A Feasibility Study of X-ray Inspection System Using 90° Compton Scattering

Abstract

A X-ray inspection system, a 90° Compton scattering inspection system coupled with a dual energy method, has been studied, which can directly give the effective atomic number of an unknown object. The 90° scattered signals by irradiating dual energy X-ray beams are measured and used to identify the unknown object hidden among other objects. Many simulations were carried out to verify the feasibility of this work with the illicit materials hidden in many kinds of sample geometries. From the simulation results, the dual energy beam method proposed in this study can find out the effective atomic numbers of the illicit materials. In the cases having simple geometry, all the relative differences between the calculated effective atomic number and the true value are shown to be less than 6.5 %. The feasibility of the dual energy beam method is also verified by scattering experiments using many kinds of sample geometries with TNT simulant. X-ray beams filtered by the ISO standard are used as the radiation source. A narrow detector collimator is employed in front of the detector for an accurate measurement of 90° Compton scattering signals. In the simple geometries containing TNT simulant, it was found that the relative differences between the reference and calculation results were less than 10%. According to the simulation and experiment results, the 90° Compton scattering inspection method coupled with a dual energy method will be effective to find the properties of unknown objects.