Active Interrogation of Nuclear Materials Using LaBr3: Ce Detectors

Active interrogation in 235U was demonstrated with LaBr3:Ce scintillation detectors using the nuclear resonance fluorescence (NRF) technique. An NRF experiment was performed at the High Intensity y-ray Source (HlyS) facility using quasi-monochromatic circularly or linearly polarized y-ray beams. Photons scattered at 90o relative to the incident beam were detected with two different sizes of cylindrical LaBr3:Ce detectors. Clear NRF peaks at 1733 and 1815 keV corresponding to de-excitations to the ground state and/or low-lying levels in 235U were observed within 77 minutes of beam time even under the high background due to the self-activity of LaBr3:Ce and the radioactive decay of 214Bi nuclei existing in the 235U target. The present study shows a possibility of using LaBr3:Ce detector to perform NRF experiments, promoting many options for inspection of special nuclear materials.