Patent ID: 8358730

Claim:
A method of detecting a presence of a material comprising an actinide in a container, comprising: a) locating at least one neutron detector capable of distinguishing neutron energy such that said detector views said container at a first angle relative to a first incident neutron beam; b) illuminating at least a portion of said container with said first incident neutron beam; c) detecting, in at least one said neutron detector capable of distinguishing neutron energy, viewing said container at the first angle, a plurality of prompt neutrons produced by a fission interaction of said first incident neutron beam with at least a portion of said container; d) for at least one of said detected prompt neutrons, determining an energy of said detected prompt neutron; and e) based upon the determined energy of a predetermined quantity of said detected prompt neutrons exceeding a predetermined value, determining that the material comprising the actinide is present in the container.