3-mode detection for widening the bandwidth of resonant gravitational wave detectors

TL;DR

This paper introduces a novel 3-mode detection scheme for resonant gravitational wave detectors, significantly increasing their bandwidth and demonstrating improved sensitivity with a two-stage SQUID amplifier on the AURIGA detector.

Contribution

It presents the first implementation of a capacitive resonant transducer matched via a high Q electrical resonator, expanding the operational bandwidth of gravitational wave detectors.

Findings

Bandwidth increased to over 110 Hz

Spectral sensitivity better than 10^-20 Hz^-1/2

Successful integration with AURIGA detector at 4.5 K

Abstract

We have implemented a novel scheme of signal readout for resonant gravitational wave detectors. For the first time, a capacitive resonant transducer has been matched to the signal amplifier by means of a tuned high Q electrical resonator. The resulting 3-mode detection scheme widens significantly the bandwidth of the detector. We present here the results achieved by this signal readout equipped with a two-stage SQUID amplifier. Once installed on the AURIGA detector, the one-sided spectral sensitivity obtained with the detector operated at 4.5 K is better than 10^-20 Hz^-1/2 over 110 Hz and in good agreement with the expectations.