Plots update

• Change plot color: gradient, the center corresponds to 9:00  a.m.
• Scale from Voltage to each physical unit

Quick resulrs

Test data of this setup

During this measurement, we found an extremely large coupling between the MN length and the TM pitch.
Efforts to reduce this coupling will be necessary.
The coupling factor will be estimated when we restart this work.

[Yuzu, YamaT]

a2A5328-4gmPRO camera was moved from a top plate of the fire alarm rack around OMC area to a top plate of k1boot in the server room (Fig.1).

It's now connected to the 10Gbps core switch directly. So a shortage of a bandwidth might be mitigated. (Even if so, we need to reconsider the system design of high resolution cameras. But we may be able to know one of requirements of that system from a change in the situation by difference in the connected switches.) Camera servers were already shut down for the planned power outage. So a test with the new configuration will be done after recovering from the power outage.
 

Today, we performed the shutdown operations for the Pcal at both end stations in response to the planned power outage.

Remote actions

First, we requested the SAFE state for the Pcal GRDs.
While the GRDs were transitioning to the SAFE state, and before turning off the laser output, we turned off the GRDs.
After confirming this, we turned off the laser output remotely.

Then, we shut down the following servers remotely:

• calexa
• caleyal
• caleya

Note: calexal was not shut down remotely due to the issue described in klog36479.

On-site shutdown procedure (both ends)

1. Turn off the AOM: power off the AOM driver.
2. Turn off the laser source:
   1. Turn the key to switch the laser OFF.
   2. If an external voltage source is connected, turn the output OFF and power it down.
   3. Turn off the laser power supply.
3. Turn off the shutter controller
4. Turn off voltage sources (for shutters, laser source, AOM drivers).
5. Turn off circuits power inside the rack under the Tx module.
6. Shut down the servers (on-site).
7. Turn off UPS units (two units).
8. Unplug the power cords.

Note: For Pcal-Y, the QPD box was already powered off (no power supplied) before starting the shutdown procedure.

I went to the third reassembly of the broken FLDACCs. #5 folded pendulum block was replaced with #9 block (Picture #1). The assembled pendulum looks fine (Picture #2).

For the preparation of the planned power outage at the KAGRA site, I shutdowned the detchar computers located in the mine.

• 10:06 shutdown of k1det0 and k1det1
  • At ~10:00 on March 5, the computers will be rebooted.
  • During that period, the automatic production of segment files at k1det1 is suspended. The automatic transfer of the segment files will restarted ~9:30 at March 6.
• 11:23 shutdown of k1dettest
  • Note that the host name in the IP address list is k1detcl3. But the actual hostname was k1dettest.

I found that when I reboot/turn off the calexal server, the laser source was turned ON! (The LPD shows ~7V)

Today, we will use the local interlock key to keep the laser OFF on site and turn OFF the server.

But, this issue should be clear for safety.

[Tanaka, Ushiba, Aso, Komori]

Abstract:

We began testing a new DARM hierarchical control scheme using only the MN and TM stages to suppress the RMS of the TM feedback signal and enable control with the low-power coil driver.
The filter tested in this trial caused high-frequency saturation in the ALS DARM state; therefore, further investigation and redesign are required.

Detail:

As described in a series of previous trials (klog:33176), we need to implement a new DARM hierarchical control scheme in which the RMS of the TM feedback signal is sufficiently reduced to allow replacement of the current high-power coil driver with a low-power one.
This replacement is crucial because the noise of the high-power coil driver is already subdominant in O4c, and we must transition to the low-power driver to further improve the detector sensitivity.

We revisited the previous trials and adopted a new approach in this study.
Our new approach uses only the MN and TM stages, as this configuration avoids the IM stage, whose actuation path includes a negative zero.

We designed a new open-loop transfer function using the MN and TM stages based on a theoretical multiple-pendulum model, as shown in Fig. 1.
The crossover frequency between the MN and TM stages is approximately 4 Hz.
Please note that the unity gain frequency (UGF) can be increased up to approximately 30 Hz at most, because the ALS DARM error signal is noisy and excessive bandwidth leads to saturation.

We successfully implemented the hierarchical transfer function as designed (Fig. 2).
However, we were unable to close the ALS DARM loop with this filter due to saturation at the MN stage.

The RMS of the current DARM feedback signal is dominated by noise around 30–40 Hz, as expected (Fig. 3).
The phase compensation filter, whose gain increases at higher frequencies, enhances the response in this band and leads to saturation around 30–40 Hz.

We will redesign the filter to mitigate this saturation in the near future.
In addition, another potential approach is to switch from the high-power coil driver with the conventional filter to the low-power driver with the new filter during the transition of the controlled TM between EX and EY after the handover to IR.
Since the IR signal is significantly quieter, we can maintain the UGF at around 100 Hz from the beginning.
This will make the implementation of the new filter more straightforward.

(Log for Friday's work)

To investigate the line noises and the low-frequency 1/f noise, whether they were actual magnetic field or sensing noise, I located the sensors at opposite direction (Y-direction) and checked their coherence and phase.
The spectrum shape is lmost the same for both channels.
There were large coherence (~1) for both the line noises and the low-frequency 1/f noise, and the phase was about 180 degree. So we can say these noises are actual magnetic field.

After these tests, I recoverd the sensor positions and directions to the original ones. (Hx for the X-direction, Hy for the Y-direction)

The FLDACCs for SRM moved back to the SR-OMC area from the BS area. I went to the second reassembly of the broken FLDACCs. #2 folded pendulum block was replaced with #8 block (Picture #1). The assembled pendulum looks fine (Picture #2).

Since newly added channels are not monitored by SDF, I started to monitor these channels as shown in fig1.

With Kenta Tanaka

We accepted SDFs caused by the works on klog36194.

[Takahashi, Ikeda]

We checked if the SDFs for VIS are 0. We attached MON flags to the SDFs that changed due to the model modification in SRM.

SDF of K1:IMC-SERVO_NPRO_TEMP_BIAS_OFFSET was changed from 5 of January.
Though laser work was conducted at that time (klog36019), there is no description on the laser temp bias changes and according to the working log, there seems no need to change temp bias.
So, I'm not so sure this change is related to this laser work.

Anyway, we confirmed IFO can be locked with the current EPICS values, I accepted the SDF shown in fig1.

[Miyoki]

The cleaning was done.

The water dropping above -X side of SRM continues. We put a wavy plastic plate and dust cloth to catch the water dropping. So we should be careful when  the top curtain will be opened.