Detection of photon-induced excitations in <sup>235</sup>U with LaBr<inf>3</inf>:Ce scintillating detectors

Abstract

Excitations in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">235</sup> U were measured with LaBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> :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 LaBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> :Ce detectors. Clear NRF peaks at 1733 and 1815 keY corresponding to de-excitations to the ground state and/or low-lying levels in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">235</sup> U were observed within 77 minutes of beam time even under the high background due to the selfactivity of LaBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> :Ce and the radioactive decay of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">214</sup> Bi nuclei existing in the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">235</sup> U target. The present study shows a possibility of using LaBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> :Ce detector to perform NRF experiments, promoting many options for inspection of special nuclear materials.