On the symmetry of photon detection arrays: A directionally sensitive 3D model

Abstract

A detector's ability to obtain the direction of a radioactive source is an invaluable operational asset. A 2D/3D model was developed based on directionally sensitive arrays. The average location of photon interactions within a symmetrical array yields the direction of the source. The model is validated with simulations and laboratory measurements, maximum systematic error being 5–10° at energies >200 keV and approaching zero at lower energies. The symmetry model yields the direction of a shielded source even when no full energy photons could be detected.