Komori, Dan, Sugioka, Tanaka

(Background will be written in Sugioka-kun's log.)

We performed a coil balance for ITMY TM coils. 

We excited each H1 and H2 coil with a 12 Hz sine wave injection, and a H1 gain adjusted so that an amplitude of the 12 Hz Pitch motion only with the H1 coil was same as the one only with the H2 coil. This time, ITMY was in the PAY_FLOAT state Similarly, we adjusted a H3 gain so that an amplitude of the 12 Hz Yaw motion only with H3 coil was same as the one only with H4 coil. (Note: This time, we chose each reference coil, H2 and H4 so that the other coil gain become smaller than 1 to avoid the saturation.) Figure 1 shows the results of this balance Brown lines in the middle and lower panels is the spectra of each Pitch and Yaw motion after the balance and the brown peak heights in each panel seems to be the same as the green peak heights in each panel.

Figure 2 shows the COILOUTF medm screens before (left) and after (right) the balance. 

After the balance, we excited TM in the L direction with 12 Hz sine injection (amp.: 10000 cnts) by using all 4 coils to check the coupling between L and others became lower or not. Fig. 3 shows the results, reds are spectra of each oplev signals before the balance and blues are the ones after the balance. the L2P coupling seems to become slightly lower after the balance. On the other hand, the L2Y coupling seems to be the almost same.