I offloaded the IP and the F0 GAS with the FRs after the pressure reached 16Pa.
In addition, we reduced the number of operated FFU from 2 to 1. Then the EYV temp became ~ 22.4C. Finally, the EY F0 seemed to back around 15000.
Sawada, Takahashi, Uchiyama
Finally, we closed dir. 800 flange with proper torque (20 -> 40 -> 60 -> 60 Nm).
After that, we started pumping down EYC by the dry pump at EYA from 13:30.
This is a follow-up to the previous klog post.
Background / Purpose
The purpose of this test was to investigate the field of view of the TCam, particularly how much of the area behind ETMX (TMS side) is visible in the TCam images.
By understanding the field of view, we may be able to identify suitable locations for reference markers that could be used to determine the viewing direction of the TCam in the future.
Additional Information on the Ruler
The attached photo shows the 30 cm ruler used in the test.
The white object near the center of the TCam image is the ruler, which was placed at the bottom of the duct on the AR side of ETMX.
Since the ruler's scale markings were not distinguishable in the TCam image, tape markers were attached at 5 cm intervals from the bottom of the ruler.
The upper edge of each tape marker indicates the corresponding 5 cm position.
Taking picture ETMX with a scaler using TCam held on 10/6
We taking picture ETMX with a scaler using TCam.
The scaler was put on the duct on AR side, and was on the bottom of the duct.
Tape was attached by 5cm.
Uchiyama-san checked the LVDT-ACT coil resistances for the BF GAS. They did not change much.
| Pin | Reference [Ω] | This time [Ω] |
| 1-6 | 217.7 | 229.6 |
| 2-7 | 95.6 | 95.6 |
| 3-8 | 129 | 128.9 |
[Uchiyama, Ushiba(remote)]
Summary:
We performed the swapping test of ETMX TM H1/H2 actuators and confirmed the problem is at the outside of the chamber.
Detail:
We performed the swapping test of ETMX TM H1/H2 actuators.
As usual, excitation was injected at 10Hz and we measured TF from excitation signals to TM OpLev PIT.
Figure 1 shows the results.
Left and right pannels show the results when H1 and H2 coil were actuated.
Blue and red represent the measurement before and after cable swapping.
Black line in the left pannels show the reference measured in 2024.
For H1 actuator, red line is higher than blue line by 3dB and comparable with black line, which means actuator efficiency was recovered by swapping the cable.
For H2 actuator, red line is lower than blue line by 3dB, which means actuator efficiency was removed by swapping the cable.
Therefore, we can conclude that the source of actuator efficiency reduction is not at the inside of chamber but at the outside.
Though we haven't confirmed which circuit has a problem, we don't have to reopen the chamber and check the suspension.
As discussed in the morning meeting today, we do not see any signals in the RF ports because the power supply of the whitening filter for the demodulated signal is still turned off.
This independent power supply was installed to mitigate the green-IR coupling as written in klog:36550.
[Fujimoto, Yokozawa, Komori]
Summary
We could not observe any error signals from the IFO REFL RFPDs, so we were unable to measure the IMC length today.
We should check the RF cable connections around the EOM, RFPDs, demodulation boards, and related electronics.
Details
Before adjusting the IMC length and the RF sideband frequencies, we tried to confirm the current IMC length.
The measurement method was exactly the same as that used previously (klog:29385).
We tried to tune the RF sideband frequency and the input offset while exciting the laser frequency through DGCARM, and monitored the peak height in the power spectrum of the error signal measured at IFO REFL.
However, we could not observe any peaks in the error-signal spectra measured by the REFL RFPDs, even when changing the RF frequency by 10 Hz or more.
We confirmed that the DC powers measured at the IMC transmission and the two IFO REFL PDs (PDA1 and PDA3) were fluctuating.
This indicates that the laser frequency was indeed being excited and that the DC ports of both REFL PDs appeared to be functioning normally.
