Investigation of the Impact of Magnetic Fields on Scattering Muography Images

Abstract

Muography is a non-invasive imaging technique that exploits cosmic-ray muons to probe various targets by analyzing the absorption or scattering of muons. The method is particularly useful for applications ranging from geophysical exploration to security screening, including the identification of nuclear materials. This study leverages both Monte Carlo simulations and the Point of Closest Approach (PoCA) algorithm for image reconstruction to specifically explore the distortions caused by magnetic fields in scattering muography images. In the PoCA algorithm, it is assumed that all scattering of a muon during its travel in material occurs at a single point, known as the PoCA point. Each PoCA point is characterized by a scattering angle, whose distribution provides insights into the density and elemental composition of the target material. However, magnetic fields can influence muon trajectories according to Lorentz law, affecting the estimated positions of the PoCA points and the calculated scattering angles. This introduces challenges in applications such as border security control systems. Moreover, the presence of magnetic fields can lead to what we term "magnetic jamming", where the resulting muography image is distorted or misleading. This effect further complicates the accurate identification and interpretation of target materials. Our findings underline the necessity to account for magnetic field distortions when utilizing scattering muography in practical scenarios.