This morning, B&K hammer measurements were carried out on SR2 suspension cage located in HAM4. Attached plots are comparing SR2 force to acceleration transfer functions in two degrees of freedom X and Y (respectively corresponding to Longitudinal and Transverse suspension's euler basis -not global coordinates-), with similar measurements carried out on MC1 MC3 PRM.

The main/lowest structural resonance below 150Hz (97Hz in both directions) is well damped, and the Q is comparable with the one from other suspension cages.

[Method]

HEPI and ISI were unlocked during the measurement. A tri-axis accelerometer was mounted on the top corner of the structure (as shown in the picture). Data acquisition was made with the Pulse software on the windows laptop, and the template used was copied from T1000697, using a hammer trigger threshold of 10N.

Data collected lives under the svn in

/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/SR2/BandK