On the other hand, we could not observe any signal from the RF-demodulated ports at any time.
We should be able to observe a PDH-like signal from these PDs during an IMC cavity scan, but no such signal was observed (Fig. 1).
Therefore, we suspect that there may be an issue with the RF signal path, such as disconnected or incorrectly connected cables around the EOM, RFPDs, or demodulation boards.
Unless we have overlooked something simple, an inspection of the components and cable connections inside the tunnel will be necessary.
As discussed in the morning meeting today, we do not see any signals in the RF ports because the power supply of the whitening filter for the demodulated signal is still turned off.
This independent power supply was installed to mitigate the green-IR coupling as written in klog:36550.
The setpoint of the F0 GAS has been changed from 4527 to 4230 to avoid saturation (klog 37563 and 37618). The gap in the F1 damper was increased by 0.3mm. The plot shows the TFs from IP Y to BF Y. The Q of the torsion mode at 31mHz became higher.
[Kimura, Yasui]
We added water because the water level in the X-15's cooling water chiller had dropped.
We searched for the source of the leak but could not find it.
Therefore, we are currently monitoring the water level in the tank with the casing removed.
I checked the F0 GAS TF when suspension is TWR_FLOAT state but no significant change happens (fig1).
Also, I checked the F0 GAS motion when moving F1 GAS filters and confirmed F0 GAS also moved (fig2).
So, the situation could not be recovered by just moving BF yaw position.
This log shows the health check results of ETMX tower.
I picked up several graphs, which needs to be discussed here, so please see klog37627 to check all transfer functions.
Summary:
Peaks around 1Hz has strange shape when exciting F0 and F1.
BF GAS transfer functions have lower gain than the reference.
Detail:
IPL and IPT transfer functions (fig1 and fig2) are different from the reference but these are due to the filter setting changes due to the FLDACC controls.
Figure 3 and 4 show the transfer functions when changing the filter setting.
Though there are still difference at 30mHz and peaks around 70mHz, they should be fine in terms of the health check because they are due to crossover between ACC and LVDT and coupling between L and T, respectively.
F0 and F1 transfer functions (fig5 and 6) are also different from the reference at the peaks around 1Hz.
According to Takahashi-san, the current suspension position is close to touching the outer flame, and large excitation could cause the suspensions to touch the flame.
So, I measured F0 GAS TF with 10 times smaller excitation (fig7) but the situation didn't change.
In addition, I checked suspension was touching somewhere by moving F1 GAS filters (fig8).
Since there is no motion at F3 and BF GAS, suspension doesn't seem to touch the outer flame.
However, F0 GAS has a strange behaviour due to the change of the F1 GAS filter position, so it is necessary to identify what happens.
BF GAS transfer function has lower gains than the reference at entire frequency bands.
Since the gain at high frequency (frequency region where suspension acts as the free mass) is low, it cannot be explained by just changing the stiffness of the GAS filter.
Since suspension doesn't seem to touch, LVDT calibration and/or actuator efficiency might be reduced.
Other than those differences, TFs are well matched with the references, so they should be fine.
Note:
About IPL and IPT transfer function, manual treatment is now necessary for measuring the TF with correct filter setting.
I will implement it into automeasurement script later but until then, please turn on FM8 of K1:VIS-ETMX_IP_FLDACCINF_H{1,2,3} and FM1 of K1:VIS-ETMX_IP_ACCBLEND_FLDACC{L,T} before starting the script and turn them off after the measurement.
I suspected that the heat-up is wrong according to the data relation between F0 GAS and temp at EYV. I asked Takahashi-san, and we decided to cool down again. I turned off the heater around 8:30. We will check whether we can cool more in EYV.
To adjust F0, I increased the heater power from zero to 900W. Then the temperature increased by 1 C degree. I hope it affected the F0 position to the better status.
This log shows health check results of ETMX payload.
Summary:
TM H1 actuator might have a problem.
