Development of a high-energy x-ray diffraction system for determining materials' signatures relevant to transportation security

As part of its mission, the Transportation Security Laboratory (TSL) of the Department of Homeland Security (DHS) Science and Technology Directorate (S&T) develops methods for characterizing materials that are of interest to transportation security and first responders. For emerging technologies, new metrics that meaningfully differentiate materials must be identified and evaluated. Although X-ray diffraction (XRD) is an established technique for identifying solid crystalline materials, the ability to complement the current generation of X-ray-based threat detection using XRD is still being investigated. The TSL has constructed a high-energy X-ray diffraction system to measure a material's scattering signature, which can vary based on the presence of organic and inorganic materials, solid crystals, and water or other liquids within a sample. Measurements have been performed on a wide range of household items as well as explosives and other threats. The scattering intensity as a function of momentum transfer was examined for each material to identify several potential metrics for distinguishing threats from inert substances.