Design and verification of a multi-layer single-sphere neutron spectrometer with water as the moderator

Abstract

Measuring the neutron energy spectrum is important in nuclear radiation detection and protection. Common neutron spectrometers include the Bonner sphere spectrometer (BSS), time-of-flight neutron spectrometer, and plastic scintillation detector. Among them, the BSS is the most widely used for its wide measurement range and simple operation. A BSS usually occupies a large space because it contains several independent spheres working at the same time, leading to poor consistency. This paper proposes a multi-layer single-sphere spectrometer using water as the moderator. The spectrometer includes a multi-layered sphere that can be filled with water or air and a ^3He proportional counter placed in the center of the sphere. To verify the feasibility of this design, we use Geant4 to calculate the moderating ability of water and the response functions of the multi-layer single-sphere spectrometer. Additionally, several standard neutron energy spectra (from IAEA) are used to test the response characteristics of this spectrometer through simulation. The simulation results prove the feasibility of the design. This research provides a theoretical basis for a multi-layer single-sphere neutron spectrometer with water as the moderator.