Resonant Detectors for the Search of Gravitational Waves

An overwiew of the experiments for the search of 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 6≈10^19 (corresponding to a total energy of less than 0.001 solar masses for a source in the Galatic Center). The sensitivity for monochromatic waves is h≈2 10^25 for one year of integration and about 7 10-22/√Hz for a sthocastic background detection. Large resonant detectors operating at 1kHz might reach, in a near future, a spectral amplitude sensitivity of the order of 7 10^24/*Hz and, for pulse and monochromatice wave sensitivity, respectively, 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.