GINGER - Toward an experimental test of General Relativity

Abstract

GINGER (Gyroscopes IN General Relativity) is a proposal for measuring the Lense-Thirring effect using an array of ring laser-gyroscopes. Those are, nowadays, the most sensitive inertial sensors to measure the rotation rate of the Earth. The Lense-Thirring contribution to the Earth gravitational field marks itself as a tiny DC perturbation onto $\Omega$, the Earth rotation rate. Its magnitude is 10$^{-9} \times \Omega$ so that to be able to discriminate it a very high sensitivity and long measurement times in order to move toward low frequency are required. For such an experiment, an underground location guarantees further isolation from anthropic as well as environmental disturbances. GINGERINO is a single axis ring laser located inside the the INFN Gran Sasso laboratory. It has demonstrated that the very high thermal stability of the cave allows continuous operation, and sensitivity well below fractions of nrad/s are feasible with duty cycle above $90\%$ even without stabilisation of the scale factor of the ring laser. Here we show the GINGER experiment concept together with the first evaluation of the GINGERINO sensitiviy that shows how such a device can be of use also in earth science and related phenomena.