J. Kissel

I'm headed into the optics lab to tune the Bounce / Roll Dampers (BRDs) for ITMX, so I want to reconfirm the measurements of the highest vertical (a.k.a. "bounce") and roll modes of the newly suspended ITMX. The previous measurement of the highest vertical & roll modes (LHO aLOG 39106) was taken while the SUS was still rubbing all over and poorly aligned. Travis and Betsy worked hard yesterday to find that the majority of Top to Top mass transfer functions were clean (barring a believed malfunctioning F1 sensor); aLOG pending. 

The results are reported below (and ASDs of the PUM/L2 and UIM/L1 stage are attached). 

Meas Date     2017-10-20      2017-10-31
V4 [Hz]         9.8022          9.8056
R4 [Hz]         13.927          13.927

The frequency bin width of both measurements is 0.5 mHz, and the effective bandwidth is 0.732 mHz.

The bounce frequency has increased ever-so-slightly (9.8056 - 9.8022)/9.8022 = 0.00035 (i.e. 0.03% increase), but the roll mode remains the same. Given our ability to tune the BRDs is at the 1% level, I expect / will be happy to get something between the 9.8056 .* (1 + [0.01 -0.01]) = [9.9037 9.7075] range.