Abstract
Monte Carlo simulations were carried out to model a thermal neutron-induced gamma-ray sensor for anti-personnel-landmine (APM) or explosive detection. This is done by employing the thermal neutron prompt gamma activation (TNPGA) technique. The neutron capture reaction on nitrogen 14N(n,γ)15N is analyzed to detect the subsequent characteristic 10.8 MeV gamma rays. This is done by modelling a suitable geometry consisting of a point 252Cf source placed inside a sphere of lead (Pb) which is contained in a cylinder of high density polyethylene (HDPE), together with a NaI (Tl) detector. The sensor geometry was optimized and the optimal configuration was selected to scan a plastic APM buried (2–10) cm. The Monte Carlo results obtained in terms of variations of the signal-to-background ratio, indicated the feasibility of employing 14N(n,γ)15N neutron capture reaction for landmine detection and the suitability of the proposed sensor for airport explosives as well.
•Monte Carlo simulations were carried out to model a thermal neutron-induced gamma ray sensor for landmine or explosive detection by employing the neutron capture reactions on Nitrogen14N(n,γ)15N and detecting the subsequent characteristic 10.8 MeV gamma rays.•The model involves a suitable geometry consisting of a point 252Cf source located inside a sphere of lead and contained in a cylinder of high density polyethylene together with a NaI (Tl) detector.•The sensor geometry was optimized against moderator radius, source position, mine burial depth and stand-off distance. An effective shield with respect to the total dose rate for the operator was considered. The optimal configuration was used to scan plastic anti personnel landmine simulant TNT buried in a relatively dry soil.•The calculations involve two steps; in the first one, the thermal neutron-induced gamma-ray flux produced by the 252Cf neutron source is calculated with a point detector tally F5. In the second step, a mono-directional photon source with the energy distribution obtained in the previous step is used to calculate the energy deposition in the NaI(Tl) detector with the pulse height tally F8.•The results were reported in terms of signal to background ratio (S/B); S/B= [(I-Io)/(Io)] ×100, with respect to the thermal neutron-induced gamma rays with (I) and without (Io) landmine presence in soil, and indicated that the proposed sensor has positively identified the buried landmines.