Detail:
I ran the automesurement scripts and checked the results of ETMX payload.
Figure 1 - 28 show the graphs of each measurement.
IM EULER DoFs measurements have different results from the reference but they are probably due to the sensor decoupling matrix modifications because there is no difference in TFs from each actuator to each sensor.
TM H1 gain is smaller than the reference by 3dB but I could not confirm the reason and it might be a hardware problem, so it is necessary to check.
Note:
TM health check template didn't work well because we installed switching circuit of ETMX TM coil drivers.
So, I modified the template and then it works well.
This log shows the health check results of ETMX tower.
I picked up several graphs, which needs to be discussed here, so please see klog37627 to check all transfer functions.
Summary:
Peaks around 1Hz has strange shape when exciting F0 and F1.
BF GAS transfer functions have lower gain than the reference.
Detail:
IPL and IPT transfer functions (fig1 and fig2) are different from the reference but these are due to the filter setting changes due to the FLDACC controls.
Figure 3 and 4 show the transfer functions when changing the filter setting.
Though there are still difference at 30mHz and peaks around 70mHz, they should be fine in terms of the health check because they are due to crossover between ACC and LVDT and coupling between L and T, respectively.
F0 and F1 transfer functions (fig5 and 6) are also different from the reference at the peaks around 1Hz.
According to Takahashi-san, the current suspension position is close to touching the outer flame, and large excitation could cause the suspensions to touch the flame.
So, I measured F0 GAS TF with 10 times smaller excitation (fig7) but the situation didn't change.
In addition, I checked suspension was touching somewhere by moving F1 GAS filters (fig8).
Since there is no motion at F3 and BF GAS, suspension doesn't seem to touch the outer flame.
However, F0 GAS has a strange behaviour due to the change of the F1 GAS filter position, so it is necessary to identify what happens.
BF GAS transfer function has lower gains than the reference at entire frequency bands.
Since the gain at high frequency (frequency region where suspension acts as the free mass) is low, it cannot be explained by just changing the stiffness of the GAS filter.
Since suspension doesn't seem to touch, LVDT calibration and/or actuator efficiency might be reduced.
Other than those differences, TFs are well matched with the references, so they should be fine.
Note:
About IPL and IPT transfer function, manual treatment is now necessary for measuring the TF with correct filter setting.
I will implement it into automeasurement script later but until then, please turn on FM8 of K1:VIS-ETMX_IP_FLDACCINF_H{1,2,3} and FM1 of K1:VIS-ETMX_IP_ACCBLEND_FLDACC{L,T} before starting the script and turn them off after the measurement.
I checked the F0 GAS TF when suspension is TWR_FLOAT state but no significant change happens (fig1).
Also, I checked the F0 GAS motion when moving F1 GAS filters and confirmed F0 GAS also moved (fig2).
So, the situation could not be recovered by just moving BF yaw position.
[Uchiyama, Ushiba(remote)]
Summary:
We performed the swapping test of ETMX TM H1/H2 actuators and confirmed the problem is at the outside of the chamber.
Detail:
We performed the swapping test of ETMX TM H1/H2 actuators.
As usual, excitation was injected at 10Hz and we measured TF from excitation signals to TM OpLev PIT.
Figure 1 shows the results.
Left and right pannels show the results when H1 and H2 coil were actuated.
Blue and red represent the measurement before and after cable swapping.
Black line in the left pannels show the reference measured in 2024.
For H1 actuator, red line is higher than blue line by 3dB and comparable with black line, which means actuator efficiency was recovered by swapping the cable.
For H2 actuator, red line is lower than blue line by 3dB, which means actuator efficiency was removed by swapping the cable.
Therefore, we can conclude that the source of actuator efficiency reduction is not at the inside of chamber but at the outside.
Though we haven't confirmed which circuit has a problem, we don't have to reopen the chamber and check the suspension.
