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We describe an innovative, dual-mode, fluxgate-induction sensor (FIS) that combines a DC magnetometer and an electromagnetic (EM) sensor. This sensor will enable one-pass unexploded ordnance (UXO) detection and discrimination using the joint measurements. The FIS is based on a [Formula: see text] long, high-permeability magnetic core and a sensing coil that are shared by both EM and magnetic (MAG) modes. This integration makes the sensor very compact and removes the potential crosstalk problem of the core material of one sensor dominating the response of the other. A prototype receiver was developed and true serial, dual-mode operation demonstrated. The FIS achieved sensitivities of [Formula: see text] rms in MAG mode and [Formula: see text] at [Formula: see text] in EM mode, which compare favorably to existing commercial instruments. Triaxial dipole modeling confirms that three-component EM data are better for shape characterization than one (vertical) component. Assuming axisymmetry, inversions of three-component EM measurements of 22 cylindrical and disk-shaped targets yielded 100% correct classification of UXO-like objects (cylinders) and 38% misclassification of disks as cylinders. Degraded classification performance with increasing vertical distance may be caused by the small cross-sectional area of the FIS; an array will provide better field sampling. Triaxial dipole modeling of the MAG data confirmed its utility for detecting deeper targets using only the vertical component. Based on these results, the FIS is ready for field demonstration and validation.

Disclosed technology can provide a process for generating reconstructed muon image resolution to optimize the use of the limited angular range muon track data collected by a muon tomography system. In one aspect, a process for improving reconstructed muon image resolution for a volume of interest (VOI) imaged by a muon tomography system includes: collecting raw muon track data of cosmic ray muon tracks passing through the VOI; grouping the raw muon track data into two or more subsets of tracks based on at least one angular distribution of the muon tracks in the raw muon track data; generating a set of images of the VOI based on the two or more subsets of tracks; and combining information from the set of reconstructed images and a reconstructed image based on the full set of the raw muon track data to obtain a resulting reconstructed image of the VOI.