Evaluation of spatial distribution of fast and thermal neutrons using array type threshold detectors

Abstract

This study aimed to verify whether neutron energy and flux could be simultaneously measured by a new technique that used array-type threshold detectors. Neutrons generated by nuclear reactions between 26-MeV protons and beryllium targets in the KIRAMS MC50 cyclotron were measured using array-type threshold detectors fabricated by superimposing four array-type activation foils composed of Au, Ag, In, and Cu. The measurement results were compared to the simulation results obtained using MCNPX and FISPACT codes. The study results showed that the spatial distribution of high-speed neutrons was mostly concentrated at the center of the beam whereas that of thermal neutrons was relatively sparse at the center of the beam.