J. A. Ortega | Searcharxiv

arXiv1998

Viscoelastic effects in a spherical Gravitational Wave antenna

Internal friction effects are responsible for line widening of the resonance frequencies in spherical gravitational wave detectors, and result in exponentially damped oscillations of its eigenmodes with a decay time which is proportional to the quality factor of the mode and to its inverse frequency. We study the solutions to the equations of motion for a viscoelastic spherical GW detector based on various different assumptions about the material's constituent equations. Quality factor dependence on mode frequency is determined in each case, and a discussion of its applicability to actual detectors is made.

gr-qc↗

arXiv1997

A hollow sphere as a detector of gravitational radiation

The most important features of the proposed spherical gravitational wave detectors are closely linked with their symmetry. Hollow spheres share this property with solid ones, considered in the literature so far, and constitute an interesting alternative for the realization of an omnidirectional gravitational wave detector. In this paper we address the problem of how a hollow elastic sphere interacts with an incoming gravitational wave and find an analytical solution for its normal mode spectrum and response, as well as for its energy absorption cross sections. It appears that this shape can be designed having relatively low resonance frequencies (about 200 Hz) yet keeping a large cross section, so its frequency range overlaps with the projected large interferometers. We also apply the obtained results to discuss the performance of a hollow sphere as a detector for a variety of gravitational wave signals.

gr-qc↗