EVALUATION OF A NEUTRON DETECTION SYSTEM IN A MARINE ENVIRONMENT

摘要

This project considered a neutron detection system housed in portable pods mounted on a rotary wing airborne platform and evaluated its efficacy for detection of relevant threat sources located inside metal ships in open ocean scenarios. Starting with a theoretical model that considers the mass and composition of neutron emitter on the ground, as well as the detector's geometric and intrinsic efficiencies, neutron count rate was predicted. Considerations were made for detector elevation, mass of source material, composition of source material, and speed of the aerial platform transporting the detection system. Results indicate that higher detection probabilities can be achieved for slower searches accomplished at lower elevations. Limits for detection capabilities were generated and plotted in a parametric fashion, considering all variables (elevation, mass and composition of source material, speed) and confidence factors for reliable detection. Additionally, the effects of background neutron flux were analyzed. Both thermal and fast neutrons were assumed to present themselves as a result of cosmic interactions and also the "ship effect" which accounts for neutrons generated by a massive metal object in a marine environment. The effect of considering the added noise due to the background reduced the predicted performance of the system, and these new predictions are presented here.