Calibration and sensitivity of resonant-mass gravitational wave detectors

A. Morse, Louisiana State University
W. O. Hamilton, Louisiana State University
W. W. Johnson, Louisiana State University
E. Mauceli, Louisiana State University
M. P. McHugh, Louisiana State University


Every gravitational wave detector needs reliable methods for quantitative tests of its performance. We have tested the ALLEGRO gravitational wave antenna with a capacitive transducer which can apply a force to the antenna. A model that incorporates mistuning of the two normal modes of the antenna is needed to properly understand its operation and to explain previous discrepancies in calibration responses. We write the transfer functions for driving point response, signal response, and noise response in terms of a parameter θ which includes all of the mistuning. Using the “reciprocity method,” we determine θ and the force-voltage constant of the force generator. Using diagnostic criteria developed from a full multimode description, we are able to identify the location of an additional parasitic resonance and determine its quantitative effect on the results. Experimental results are presented. © 1999 The American Physical Society.