Simulation Study Of High Spatial Resolution NMCP Using In Neutron Imaging

Neutron imaging has developed into an important nondestructive testing technology.Energy resolved neutron imaging is a new type of neutron imaging technology,which can measured the crystal structure by selecting the neutron energy.Energy resolved neutron imaging requires high position resolution and fast time resolution for imaging detector.As a fast signal response and high spatial resolution neutron detector,the neutron microchannel plate（nMCP）is the best choice for energy resolved neutron imaging.In this thesis,the detection efficiency,spatial resolution and the performance of gamma discrimination of nMCP are studied by using Geant4.First of all,the types and concentration of neutron sensitive nuclide which doping in nMCP are optimized.The simulation results show that the detection efficiency of boron doped nMCP is about 20%at10mole%doping concentration,while that of gadolinium doped nMCP is more than 45%at3mole%doping concentration.The spatial resolution of boron doped nMCP is less than20μm,while that of gadolinium doped nMCP is more than 50μm.According to the simulation results,it can be concluded that:in terms of detection efficiency,gadolinium doped nMCP is better than boron doped nMCP,but in terms of spatial resolution and the performance gamma discrimination,boron doped nMCP is better than gadolinium doped nMCP.For the nMCP doping with 10mole%¹⁰B2O3,the variation of detection efficiency,spatial resolution and the performance of gamma discrimination with the geometric parameters of nMCP is simulated in this thesis.The change rule of the performance with parameters has been researched.At the same time,the parameters of nMCP detector with high performance are obtained according to the rule and craft.According to the simulation results,24%of detection efficiency,13μm spatial resolution and good gamma discrimination can be reached with 0.6mm thickness,6μm channel diameter,2μm wall thickness and 1 degree bias angle.In addition,a boron and gadolinium doped nMCP is researched,which can break the limit of detection efficiency in boron doping nMCP,with acceptable sacrifice in spatial resolution.According to the simulation results,26%detection efficiency and 35μm spatial resolution and good gamma discrimination can be reached with 10mole%¹⁰B2O3 and0.2mole%¹⁵⁷Gd₂O₃,0.3mm thickness,6μm channel diameter,3μm wall thickness and 2°the bias angle.The simulation results reveal the change rule of the performance of nMCP with the doping materials and geometric parameters,which provides the research basis and data support for the future research of nMCP.The parameters of nMCP which have good performance are determined,which provides a scheme for the high performance detector of neutron imaging and energy resolved imaging.