[kimura]
  The parallel threaded seal joint with O-ring, which was the cause of air leakage in the valve drive of the GVetmy,
 was replaced with a regular tapered threaded seal joint.
This replacement work has completed the replacement of all gate valves driven by compressed air.

Day 2  [miyoki, uchiyama, hayakawa, yoshimura, yamaguchi, omae, takahasi]

Progress and concerns

1. We removed the cleaning water inside EYA. (This water was transferred again in the poly-tank and abandoned at the Data analysis building.) 
2. We injected the filtered tap water inside the EYA with hard bubbling for washing the bottom of the EYA vacuum tank and the bottom surface of the optical bench and the optical table pole surface. after the tap water was filled enough to reach the bottom surface of the optical bench, I washed the bottom surface of the optical table and the surface inside the EYA bottom part by using the silicon brush and the sponge brush that could reach the edge of the optical table from the center hole of the optical table.
3. We drained the tap water to the poly-tanks.
4. We washed the area between the bottom surface of the optical table and the bottom of the EYA vacuum tank with "showered water" (tap water at the EY area). We drained the showered water again to the poly-tanks.
5. We tested water absorption for the space between the bellows and the optical table poles. We found that the water in one of the spaces seemed to have cleaning liquid even  after washing the tap water. 
6. So we need to inject a large amount of tap water directly in these spaces to replace the water that still had cleaning liquid.
7. During the absorbing activities, we noticed that the prepared pumping tools were not so good. One of them finally lost its absorbing power for the thin tube. We need improved absorbing techniques not to break the pumping unit.
   • Maybe we need to enlarge the diameter of the thin absorber tube.
   • etc.
8. After removing the tap water and washing by the shower water, I noticed that the surface of the bottom surface of the EYA vacuum tank and the bottom surface of the optical plate became cleaner (shiny) than before. However, I saw some non-shiny surface on the poles for the optical bench. We need to check them again.

Tomorrow Plan

1. We will inject a large amount of tap water directly in these spaces to replace the water that still had cleaning liquid.
2. Try to remove the water around the bellows with a safer and reliable manner.

Abstract:

I modified bandpass filters for NBDAMP.
All NBDAMP filters seem to work well.

Detail:

Since the NBDAMP filters for ETMX were designed when ETMX was cooled at 90K, some filters do not work well, so I modified them.
To make bandpass filter systematically, I made a code to look for good cutoff frequencies.
The code gives lower and higher cutoffs of 4th order Butterworth bandpass filters when we specify the resonant frequency of the resonance that we would like to damp.
The bandwidth of the bandpass filter is 0.1*[resonant frequency].

Then, I measured the resonant frequencies of each mode that was damped before.
Followings are the lists of resonant frequencies, DoFs, and signals used for damping.

Figure 1-7 shows the OLTF measurement of each loop in the LOCK_ACQUISITION state.
The top right graph shows the TF from EXC to IN2, which represents the suppression rate of the loop (I forgot to change the title but it is not OUT to IN1 but EXC to IN2).
All loops seem to work well.

Note:

ETMX can maintain the LOCK_ACQUISITION state but the damping performance is now not good because the MN OpLev signals are far from the linear range.
So, before starting the IFO commissioning, we need to perform MN OpLev centering.

[Ikeda, Takahashi]

We checked the EQ stops of the SR3 payload. The pictures are archived in the KAGRA Dropbox.

[Ikeda, Takahashi]

We checked the EQ stops of the SR2 payload. The pictures are archived in the KAGRA Dropbox.

[Ikeda, Takahashi]

We checked the EQ stops of the SRM payload. The pictures are archived in the KAGRA Dropbox.

Yokozawa, Washimi, Tanaka

### Abstract

We stomped the ground around MCF and MCE chamber with locking IMC to check the resistance for the blasting. However, we could shake the ground around MCF and MCE chamber at most +/- 60~70 um/s and IMC could keep the lock during our stomping. According to IMC LSC feedback signal to the laser PZT (K1:IMC-SERVO_SLOW_DAQ_OUT_DQ), when the ground shaked +/- 60~70 um/s, the amplitude of the feedback signal became +/- 0.2 V at 1 Hz (which is the length resonance frequency of Type-C sus.). If the blasting shake the ground with the amplitude of 200 um/s, which is estimated by the construction company, the feedback signal is expected to become +/- 0.6~0.8 V. This value is in the range (+/- 5V) so IMC will be able to keep the lock during the blasting. At worst, IMC lock can restore by guardian automatically even if IMC goes down.

