gabriele.vajente@LIGO.ORG - posted 13:38, Saturday 06 June 2015 - last comment - 14:49, Saturday 06 June 2015(18935)
Brute force coherence report
The BruCo report for the improved sensitivity can be found here:
https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1117636216/
Some highlights:
- SRCL is now the winner between 20 and 70 Hz (plot 1)
- Coherence with intensity noise (ISS_SECONDLOOP) is quite large, expecially at the jitter peaks (plot 2). This confirms Robert's conclusion that the IMC alignment is likely no more good
- Coherence with calibration lines is high on a rathe large band (34-37 Hz, plot 3). Are we injecting multiple lines close to each other?
- Magnetic line at about 75 Hz from EY (ring heater? plot 4)
- Coherence with POP signals (RF9_Q and LF) is rather large everywhere (plot 5 and 6). I don't have any good explanation for this (frequency noise, intensity noise, quantum-correlated shot noise into the IFO?). This coherence is high with POP9_Q, POP18_I, AS_A_DC_SUM, AS_RF36, and a bit lower with POP45. There's not much coherence with REFL signals.
- At even higher frequencies there is coherence with REFL_9I (plot 7)
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Comments related to this report
Gabriele: I was wondering whether you see any significant differences in coherences between the data pre 2015/6/6 7:32 UTC (pick a good time where we saw about 70Mpc range) and the data after 2015/6/6 8:32 UTC. alog 18931 suggest there was an alignment shift of the signal recycling cavity between them. (I attached the summary page range plot.)
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