I compared the IMMT1 trans QPD2 signal(pitch and yaw)
(Blue) Before the install (09:00:00(JST))
(Red) After the install (12:00:00(JST))
Obviously, the signal around 117 Hz can be reduced.
(This is too optimistic result, we need to investigate more!!!!)
I also showed the pictures
Following the Yokozawa-san's original post, I just checked the spectra by my self and compared some, and found strange points.
In Fig. 1,
PRFPMI locked
- Blue 3/22 04:47 UTC
- Brown 3/23 6:29:00 UTC
PRFPMI Unlocked (only IMC locked with IMC ASC)
- Green 3/23 15:00 UTC
- Magenta: 3/24 0:00 UTC
- Red 3/24 03:00 UTC
Fig. 2 is the one that the red curve is removed from Fig. 1 for clearity.
What I found are:
- 60Hz peak and its harmonics can be seen when PRFPMI unlocked. I am not sure if this would be occasional or not, but might be related to electric grounding issue.
- Bumps at 20-30 Hz and 120Hz and 180? Hz can be seen when PRFPMI locked, but not seen when unlocked. Does this fact suggest that these bumpy structure might be introduced via MCL feed around path from CARM???
Diaggui time stamp bug? Against the original post by Yokozawa-san, the time stamp assignment for the red and magenta curves are opposite. If this would be true, locating the sheets on the IFI chamber bellows legs might not be so effective (or at least this instance the noise floor got larger, but in my observation, this seems occasional... I am actually puzzeld.-> due to differet choice of frequeny resolution, according to Yokozawa-san. So breathing...
I showed the spectrogram.
There are so many glitches above 100 Hz.
I may select accidentally not good timing for before IFI work(9:00) and accidentally good timing for after IFI work(12:00), but its spectrum is strongly depend on the glitch.
So, the effect of sound protect sheet is still unknown.
Anyway, please don't believe the spectrum of klog24526
The 128Hz bump, which is suspected to be an environmental noise, is not changed.
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I removed all rubber sheets around 12:00 on 28th March.