Simulation and design of fast neutron sensitivity silicon microchannel plate

Abstract

BackgroundA fast neutron image detector developed by Lanzhou University is composed of polyethylene converter, lead glass microchannel plate and charge coupled device (CCD) camera. In order to further improve the spatial resolution of the detector, a silicon microchannel plate (Si-MCP) is proposed as both converter and multiplier.PurposeThis study aims to improve the conversion efficiency and spatial resolution of Si-MCP by simulation design.MethodsFirst of all, Monte Carlo code Geant4 was employed to build the simulation model of a Si-MCP and neutron source. Then, the conversion efficiency and the spatial resolution of the Si-MCP for 14 MeV fast neutrons in various geometrical configurations were simulated. Finally, geometric structure of Si MCP was optimized, and the geometric parameters of Si MCP were determined by analyzing the simulation results.ResultsThe simulation results indicate that the conversion efficiency of the Si-MCP increases with its thickness. The spatial resolution mainly depends on the thickness and bias angle of the plate. When the plate thickness is 1 mm, the micropore diameter is 10 μm, the wall thickness is 10 μm, and the bias angle is 2°, a conversion efficiency of 0.15% with a spatial resolution of 43 μm can be achieved. Double layer Si MCP detection system with V-type superposition structure can be adopted to achieve 0.31% conversion efficiency for 14 MeV fast neutrons.ConclusionsThe calculation results can provide reference for the design of the Si-MCP in fast neutron image detector.

Keywords

• silicon microchannel plate
• fast neutron imaging
• conversion efficiency
• spatial resolution