A detection pixel includes a material that is chosen so that its (averaged) atomic number density leads to the Compton process being the dominant scattering mechanism in response to incident photons, leading to production of Compton electrons with sufficient number and kinetic energy to produce an electric or magnetic response in the material. The incident photon and Compton electrons each have a characteristic travel distance in the material, and the detection pixel has at least one dimension that is selected according to a range defined by these characteristic travel distances. The detection pixels may be arranged in an array for imaging.
