The principle is "Multiple Coulomb Scattering", and there is a nice brief overview of that in <https://arxiv.org/abs/2212.04947 https://arxiv.org/abs/2212.04947

The principle is "Multiple Coulomb Scattering", and there is a nice brief overview of that in <https://arxiv.org/abs/2212.04947 https://arxiv.org/abs/2212.04947> notably in fig. 1 and fig. 2. There are even more gory details at <https://sci-hub.se/https://doi.org/10.1016/j.nima.2015.06.054 https://sci-hub.se/https://doi.org/10.1016/j.nima.2015.06.05...> (s c y h o b link to Anghel et al 2015, a Canadian muon tomography experiment interested in detecting high atomic number elements for e.g. anti-proliferation/anti-smuggling purposes).