Compact, inexpensive, high-energy-resolution, room-temperature-operated, semiconductor gamma-ray detectors for isotope identification

Many homeland security applications involving gamma-ray detectors require energy resolution of better than 1%–2% for isotope identification. Existing High-Purity germanium (HPGe) detectors have the needed energy resolution but suffer from large size and the need for liquid-nitrogen or electromechanical cooling. Compact, inexpensive, room-temperature-operated devices are needed for handheld monitors, portal monitors, and monitors for nuclear materials in storage or transit. At Kansas State University, CdZnTe (CZT) gamma-ray detectors with better than 1% energy resolution have been developed. Mercuric Iodide detectors with better than 2% energy resolution have also been developed. Both devices make use of the Frisch-collar technology developed at KSU, and the quoted results were achieved without electronic corrections. The goal of the research at KSU is to maximize the energy resolution of the signals coming from the detectors, before any electronic corrections are made. The characteristics of these small, inexpensive devices will be discussed.