Speaker
Description
Increased concern about nuclear security in recent years has sparked a large effort to discover and develop new high performance radiation detectors for both gamma rays and neutrons. For a number of years, the primary options for gamma-ray detection have relied on: a) high purity germanium detectors with excellent performance but high cost and significant operational burden, b) cadmium zinc telluride semiconductors with very good energy resolution and room temperature operation but high cost, c) thallium-doped sodium iodide scintillators with reasonable cost but relatively poor energy resolution, and d) plastic scintillators, mainly polyvinyl toluene, with low cost but almost no spectroscopic capability. Recent research has focused on new inorganic scintillators with energy resolution that enables isotope identification previously attainable only with semiconductor materials. As a result, factors that impact energy resolution, such as nonproportionality and nonuniformity, are now much better understood than just a few years ago, and they continue to be active areas of investigation. Neutron detection with scintillators has also seen important advances as the shortage of 3He puts pressure on the development of alternative thermal neutron detection technology. For instance, inorganic crystals with high sensitivity for both gamma rays and neutrons have been developed, and organic crystals have been developed with gamma-neutron discrimination previously only attained by organic liquids. However, despite the discovery of numerous scintillating compounds that work well at the cubic millimeter scale of laboratory samples, most of them have defied cost-effective scaling up to the larger sizes required by security applications. Consequently, the development of inexpensive synthesis techniques will be critical to the successful widespread deployment of new radiation detection technologies.
