KAGRA Logbook

After the morning initial alignment, we performed the vibration injection to IFI bellows legs.
I tried to inject the vibration to all three IFI bellows legs.

Red : IFI leg1 : plus Y side
Blue : No injection
Green : IFI leg2 : minux X minus Y side
Brown : IFI leg3 : plux X minus Y side

We summarized the figure with same injection frequency.
Left top : Scaled DARM spectrum
Left bottom : TEAC710 accelrometer which was placed near the vibrator
Right top : IMMT1 TRANS QPD2 PIT
Right bottom : IMMT1 TRANS QPD2 YAW

Fig.1. Injection 50 - 100 Hz (Same amplitude in vibrator)
As you can see, the IFI leg2 response was largest and widest.
Some resonant frequency around 70 Hz?

Fig.2. Injection 100 - 200 Hz (Same amplitude in vibrator)
Only green(minux X minux Y leg) showed the 107 Hz large amplitude.
All legs have 128 amplitude

Fig.3. Injection 200 - 300 Hz (Same amplitude in vibrator)
Green and Brown (minux Y side leg) have large amplitude in 217 Hz
Behavior of the acclerometer spectrum was different between ea h color.

I also injected the vibration 400 - 500 Hz, but no significant excess was detected.