Development of neutron image plate for low-flux measurements

Abstract.

The results of an experimental test for the performance of a commercially available neutron-sensitive image-plate detector are presented. The particular aim of the experiments is to study the nature of noise in a neutron image obtained under the real conditions of a reactor hall. The most significant component of noise was found to be an external γ-ray background. The γ-ray dose of 1 μS/h leads to a noise in a neutron image with a neutron equivalent of about 1.2 n/cm² s , which is comparable to magnitudes of weak diffraction peaks and diffuse scattering at thermal neutron scattering experiments. The high sensitivity of image plates to γ-rays results from the high charge density of storage-phosphor (BaFBr:Eu²⁺) and neutron-converter (Gd₂O₃) materials used in commercially available neutron image plates. The possibility of the use of ⁶LiF as a neutron converter instead of Gd₂O₃ to reduce the γ-ray sensitivity is discussed.