Patent ID: 7151815

Claim:
A method of detecting concealed fissile material in an article, where the presence of the concealed fissile material is unknown, comprising: providing at least one solid state fast neutron detector and at least one source of irradiating fast neutrons, the irradiating fast neutrons characterized by a particle energy, a pulse strength, a pulse width and a pulse frequency, wherein said pulse width is about 4 ns to 200 μs, said pulse frequency is about 100 to 10,000,000 Hz and said pulse strength is approximately 10 7 to 10 12 neutrons per second; irradiating said article with said irradiating fast neutrons to effect emission of prompt, fast neutron radiation from said fissile material directly resulting from fissions occurring from neutron irradiation by said at least one neutron source, if the fissile material is present in the article and determine the presence of fissile material in the article; monitoring the emissions of such prompt fast neutron radiation directly resulting from fissions occurring from the neutron irradiation by said at least one neutron source, with the solid state fast neutron detector capable of discriminating between fast neutrons and thermal and epithermal neutrons and collecting counts of the prompt fast neutrons detected in the time between pulse widths without saturating; acquiring prompt fast neutron data indicative of a number of prompt fast fission neutrons emitted from said fissile material during a predetermined time period; and analyzing said data to determine the presence or absence of said fissile material.