KAGRA Logbook

MIF (Noise Budget)

takafumi.ushiba - 22:03 Thursday 06 July 2023 (25877)

Peak identification of type-Bp suspensions

Continued work with klog25830.

To identified the reesonance of Type-Bp suspensions, I injected white noise from 10 Hz to 60 Hz at IM stage of Type-Bp suspensions and measured the spectra of each sensor.
Only T DoFs are remained, so I will continue when I have time.

After finishing all the measurement, I will summarize the results.
Data are stored at /users/Commissioning/data/VIS/{PRM,PR2,PR3}/2023/{0705,0706}/.

Comments to this report:

takafumi.ushiba - 19:49 Tuesday 11 July 2023 (25950)

I summarized identified eigenmode frequencies of Type-Bp suspensions in the following documents.
https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=15070

Many of peaks cannot be seen in DARM but lowest vertical resonance of PR3 can be seen in DARM.
It probably comes from BF GAS control noise, so we might reduce it by adding notch filter in the local control.

takahiro.yamamoto - 1:51 Wednesday 12 July 2023 (25952)

Only a mode 1 of PR3_V (11.29Hz) seems to be matched with the spectral peak on DARM as shown in Fig.1.
Other peaks coming from a mode 1 of Vertical (around 11Hz) and a mode 1 of Roll (around 15Hz) are not matched with DARM peaks.

A mode 2 of PR2_V (43.31Hz) is close to the DARM peak at 43.266Hz (see Fig.2).
But this peak is matched also with a mode 2 of ITMX_P (43.26Hz).
Other peaks coming from a mode 2 of Pit (around 43Hz) are not matched with DARM peaks.

A mode 2 of PR3_R (53.40Hz) is close to the DARM peak at 53.369 (see Fig.3).
But this peak is matched also with a mode 2 of ITMX_R (53.36Hz).

A mode 2 of PRM (56.72Hz) is close to the DARM peak at 56.80Hz.
The difference as 0.08Hz is slightly large (?) because frequency resolution of Ushiba-kun's investigation and my spectrum estimation is 1mHz.

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