### What we did

• Fig. 1 is the view of the location of the seismometer and the stomping
• With locking IMC, firstly, we stomped the corners of the MCF ENGIRI as following order (see the movie). However, we could shake the ground with the amplitude of at most +/- 60 ~70 um/s by our stomping. This is the one third smaller than the estimated amplitude of the ground motion by blasting. And then IMC kept the lock during the stomping.
  1. -X, +Y (nearby MCi camera, we disconnected the LAN cable during our stomping. After our work, we reconnected the LAN cable.)
  2. -X, -Y (nearby MCi oplev)
  3. +X, -Y (nearby MCo oplev)
  4. +X, +Y (nearby MCF seismometer)
• Then, we moved the MCE area and stomped the MCE ENGIRI corners with the same procedure as the MCF trial. Simirally, IMC kept the lock.
• According to IMC LSC feedback signal to the laser PZT (K1:IMC-SERVO_SLOW_DAQ_OUT_DQ), when the ground shaked +/- 60~70 um/s, the amplitude of the feedback signal became +/- 0.2 V at 1 Hz (which is the length resonance frequency of Type-C sus.) (Fig. 2).
• If the blasting shake the ground with the amplitude of 200 um/s, which is estimated by the construction company, the feedback signal is expected to become +/- 0.6~0.8 V. This value is in the range (+/- 5V) so IMC will be able to keep the lock during the blasting. At worst, IMC lock can restore by guardian automatically even if IMC goes down.

I redesigned the MN_NBDAMP_DOF5 filter not to oscilate at LOCK_ACQUISITION state.
At 296K, ETMX forth L resonance is about 5.04 Hz while it was 5.13 at 90K.
So, I made new filter (BP5.04(296K)) at FM1 of DOF5 and moved old filter from FM1 to FM2.
After changing the filter, damping seems working well (fig1).

Figure 2 show the one hour trend of PS DAMP signals at LOCK_ACQUISITION state after changing the filter.
For one hour, no oscillation can be observed, so the control seems stable.
 

Note that the TFx and TFy are the vertical -> horizontal coupling in this shaking test, but were the horizontal -> horizontal coupling in the previous hammering test. So their comparison is not fair.

HWP vs IMC trans power relationship

I took the picture 21st May. (Tuesday)

[miyoki, uchiyama, hayakawa, yoshimura, yamaguchi, omae, takahasi, sawada]

Progress

We filled the cleaning water just above the bottom surface of the optical table. We left it for one night.

Cleaning Process

1. Water preparation
   • We prepared water filtered by cascading 25um and 5um filters from the tap water obtained at the EY area.
   • We also prepared hot water by using the electrical pot from this filtered water.
   • We once put this water in poly-tanks and mixed it with the hot water to make warm water, then moved the poly-tanks to the EYA area.
   • We made the "cleaning water" by diluting the neutral detergent liquid with 50 times amount of warm water.
2. Absorber setting
   • Because I have set two of three thin red tubes to absorb the water between the bellows and the poles for the optical table, I set the last one for the space at +x/+y side.
3. Bubble shield setting, etc (Fig.1, 2, 3)
   • We inserted sponge bars that were wrapped with stretch seals in the space between the optical table and the side wall of the EYA vacuum tank to reject bubbles from the cleaning water when we injected air for mixing the cleaning water.
   • We put vectra alpha cloths on the mirrors for the P-cal. We are very sorry but one of mirrors seemed to get a liquid drip on the left surface of the mirror. We tried to clean this drip by acetone and apparently, the surface seemed to be clean. However, anyway, please check and clean all mirrors after the EYA tank cleaning.
4. Cleaning wroks
   • This cleaning water was transferred from the poly-tank to the bottom of the EYA vacuum tank by a pump.
   • During the transfer of the cleaning water, we also injected air by using an air pump to mix the cleaning water in the EYA tank. (Fig.4)
     • I tested the water absorber for the bellow-pole space, and I confirmed that water could be absorbed.
   • We stopped the cleaning water injection when the water surface was over the bottom surface of the optical table.
   • I washed the bottom surface of the optical table with a silicon brush that had a long handle. However, the most outside area of the optical table could not to be reached. I will try washing with a wiper that has a longer handle again tomorrow. (I have already bought a longer brush in DAISO)
   • Because the time was up, we left the cleaning water inside the EYA tank.
   • To avoid too much moisture inside the EYA vacuum tank, we left two side hatches to be open and one side mouse on the Y-arm axis on the EYC side was closed. So the air from the FFUs is expected to flow from the -x side to +x side.
   • (When the water surface was approaching the bottom surface of the optical table, the bubbles came out through several holes in the optical bench because these holes completely penetrated the optical bench. So we stopped the bubbling. As we expected, the sponge bars could prevent these bubbles from going on to the optical table surface.)

