muon tomography

An imaging technique that uses muons — high-energy subatomic particles created when cosmic rays strike the upper atmosphere (and also producible with particle accelerators) — to see inside large or dense objects that ordinary imaging can't penetrate. Muons pass through great thicknesses of matter, but are absorbed and deflected at rates that depend on density, so detectors on the far side can reconstruct a “shadow” image of what lies within. It has been used to map the interiors of volcanoes, inspect nuclear reactors (including Fukushima), scan cargo for shielded nuclear material, and reveal hidden voids in the Great Pyramid of Giza and beneath ancient Jerusalem.

Related terms: non-ionizing radiation, hardware, Directed-energy

Sources: Muon imaging at an ancient Jerusalem site — AIP, Journal of Applied Physics; Directional muon beam for imaging — Lawrence Berkeley National Lab