A Ground-Bas ED Squid Magnetometer

Over the past five years, our group has focused on development of airborne magnetic and<br>electromagnetic systems for mapping and detection of unexploded ordnance (UXO). Among<br>these projects is one involving testing and development of a high temperature airborne<br>Superconducting Quantum Interference Device (SQUID) tensor magnetometer. In association<br>with the airborne SQUID development, we are conducting tests of the SQUID as a ground-based<br>instrument for UXO mapping and detection.<br>The ground-based SQUID is mounted on a man-portable litter with ancillary<br>instrumentation mounted on a cart and connected by an umbilical. High-temperature SQUIDs<br>use liquid nitrogen as the cryogen, which is more convenient than the helium-cooled lowtemperature<br>devices. Preliminary data from the ground-SQUID prototype show good agreement<br>with cesium vapor total magnetic field data along a test line. Noise frequencies and levels<br>appear manageable and we anticipate that specialized processing should make it possible to<br>extract more details about UXO items from their tensor magnetic properties.