[YokozaWashimi]

We changed the Large sparaker from a JRX212 (60Hz - 20kHz) to a KF92 (11Hz - 200Hz) at the OMC booth.

Tha DAC channel is not changed, K1:PEM-EXCITATION_SR3_RACK_2_EXC

It can emit enough large (BG x100) 20Hz line sound with 10 DAC counts.

Today I tried injecting sound with the low-frequency speaker, but it did not work and its power lamp was red (nominal is green).

So I reconnected the DAC cable to the old speaker.

Since we found the beam duct is the most sensitive part (See klog30466), I located an ACC and a mini shaker on there.
Channels are:

• ACC : K1:PEM-PORTABLE_OMC_RACK_OMC1_ADC0_DSUB15_OUT_DQ
• Shaker : K1:PEM-EXCITATION_SR3_RACK_3_EXC (up to 200 count)

CAUTION

This setup is temporal one and the cables are running the floor.
Please be careful if you work here. 

[Takano, Washimi]

We performed shaker injection tests for the OMMT-OMC duct, remotely from the control room.

Fig.1 is the spectrograms of 70-200Hz and 70-100Hz swept sine injection test. DAC amplitude was 40 counts.
At 82Hz and 92Hz, broadband excess were found in the OMC TRANS.

Fig.2 and Fig.3 are the results of the single line injection for these frequencies.

 We performed single line shaker injections at 82Hz, for 4 different amplitudes.
 The injection amplitude dependence of the excited noise is also checked.

For the narrow peaks at 142Hz, 164Hz, 208Hz, and 262Hz, I plotted these peak amplitudes as a function of the injected amplitude. 
Only the 164Hz (2nd harmonics) looks a quadratic function, and the others look liner.

I also performed the same analysis for the 92Hz injections. 

Narrow peaks are found at 152Hz, 184Hz, and 272Hz.

Although the coupling from vibration to the OMC TRANS signal is non-linear, that to the OMC Error signal looks linear.

I plotted the TF magnitudes and coherences of ACC->Geophone and Geophone -> OMC Error (40-200Hz and 70-100Hz)

They will be compared to the results of the ground-shaking test, planned for the next week.

[YokozaWashimi]

We disconnected the small shaker (on the bean duct) and connected the larger shaker (on the ground) from/to the DAC output.

Large shaker

• K1:PEM-EXCITATION_SR3_RACK_4_EXC
• 2000 cnt is maximum

[Takano, Ushiba, Tanaka, Washimi]

We performed shaker injection tests for the ground around the OMC chamber.

At first, I tuned the excitation amplitude (70 counts, finally) to make the geophone signal about the same as the duct-shaking (40 counts) last Friday at 82Hz. 
Fig.2 is the comparison between the ground shaking and the duct shaking tests, for the geophone, the OMC error, and the OMC trans. They look almost the same. It means the noise increase by PEM injections is caused by the vibration of the OMC in-vac table.

The injection amplitude dependence of the induced noise for the 82Hz and 92Hz line injections are also performed.

TF measurements for the SEIS(Z) -> Geophone and Geophone->OMC-Err are also performed.

We performed TF measurements up to 500Hz, with the single-bouns configuration. 

However, no significant excess was found in the OMC-Error (and -Trans) over 200Hz injection. 

Fig. 1:   40-500Hz ( 70 DAC counts) swept sine injection
Fig. 2: 240-500Hz (500 DAC counts) swept sine injection

I overplotted the TFs from the Geophone to the OMC error signal of the duct shaking and the ground shaking data (with the X-arm, not the single bounce).

Some differences are found in details.

(This is an analysis of the 7/19 and 7/22 data)

I also checked the TFs from the ground seismometers (X/Y/Z) to the vac-table geophone (Y).
For most frequencies, the amplitude was larger in the ground-shaking than in the duct-shaking case.
It suggests that the vibration from the duct propagates to the optical table through the stacks, rather than short-cutting through something (e.g. cables).

I projected the Geophone signal into the OMC error signal using the TFs in klog30521, measured by shaker injection tests.
For the frequencies the TF value was not measured due to bad coherence, I set 1e-3 counts/(um/s) as an upper limit.

I plotted the spectrograms for the 40-500Hz swept sine ground shaker injection test with single-bounce (klog30511)

We couldn't see any excess in the OMC trans signal except for <100Hz injection.