Obtaining Schenberg detector frequencies antenna under gravity and misalignment using finite element modeling.

The resonant-mass gravitational wave detector SCHENBERG is a spherical detector that will operate with a central frequency around 3200 Hz with a bandwidth of 100 to 200 Hz. It has a spherical mass that works as an antenna that weighs 1150 kg and is connected to the outer environment by a suspension system designed to attenuate local noise due to seismic as well as other sources of vibration. The sphere is suspended by its center of mass. When a gravitational wave passes by the detector, the antenna is expected to vibrate; this motion is monitored by six parametric microwave transducers whose output signals are digitally analyzed. In order to determine the detector performance better, it is necessary to obtain the vibration frequencies of the sphere with a better precision. To achieve such a goal the sphere with the holes to mount the transducers and the central hole from which the sphere is suspended is simulated in a finite element method program when the gravity is applied to the sphere and the deformation is kept. After that the vibration normal modes of the sphere are calculated and they are compared to the experimental results. After that the gravity is misaligned with the suspension of the sphere to simulate the effects of it, then the simulation is done again and no differences were found. [ABSTRACT FROM AUTHOR]