热中子透射成像转换屏物理设计研究  

Physical design of conversion screens for thermal neutron transmission imaging

作　　者：刘兴宇 于筱雪 李航洲 彭锦秋 杨旭 吴康 白晓厚 王俊润 邓志勇[1,3] 吴璐 高艮涛[3] 万国荣 刘莉 何鹏[3] 张芸[3] 张宇 姚泽恩[1,2] 韦峥[1,2] LIU Xingyu;YU Xiaoxue;LI Hangzhou;PENG Jinqiu;YANG Xu;WU Kang;BAI Xiaohou;WANG Junrun;DENG Zhiyong;WU Lu;GAO Gentao;WAN Guorong;LIU Li;HE Peng;ZHANG Yun;ZHANG Yu;YAO Zeen;WEI Zheng(School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China;Engineering Research Center for Neutron Application,Ministry of Education,Lanzhou University,Lanzhou 730000,China;Nuclear Power Institute of China,Chengdu 610213,China)

机构地区：[1]兰州大学核科学与技术学院,兰州730000 [2]兰州大学中子应用技术教育部工程研究中心,兰州730000 [3]中国核动力研究设计院,成都610213

出　　处：《核技术》2023年第11期21-29,共9页Nuclear Techniques

基　　金：国家自然科学基金(No.11875155,No.12075105);兰州大学中央高校基本科研业务费专项资金资助项目(No.lzujbky-2022-kb07)资助。

摘　　要：中子像转换屏是热中子透射成像技术的关键部件,中子像转换屏的参数严重影响空间分辨率和热中子-光子转化效率两方面的特性。采用Geant4程序模拟热中子透射成像的物理过程及透射光子二维图像,建立了基于LiF(ZnS)和LiF(GOS)像转化屏的热中子透射成像模拟模型和Siemens star像指示器模型,利用线扩散函数(Line Spread Function,LSF)计算空间位置分辨率,获得热中子像转化屏厚度与空间位置分辨率、中子-光子转换效率的关系。基于兰州大学紧凑型D-D中子源的热中子透射成像系统参数,推荐选取LiF(GOS)像转化屏的厚度为40μm,LiF(ZnS)像转化屏厚度应选取80μm,热中子透射成像空间分辨率分别可达到45μm和63μm,为基于紧凑型D-D中子源的热中子透射成像系统的研发奠定了技术基础。此外,本工作得到的LiF(GOS)、LiF(ZnS)像转化屏优化参数同样适用于其他热中子成像装置,可为热中子透射成像系统的搭建提供了技术参考。[Background]Although the neutron image conversion screen is a key component of thermal neutron radiograph,its parameters can severely affect both the spatial resolution and thermal neutron-photon conversion efficiency.[Purpose]This study aims to design a neutron image conversion screen for a thermal neutron transmission imaging system based on a compact D-D neutron source.[Methods]Firstly,the Geant4(Geometry and Tracking)program was used to simulate the physical process of thermal neutron transmission imaging and two-dimensional images of transmitted photons,and establish a thermal neutron radiography model based on LiF(ZnS)and LiF(GOS)image conversion screens,and the Siemens star image indicator model.Then,the line spread function(LSF)was employed to calculate spatial position resolution of neutron transmission imaging,and the relationships between the thickness of thermal neutron image conversion screens and the spatial resolution,as well as that between the thickness of thermal neutron image conversion screens and neutron-photon conversion efficiency were evaluated and calculated.Finally,based on parameters of thermal neutron radiography imaging system based on compact D-D neutron source at Lanzhou University,recommended thicknesses for LiF(ZnS)and LiF(GOS)conversion screens were applied to the spatial resolution test experiments.[Results]The recommended thicknesses for LiF(GOS)and LiF(ZnS)image conversion screens are 40μm and 80μm,respectively,the spatial resolution of the thermal neutron radiography reach 45 and 63μm,respectively,and the neutron-photon conversion efficiencies are 136.34 and 126.81,respectively.[Conclusions]This study lays the technical basis for the development of a thermal neutron radiography based on compact D-D neutron sources.It may be also applicable to other thermal neutron imaging systems.

关 键 词：热中子透射成像 像转换屏 空间位置分辨率 光转换效率 

分 类 号：TL816.3[核科学技术—核技术及应用]