Abstract: Systems and methods for inspecting an object with a scanned beam of penetrating radiation are disclosed. Scattered radiation from the beam is detected, in either the backward or forward direction. Characteristic values of the backscattered radiation are compared to expected reference values to characterize the object. Additionally, penetrating radiation transmitted through the inspected object may be combined with scatter information. In certain embodiments, the inspected field of view is less than 0.1 steradians, and the detector is separate from the source of penetrating radiation and is disposed, with respect to the object, such as to subtend greater than 0.5 steradians in the field of view of the object.

Abstract: An x-ray inspection system for identifying fissile material includes one or more sources of penetrating radiation that generate first, second, and third instantaneous spectra where the object is exposed to the second only if there is no penetration of the first and the object is exposed to the third only if there is no penetration of the second. Further, the source of the second and the third spectra is a source adapted to provide single pulses. Consequently, ambient levels of radiation may be held below cabinet levels while identifying objects containing fissile material.