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 γ-ray Source (HI?S) facility using quasi-monochromatic circularly or linearly polarized γ-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 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.