Active Interrogation of Nuclear Materials Using LaBr₃: Ce Detectors

Abstract

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.