Review of Feasibilities studies for the Localization of Radioactive Sources from a Portable Radiation Detector based on pixelated CdTe crystals

Abstract

We review the feasibility studies performed regarding the ability of a proposed portable radiation CdTe pixelated detecting system to localize radioactive sources. The proposed instrument is a stack of ten CdTe layers consisting of 10000 pixels of 400μm x 400μm size, in a two-dimensional arrangement,occupying an area of 4cm x 4cm, placed 2 cm apart. Simulation results show that the system is able to achieveareconstructed image resolution less than ~4x10-3srand that it can accurately estimate the direction of point-like radioactive sources within 1° (both in azimuth and inclination) for inclination angles up to 50°.Moreover, the ability of the system to estimate the source-to-detector distance has beenevaluated by studying three different algorithms tested on a large number of simulated photons over a wide energy range (from 200 keV to 2 MeV) emitted by point-like radioactive sources located at different orientations and source-to-detector distances. Results show that the technique based on the quality of reconstructed images can accurately estimate sources located in the near field of the detector. The technique based on the number of fully absorbed photons in each detecting layer can estimate source-to-detector distances up to 2 m for incident photon energies up to 2 MeV, within 2σ, whereas the triangulation technique can estimate the position of point-like sources within 3 cm centimeters for sources located at 50cm distances from the detector’s center