Investigation of the Impact of Magnetic Fields on Scattering Muography Images

Abstract

Muography is a noninvasive 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’s 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.