Reports until 04:46, Sunday 25 October 2015
LHO General (PEM, SUS)
corey.gray@LIGO.ORG - posted 04:46, Sunday 25 October 2015 - last comment - 06:33, Sunday 25 October 2015(22808)
Mid Shift Summary: Violin Mode Work

State:  Out of Observation Mode and at DC_READOUT for Violin Mode work.

As noted earlier, we had rung up violin modes.  Kiwamu is now on site.  We are pausing Guardian so we can address the ETMy 2nd order violin mode.  (was not sure what to mark this as with Observatory Mode....used Preventative Maintenance at first, but then switched to Corrective Maintenance.   We will stay here until we are able to bring down these huge violin modes.

Comments related to this report
kiwamu.izumi@LIGO.ORG - 06:33, Sunday 25 October 2015 (22810)ISC

No success so far.

It seems that there are two modes close to each other separated by roughly 46 mHz according to the beatnote I see in the damping signal.

Having +120 deg with a gain of -4500 allowed us to damp one of them while the other rung up. The nominal gain setting seems to bring us to some kind of equilibrium state where the two modes neither ring up nor down, perhaps it is very slowly ringing up.

The 1st stage of the OMC whitening is currently OFF in order to prevent the DCPD from saturation. This must be ON when we turn into observation.