Ushiba, Tanaka

We performed TF measurements from IMC WFSs to DARM by shaking IP1 and IP2 PZTs. However, since many earthquakes were occured during the today's commissioning time, we could not performed the measurement from IP2 YAW to DARM. As for other DoFs, we did them. Fig.1-3 show the result. 

Then, we performed the noise projection from IMC WFS1 PIT/YAW to DARM by using TF results from WFS1 to DARM by shaking IP1. Fig. 4 shows the result, red curve is the DARM spectrum. blue curve is the projection of WFS1 PIT and green curve is the projection of WFS1 YAW  According to the projection result, some peaks, for example ~152 Hz, ~281 Hz, seem to be cauesd by the jitter in PSL. However, the some peaks' height, especially around 330 Hz and 360 Hz seem to surpass the DARM spectrum. The one of possibilties is that the coherences from WFS to DARM by shaking IPs are not enough at the first place. So we may need to increase the coherece by increasing the excitation amplitude or the average time. Or the other is that WFS1 signal is not decoupled among their WFSs. So we may use the decouled sensor (DOF{4,5}_{P,Y}_IN1) instead of WFS1 and WFS2.