Geophysical exploration using magnetic gradiometry based on HTS SQUIDs

C. P. Foley*, D. L. Tilbrook, K. E. Leslie, R. A. Binks, G. B. Donaldson, J. Du, S. K. Lam, P. W. Schmidt, D. A. Clark

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    24 Citations (Scopus)

    Abstract

    Magnetic tensor gradiometry provides gradient components of true potential fields which enables unique depth estimates and improves analytic signal methods as well as providing a number of other advantages. A high temperature SQUID (HTS) gradiometer can provide measurements of the components of the earth's field tensor creating a new tool for mineral exploration. A successful comparison between a HTS SQUID gradiometer and a Cs-vapour gradiometer under survey conditions has been conducted. Both instruments were configured vertically. The HTS gradiometer measured the Bzz component of the gradient tensor, while the Cs-vapor gradiometer measured the vertical gradient of the total magnetic intensity. The HTS gradient measurement was the difference in output between two coaxial SQUID sensors. Effective noise levels achieved were 0.16-0.3 nT/m RMS, compared with 0.1-0.5 nT/m RMS for the Cs-vapor system. The SQUID noise was dominated by vibration with additional contributions from the multiplexed sampling between the SQUIDs. This paper reports on the system development, design issues, trial results and the implications for geophysical exploration.

    Original languageEnglish
    Pages (from-to)1375-1378
    Number of pages4
    JournalIEEE Transactions on Applied Superconductivity
    Volume11
    Issue number1 I
    DOIs
    Publication statusPublished - Mar 2001

    Keywords

    • Geophysics
    • Gradiometer
    • HTS
    • Mineral exploration
    • SQUIDs

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