J. Kissel

I've taken the time to export all of the 2017 data from H1 SUS ITMX so I could compare it all and against 2014 data, data other ITMs, and the QUAD model. In short: The data looks consistent with the model, and with all other ITMs. Nice!

I attach 4 sets of plots in support of this, 2 for each chain.
Main Chain (M0): 
    (1) "H1SUSITMX_Phase3 ... ALLM0" This shows the progression of H1 ITMX M0 from the 2014 acceptance measurement to the three measurements from this year, all compared against the QUAD model. For reference I also include L1 ITMY. No major deviations from the model or each measurement. The largest outlier appears to be the 2017-01-17_2134 measurement, but these "extra" resonances are cross-coupling from other degrees of freedom's previous transfer function. For example, the 2017-01-17_2134 Roll measurement contains a good bit of the 0.55 Hz vertical mode, because the Roll measurement was started too quickly after the Vertical measurement, without damping the SUS in between. In the latest measurement (2017-05-22_2056) I took the time and damped the SUS between each DOF's measurement, and et voila! No V resonances in your R measurement.

    (2) "AllITMs_Phase3 ... ALLM0" This shows the latest H1 SUS ITMX measurement against every other ITM main chain. This shows that ITMX is remarkably consistent.

Reaction Chain (R0):
    (3) "H1SUSITMs_Phase3 ... ALLR0" The shows the progression of ITMX R0 from the 2014 measurement to the three 2017 measurements, all compared against the model and L1 ITMY. It is here -- specifically in the Pitch direction that we're reminded that the transfer function looks nothing like the model, but it's because of the cabling down the reaction chain that's not included in the model. The only other mildly suspicious feature is the changes in Q of the 2nd, 0.8 Hz Longitudinal mode, but I think this again depends on how excited these modes are before the measurement, and there's some mixing between the 0.79 Hz Pitch mode -- unpredicted by the model because of the cabling.

    (4) "AllITMs_Phase3 ... AllR0" This comparison is the best reminder that the Pitch TF is a function of the cabling on the reaction chain. The fifth page shows the nice rainbow of the 2nd pitch mode (modelled to be 1.34 Hz) across the various builds of the suspension throughout the project.

So -- other than its alignment, I think this SUS is ready for an IFO.

One more thing to note: since there is little to no difference between the 2017-05-16_2345 and 2017-05-23_0047 measurements, this would argue that we no longer need the 150000 V or -5000 P offsets from a rubbing stand point. Perhaps we can assess and explore removing them once we get back to a comfortable BNS sensitivity.