About the ~3 Hz oscillation of the yaw during the pitch OLG measurement, Ushiba-san suggested me to apply the NBDAMP Y1 filter (3.13Hz).
I followed his suggestion and confirmed the oscillation was not occurred in the yaw.
I measured the OLG of the ITMX MNOLDAMP Filter of roll. It's coherence and phase were looked OK, but the gain was smaller than the reference, about -60dB. [Fig. 1]
At that time, the ROL oplev light was almost only in thee SEG4.
Yokozawa-san went into the mine to perform the centering, and I measured the OLG. Then the result was similer to the reference. [Fig. 2]
We changed FM5 to FM1 in the T1 loop filter. As a result, the saturation disappeared.
The values of COILOUTF are now slightly larger than they were in O4c. So we decided to keep this situation.
The TF of this T1 loop when using FM1 is the attached figure.
Even if LOCK_ACQUISITION can be kept, this issue should be solved because the output is continuously saturating.
So, some modifications of the NB DAMP T filter (and others if necessary) is necessary.
[YokozaWashimi]
We measured the OLGs of the OLDAMP filters (P, Y) at the LOCK-AQUISITION state.
We found the MN COILOUTF values are very high comparing to other suspension.
It can be caused by the loop of NBDAMP T1.
After the adjustment FM5 was used. If we use FM1 for the loop, the COILOUTF values are smaller a little.
FM5 = FM1 + 10dB.
As the suspension could be kept at LOCK_AQUISITION state for long time (>1day), I did not change it.
We measured MN OLDAMP filters.
- Red lines: today
- Blue lines: 2024/8
- Green lines: 2025/2
We measured these with LOCK_AQUISITION state.
I offloaded the F0 GAS with the FR.
Fig.1. - Fig.3. showed the OLTF of the DARM, MICH and PRCL.
[Kimura, Yasui, M. Takahashi, H. Sawada, Ohmae and Yamaguchi]
On 15 Jan., as part of maintenance work on the cryo-cooler units, the compressor ( Yea ) for the duct shield cryo-cooler unitin the Y-end machine room was replaced.
The removed compressor was packaged for repair.
Preparatory work was performed for replacing the two failed compressors in the center machine room.
Replacement with refurbished compressors is scheduled for next week or later.
The compressor from the Y-end machine room and the two failed compressors from the center machine room ( X-P53 and Y-P-53 ) are scheduled to be returned to the factory in February.
The cooling water circulation system in the central machinery room has been temporarily shut down for compressor replacement work.
Operation is scheduled to resume in early February.
Fig.1. showed the TM to ALS DARM.
Compared from July 2024, the gain increased about 0.758 (-259.51718 - (-258.75964) at 5 Hz), so I changed the FM4 of the K1:VIS-ETMX_TM_LOCK_L filter bank
gain(1.255)gain(0.80352)
->
gain(1.255)gain(0.80352)gain(-0.75754)
->
gain(1.3229952)
Fig.2. and Fig.3. showed the IM and MN, respectively, we didn't change the gain for IM and MN (but coherence above the 5 Hz in MN became worse)
Then, we can continuously lock the ALS DARM more than at least 15 min.
Fig.4. showed the OLTF for ALSDARM
Compared from previous measurement klog35415, the UGF became lower (1.99 kHz -> 1.75 kHz)
I don't know due to lower UGF, the stability of the ALS CARM was too low (continued to lock around 1 min)
After increasing the gain
K1:LSC-CARM_SERVO_IN2GAIN 22 -> 24, the stability became better.
Fig.1. and Fig.2. showed the measured OLTF before and after increasing CARM gain
LSC_LOCK guardian
~L935
from
if ezca['LSC-CARM_SERVO_IN2GAIN'] < 23.5:
CMS_CARM.gain('IN2',ezca['LSC-CARM_SERVO_IN2GAIN']+1)
to
if ezca['LSC-CARM_SERVO_IN2GAIN'] < 23.5:
CMS_CARM.gain('IN2',ezca['LSC-CARM_SERVO_IN2GAIN']+1)
[YamaT-san, Ikeda]
We created and executed the K1IZ1 model file.
The model was based on K1IX1 and modified to K1IZ1.
All RFM-related components were removed and changed to either terminate or connect to GND.
Not yet registered with the DAQ.
On the maintenance day, add all models to rtsystab and register only the Testpoint for k1iopiz1 with the master.
The following numbers were assigned for DCUID:
58: k1iopiz1
62: k1visitmzt
67: k1visitmzp
77: k1visitmzlsc
118:k1sendbeaconiz
We launched up a new V4 computer as K1IZ1.
Now both V4 front-end and a new IO chassis are in the server room to check the stability with short cable connection.
