A very low losses superconducting LC resonator

Abstract A superconducting electrical LC resonator has been developed operating at 2 KHz and 4.2 K with a quality factor Q of 10 5 and a coil inductance of 1.6 H . The experimental set-up has been accurately designed to reduce stray losses as much as possible. As detector of the oscillation has been used a commercial r.f. SQUID which permits very high Q measurements without adding losses. Applications to a resonant ultracryogenic gravitational wave antenna and future development are discussed.