GINGER - Toward an experimental test of General Relativity

GINGER (Gyroscopes IN General Relativity) is a proposal for measuringthe Lense-Thirring effect using an array of ring laser-gyroscopes. Those are,nowadays, the most sensitive inertial sensors to measure the rotation rateof the Earth.The Lense-Thirring contribution to the Earth gravitational field marks itself as a tinDC perturbation onto Ω Ω, the Earth rotation rate. Its magnitude is 10−9×Ω−9×Ω so that to be able to discriminate it a very high sensitivity andlong measurement times in order to move toward low frequency are required. For such an experiment, an undergroundlocation guarantees further isolation from anthropic as well as environmentaldisturbances.GINGERINO is a single axis ring laser located inside the theINFN 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.