Study on detection technique of illicit materials using pulsed fast white neutron analysis

A feasibility study has been conducted to develop a novel method using pulsed fast neutron analysis for the detection of illicit materials. The unique approach of this method is using the total attenuation of white neutron beam with a range of 0.5 ∼ few MeV to determine the contents of carbon, nitrogen and oxygen in unknown materials. Those total cross-sections were measured for thick-single element materials such as graphite, LN2 and LO2, and were agreed well with ones of ENDF-6 library and the calculated using the MCNPX code. The resonance peaks in the spectrum are the key-points for identifying the contents. The spectral dependence on the geometrical distribution of investigated goods was confirmed. The transmission spectra of composite or compound materials including dry-ice such as sugar, polyurethane, and PMMA were measured and compared well with the calculated results. The unfolding scheme using several resonance peaks to determine contents of issued elements in unknown materials is described in this paper.