And also, K1IZ1 runs only with PXE/NFS connection to k1boot and without DAQ/RFM connection to another CDS nodes to separate from existing control system.
After checking the stability by short cable connection during next few weeks, a new IO chassis will be moved to IXV or IYV area to check a stability with long (~100-150m) cable connection.
After starting SRM work in March, K1IZ1 will be connected to DAQ/RFM and finally it will be replaced as current ITMX or ITMY until the end of March.
For launching K1IZ1, node information was added to dhcp@k1boot and dns@k1gate.
-----
Rack layout
- An unused old type of IO chassis (S1605837) were moved from U8-11 of C2 rack to U6-9 of C4 rack.
- K1IZ1 front-end and a new type of IO chassis (S2416127) were installed at U29-30 and U8-11 of C2 rack, respectively.
- Spare V4 computer at U1-2 was brought back to SK building for future tests.
Card configuration (same as ITMX and ITMY
- 1 IRIG-B card in front-end
- 1 RFM card in front-end
- 1 4-port Adnaco card in front-end
- 3 ADC boards (S2213882, S2213881, S2113340) in IO chassis
- 3 DAC boards (S2012040, S2517026, S1605727) in IO chassis
- 1 BIO1616 board in IO chassis
- 5 BIO6464 boards in IO chassis
- 1 BO32 board in IO chassis
I owrked on the ITMX MNOLDAMP filter tuning for R and Y, at the PAY_FLOAT state and applying R, P, Y filters.
During the pitch measurement, the yau was oscillated and it was not stopped at the excitation was finisshed. Whan I turned off the yau filter, this oscillation was stopped.
The frequency was about 3.12 Hz. So the notch filter (FM8; 3.14Hz, Q=10, 60dB) for yaw needs to be tuned.
About the ~3 Hz oscillation of the yaw during the pitch OLG measurement, Ushiba-san suggested me to apply the NBDAMP Y1 filter (3.13Hz).
I followed his suggestion and confirmed the oscillation was not occurred in the yaw.
https://www.data.jma.go.jp/multi/quake/index.html?lang=en
| Observed at | Place name of epicenter | Magnitude | Maximum seismic intensity | Date and time of issuance |
|---|---|---|---|---|
| 2026/01/15 14:52 | Hida, Gifu Prefecture | 2.9 | 1 | 2026/01/15 14:55 |
| 2026/01/15 14:48 | Hida, Gifu Prefecture | 5.2 | 3 | 2026/01/15 14:52 |
| 2026/01/15 14:43 | Eastern Toyama Prefecture | 4.3 | 2 | 2026/01/15 14:46 |
| 2026/01/15 14:40 | Eastern Toyama Prefecture | 4.7 | 4 | 2026/01/15 14:44 |
Shindo around Kamioka was about 3.
Shindo around Kamioka was about 0.
![36144_1768456980_FireShot Capture 342 - Japan Meteorological Agency - Earthquake information - [www.data.jma.go.jp].png](uploads/tn/tn_36144_1768456980_FireShot Capture 342 - Japan Meteorological Agency - Earthquake information - [www.data.jma.go.jp].png)
I checked the IX MN damp filters (L, T), at the PAY_FLOAT state with turned on both filters (L, T) manually.
Thay look OK without finler tuning.
Note that the 5.1Hz peakings are found, and they are got larger then the notch filter (FM8) is applied.
I changed the setpoint for the BF GAS from 3440 to 3700 so that the MN V Oplev can be zero. The BF GAS was offloaded with the FR.
During the Xarm and Yarm initial alignment, PRM default state was MISALIGNED_BF (for the daily finesse measurement mode)
Today, I backed to the MISALIGNED_FOR_LOCK_ACQ for the default PRM state during the Xarm and Yamr initial alignment.
NBDAMP
L1, L2, L3
T1, T2, T3
MNDAMP
L, T
MNOLDAMP
R, P, Y
Even after tuning the following filters, the ETMX suspension started oscillating around 1.67 Hz.
I changed the MNOLDAMP R, P notch fireqencies (1.685 -> 1.67) and turned off the ACALIGN matrix K1:VIS-ETMX_MN_ACTALIGN_6_5 (P->Y) from 0.017 to 0 (temporary)
The oscillation can be stopped(at least 1 hour).
So, next step would be ALS DARM lock!
After turnning ON Y4 filter, the oscilation observed yesterday looks dissapeare.
After more adjustment for Y4 filter, we measured the TFs again for L1, Y4, T1 which are close to the oscilation 2.2Hz.
All of them look OK.
Then, the TFs of MNOLDAMP floops were measured.
We did not change anything for it as they look OK and there was not mergin to increase the gain.
We will keep the suspension at LOCK_AQUISITION for a while to check the stability and noise.
