Patent ID: 8345812

Claim:
A system for detecting fissionable material, the system comprising: a source configured to accelerate a pulsed beam of charged particles; a first target configured to generate a first neutron beam in response to being struck by accelerated charged particles, the first neutron beam including neutrons having a first energy that is sufficient to cause fission in a first class of fissionable material, wherein said first class of fissionable material is non-weaponizable fissionable material; a second target configured to generate a second neutron beam in response to being struck by accelerated charged particles, the second neutron beam including essentially only neutrons having a second energy that is lower than the first energy, the second energy sufficient to cause fission in a second class of fissionable material, wherein said second class of fissionable material is weaponizable fissionable material, and insufficient to cause fission in the first class of fissionable material; a sensor configured to detect radiation from a fission product; and a processor coupled to a non-transitory computer-readable storage medium, the medium storing instructions that, when executed, cause the processor to: cause the source to accelerate a first pulsed beam of charged particles toward the first target such that the first neutron beam is directed toward a physical region, cause the source to accelerate a second pulsed beam of charged particles toward the second target such that the second neutron beam is directed toward the physical region, determine, based on data from the sensor, whether the physical region includes a fissionable material, and in response to a determination that the physical region includes a fissionable material determine whether the fissionable material is part of the first class of fissionable material or the second class of fissionable material based on the data from the sensor.