Investigation of a Passive, Temporal, Neutron Monitoring System that Functions within the Confines of Start I

This study is an investigation of the theoretical and experimental possibilities of using activation foils to detect and monitor special nuclear material for treaty monitoring purposes. None of the experiments demonstrated sufficient sensitivity to detect the target flux of 0.5 neutrons/cu cm--sec. The target flux could be detectable, if the limit of detection had been reduced by a factor of 4 to 6. However, many issues identified could enhance the sensitivity including: increasing foil size, increasing detector efficiency, and optimizing foil selection. The theoretical portion focused on gold, silver, indium, europium, and gadolinium foils and determined the minimum flux detectable, minimum time needed to detect a specific flux, and what gaps in coverage exist when a detection package consists of all combined foils. All calculations are based on actual gamma and beta detector responses and statistics in a high and low background. The second section consists of experiments with gold, indium, and silver foils. Detectors in a low background counted emitted gammas or betas to establish three-sigma limits of detection, which is the lowest neutron flux detectable with a 99 percent statistical reliability. The dominant factor in determining the limit of detection is the error associated with the total activity. The determined value for limit of detection was used to calculate the minimum foil surface area required to detect the target flux.Air Force Inst of Tech Wright-Patterson AFB OH School of Engineering and Management is the author of 'Investigation of a Passive, Temporal, Neutron Monitoring System that Functions within the Confines of Start I', published 2003 under ISBN 9781423504740 and ISBN 1423504747.