HTS dc SQUID systems for geophysical prospection

We describe the use of high T, flip-chip de SQUID magnetometers in systems for several geophysical prospection methods, For use in the Transient Electro Magnetics (TEM) method, a one-channel SQUI D magnetometer system (vertical field component) was adapted to rough condi tions in the field, We report on measurements in South Africa over a geophy sically interesting target in real production mode. Transients up to 200 ms could be recorded, which is about a factor of 100 more than with conventio nal coils. For investigation of the magnetic field gradient a two-channel system, buil t as a first-order electronic gradiometer with a baseline up to 1 m was des igned and manufactured, It can be used, e,g,, for surface exploration or fo r archeometry, The system can be moved in the Earth's magnetic field. We ac hieve a common mode rejection of 100, The reasons for the imbalance and the possibility of further improvement of the system are discussed.