# Sensitivity of the spherical gravitational wave detector MiniGRAIL operating at 5 K - General Relativity and Quantum Cosmology

Abstract: We present the performances and the strain sensitivity of the first sphericalgravitational wave detector equipped with a capacitive transducer and read outby a low noise two-stage SQUID amplifier and operated at a temperature of 5 K.We characterized the detector performance in terms of thermal and electricalnoise in the system output sygnal. We measured a peak strain sensitivity of$1.5\cdot 10^{-20} Hz^{-1-2}$ at 2942.9 Hz. A strain sensitivity of better than$5\cdot 10{-20}Hz{-1-2}$ has been obtained over a bandwidth of 30 Hz. We expectan improvement of more than one order of magnitude when the detector willoperate at 50 mK. Our results represent the first step towards the developmentof an ultracryogenic omnidirectional detector sensitive to gravitationalradiation in the 3kHz range.

Author: L. Gottardi, A.de Waard, A.Usenko, G.Frossati, M.Podt, J.Flokstra, M.Bassan, V.Fafone, Y.Minenkov, A.Rocchi

Source: https://arxiv.org/