Monte Carlo Simulations Of High Energy X-ray In Material Identification

With the increasing emphasis on security throughout the world, how to accurately and quickly check out the contraband in public places becomes a topic of concern. As a kind of widely used technique in contraband detection, X-ray technique has made a rapid development in recent years, such as single energy X-ray technique, dual-energy X-ray technique, multi-angle X-ray technique, X-ray scattering technique and computer tomography (CT technology), etc. Among them, dual-energy X-ray imaging technique can measure the effective atomic number of materials because materials vary in absorbing the high-energy and low energy X-ray, thus this technique can be used to achieve material identification. Due to dual-energy X-ray energy spectrum characteristics and differences, dual-energy X-ray imaging technique can be more accurate for material identification. The X-ray security inspection equipment in most public places is for the luggage, parcels and other small items with the X-ray energy in general 450KeV. But for large vehicles, containers, etc., we need high-energy X-ray detection. X-ray energy should be greater than 1MeV.This paper has carried on the simulation with the Monte Carlo method to dual-energy X-ray imaging technique in material identification. The simulation uses the MCNP4C Monte Carlo procedure. It has first conducted the simulation to the high-energy electron target practice's bremsstrahlung and obtained the X beta spectrum and the angle distribution of 6MeV and the 9MeV electron bremsstrahlung. The simulation result is in accordance with the theory and the experiment. With the obtained X beta spectrum of the high and low bremsstrahlung, this paper has carried on theMonte Carlo simulation to the X-ray material scanning, obtained six material recognition curves of Pb (lead), Fe (iron), Al (aluminum), KCl (potassium chloride), RDX (Hexogen), CH2 (polyethylene) and then summarized the relations between each material recognition curve and their respective effective atomic numbers. This paper has also conducted the simulation study to the above six material's compton scattering (fore scattering) and obtained the relations between light fraction and the density which can further increase the accuracy in material identification.