Year
1997
Abstract
As recent world events show, criminal and terrorist access to nuclear materials is a growing national concern. The national laboratories have developed quantitative models to simulate the response of detection equipment when looking for lost or stolen nuclear material. SYNTH, a code written to synthesize typical gamma-ray spectroscopy experiments, and QUEST, a model to Quantify Uncertain Emergency Search Techniques, calculate the response functions of gammaray detectors for arbitrary source types and shielding configurations. In addition, QUEST provides an interactive, threedimensional user interface supporting the virtual quest for nuclear materials, making possible quantitative comparisons of various sensor technologies and inspection methodologies. The probability of detecting a radioactive source during an inspection is a function of many different variables, including source type, structure geometry (including shielding), inspection dynamics (path and speed), detector (type, size, and resolution), and analysis algorithms. We present the results of our study comparing the synthetic Sodium Iodide (NaI) and Germanium (Ge) detector responses generated by both SYNTH and QUEST with those generated by real detectors deployed in the field. Quantitative models, such as the ones presented here, are important since they, (1) allow inspection teams to maximize the probability of finding materials of interest, (2) aid in the development of new instruments and detection techniques, and (3) support other diverse applications including environmental monitoring, nuclear facilities inspections, and radiation safety responder training.