.2 x 10^2 Pa

 14:32 2.0 x 10^2 Pa

 14:40 4.0 x 10^2 Pa

 14:53 7.0 x 10^2 Pa

 14:57 8.6 x 10^2 Pa

 15:01 9.8 x 10^2 Pa

 Stopped injection

5. Turned on the innerradiation shield heaters in IXC, again.

The warming-up status.

[Kimura]

 I connected DC power supplies to the heaters in the duct shiels cryo-coolers, and apply 30 W to the each heter  at 15:58 on 5th/Feb..

I applied 0.2A to the IM heater on ITMX (fig1).

Note:
Somehow, I could not access to the power supply remotely and Ikeda-san checked the status of power supply at IXV.
The power supply seems working but I asked Ikeda-san to turn off it once and restart it.
Then, we could access to the power supply remotely.

[Chiba, Washimi]

We turned off the FFUs in IXC booth for about 2 minutes (13:22~13:24 JST) and checked their contribution on MN oplevs.
The FFUs are recovered soon after this measurement to avoid temperature change.

Blue : Normal mode (4 FFUs are working)
Red : All FFUs are off

No significant differences are found.

Abstract:
I checked the actuator range of CRY moving mass.
Actuator range of both HR and AR side moving mass has a range of over +/-1mrad.

Detail:
To confirm the actuator range of CRY moving mass is enogh large, I moved moving mass.
For avoiding to tilt suspension so much, I compensate the inclination by using MN coil-magnet actuators.
Figure 1 shows the time series data of OpLev PIT signal and PIT OPTICALIGN values.
As you can see, moving masses can change the inclination of the mirror from -7000 cnts to +7000 cnts of PIT OPTICALIGN values.
The actuator efficiency of MNP actuator is about 0.15 urad/cnts, so the above values are corresponding to +/- 1mrad.
These values are enough large to compensate the inclination change during the cooling, which is about 150 urad.

Note:
The signs of stepper motors for moving mirror to positive pitch direction are follows:
HR side: REVERSE
AR side: REVERSE

AR and HR side test was done before and after -30 min in fig1, respectively .

[Tamaki, Ushiba]

Related work of klog19044.

After the closure work of radiation shields at IXC including to set the super insulations, we visually inspected the oplev beam paths.
Since we found one of the beam path is close to the SIs (gap is about 1cm or so), I asked Kimura-san to repair it.
Photos during the visual inspection can be seen from the following links:
https://www.dropbox.com/sh/4lqh0pwmseov43q/AADi3etxRNi75YfOB6Op3wx4a?dl=0

So, we are now ready to start the final health check of the suspension.

[Tomaru, Tamaki, Ushiba]

Continued work from klog19018 and similar work with klog19005.

Abstract:
Retightening the screw for HLs and cleaning inside the cryostat were done.
Moving mass was centered and a part of ballast mass is moved for pitch inclination adjustment.
During the work, we found one of moving mass doesn't work well. It needs to be fixed.

Detail:
In this afternoon, we retighten the HL screws and cleaned the inside of the cryostat.
After that, we centered the moving mass and roughly adjusted the inclination by moving ballast masses on MN.
After the rough adjustment, we finely adjusted by using moving masses.
The adjustment itself can be done but we found one of the moving mass (HR side moving mass, ch1) doesn't seem working well.
It is necessary to investigate the reason and fix it.

Note:
For redundancy, we have two moving masses, which can drive the pitch inclination of the mirror and each moving mass has enough range to compensate the drift of the suspension even during cooling.
So, the suspension can be aligned even if HR side moving mass cannot be recovered easily.
But anyway, we will investigate more detail tomorrow.