替代比率法中复合核自旋宇称分布对中子俘获截面推导的影响  

The Effect of Spin-parity Distribution in(n,γ)Cross Section Determination

作　　者：颜胜权[1] YAN Shengquan(China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院,北京102413

出　　处：《原子核物理评论》2024年第1期366-370,共5页Nuclear Physics Review

基　　金：国家重点研发计划项目(2022YFA1602301);国家自然科学基金资助项目(12125509,12222514,12005304,11961141003,12275361,U2267205)。

摘　　要：不稳定核中子俘获截面对于恒星核合成及恒星内部中子密度研究有重要意义,但由于难以制靶,直接测量极其困难。在前期工作验证了替代比率法可以可靠推导不稳定核的中子俘获截面的基础上,本工作主要讨论了复合核自旋宇称态分布差异对复合核γ衰变概率比的影响。本工作计算了不同自旋宇称态下^(94)Zr*和^(92)Zr*衰变到γ道的衰变概率比,计算结果显示在中子入射能较高的区域复合核自旋宇称态分布差异对γ衰变概率比影响较小。同时,理论计算结果与实验数据比较显示,在低能区域(^(18)O,^(16)O)的替代反应生成的复合核倾向布居与中子俘获反应生成的复合核相近的低自旋宇称态。本工作的计算和讨论进一步证明了替代比率法推导(n,γ)截面的可靠性。The neutron capture cross sections of unstable nuclei are important to the study of the stellar nucleosynthesis and the neutron densities in massive stars.Due to the difficulties of the target fabrication,it is very hard to measure the neutron capture cross section of unstable nuclei directly.Therefore,the surrogate ratio method had been employed in(n,γ)determination and proved valid previously.In this work,the difference of the spin-parity distribution in compound nuclei that formed by surrogate reaction or neutron capture was discussed in(n,γ)determination with surrogate ratio method.Theγ-decay probabilities ratio of ^(92)Zr*and ^(94)Zr*were calculated in various spin-parities,and the calculation showed the ratio is insensitive to their spin-parity distribution in high incident neutron energies.The measuredγ-decay probabilities ratios of ^(92)Zr*and ^(94)Zr*were compared to the theoretical calculations,it imply that the spin-parity distributions of compound nuclei formed by(^(18)O,^(16)O)reactions are similar to the one formed by neutron captures,and the validity of the surrogate ratio method was further proved in this work.

关 键 词：替代比率法 中子俘获截面 不稳定核 

分 类 号：O571.1[理学—粒子物理与原子核物理]