高能中子照相转换屏性能初步研究  

A preliminary study of the performance for high energy neutron radiography convertor

作　　者：吴洋[1] 唐彬[1] 孙勇[1] 刘斌[1] 霍合勇[1] 尹伟[1] WU Yang;TANG Bin;SUN Yong;LIU Bin;HUO Heyong;YIN Wei(Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics,Mianyang 621900,China)

机构地区：[1]中国工程物理研究院核物理与化学研究所,绵阳621900

出　　处：《核技术》2020年第7期34-39,共6页Nuclear Techniques

基　　金：国防基础科研计划(No.JCKY2017212B002);核安全项目(No.41426020401);国家重大研发计划(No.2016YFA0401502)资助。

摘　　要：高能中子照相技术因其超强的样品透视能力而成为射线无损检测技术近年来研究的热点,转换屏是中子照相装置的一种关键部件。目前耦合科学级中子数字相机系统用到的高能中子照相转换屏主要有塑料闪烁体、光纤阵列、压制荧光屏和光纤转换屏等,其性能差异很大,需进行性能测试以确定不同转换屏的应用特点或场景。本文针对传统中子照相转换屏探测效率的定义问题,在物理原理基础上对其定义进行了修正,通过实验方法对各类转换屏的高能中子探测效率、空间分辨力等性能指标进行了测试。结合实验系统参数对转换屏绝对效率进行了反推计算,结果表明:压制荧光屏和光纤转换屏分别具有最高的空间分辨率和探测效率。[Background]High energy neutron radiography is a potentially powerful method for non-destructive inspection due to the extremely high penetration depth of fast neutrons in comparison with other radiation in most materials of industrial interest.Convertor is one of the key components in a high energy neutron radiography.Plastic scintillator,fiber matrix,pressed fluorescent screen,and waveshift fiber converter,etc.can be used in a high energy neutron radiography system based on charge coupled device(CCD)camera.The performances of these convertors are different.[Purpose]This study aims at performance test of these different convertors as to determine the application characteristics or scenarios of different converters.[Methods]First of all,for the problems in the definition of the detection efficiency of traditional neutron radiography conversion screen,the definition was revised on the basic of physical principle.Then,the efficiency and spatial resolution of the three types of convertor were tested by neutron radiography experiment,and the absolute efficiency was calculated based on experimental system parameter.[Results]Pressed fluorescent screen has the best spatial resolution and waveshift fiber converter has the best absolute efficiency.[Conclusions]The waveshift fiber converter screen achieves a good balance between resolution and efficiency.Pressed fluorescent screen can be used in high-energy neutron photography scenes with high resolution requirements.The plastic scintillator is only suitable for high-energy neutron photography under the conditions of strong neutron source and large collimation ratio,and its high sensitivity toγ-rays has a great impact on imaging quality.

关 键 词：高能中子 照相 转换屏 

分 类 号：TL99[核科学技术—核技术及应用]