35MeV以下^(56)Fe(n,p)^(56)Mn反应截面及协方差评价  

Reaction Cross Section and Covariance Evaluation of ^(56)Fe(n,p)^(56)Mn below 35 MeV

作　　者：李小军 兰长林[1] 张玥 杨宪林 张智 孙小东 LI Xiaojun;LAN Changlin;ZHANG Yue;YANG Xianlin;ZHANG Zhi;SUN Xiaodong(School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China;China Nuclear Data Center,Key Laboratory of Nuclear Data,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]兰州大学核科学与技术学院,甘肃兰州730000 [2]中国原子能科学研究院核数据重点实验室,中国核数据中心,北京102413

出　　处：《原子能科学技术》2022年第5期905-917,共13页Atomic Energy Science and Technology

基　　金：国家自然科学基金青年基金(12005303)。

摘　　要：^(56)Fe(n,p)^(56)Mn通常作为标准反应来监测中子场通量,该反应截面数据的准确性直接影响到活化法测量结果的精确度,进而影响到实验待测物理量的精度。本文开展了^(56)Fe(n,p)^(56)Mn反应截面实验测量数据评价工作与协方差计算工作,首先系统分析EXFOR中现有的^(56)Fe(n,p)^(56)Mn反应截面实验测量数据,对实验数据进行了归纳总结分析,并从中子源、测量方法、探测器类型等方面对^(56)Fe(n,p)^(56)Mn直接测量实验数据进行评价。然后,拟合给出适用入射中子能量区间为2.95~35 MeV的激发曲线。随后,针对评价中重点推荐的实验数据开展了关联协方差矩阵的计算工作。最后,使用核反应计算程序TALYS对^(56)Fe(n,p)^(56)Mn激发曲线进行了调参计算并和评价数据进行了比较分析。该工作拓展了现有的中子活化反应截面实验数据的评价方法,结果提高了35 MeV以下中子诱发^(56)Fe(n,p)^(56)Mn反应的评价数据精度。Neutron induced reaction cross sections play an important role in nuclear science and technology research,such as national defense,nuclear energy construction and development,nuclear medicine,radiation protection and nuclear safety.With the rapid development of nuclear technology,there are increasing demand for the variety and accuracy of neutron data.As an important structure material nuclide,the accuracy of neutron induced reaction cross section on 56 Fe is directly related to the design and operation of reactors,spent fuel disposal and miniaturization design,and also of great significance to nuclear physics basic research.The ^(56)Fe(n,p)^(56)Mn reaction is usually used as the standard to monitor the neutron field flux in the experiment.It greatly influences the results of nuclear data measurement,and also has guiding significance for upon carry the determination of the parameters in the nuclear reaction model.Due to the obvious differences existing in the previous experimental data and inconsistency between the evaluation databases,the experimental measurement data evaluation and covariance analysis were carried out for the ^(56)Fe(n,p)^(56)Mn reaction cross section in this paper.Firstly,the existing experimental measurement data of ^(56)Fe(n,p)^(56)Mnreaction cross section in EXFOR and literature were downloaded and systematically collected,then summarized,contrasted,and classified in terms of neutron source,measurement method,detector kinds,etc.Secondly,the data with low reliability were discarded with checking the original papers,and the uncertainty mentioned in these papers was also analyzed.Additionally,previous experimental results which using the imprecise values were adjusted and modified with the more accurate data such as recently ratios,supervised reaction standard cross sections,and isotopic abundances.The data with significant divergence near 14 MeV were normalized,which made it more concentrated and less divergent.The polynomial curve fitting was applied to obtain the excitation curve of ^(56)Fe

关 键 词：^(56)Fe(n p)^(56)Mn 反应截面评价 数据库建立 协方差分析 

分 类 号：O571.53[理学—粒子物理与原子核物理]