Noise measurements and optimization of the high sensitivity capacitive transducer of AURIGA

Tests of the new AURIGA readout have recently started in the AURIGA ultracryogenic test facility. The most important modifications, with respect to the previous version of the readout, are a new, heavier, resonant capacitive transducer, the tuning of the electrical mode to the two mechanical ones and the use of a low noise two-stage SQUID amplifier. Results regarding the quality factor and the noise of the transducer mechanical and electrical modes are presented.