基于微通道板的快中子像探测器转换器的模拟研究  

Simulation study on the converter of fast neutron imaging detector based on micro-channel plates

作　　者：冉建玲 卢小龙[1,2] 马占文[1] 王伟[1] 张杰[1] 王洁[1] 孟繁良[1] 张宇[1,2] 姚泽恩[1,2] 

机构地区：[1]兰州大学核科学与技术学院,兰州730000 [2]兰州大学教育部中子应用技术工程研究中心,兰州730000

出　　处：《核技术》2015年第9期29-35,共7页Nuclear Techniques

基　　金：国家自然科学基金(No.11375077);国家重大科学仪器设备开发专项(No.2013YQ40861);兰州大学中央高校基本科研业务费专项资金(No.lzujbky-2015-bt07)资助

摘　　要：提出了一种由聚乙烯(Polyethylene,PE)转换器、微通道板(Microchannel Plate,MCP)电子增强器和CCD(Charge-Coupled Device)相机组成的快中子照相像探测器新方案。采用Geant4软件模拟研究了14.5 Me V快中子入射在PE转换器上的出射质子产额、能谱随PE厚度的变化规律,确定了PE转换器的厚度范围和转换效率等重要参数。模拟结果显示,PE转换器的厚度应该选择在2.5 mm左右,此时的转换效率约为0.37%。采用Geant4软件模拟了14.5 Me V快中子入射在PE转换器的质子输运和质子在MCP中电子的产生和倍增过程,给出了MCP输出的电子束斑图像。模拟结果显示,由PE和MCP组成的转换器系统能将入射的快中子转换成电子束斑点阵信息,各电子束斑之间的界限清晰,单孔电子束斑直径略大于MCP孔径,即电子束斑点阵像素可以达到MCP孔径量级。Background： As a unique non-destructive testing technique, fast neutron radiography has been widely concerned in recent years. However, the fast neutron imaging detector with higher resolution and higher detection efficiency still needs to be researched. Purpose： A new fast neutron imaging detector consisting of a polyethylene （PE） converter and a microchannel plate （MCP）, is proposed for 14.5-MeV fast neutron radiography. Simulation studies are conducted for the design aim. Methods： The yields and energy spectra of the recoil proton produced by 14.5-MeV fast neutron on the PE converter are simulated using Geant4 code. The yields and the energy spectra of the recoil proton under the different PE converter thicknesses are presented in order to determine the converter efficiency and the reasonable thickness of the PE converter. Less than 14.5 MeV, fast neutron incident, the electronic gain process in MCP is simulated using Geant4 code. In order to analyze spatial resolution, the electron beam spot images are recorded after MCP. Results： The simulation results show that the thickness of PE converter should be selected in the range of 2.5 mm, and the converter efficiency is about 0.37%. The electron images show that the electron beam spot diameter is slightly bigger than MCP aperture. Conclusion： It can be predicted that the spatial resolution of the detector is close to MCP aperture.

关 键 词：快中子照相 聚乙烯转换器 微通道板 电子增益 空间分辨 

分 类 号：TL99[核科学技术—核技术及应用]