- 7:19 silent run
1. Large vibration injection
To evaluate how large vibration can be performed in OMC area, I turned off the BPC controls and inject the signal
Excitation : K1:PEM-EXCITATION_SR3_RACK_7_EXC
Reference PEM : K1:PEM-ACC_OMC_CHAMBER_OMCLEG_Z_OUT_DQ
02/05 07:27 - 07:47
Sweep the 900 - 1 Hz, 600 s, 100 cnt, 2 times injection
Fig.1. showed the whitened spectrogram.
During this measurement, no locked loss detected. so it would be the large vibration for each frequency.
2. For the evaluation of the noise projection from OMC bellows leg
02/05 08:26 - 09:23(?) Locked loss happened around 09:23 due to the earthquake, stopped the injection around 130 Hz
Swept sine 400 - 50 Hz, 1 Hz resolution, 10 s in each frequency, 10 cnt
Before this injection, I performed the 100 cnt injection, but it seemed too large vibration, the DARM sensitivity always bad, so I reduced the injection amplitude (100->10 cnt)
Even the 10 count injection, the amplitude is more than 10 times larger than background (8 s FFT)
(10 cnt would be something small below 200 Hz, so we will perform to apply the envelope with checking the amplitude tomorrow)
I plotted the Spectrograms and ASDs for the "1. Large vibration injection" tests.
Ground Vibration ASDs:
- Blacks: Median ASDs for the reference time (No injection)
- Reds: the Max valuses along the time during this test
- So each points are "the peak height of a single line injection, individually", not a simultaneous broadband injection spectrum
- Dark color lies: Seismometer (Z) below the OMC chamber
- Light color lies: Accelerometer (Z) on an OMC-bellows-leg foot (transformed to velocity, by dividing by 2πf)
Somehow, the SEIS and ACC responses were not consistent. The ease of shaken would be different between the ground and the leg
I converted the Ground (or Foot) vibration to the OMC in-vac table vibration, by applying the transfer function measured in klog31391
