Crosscorrelation measurement of stochastic gravitational waves with two resonant gravitational wave detectors

We report on the crosscorrelation analysis of the data recorded by the gravitational wave (g.w.) resonant detectors Explorer and Nautilus, performed to obtain information on the g.w. stochastic background. We found that the quantity Omega(gw)(f), that measures the closure of the Universe, is Omega(gw)(f) less than or equal to 6.10, at 907.20 +/- 0.05 Hz, where the factor 10 is obtained by the crosscorrelation analysis and the factor 6 takes into account the distance (similar or equal to 600 km) between Explorer and Nautilus. This is the first experiment where the data of two g.w. cryogenic resonant detectors are crosscorrelated.