Dual modality detection system of nuclear materials concealed in containers

1. A dual modality detection device for simultaneously detecting gamma rays and neutrons following active interrogation of nuclear materials, the dual modality detection device comprising a tiled structure configured to detect the gamma rays and the neutrons, the tiled structure comprising:

neutron detection modules each comprising a moderator material and a neutron sensitive material embedded within the moderator material, at least a portion of the neutron sensitive material substantially surrounded by the moderator material; and

gamma ray detection modules each comprising a scintillator in optical communication with a photodetector and configured to be a moderator and a reflector for the neutron detection modules,

wherein the neutron detection modules are positioned directly adjacent the gamma ray detection modules to define the tiled structure.

2. The dual modality detection device of claim 1 , wherein the tiled structure comprises alternating vertical arrays of the neutron detection modules and the gamma ray detection modules.

3. The dual modality detection device of claim 1 , wherein the tiled structure comprises alternating horizontal arrays of the neutron detection modules and the gamma ray detection modules.

4. The dual modality detection device of claim 1 , wherein the tiled structure comprises a random array of the neutron detection modules and the gamma ray detection modules.

5. The dual modality detection device of claim 4 , wherein at least a portion of the neutron detection modules and the gamma ray detection modules have different thicknesses and dimensions.

6. The dual modality detection device of claim 1 , wherein the neutron detection modules are disposed at least one of in front of the gamma ray detection modules, behind the gamma ray detection modules, and between the gamma ray detection modules.

7. The dual modality detection device of claim 1 , wherein active interrogation comprises injecting at least one of x-rays, neutrons, and gamma rays into a cargo container.

8. A process for simultaneously detecting gamma rays and neutrons from a nuclear material concealed in a container, the process comprising:

actively interrogating the nuclear material disposed within the container to cause a fission reaction;

generating the gamma rays and the neutrons characteristic of the nuclear material; and

simultaneously detecting the gamma rays and the neutrons, wherein said detecting comprises:

reacting the gamma rays with a plastic scintillator to emit a wavelength pattern characteristic of the gamma rays specific to the nuclear material;

moderating an energy of the neutrons with the plastic scintillator; and

reacting the neutrons with a neutron sensitive material to form ionized particles, the neutron sensitive material comprising scintillating fibers embedded within the plastic scintillator such that at least a portion of each scintillating fiber is circumscribed by the plastic scintillator.

9. The process of claim 8 , wherein said actively interrogating the nuclear material comprises injecting high-energy neutrons or gamma rays into the container to cause a fraction of the nuclear material container therein to undergo the fission reaction and emit the gamma rays and neutrons characteristic of the nuclear material in an amount effective to be detected outside of the container.

10. The process of claim 8 , wherein simultaneously detecting the gamma rays and the neutrons further comprises simultaneously detecting the gamma rays and the neutrons using at least one of a doped plastic scintillator and an undoped plastic scintillator and a gamma ray detector that is surrounded by a slow-neutron absorber.