Resonant detectors for the search of gravitational waves

An overview of the experiments for the search of gravitational waves by means of resonant detector is given. Since 1990 cryogenic resonant antennas have been in operation and data have been recorded by Explorer, Allegro, Niobe and Nautilus. The sensitivity for pulse detection with SNR = 1 is now h ≅ 6 10-19 (corresponding to a total energy of less than 0.001 solar masses for a source in the Galactic Center). The sensitivity for monochromatic waves is h ≅ 2 10-25 for one year of integration and about 7 10-22/√Hz for a stochastic background detection. Large resonant detectors operating at 1 kHz might reach a spectral amplitude sensitivity of the order of 7 10-24/√Hz and h = 3 10-22 and h ≅ 10-27. Cross-correlating two of such large antennas for one year can give a sensitivity for stochastic background detection of the order of 3 10-26/√Hz corresponding to a ratio between the gw energy density to that needed for a close Universe of 10-6