An Electronically-collimated Gamma-ray Detector for Localization of Radiation Sources

Small hand-held radiation detectors that can image a gamma-ray source and yet can be transported by a single operator could have numerous applications, either in medical intraoperative procedures or in nuclear security field work. We report on the design of a device intended for such applications and we present results of simulations that indicate expected performance for such a compact system. The device is electronically collimated and uses coincidence detection of Compton scattering interactions to locate distant unknown gamma ray emitters. Pixellated CZT semiconductor detectors are used, to allow a compact system with room-temperature operation. Detector energy resolution and detector geometry both impact performance, with detector geometry being a significant issue for this compact design. The useful field of view was found to be plusmn60deg in the zenith and azimuthal directions, measured outward from the front face of the detector. The radial field of view is determined by the sensitivity of the detectors, and depends upon the strength of the source. Suggestions for design improvements are discussed in our conclusions, with the goal of a hand-held device as the main stipulation.