The non-invasive inspection of baggage using coherent X-ray scattering

An inspection technique based on angular dispersive X-ray diffraction (AAXR D) has been developed to provide chemically specific detection or explosive s for security screening applications. The technique identifies explosives from benign materials using the characteristic Bragg features seen in coher ently scattered X-rays. To implement this technique in a prototype screening system, a detector has been designed which, when coupled with the appropriate analysis algorithm, provides chemically specific material identification. Profile analysis has been performed using the Singular Value Decomposition (SVD) maximum likeli hood technique. The detector system combines a custom designed collimator with an X-ray ima ge intensifier tube and is capable of acquiring diffraction profiles from s everal independent volume elements (voxels) within the region of interest. The acquisition of spatially and energy resolved diffraction profiles for b oth benign and explosive materials using a separate cooled germanium detect or, has allowed the data analysis algorithm to be optimised. Results from the prototype detector system show that explosives such as Sem tex, RDX, and PETN have sufficient order to produce unique diffraction prof iles, which may then be differentiated from benign materials.