Tunable mechanical monolithic horizontal sensor with high Q for low frequency seismic noise measurement

Abstract

A tunable mechanical horizontal monolithic seismometer/accelerometer, developed for applications in the fields of geophysics and interferometric detection of gravitational waves of second and third generation, is described. The large measurement band (10−3 ÷ 10 Hz) with sensitivities of ≈ 10−12m/, as seismometer, and better than 10−11 m/s2/, as accelerometer, have been obtained with an optimised mechanical design and the introduction of a very sensitive laser interferometric optical readout, the latter aimed also to ensure a very good immunity to environmental noises. Prototypes of seismometers are operational in selected sites both to acquire seismic data for scientific analysis of seismic noise and to collect all the useful information to understand their performances in the very low frequency band (10−6 ÷ 10−3 Hz).