Simulation of a tagged neutron inspection system prototype

Abstract

The illicit trafficking of explosive materials in cargo containers has become, in recent years, a serious problem. Currently used X-ray or γ-ray based systems provide only limited information about the elemental composition of the inspected cargo items. During the last years, a new neutron interrogation technique, named TNIS (Tagged Neutron Inspection System), has been developed, which should permit to determine the chemical composition of the suspect item by coincidence measurements between alpha particles and photons produced. A prototype of such a system for container inspection has been built, at the Institute Ruder Boskovic (IRB) in Zagreb, Croatia, for the European Union 6FP EURITRACK project. We present the results of a detailed simulation of the IRB prototype performed with the MCNP Monte Carlo program and a comparison with beam attenuation calculations performed with GEANT3/MICAP. Detector signals, rates and signal over background ratios have been calculated for 100 kg of TNT explosive located inside a cargo container filled with a metallic matrix of density 0.2 g/cm3. The case of an organic filling material is discussed too. © 2006 IOP Publishing Ltd.