The all data summary will appear soon.
1. Fun near the SR cooler on/off(Fig.1.)
There is fun to circulate the air flow near the SR cooler.
Currently it was turned off.
I tried to turn on and off and compare the spectrum
2. SR cooler on/off (Fig.2.)
I put the accelerometer on the frame under the SR cooler and turned on and off the SR cooler.
3. Vibration injection test (Fig.3.)
I injected the vibration by mu leg.
Check the transfer function and coherent
4. FFU(OMC/SRM/SR3) on/off (Fig.4.)
Four FFUs on in each area (OMC, SRM, SR3)
We turned off the all FFUs and compared the spectrum
All frequency above 100 Hz was reduced of factor two and disappeared several peaks.
Especially, 120 Hz reduction is so much! (But increased in 180 Hz??)
Anyway, the vibration level below 200 Hz is very close to O3GK one.
I estimated the OMC ground vibration noise on DARM based on the FFU off data on 2023-02-24.
Red spectrum is always OMC leg.
Coherence is between OMC leg and acc in each place.
Fig.1. mini rack near the OMC
Fig.2. decicator near the OMC
Fig.3. silver rack near the OMC
Fig.4. OMC0 digital rack
Fig.5. FFU controller for OMC area
