Monitoring the acoustic emission of the blades of the mirror suspension for a gravitational wave interferometer

We monitored the acoustic emission activity of the steel blades to be used for the mirror suspension system of a gravitational wave interferometer. We have collected several sets of events getting evidence of a material memory effect (Kaiser effect) associated to the dislocation motion in the steel. This result is more evident when we apply a standard fractal analysis procedure (box counting method) to the timing series of acoustic emission bursts. We conclude that a significant reduction of the emission rate is obtained by applying a few stress cycles to the elastic blades.