Integrated gradiometer with large Β SQUID

An integrated thin-film dc SQUID gradiometer utilizing large β SQUIDs is designed. A damping resistance in shunt with a SQUID inductance is introduced in order to improve the performance of large β SQUIDs. Usefulness of the damping resistance is verified both theoretically and experimentally, so that we can use large β SQUIDs without significant degradation of performance. Large β SQUIDs simplify a configuration of the coupling section between an input coil and the SQUID, and will be a useful method to realize both an efficient magnetic coupling and a high balance of the gradiometer.