[Yong-Xiang Yang, Chia-Hsuan Hsiung, Gui Chin Liu (from Tamkang university), Chia-Jui Chou, Yuzurihara]
We started the lockloss investigation during the end-year holiday, with powerful supporters from Taiwan. We checked the timeseries by using ndscope and time-frequency map by using the Pastavi.
Details
- This is a continuous work of klog. So, we focused on the lockloss during 2024/12/21~12/30.
- The generated plots were collected on wiki.
OMC saturation
We found the OMC saturation was happening only on 2024/12/29. (Fig) (Fig) Times are below:
- 2024-12-29 21:19:16 UTC (lock duration=151 s, saturation duration=32s)
- 2024-12-29 19:41:26 UTC (lock duration = 193 s, saturating duration = 58 s)
- 2024-12-29 19:04:37 UTC (lock duration = 702 s, saturating duration = 600 s)
- 2024-12-29 17:26:56 UTC (lock duration = 278 s, saturating duration = 100 s)
The frequency of the oscillation is ~5 Hz or ~5.2 Hz. (Fig) Even though the OMC saturation was happening, the interferometer kept the locking. Is that health?
Excess at f<=10 Hz in PRCL and MICH
Sometimes we observed the excess at ~10 Hz in error or feedback signals of PRCL and MICH, ~30 seconds before the lockloss. (Fig) For example. 2024-12-30 21:38:25 UTC.
Possible scenario is to feedback this excess to the PRM(?). We will check more data and discuss with the interferometer experts.
It's difficult to see this excess in the timeseries. We started to collect more statistics by checking the time-frequency map. We will collect more statistics abour this phenomena.
Related to this, I prepared the script to pass the lockloss time to Pastavi web page.
- Usage
- /users/yuzu/lockloss/open_Pastavi.sh 481
Drift by BPC feedback control
Sometimes we observed the sudden drift by the BPC feedback control. (Fig) In this case, after the sudden drift, the ETMX overflow happened.
We will collect more statistics abour this phenomena.
ETMY MN oplev glitch
We checked the coincident lockloss with the ETMY MN oplev glitch, since 2024-12-28 12:24:50 UTC. After 12/28 13:05, there is no coincident lockloss with the ETMY MN oplev glitch. Three coincident lockloss are:
