Application of quantum magnetometers to security and defence screening

• Main Author: Hussain, S. Y.
• Other Authors: Renzoni, F.
• Published: University College London (University of London) 2018
• Subjects: 500
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.747602

Over recent years the sensitivity of alkali-metal vapour magnetometers has been demonstrated to surpass that of even Superconducting Quantum Interference Devices (SQUIDs), the current commercial gold standard in laboratory weak- field magnetometry sensing. Here we present a proof-of-principle approach to building an RF atomic magnetometer which is robust, portable, tunable, non-invasive and operable at room temperature in an unshielded environment. In view of these characteristics, we discuss the potential application of alkali-metal magnetometry in imaging concealed objects, non-destructive evaluation of the structural integrity of metallic objects (e.g. pipelines and aircraft), and detection of rotating motors. We present a cost-effective approach to operating an atomic magnetometer in a Magnetic Induction Tomography (MIT) modality, to non-invasively map the conductivity of conductive objects concealed by conductive materials remotely and in real time. This is achieved by measuring the secondary eld in the subject due to eddy currents circulating as a result of application of a tunable radio-frequency oscillating eld, which overcomes the bandwidth and sensitivity limitations of using coils for sensing as in conventional MIT. In addition, we demonstrate the use of the atomic magnetometer for the remote detection of DC and AC electric motors with an improved response compared with a commercial fluxgate magnetometer in the sub 50 Hz regime (particularly detection down to 15 Hz). Its capability for non-invasive measurement through concrete walls is established, with potential for use in industrial monitoring and detection of illicit activity. Finally, the possibility of detection of submerged targets or for the atomic magnetometer to be mounted on submarine vehicles was explored. Promising results were obtained, but further investigation is required in this environment to establish this as a viable marine detector.