Reports until 02:03, Monday 17 August 2015
H1 ISC
sheila.dwyer@LIGO.ORG - posted 02:03, Monday 17 August 2015 - last comment - 04:48, Monday 17 August 2015(20581)
rephasing refl 45 WFS, refl wfs sensing matrix

We had noticed last week that the refl 45 WFS were phased incorrectly, and tonight Jenne and I rephased them by moving PR3 100 counts in pitch.  This only affects the PRC2 loop.  We've locked and engaged the ASC several times since then, and this seems fine.  

While we did improve the phasing and tuned it to within 5 degrees, I is only about 9 dB higher than Q for PR3 motion.  We will need a different phasing strategy, where we phase 45 to minimize the signal from chard in one quadrature if we want to distinguish between PR3 motion and CHARD.

 C

The first two attached screenshots are the phases before we started, except that for REFL A the phase of the first quadrant was -165 not -145.  The following 2 screenshots were the phases we rephased.  For the time being we have reverted. 

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jenne.driggers@LIGO.ORG - 04:48, Monday 17 August 2015 (20586)
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Earlier tonight, we rephased the REFL 45 WFS to be maximally sensitive to PR3 motion, but I think that instead, we should phase them to be minimally sensitive to CHARD motion.