Monte Carlo simulations to advance characterisation of landmines by pulsed fast/thermal neutron analysis

The performance of a detection system based on the pulsed fast/thermal neutron analysis technique was assessed using Monte Carlo simulations. The aim was to develop and implement simulation methods, to support and advance the data analysis techniques of the characteristic γ-ray spectra, potentially leading to elemental characterisation of innocuous objects using the full spectrum analysis (FSA) approach. The simulations were carried out with a simplified tool, based on a 14 MeV DT pulse-neutron source and a bismuth–germanate detector. A MCNP-based method for de-coupling the radiation transport in mixed (n,γ) fields, to generate separate sets of standard detector γ-ray responses for individual elements, is outlined. When normalised and experimentally benchmarked in terms of the pulse-neutron source production rate, the standard spectra can be incorporated into algorithms for the FSA of in situ measurements and elemental fingerprinting of the inspected object.