Design and optimization of thermal neutron device based on deuterium-deuterium neutron generator

Abstract

A thermal neutron device based on a portable D-D neutron generator has been designed and optimized by Monte Carlo method. The goal of optimal design is to maximize the thermal neutron flux at the output surface and improve the utilization efficiency of the neutron generator. The simulation of the reference device is experimentally verified. The contributions of different types and sizes of moderators, reflectors, and collimators to the thermal neutron intensity were simulated to obtain the optimum dimensions of the proposed design. Two parameters P and K were defined to describe the performance of device. It was determined that the final device uses high-density polyethylene (HDPE) as the moderator, nickel as the reflector, and HDPE as the collimator. The parameter K of the final device was 1.72. The P-value was 8 times that of the reference device. The thermal, epithermal + intermediate, fast, and total neutron flux on the output surface were 4.65, 2.52, 1.86, and 2.72 times of the reference device, respectively. The ratio of thermal to fast neutron flux ϕth/ϕfast increased from 0.52 to 1.30. The neutron irradiation device is supposed to be employed principally for neutron activation analysis, testing and calibration of neutron dosimeter and detector.