sheila.dwyer@LIGO.ORG - posted 20:08, Tuesday 12 May 2015 - last comment - 01:43, Wednesday 13 May 2015(18395)
ITMY roll mode damping
Both the bounce and roll mode were rung up on ITMY.
Roll: freq 13.934Hz damped using AS WFS, a gain of -100dB, bandpass 13.9Hz, and a negative gain around 1. This was done at a CARM offset of 10 pm since the IFO wasn't stable if we tried to go on resonance.
ITMY bounce is damped at M0 with +60 degree rotator and positive gain.
At one point the mode was rung up so high that we weren't making much progress on M0, so we sat at 10 pm CARM offset for a while and instead damped by feeding a bandpassed version of DARM error onto ITMY L2 (0 degrees of phase and positive gain, but since this is the DARM error point, these settings aren't necessarily very repeatable).