Monte Carlo study of detection systems of explosives and illicit substances using a D-D neutron generator

Prompt gamma neutron activation analysis (PGNAA) using a Deuterium-Deuterium (D-D) neutron generator, is one of the most promising method to detect explosives and illicit substances. Using Monte Carlo methods with MCNP6 code, a model of a DD Generator (DD-110 Adelphi Technology [1]) has been built with one or two NaI(Tl) detectors of 1.5" x 1" size in order to determine an optimal configuration. Several calculations have been performed to analyse the detection power for samples of different explosives: RDX, Ammonium Nitrate, land mines, military and homemade explosives, have been selected. Different models have been made varying moderator and shielding thicknesses (polyethylene and lead) and we conclude that the configuration with 10 cm thickness of polyethylene, is the best configuration to obtain a neutron thermal flux appropriate for detection of these simulated samples of explosives