Resonant detectors for the search for gravitational waves

An overview of the experiments for the search for gravitational waves by means of resonant detectors 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 approximate to 6 x 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 approximate to 2 x 10(-25) for one year of integration and about 7 x 10(-22) Hz(-1/2) for stochastic background detection. Large resonant detectors operating at 1 kHz might reach, in the near future, a spectral amplitude sensitivity of the order of 7 x 10(-24) Hz(-1/2) and, for pulse and monochromatic wave sensitivity, respectively, h = 3 x 10(-22) and h, 10(-27). Cross-correlating two such large antennas for one year can give a sensitivity for stochastic background detection of the order of 3 x 10(-26) Hz(-1/2), corresponding to a ratio between the gravitational wave energy density to that needed for a closed Universe of 10(-6).