Pulsed Power Active Interrogation of Shielded Fissionable Material

We irradiated a depleted uranium (
²³⁸
U) target with intense, single 50 ns pulses of bremsstrahlung to study the behavior of
³
He, BF3, NaI(Tl), and liquid scintillation detectors in a harsh radiological environment. The target was exposed unshielded, and shielded with borated high-density polyethylene, or steel, and delayed γ-ray and neutron signatures were measured. We found that a high confidence measurement of the delayed emission could be obtained in this environment and show the results from each detector array, for varying amounts of shielding, in terms of the signal-to-noise ratio vs. time and the relationship between the mean of the signal-to-noise ratio vs. areal mass density.