THERMAL NOISE IN MIRRORS OF INTERFEROMETRIC GRAVITATIONAL-WAVE ANTENNAS

We present a direct and very fast calculation of the low frequency tai l of the spectral density of thermal noise due to the thermal motion o f matter in the cylindrical mirrors generally used in gravitational wa ve interferometric detectors. This calculation is based on the method recently proposed by Levin, that we extend to the case of finite mirro rs, allowing one to study the aspect ratio dependence of the noise. Re sults are found in good agreement with those found in heavier precedin g approaches, and provide a useful cross-check. (C) 1998 Elsevier Scie nce B.V.