Comparison of Laboratory-Based Multi-Frequency Systems for Measuring Magnetic Susceptibility

Magnetic soils can have significant influence on instruments that are used for detecting<br>unexploded ordnance (UXO) as well as landmines. Magnetic susceptibility is a measure of the degree to<br>which a material can be magnetized. Magnetic viscosity is the frequency dependence of the magnetic<br>susceptibility and is normally characterized as the percentage difference of the magnetic susceptibility at<br>two frequencies separated by one decade (e.g. 465 Hz and 4.65 kHz). This may be too simplified of an<br>approach. Queensland Magnetic Research has built a prototype magnetic-susceptibility-measurement<br>system (MAGNASAT) that can measure the magnetic susceptibility of a small soil sample at multiple<br>frequencies ranging between 10 Hz and100 kHz. The comparison between the Queensland Magnetic<br>Research MAGNASAT and the Bartington MS2 is the focus of this presentation. Six different chemical<br>salts with known magnetic susceptibility values were measured multiple times with each system. The<br>results will demonstrate the accuracy and precision of each instrument. Characterization of a<br>measurement system is an important first step for collecting quality data.