KAGRA Logbook

DetChar (General)

hirotaka.yuzurihara - 17:06 Monday 02 June 2025 (34029)

Transient noise in sensitivity and PRCL

I heard that Kenta-san and Komori-san frequently saw the sudden worsening of sensitivity of the PRCL signal on the diaggui in the control room, during their work.

Note that previously, we observed a similar transient noise in the PRCL channel, as reported in klog32887 on 2025/03/04; the appearance on the time-frequency map is available on JGWdoc; we recognized this because it makes it difficult to identify the scattered light noise on the PRCL channel, but this noise disappeared somehow...

I checked the Gauch since 2025/05/22. The transient noise on the PRCL channel began on 5/24 at 17:00 JST (Figure 1). Initially, this noise happened several times per hour, and sometimes it didn't happen (such as 5/25 and 5/27). However, it has recently become more frequent after 5/28 (such as 5/29, 5/30, 5/31, 6/1).
Is it related to the adjustment of the beam position on IY or IX? I will check the past beam position images on a screenshot monitor.

Images attached to this report

34029_1748850288_K1-LSC-PRCL_OUT_DQ_beg1432119618_time3600_int20_fft1_10_1500_pv_log.png

Comments to this report:

hirotaka.yuzurihara - 12:40 Tuesday 03 June 2025 (34049)

I identified the occurance time of the PRCL transient and check the timeseries data by ndscope. If you made the whitened timeseries plot, you can find the transient time easily.

Figure 1 shows the channels related to PRCL and RFPD on the POP table. You can see clearly the transient behavior on POP error / feedback signals and K1:LSC-POP_PDA1_RF45_{I, Q}_IN1_DQ. We can't see the coincident transient in oplev for the PRM and other oplevs.
Figure 2 shows the channels related to the LSC control. we can't see the transient behavior, except for the PRCL and K1:LSC-POP_PDA1_RF45_I_ERR_DQ.
I and Ushiba-san checked the other channels, such as POP90, IMMT1 oplev, ASC for IMMT2, ASC for PR3, and ASC for BS. We can't ses the coincident transient. Some plots are summarized on DAC wiki.

Images attached to this comment

34049_1748921610_Screenshot from 2025-06-03 12-33-26.png

34049_1748921613_Screenshot from 2025-06-03 12-30-36.png

hirotaka.yuzurihara - 15:43 Tuesday 03 June 2025 (34053)

I checked the whitened timeseries of the PEM channels (ACC, MIC, MAG, and SEIS). But, there was no coincident transient.