Application of neutron activation analysisin discovering plastic explosive

In this work, the ability of neutron probes to detect plastic bombs in airway luggage or postal parcels has been investigated. As explosives are rich in nitrogen, 10.83 MeV gamma radiations may be employed to detect this nitrogen. First, the method is studied theoretically by using the Monte-Carlo simulation method and the MCNP code. The optimum distance, the positions of the detector and the sample, and the optimum moderator thickness are determined by considering the important pile-up effect. Second, by using the model obtained from the data, the Am-Be neutron source is deployed experimentally. In practice, given the role of the source and the pile up effect, the optimum conditions found by calculations are changed and the primary plan is revised, according the experimental results. Finally, the potential of this method is tested by analyzing the results which are obtained for the two kinds of moderations, paraffin and graphite. The data are then reviewed from different perspectives, and different effect on the response of the detectors