Performances of 'G-Pisa’: a middle size gyrolaser

G-Pisa is an experiment dealing with a high sensitivity laser gyroscope with an area of the order of 1 m 2 . It aims at improving the performances of mirror suspensions of the future-generation gravitational-wave antenna Virgo. The experimental set-up consists in a He-Ne ring laser with a four-mirror square cavity. The device is operational on a stable regime, with the laser operating in both single mode or multi mode. The low-frequency sensitivity, 0.001-1 Hz, is limited by the environmental noise, but it has been checked that the requirements for the inverted pendulum tilt control given for AdVirgo are fulfilled (10 -8 rad Hz -1/2 at 30 MHz).