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24 May 2006 Comparison of shielded uranium passive gamma-ray detection methods
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The detection of shielded special nuclear materials is of great concern to the homeland security community. It is a challenging task that typically requires large detectors arrays to achieve the required sensitivity to detect shielded enriched uranium. We simulated the performance of three different configurations of scintillation detectors in a realistic gamma ray background. The simulations were performed using the GEANT4 simulation package fine tuned for low energy photon transport. The background spectrum was obtained by modeling high-resolution background spectra obtained by various groups in various locations. The performance of a non-imaging scintillating array was compared to the performance of two imaging arrays: a coded aperture imager and a Compton imager. The sensitivity was modeled at three energies for the emission from a 1 kg sphere of uranium enriched to 95% U-235: the 185 keV emission from U-235, the 1001 keV emission from U-238, and the 2614 keV emission from U-232. The instruments were modeled with and without passive shielding. The most detectable signal is the 2.614 MeV emission from U-232 contamination if present at a level greater than tens of parts per trillion. While the non-imaging array has the highest efficiency, it also has the highest background rate and is therefore not the most sensitive instrument. We present the expected performance for the three different configurations.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bernard F. Phlips, Elena I. Novikova, Eric A. Wulf, and James D. Kurfess "Comparison of shielded uranium passive gamma-ray detection methods", Proc. SPIE 6213, Non-Intrusive Inspection Technologies, 62130H (24 May 2006);


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