Design of Coded Neutron Source Based on a RFQ Accelerator by MCNP Simulation

In this paper, the influence of non-ideality factors of thermal neutron source for coded neutron source imaging has been studied by numerical calculation,in order to establish the design standard of coded neutron source. Then, the pinhole imaging detector (pinhole) of MCNP has been used to simulate the imaging process of the coded neutron source imaging, and the parameters such as the uniformity of the spatial distribution of the thermal neutron flux at the imaging plane and the uniformity of the angular emission of the coded neutron source are studied. The design results show that the spatial distribution of thermal neutron flux is less than 13% and the angular distribution is less than 10% with the optimized structure of moderator including a 4 cm thick polyethylene disk and a wedge of neutron absorbing layer closed to the junction surface of collimator and water tube.