Integrated SQUID gradiometers for measurement in disturbed environments

Abstract

Planar dc SQUID gradiometers with integrated antenna were designed and investigated. With low-T/sub c/ superconductors they were realized as washer type and as transformer type SQUID gradiometers. With high-T/sub c/ superconductors we tested galvanometer SQUIDs. Field gradient sensitivities of 32 fT/(cm/spl radic/(Hz)) could be achieved with low-T/sub c/ SQUIDs and of 520 fT/(cm/spl radic/(Hz)) with high-T/sub c/ SQUIDs, respectively. All types of gradiometers could work stable in disturbed environments. The influence of the SQUID gradiometer layout and the construction of the sample holder on the degree of disturbance suppression is shown.