robert.schofield@LIGO.ORG - posted 23:14, Monday 24 October 2016 - last comment - 23:14, Monday 24 October 2016(30835)
Shaking ISCT1 produced noise, beam diverter now closed
This morning a broad increase in ground motion around 12Hz reduced the range. ISCT1 has a table resonance there so I shook it and noticed that shaking by several times normal produced significant noise (see attached Fig). We switched to REFL B 9I and 45I so that we could close the beam diverter. The coupling went away.
Robert Stefan Jenne Evan
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The Guardian now again uses the REFL WFS for PRC2 by default, and closes the beam diverters. While this didn't change the range much, it seems to have improved the non-staionarity in that frequency band. One down, more to go.