Extents and limits of radioscopic detection of nuclear materials in cargo containers with two megavoltage energy barriers

The megavoltage X-ray technology is utilized for detecting nuclear materials in cargo containers. Interlaced response is obtained by switching rapidly between 6MeV and 9 MeV beams. It is known that the ratio of penetration levels of cargo contents taken at nominal and dual energies provides the information about atomic numbers of materials, and thus can also indicate the threat group. However, the identification is not straightforward if combinations of materials are present. The latter can lead to misdetections. It is imperative to know what are the extent and the limit of the currently employed technology, and how to carry out the inspection in real-time by balancing the human involvement and the computer assistance. We have performed experiments with Linatron K9, analyze data and conclude on an efficient system configuration. The following are addressed: (a) visualization the contents to produce an image suitable for the visual analysis, and (b) prompting the custom personnel on the presence and the location of suspicious objects.