J. Kissel, E. Bonilla

I've formally processed Travis' interim transfer functions that he took a few days ago after he and Betsy were approaching happiness about the suspension being free (see LHO aLOG 40585). Both chain's results are interesting:

Main Chain:
   - I see some high Q cross coupling on the higher frequency resonances that I don't like between 2 and 3 Hz. M0 P to P shows it the worst, and it seems to have R0 T, M0 Y, R0 V, and M0 L modes that aren't expected, and indicate interaction between the chains.  We should look take a look for subtle rubbing at or between the lower stages of the main chain.

Reaction Chain:
   - I've worked with Edgard to get the new model for the AERM reaction chain suspension up and running, and incorporated into the traditional testing & commissioning infrastructure. The required changing several of the files inside the 
       /ligo/svncommon/SusSVN/sus/trunk/QUAD/Common/MatlabTools/QuadModel_Production/
     directory, but all is now functional. 
     I'm excited to say that the model matched the data extremely well right out of the box. Also, the obvious, expected changes between an ERM and an AERM are evident in the middle-frequency modes, most obvious in the Longitudinal and Yaw TFs, which typically only depend on highly controlled parameters -- the mass and lengths of wires. We only had to 
         - adjust the mass of the PenRe (Reaction Mass' PUM) to what Betsy reports in LHO aLOG 40291, (from 65.1 to 64.356 / kg)
         - update the PenRe's Pitch and Yaw (and associated off-diagonal) moments of inertia to match -v5 of T1500563, 
         - fiddle with the Roll moments of inertia for the PenRe and Annular Reaction Mass itself (I2x from 0.998 to 0.6 / kg.m^-2, I3x from 0.3064 to 0.4 / kg.m^-2)
     in order to get the data to match as well as shown. The metrics for success (and what originally didn't match well) were the T / R modes (now modeled) at 0.91 and 2.68 / Hz. The latest model parameter set is committed to 
         /ligo/svncommon/SusSVN/sus/trunk/QUAD/Common/MatlabTools/QuadModel_Production/quadopt_aerm.m
    The biggest descrepancy from the model is the Pitch transfer function, but we've seen this with every reaction chain type -- the ESD, PUM adn UIM OSEM cabling have always significantly altered / stiffened up the Pitch TF. No surprise or alarm there.
    Nice -- glad to see a new suspension type measured and successfully compared to its first-principles model!

    But, we've still got some work do to before we're happy with the dynamics and are confident the isolation stages are free.