Detection of Gravitational Waves with Spherical Antennas

We report on an investigation of the possibilities offered by solid resonant spheres to detect gravitational radiation. a spherical detector has isotropic sensibility and can determine the source direction and wave polarization providing vetoes on General Relativity. A deconvolution procedure for a general gravitational wave is described, along with tests and vetoes on the trace and transversality properties of gravitational waves. We find that the sphere's gravitational wave absorption cross section is large at two frequences and that if the wave direction is known, a spherical detector can determine all thesix polarization states predicted by the most general metric theory. Assuming General Reativitiy, a two sphere observatory completes the devolution process, removing the 180^ ambiguity in the source position, enablingthe determination of the gravitational wave speed and providing powerful vetoes on local disturbances. We discuss the sensibility of spheres of different materials and frequences of operation. A 3 metres diamenter Al5056 sphere is shown to be able to reach a 1 ms burst sensibility of h = 6 x 10-22 if operated at the quantum limit.