Chiara, Jenne.

Today we tested the new configuration for ISI motion suppression through CPS feedback. We looked at the effect on MC2, ground motion and IMC; sensor correction was off everywhere.

First attachment shows the plots: we tested the system in OFF status (green trace) and in ON status, with two different 100mHz low pass filters, one called "100 mHz" and it is in blue trace, the other is called "new_lp" and it is in pink trace.  Both filters are shown in the second attachment. We got a factor of about 3 of improvement at 60mHz.

With both filters there is an improvement below 0.1 Hz and the ground motion was always comparable. The new_lp filter already has an AC-coupling; next step will be to apply an AC-coupling also to the 100mHz filter and test again.

We left the system on. To turn it off, the gain on H1:ISI-HAM3_SUSINF_X has to be set to zero. To get here, open ISI -> HAM3 -> OFFLOAD screens.