Muon tomography or muography is a technique that uses cosmic ray muons to generate two or three-dimensional images of volumes using information contained in the Coulomb scattering of the muons. Since muons are much more deeply penetrating than X-rays, muon tomography can be used to image through much thicker material than x-ray based tomography such as CT scanning. The muon flux at the Earth's surface is such that a single muon passes through an area the size of a human hand per second.[1]
Since its development in the 1950s, muon tomography has taken many forms, the most important of which are muon transmission radiography and muon scattering tomography.
Muography uses muons by tracking the number of muons that pass through the target volume to determine the density of the inaccessible internal structure. Muography is a technique similar in principle to radiography (imaging with X-rays) but capable of surveying much larger objects. Since muons are less likely to interact, stop and decay in low density matter than high density matter, a larger number of muons will travel through the low density regions of target objects in comparison to higher density regions. The apparatuses record the trajectory of each event to produce a muogram that displays the matrix of the resulting numbers of transmitted muons after they have passed through objects up to multiple kilometers in thickness. The internal structure of the object, imaged in terms of density, is displayed by converting muograms to muographic images.
Muon tomography imagers are under development for the purposes of detecting nuclear material in road transport vehicles and cargo containers for the purposes of non-proliferation.[2][3] Another application is the usage of muon tomography to monitor potential underground sites used for carbon sequestration.[1]