Detection of photon-induced excitations in 235U with LaBr3:Ce scintillating detectors

Excitations in ²³⁵U were measured with LaBr₃:Ce scintillation detectors using the nuclear resonance fluorescence (NRF) technique. A NRF experiment was performed at the High Intensity y-ray Source (HIyS) facility using quasi-monochromatic circularly or linearly polarized y-ray beams. Photons scattered at 90· relative to the incident beam were detected with two different sizes of cylindrical LaBr₃:Ce detectors. Clear NRF peaks at 1733 and 1815 keY 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 selfactivity 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.