A superconducting gravitational radiation antenna

In this paper we describe the superconducting gravitational radiation antenna being developed at the University of Western Australia (UWA) with particular reference to its high Q properties and the low loss mechanical filter used to support it. Recent measurements of the acoustic quality factor, Q, of the fundamental longitudinal mode of the bar are reported. It is shown that the Q is sufficiently high that it will not contribute significant noise to the antenna until the transducer becomes ´quantum limited´. We also report measurements on a smaller sample down to 0.4 K in which we observe that Q^-1the acoustic loss, decreases exponentially with T^-1between 2 K and 0.4 K.