原子能科学技术 ›› 2022, Vol. 56 ›› Issue (5): 896-904.DOI: 10.7538/yzk.2022.youxian.0213

• 核数据模型理论与评价 • 上一篇    下一篇

142~146,148,150Nd光核反应理论计算

金永利;田源;陶曦;王记民;续瑞瑞;刘萍;葛智刚   

  1. 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
  • 出版日期:2022-05-20 发布日期:2022-05-20

Theoretical Calculation for Photonuclear Reaction of 142-146,148,150Nd

JIN Yongli;TIAN Yuan;TAO Xi;WANG Jimin;XU Ruirui;LIU Ping;GE Zhigang   

  1. China Nuclear Data Center, Key Laboratory of Nuclear Data, China Institute of Atomic Energy, Beijing 102413, China
  • Online:2022-05-20 Published:2022-05-20

摘要: 基于我国自主研制的核反应理论计算程序MENDG,针对200 MeV能量范围内光子诱发142~146,148,150Nd的核反应数据开展了系统的理论计算研究。首先分析了现有的多种光核反应测量数据,筛选出以实验数据作为理论计算依据;利用8种经典的光子强度函数模型和准氘模型,描述光子吸收截面;在此基础上,采用MENDG程序对142~146,148,150Nd开展光核反应理论计算,并通过优化6个GilbertCameron能级密度参数,得到适用于Nd天然稳定同位素的普适能级密度,同时针对142,143Nd得到与实验结果符合更好的定域能级密度参数。通过对分光中子出射截面的系统分析,建立了ENDF6格式的光核反应数据。结果表明,推荐的光核数据合理,与实验测量数据一致性较好,该数据已收录在CENDL32光核子库中。

关键词: 光核反应, 142~146,148,150Nd, 核数据理论计算, 能级密度

Abstract: Photonuclear reaction data can describe the physical process of the interaction between photons and nuclei as well as the emission of particles. It has important applications in nuclear reactor physics, accelerators, radiation shielding, activation analysis, nuclear waste transmutation, and nuclear synthesis of celestial bodies. The natural stable isotopes of neodymium (Nd), 142Nd, 143Nd, 144Nd, 145Nd, 146Nd, 148Nd and 150Nd, are important fission products which are necessary in the activation analysis and reactor physics. In order to provide more complete and better quality data to the nuclear application, the Chinese theoretical photonuclear reaction program MENDG is developed by China Nuclear Data Center and Nankai University, which contains the optical model, HauserFeshbach model and Exciton models, and can deal with the complicated particle emission reactions below the photon induced energy 200 MeV. Base on MENDG, the nuclear data of photon nuclear reactions of 142146,148,150Nd in the energy range below 200 MeV were systematically calculated in this work. It should be noticed before the theoretical calculations that, various existing experimental data in EXFOR for photonuclear reaction including (γ, xn), (γ, sn), (γ, in) (i=1,4) and so on were collected and evaluated, some discrepancies and selfinconsistencies among different data were removed, and the present theoretical calculations were guided under the well evaluated measurements. Photon absorption cross sections for the photon incident energy below 200 MeV were firstly determined with the classical photon strength functions and the quasideuteron model. Eight formula with Lorentz functions including the standard Lorentzian (SLO) model, the enhanced generalized Lorentzian (EGLO) model, the Hybrid  (GH) model, the generalized Fermiliquid (GFL) model, and the three kinds of modified Lorentzian (MLO1, MLO2, MLO3) models were all utilized to describe the giant dipole resonance below about 40 MeV, and SLO model was validated as the suitable one in this case with the minimum Chi square for experimental data and calculations. Then, the theoretical calculations of photonuclear reaction of 142146,148,150Nd were carried out by MENDG. The competing reactions especially for the multiple neutron emissions were globally obtained by the six optimized GilbertCameron level density parameters, the theoretical selfconsistency for 142146,148,150Nd were satisfied as much as possible. The partial photoneutron cross sections were specially discussed systematically, and satisfying theoretical descriptions were observed in the global case. Moreover, to improve the theoretical results, the local parameters were also adjusted for each isotope and better fitness with the experimental data can be observed comparing to the global ones. As a result, all the theoretical data are good in physics and are included in the photonuclear data sublibrary of CENDL32.

Key words: photonuclear reaction, 142-146,148,150Nd, nuclear theoretical calculation, level density