摘要
238U作为一种重要的裂变材料,其含量的准确测定在裂变产额数据测量中具有重要意义。在四川大学2.5 Me V质子静电加速器上,利用T(p,n)3He反应产生的483 ke V单能中子照射金属铀样品,对照射后生成放射性核素239Np的特征γ射线进行测量,利用已知的238U(n,γ)俘获截面数据实现了对238U含量的准确测量。对影响测量结果准确性的因素做了细致分析,采用蒙特卡罗方法应用软件MCNPX(Monte Carlo N-Particle e Xtended)对中子的多次散射效应和中子注量衰减效应进行了修正,对γ射线在样品中的自吸收也进行了修正,修正后的实验结果是2.884 2 g金属铀含5.712 8×1021个238U原子,实验结果的不确定度是4.1%。
Abstract Background： As a kind of important fission material, the accurate quantification of 238U is of great significance in the measurement of fission yield data. Purpose： The aim is to nondestructively measure the content of 238U by using the activation method. Methods： Neutron of 483-keV produced by the reaction of T（p,n）3He induces 238U occurring radiative capture reaction on the 2.5-MeV electrostatic accelerator of Sichuan University. The atomic number of 238U in uranium samples is measured by using 278-keV gamma ray of 239Np on the detector of high purity germanium （HPGe） and the data of capture cross section. Results： The deflections which were caused by multiple scattering and self-shielding of the target and sample in the experiment were corrected with MCNPX （Monte Carlo N-Particle eXtended）. The result of the experiment is that the atomic number of 238U in the 2.884 2-g metal uranium is 5.712 8× 10 21. Conclusion： The uncertainty of the experimental result is 4.1%. We can reduce the effect of multiple scattering effects and self-shielding by decreasing the thickness of the bottom lining, target tube, water layer and cladding material of the sample.
出处
《核技术》
CAS
CSCD
北大核心
2016年第8期15-19,共5页
Nuclear Techniques
基金
中国工程物理研究院中子物理学重点实验室项目(No.2014BA06)资助~~
关键词
28U准确定量
俘获截面数据
蒙特卡罗修正
Quantification analysis of 238U, Data of capture cross section, Monte Carlo correction
