Material Discrimination for Treaty Verification with Multi-energy, X-ray Radiography

As nuclear warhead stockpiles are reduced under current and future arms treaties, accurate methods with which to account for stockpiled material become increasingly important. Image-based active interrogation offers advantages to spectroscopic detection in its ability to measure the location and extent of a material, or materials, of interest. However, the detail that imaging provides is often viewed as too intrusive due to its potential to disseminate sensitive information. Here we present a method for reducing multi-energy x-ray radiography data to a few important attributes, which can then be used to confirm or deny a declaration. We build on previous work by improving the physics modeling; considering currently attainable, multiple-endpoint x-ray systems; and posing the problem as a nonlinear, inverse problem. Regularization is added to the problem, which smooths the solution and stabilizes an otherwise unstable solution. Here we show the ability to discriminate high-atomic–number materials from others with simulated single-view multiple-endpoint radiography data and present results from initial bench-top measurements.