MI2021 - 17 Michael Grappone: A prototype, three-axis automated stepwise thermomagnetometer
Channel: MagNetZ
Date: 18/02/2021

SMARTr: A prototype, three-axis automated stepwise thermomagnetometer system

Michael Grappone, University of  Liverpool, UK

Investigating the Earth’s magnetic field provides a unique window into the history of Earth’s outer core, where the field is generated. Given the ages of rocks commonly studied (millions to billions of years old), paleomagnetic data are often noisy and complex. Paleomagnetic intensity data, in particular, have long been plagued by large and poorly quantified uncertainties. Extracting accurate magnetic measurements relies on having the most advanced equipment and best experimental techniques. Modern paleomagnetic equipment is highly accurate but can be slow. Therefore, new, faster equipment is necessary to increase the amount of data generated to maximize the fidelity of paleomagnetic surveys.This novel magnetometer system’s name summarizes its functions: Superconducting Magnetometer for the Automated Recording of Thermoremanence. SMARTr automatically measures the remanent magnetic field of a specimen at an elevated temperature (up to 600°C) without needing to cool the specimen to room temperature. Without repeated heating/cooling cycles, thermochemical alteration is minimized, and the rate of data collection is greatly increased. Preventing the specimen from cooling ensures that low blocking temperature components remain unblocked and thus do not influence the data at higher temperatures. The system uses radio frequency superconducting quantum interference devices (RF SQUID sensors) that operate in a liquid nitrogen bath. These sensors provide a sensitivity between that of a fluxgate system and that of a liquid helium DC-biased SQUID system.The prototype sensor uses two RF SQUID sensors to generate full vector (three-axis) magnetic data. Paleodirectional data and specialized “Walton-style” paleointensity data are presented herein; they have been generated using real specimens given laboratory TRMs. Going forward, the best technology and appropriate methods will allow large, outstanding questions in geosciences to be solved through paleomagnetism.