Agenda and Minutes, 16 June 2008
Agenda: Tues, 16 June 2008
We will meet with Adrian and Stefanos to discuss environmental correlations and timing.
Attending: Virginia, Stefanos, Adrian, Warren, Robert - Environmental correlations : high frequency magnetic fields in LVEA which couple into one interferometer and probably into both (Robert was only able to measure one). There are features in the spectrum from these - the features wander in frequency. This is at 37.5 kHz region - 75 kHz is worse. Robert suspect that these are VEM crate and power supplies. Robert would like paper to acknowledge this and account for it. There were no PEMs during S5 at this frequency, so it is a special case. Only 37.5 kHz being analyzed, 36,864 line. Robert wants a more detailed analysis of coherence - high resolution and broader band. Broader band can only be done with fast channel, quite difficult. High resolution is agreed to be a good idea. Coherence is clean, but what about canceling positive and negative contributions? Adrian says that changing phase of H1 acts in similar way to overlap reduction function and can be used to make argument of implausibility (as with H1-L1). Warren and Robert suggest that everything that can be done for this should be done. They also suggest trying to marginalize over possible cancelations of anti-correlated nois and correlated signal. - Stefanos describes method of correlating FSR and ASQ. Warren wants to know why sinc function width is more than resolution. Is the line wandering? No, plot of phase differences between H1 and H2 0FSR shows constant phase diff to within 1 microsecond (distribution not explicitly plotted). Adrian points out amplitude variation calculation that we have not got to in review yet. - Stefanos and Adrian will provide us a technical document with more of these issues discussed and clarified.
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