Tomorrow plan

1. Wash the bottom surface of the optical bench again by using a longer brush.
2. Drain the water inside the EYA tank. (The abandoned water should be transferred again into poy-tanks because we cannot abandon this used cleaning water in the mine water routes.)
3. Inject the warm water again and wash the bottom surface of the optical table again.
4. Drain the water inside the EYA tank and check inside by using the 3D camera.
5. ...

I checked the TFs measured in air. They are consistent with the reference (measurement before O4a) and look healthy.

Abstract

Details

Over the last few days I have been trying to understand the reason for the instability of the 30 mHz blending strategy along the T direction. As already mentioned, the T TF still shows the phase lag visible in the TFs measured with the blended sensor, despite the phase compensator implemented to compensate for it. As with the EX, I first modified the phase compensator to avoid DC saturation of the ACC and GEO (see Figure 1, Figure 2, Figure 3, and Figure 4), and then measured the TFs: LVDT/IS{L,T}.

Figure 5 and Figure 6 show the TF: LVDT/IS{L,T}. It is clear that there is still a phase lag which introduces instability into the loop. To reduce the phase lag, I implemented a new phase compensator on the virtual inertial sensor. I then re-measured the TFS and it seems that it helps to reduce the phase lag and should stabilise the loop (see Figure 7, Figure 8).
Next step:
Test the stability of the loop and redesign the blend filters.

I calculated the transfer functions from the base vibration (z) to the table vibration (x,y,z).

Comparing the results of hammering (klog29515), inconsistency is found.

The underestimation below 70Hz is solved.

I performed the shaker injection tests for the OMC base plate, by locating a 3-axial accelerometer (TEAC710Z) on the optical table and a 1-axial accelerometer (TEAC710, for vertical) on the base plate.

I performed actuator and center balancing of ETMY to confirm strange MNV TF can be better by sensor/actuator decoupling.
Figure 1 shows the MNV TF after decupling.
MNV TF becomes healthy.

Also, I measured TFs from V1 and V3 coils (fig6: V1, fig7: V3).
Since the gain of V1 becomes smaller, the gain of TF is smaller than before but it is not problematic.
Also, gain of MN V3 is now same as the reference, so the smaller gain, which was measured previously, seems due to the gain change in DGS.

So, MN stage TF seems fine now.

What I did:
1. Photosensor gain (MN_OSEMINF_{H1,H3}_GAIN) was changed to minimize the coupling between MNV and MNP (fig2:before, fig3:current).
2. Actuator balance was performed for reducing V2P coupling (fig4: before, fig5:current).
3. V2Y actuator decoupling was performed (fig6)

Is this actual number of the pressure inside IFI-IMM-PRM chambers?? I wonder if the GV between this CC-10 and the IFI-IMM-PRM chambers might open ot not.

[Kimura]
The serial communication settings on the replaced CC-10 were reset to factory settings, but the connection to the network was not restored.
Therefore, the electronic board of the CC-10 was replaced with the removed CC-10 electronic board and the sensor calibration curve was reset.
 As a result, the connection to the network was restored. (Figure 1)
The values were confirmed to be consistent with the displayed values seen by the network camera. (Photo 1)
The CC-10 with communication failure will be sent for repair.

At 11:16 a.m., CC-10 indicated 8.0 x 10^-5 Pa.

Around 9:00, 8.2x10^-5 Pa.