Computed Tomography (CT) for Detecting and Imaging Fissionable Material
S. Naeem1; D.P. Wells1; T. White2; and T. Roney2 (1Idaho State University; 2Idaho National Laboratory)
Computed Tomography (CT) is a radiographic technique to use penetrating x-ray beams that passed through an object to generate an image. Final 3-D images are constructed after performing certain projective image processing procedures that display areas of interest. The Department of Homeland Security (DHS) is interested in identifying transportable fissionable materials in cargo containers, andlocating its position regardless of the shielding material(s) used to hide it. We use bremsstrahlung radiation beams from electron linacs with endpoint energies that range from 8 to 20 MeV to activate photo-fissionable material via (gamma, f) reactions. We use multiple detectors to spectroscopically detect the beat-delayed photons (Egamma,max ≈ 4 MeV) from fission products, identify the associated fissionable material, and construct an image of its location, mass and distribution. We have investigated the relative advantages of germanium Ge(Li) and NaI(Tl) detectors. By rotating the detectors about the object under interrogation, we construct a 3-D image of the distribution of fissionable material.