Anomalous low frequency dissipation processes in metal springs

The dissipation processes of leaf springs used in seismic isolation chains of Gravitational Wave detectors have been studied. A low frequency phase transition from visco us-like to fractal-like dissipation, controlled by Self Organized Criticality of dislocations, was observed. The new understandings suggest different best practices for the operations of the seismic isolation chains of the second generation of Gravitational Wave observatories and require new techniques and materials for the third generation.