镀膜型^(n)MCP探测效率和位置分辨优化的蒙特卡罗模拟研究

Monte Carlo Simulation Study on Optimization of Detection Efficiency and Spatial Resolution of Coated ^(n)MCP

中子敏感微通道板(Neutron sensitive microchannel plate,^(n)MCP)因其具有高探测效率和位置分辨,配合先进的读出电子学可作为能量分辨中子成像探测器的优先选择。相比于基体掺杂型的^(n)MCP,基于原子层沉积技术(Atomic Layer Deposition,ALD)的^(n)MCP具有原材料消耗少、通道内壁具有高的二次电子发射系数等优势。首先,通过实验对掺杂natGd型^(n)MCP的典型中子和伽马信号进行研究。然后,采用Geant4模拟和理论计算对镀膜10B_(2)O_(3)型^(n)MCP的孔径、壁厚、倾角和镀膜厚度进行优化。计算结果表明,当^(n)MCP的几何参数选择为镀膜厚度1μm、孔径10μm、壁厚1μm以及倾角3°时,^(n)MCP性能达到约56%的热中子探测效率和约22μm的位置分辨。计算结果对CSNS能量选择中子成像探测器^(n)MCP的几何参数设计具有重要意义。

Since neutron sensitive microchannel plates(^(n)MCP)has high detection efficiency and the spatial resolution,combined with advanced readout electronics it can be a better choice for energy-resolved neutron imaging detectors.Compared with the matrix-doped ^(n)MCP,the ^(n)MCP based on Atomic Layer Deposition(ALD)has the advantages of less neutron sensitive material consumption and high secondary electron emission coefficient on the inner wall of the channel.Firstly,the typical neutron and gamma signal of natGd-doped ^(n)MCP were studied experimentally.Geant4 simulation and theoretical calculation were performed to optimize the pore diameter,wall thickness,bias angle and coating thickness of the coated 10B_(2)O_(3) ^(n)MCP.It was shown that the thermal neutron detection efficiency was about 56%and the spatial resolution was about 22μm when the coating thickness was 1μm,the pore diameter was 10μm,the wall thickness was 1μm and the bias angle was 3°.The results are of great significance to the geometric parameter design of ^(n)MCP used as energy-resolved neutron imaging detectors at CSNS.