Seismic attenuation performance of the first prototype of a geometric anti-spring filter

Next generation gravitational wave detectors, such as an advanced LIGO, will generally require improved sensitivity at low frequency. One of the principal challenges for low-frequency sensitivity is isolation from seismic motion. anical seismic isolation filter specifically studied for the next generation of the LIGO detectors, based on a geometric anti-spring concept, has been developed with the aim to provide thermal noise limited sensitivity to frequencies of 10 Hz. sign and the performance of the isolation filter, mainly for the vertical degree of freedom are discussed.