Future prospects for the University of Western Australia's cryogenic resonant-mass gravitational wave detector

The two-mode resonant-mass gravitational wave (GW) antenna at the University of Western Australia (UWA) is currently operating with a noise temperature of about 2 mK. This low noise temperature is partly due to the successful operation of a readout based on 9.5 GHz superconducting re-entrant cavity. The amplitude and phase noise of the pump oscillator limit the sensitivity of the detector. Newly developed cryogenic microwave oscillators are now available with ultra-low noise levels of -165 dBc/Hz. With the advent of new noise suppression schemes this can be further reduced to -185 dBc/Hz. This type of pump oscillator can reduce the detector noise temperature to 20 mu K. Further improvements to the superconducting re-entrant cavity system are limited. We show by using an ultra-low loss Sapphire Dielectric Transducer the mode temperature can be reduced to about 2 mu K.