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MIF (General)
takafumi.ushiba - 19:47 Monday 17 March 2025 (33013) Print this report
Kick of the violin mode when PRFPMI_RF_LOCKED

Abstract:

I checked the DARM error spectrum when the violin mode was kicked strongly.
The kicked suspension (or at least resonances) seem to be different between two different timing.
he kicked suspension should be idntified by exciting violin mode to investigate the glitch sources.

Detail:

Today, we observed clear peak around 180 Hz when PRFPMI was locked with RF signals, so I measured the spectrum at that time with 0.008 Hz bandwidth (fig1).
Red shows the spectrum around 2025/03/17 08:18 UTC and blue shows the spectrum around 2025/03/17 06:51 UTC.
There are large peaks at 178.94, 180.25, and 182.91 Hz in red graph while there are at 181.91 and 183.25 Hz in blue.

It is necessary to identify which suspension is kicked by intentionally exciting the violin mode but it is very likely that different suspensions were kicked because it is hard to excite not all fibers by chance.
Also, ETMY violin mode was higher/lower frequencies (around 165 Hz and 190 Hz), it is not likely tobe ETMY violin mode.
So, we suspected the cooling of the mirror might cause the glitches but out guess should be carefully checked.

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Comments to this report:
hirotaka.yuzurihara - 10:56 Tuesday 18 March 2025 (33021) Print this report

[Yuzurihara, Obayashi(Aogaku)]

We checked the band-pass filtered time series (same as klog32973) when the interferometer was locked at K1:GRD-LSC_LOCK_STATE_N = 1301 (INCREASING_LAS_POWER).
We also saw that the resonance kick in the frequency band of both violin mode (this was reported by Ushiba-san) and 40~50 Hz occurred when the interferometer was locked by RF_LOCK. In the case of 03/16, we saw this phenomenon for all four RF_LOCK.

In the case of RF_LOCK, we didn't see the clear resonance kick of violin mode in the middle of the lock, except for the starting of RF_LOCK. 

Although we wanted to check the data on 03/17, the data transfer is still underway. 

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