Patent ID: 8106365

Claim:
A system for detecting the presence of fissionable material, the system comprising: a source of radiation that is switchable between a screening mode and a verification mode, the source configured to: produce, in the screening mode, a first type of radiation having a first energy and a second type of radiation having a second energy, the second energy being higher than the first energy, direct, in the screening mode, the first type of radiation and the second type radiation toward a physical region, such that the first type of radiation propagates towards the physical region in a first direction and the second type of radiation propagates towards the physical region in a second direction that is substantially parallel to the first direction; produce, in the verification mode, a third type of radiation, and direct, in the verification mode, the third type of radiation toward the physical region, the third type of radiation being sufficient to induce fission in a fissionable material; a sensor system comprising: a sensor configured to sense radiation comprising the first energy and the second energy from the physical region, and a sensor configured to sense a fission product; and a processor operable to: access data sensed by the sensor configured to sense radiation comprising the first energy and the second energy, determine, for the physical region represented by the accessed data, an absorption of the first type of radiation and the second type of radiation, determine whether the physical region is a region of interest based on the absorption, and cause the source of radiation to switch from the screening mode to the verification mode when the physical region is a region of interest.