GINGER

摘要

The Gross Ring G is a ring-laser, it is located in the geodetic observatory of Wettzell. It has demonstrated that a ring laser has a sensitivity and stability such to measure the Earth rotational rate with the relative precision of 5 part in 10~9 and a long term stability of 3 hours. The GINGER project is intending to take this level of sensitivity further and to improve the long-term stability. A factor of about 10 improvement in sensitivity could allow the observation of the frame dragging produced by the Earth rotating mass (Lense-Thirring effect), and predicted by General Relativity. At the same time GINGER will provide a local measurement of the Earth rotational rate with a sensitivity comparable to that of the International Earth Rotation and Reference Systems Service (IERS). In GINGER the stability of each ring and the relative alignment of the different rings play a crucial role. Therefore the preliminary goal is the demonstration of the feasibility of a larger gyroscope structure, where the mechanical stability is obtained through an active control of the geometry. A ring-laser prototype (GP-2) has been set up in Pisa in order to develop and test the active control of the ring geometry, while a second apparatus (GINGERino) has been installed inside the Gran Sasso underground laboratory in order to investigate the seismic noise of the site in view of an installation of GINGER. The status of both prototypes is presented.