Resonant gravitational wave antennas for stochastic background measurements

The sensitivity of a resonant gravitational wave (GW) antenna is calculated in terms of spectral density and frequency bandwidth. For a quantum-limited detector the bandwidth might reach values greater than 100 Hz, with a sensitivity to bursts of h = 3 x 10(-21) (SNR = 1). The spectral amplitude sensitivity for the Nautilus detector has been measured to be 7 x 10(-22) Hz(-1/2) and its target value is 7 x 10(-23) Hz(-1/2). Using two near-Nautilus detectors the GW stochastic background can be measured with a sensitivity, with respect to the critical density, of a few 10(-5) for an integration time of one year, as shown by simulations.