Monolithic fused silica suspension for the Virgo gravitational waves detector

Thermal noise in mirror suspension wires is the most severe limit to the low frequency sensitivity of interferometric gravitational wave detectors presently under construction. The pendulum mode mechanical quality factor of the suspension last stage significantly affects the noise level of the detector output. The monolithic design for this suspension stage, using a low dissipation material, is proposed for Virgo. High mechanical Qs and high breaking strengths have been obtained for monolithic fused silica fibers. A low dissipation and high strength bonding technique using potassium silicate bonding is proposed.