J. Kissel

Given the recent success at recovering the interferometer (e.g. LHO aLOGs 45632, 45629), and the pending engineering run, I'm gearing up to craft DTT templates for measuring the DARM loop and its sensing function that are more likely to provide better uncertainty in calibration parameters. One of the sticking points between L1 and H1 calibration analysis in O2 was the difference in frequency vectors over which we'd measured.

As such, I've compared the frequency vectors of latest sensing function measurements between sites. There're some good qualities from each site that we should both do:
(1) L1 has frequency points that directly line up with their calibration lines.
(2) H1 has more densely packed points below 10 Hz in order to better inform the MCMC algorithms that determine the fit SRC detuning spring frequency (f_s) and Q (Q_s) for the reference model.
(3) H1 measures out to 1.2 kHz
(4) L1 has more densely packed frequency points around the cavity pole.
(5) H1's measurement takes 4 minutes for PCAL, and 25 minutes for DARMOLG, for a total of less that a 1/2 hour.

I'll be working on a frequency vector that satisfies all of these good features over the next few days as we measure H1. As soon as I'm happy I'll recommend the same vector to L1.