Uchiyama-san checked the LVDT-ACT coil resistances for the BF GAS. They did not change much.
| Pin | Reference [Ω] | This time [Ω] |
| 1-6 | 217.7 | 229.6 |
| 2-7 | 95.6 | 95.6 |
| 3-8 | 129 | 128.9 |
[Kimura, Yasui. H.Sawada and M.Takahashi]
We temporarily closed the side flange on the -Y side of the EXC.
After completing the tightening work, we cleaned up the area around the EXC clean booth.
The cleanup work included removing compressed air cylinders for venting to atmosphere in EXC and flexible piping for the duct-shield cryocooler unit of TMSX side called Xer.
After performing a health check on the EXC suspension, we will tighten the side flange mounting bolts to the specified torque. We then plan to begin evacuating the EXC.
I offloaded the F3 and BF GAS filters with the FRs after closing the EXC.
The health check was performed again after solving the low-coherence problem in BF GAS. Compared with the reference, the coupling from Y to T and R in IM changed. Other TFs look healthy.
ETMX Triangulation Survey — Day 2
A detailed report on the triangulation survey will be added later.
Following the preparation described in [klog 37607](https://klog.icrr.u-tokyo.ac.jp/osl/?r=37607), we carried out a triangulation survey at the X-end using a total station placed at three locations: A, B, and C.
The following points were observed from these three locations for triangulation:
- Reference markers P1 and P2.
- Four corners of the copper housing, circled in red and named C1–C4.
- Four corners of the sapphire nail heads, circled in green and named S1–S4.
In addition, the following points were measured from location C only:
- The HR-side corner of the test-mass ear.
- The HR-side upper corner of the AR-side sapphire nail head bonded to the ear.
Supplements
We aligned the horizontal line of a green laser level with the top surface of the sapphire nail head and made a best-effort adjustment to align it with the center of the P1 marker.
[Moriwaki, Aoumi, Shimode, Hirose]
We checked the existing beam shutter connections in the PSL room and around the OMCDCPD in preparation for the future installation of the Fast Beam Shutter.
- The connection of the beam shutter in the PSL room was checked and confirmed as follows(Fig1):
k1shutter model→ (D-sub 37-pin cable) → Binary In/Out Converter (S1605341, S1910323)→ (BNC cable)→ Shutter Driver (S2314812)→( BNC cable→ Split into two cables: Fig2)→ Shutter
- In addition, since we plan to connect a fast beam shutter to the OMCDCPD in the future, we also checked the circuitry around the OMCDCPD.(Fig3)
OMC DC Driver ["Zsw Ctrl"] (S2416233)→ (D-sub 9-pin cable)→ Binary In/Out Converter (S1910321)["Ch00-07"->"Ch24"]→ (BNC cable)→ OMC Piezo Driver [Shutter Trigger](S1910872)
For the future installation of the Fast Beam Shutter, we are considering disconnecting the D-sub 9-pin cable currently connected between OMC DC Driver ["Zsw Ctrl"] and the Binary In/Out Converter, and connecting the BI/BO of the Fast Beam Shutter directly to OMC DC Driver ["Zsw Ctrl"] instead.
The current connector of the Fast Beam Shutter circuit is a D-sub 25-pin connector, while the output from OMC DC Driver ["Zsw Ctrl"] uses a D-sub 9-pin connector.
Therefore, we are considering changing the connector of the Fast Beam Shutter circuit from D-sub 25-pin to D-sub 9-pin.
Before making this modification, the pin assignments and electrical interface (signal levels, BI/BO configuration, etc.) need to be checked to confirm compatibility with OMC DC Driver ["Zsw Ctrl"].
I offloaded the F0 GAS with the FR.
I offloaded the F0 GAS with the FR.
Though I tried to offload the F0 GAS with the FR, the FR didn't work well. So I changed the setpoint for the F0 GAS from 4250 to 4230 temporarily to avoid saturation.