Reports until 13:04, Wednesday 27 January 2016
H1 DetChar (DetChar, ISC)
thomas.massinger@LIGO.ORG - posted 13:04, Wednesday 27 January 2016 (25202)
Post-O1 update on RF45 glitches

TJ, Laura

We've been working on tracking the RF45 glitches to veto them out of the astrophysical searches. We were initially tracking the control point of the RF45 MHz amplitude stabilization loop, H1:LSC-MOD_RF45_AM_CTRL_OUT_DQ, which seemed to be correlated with the severe glitching in DARM. However, as O1 progressed we noticed that the monitors we had built for this channel were missing some periods of severe glitching in DARM that we recognized as RF45 glitches. During these periods, the 45 MHz amplitude stabilization loop control point was completely quiet, but glitching was evident in MICH alignment degrees of freedom and DARM.

Since then, we've found that the most consistent witness to the RF45 glitches is a vertex alignment control signal, H1:ASC-AS_B_RF36_I_YAW_OUT_DQ. This signal is correlated with the glitches in DARM even when the 45 MHz amplitude control signal shows no discernable features. We've never seen any activity in the 9 MHz amplitude control signals during these glitchy periods. It doesn't seem like the amplitude stabilization of the 45 MHz sideband is the root cause of the noise in DARM, perhaps it's more of a witness to a broader issue in the RF electronics that commonly impacts generation of the 36 MHz signal.