Abstract: An x-ray inspection system for automatically detecting nuclear weapons materials generates a high energy x-ray fan beam or a traveling x-ray pencil beam that traverses an object under inspection. An x-ray detector detects x-ray energy that passes through the object and provides a detected signal indicative thereof. The detected signal is processed to detect the presence of an area of very high x-ray attenuation within the object under inspection, which is indicative of nuclear weapons materials. Because of the high atomic number (Z) and high density of nuclear weapons materials Uranium and Plutonium, both of these materials attenuate (i.e., absorb) incident x-rays significantly more than ordinary materials. That is, very high Z materials such as nuclear weapons materials, produce no x-rays outside of their block of material because the x-rays are self absorbed within the very high Z materials.

Abstract: Transmission and scatter detectors for an x-ray inspection system preferably employing a moving pencil beam comprise a solid plastic scintillating material having a front planar surface that is impinged by incident x-ray energy. The detectors also include light detectors that are cooperatively mounted to the plastic scintillating material to detect photons within the plastic scintillating material created in response to x-rays incident on the front planar surface. The detector may be a transmission detector or a scatter detector. The detectors of the present invention are relatively thin in comparison to prior art detectors, which allows shielding to be reduced. In addition, the detectors of the present invention have a greater efficiency of detection in comparison to the prior art detectors.