中子引起的氙同位素核反应激发函数研究

The neutron-induced cross section of xenon isotopes is very important for the nuclear energy development, Nuclear weapons security verification, nuclear decay, and establishment of nuclear reaction model. In this project, the fast neutrons were produced via the 3H(d,n)4He reaction on Pd-300 or K-400 Neutron Generator at Chinese Academy of Engineering Physics (CAEP) or ZF-400 Intense Neutron Generator at Lanzhou University. Induced gamma activities were measured by a high-resolution gamma-ray spectrometer with high-purity germanium (HPGe) detector. Nuclear model calculations using the code Empire and Talys, which employs the Hauser-Feshbach (statistical model) and exciton model (precompound effects) formalisms, were undertaken to describe the formation of the products. The cross sections for the (n,2n)、(n,p)、(n,a) reactions induced by neutrons on enriched xenon isotopes are compared with experimental data found in the literature, with values of model calculations including the pre-equilibrium contribution, and with the evaluation data, to analyse conformity of data, to find out the cause of disagreement in those data, and also to correct the discrepant data. We will carry on exploratory experiment for the cross sections which have not been reported in the database and give the corresponding results. The present research is very important for the strengthening and complementing of the nuclear data libraries, for the development of the nuclear reaction theory, and for the improvement of the basic research in nuclear physics of China (especially for the accurate measurement of the activation cross sections for reactions induced by neutrons).

中子引起的氙同位素核反应截面对核能的开发、核武器安全核查、核衰变研究及核模型的建立都有重要意义。本项目以中国工程物理研究院Pd-300和K-400型中子发生器、兰州大学ZF-400型强流中子发生器为实验平台，用快中子活化高富集度的氙同位素样品，通过高分辨率的高纯锗探测器对核反应生成核活度进行测量，从而对氙同位素的(n,2n)、(n,p)、(n,a)等核反应截面进行系统的实验研究。同时结合统计与激子理论模型,用国际原子能机构提供的Empire和Talys程序对其激发函数进行计算并评价，对核反应截面数据库中已有数据进行对比，分析数据的符合性，找出数据分歧的原因，并对其进行矫正。而在数据库中尚未有报道的数据，我们会进行探索性的测量，并给出相应的结果。本项目的研究，对增强和补充中子核反应截面数据库、完善核反应模型理论、提高我国核物理基础研究（尤其是中子引起的核反应截面精确测量）水平有重要作用。

中子引起的氙同位素核反应截面对核能的开发、核武器安全核查、核衰变研究及核模型的建立都有重要意义, 也是研究核反应机制和核结构的基础数据。本项目以中国工程物理研究院K-400型中子发生器为实验平台，通过d-T中子活化天然丰度（或高富集度）稳定同位素124-Xe、126-Xe、128-Xe、130-Xe、131-Xe、132-Xe、134-Xe和136-Xe，并用高分辨率高纯锗探测器对其(n,2n)、(n,p)、(n,a)反应生成核的活度进行测量, 从而对中子引起氙同位素(n,x)核反应截面进行了系统的实验研究，给出了相应反应截面的测量结果。同时结合统计与激子理论模型, 用Talys-1.95程序对其激发函数进行了计算并进行了评价，对中子核反应截面数据库中已有的数据进行了对比，分析了数据的符合性，找出了数据分歧的原因，并对其进行了矫正；而在数据库中尚未有报道的数据，我们也进行了探索性的测量。本项目的研究，对增强和补充中子核反应截面数据库、完善核反应模型理论、提高我国核物理基础研究（尤其是中子引起的核反应截面精确测量）水平有重要作用。