Prompt fission neutron spectra of n+235U above the (n,nf) fission threshold
Prompt fission neutron spectra of n+235U above the (n,nf) fission threshold
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n 235U 高于 (n,nf) 裂变阈值的瞬发裂变中子谱
DOI：
10.1088/1674-1137/39/5/054101
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
舒能川, 贾敏, 陈永静, 刘廷进
中科院分区：
文献类型：
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作者：
舒能川, 贾敏, 陈永静, 刘廷进
用半经验方法计算了能量为En = 7.0和14.7MeV的~（235）U（n，f）反应的瞬发裂变中子能谱。总PFNS是由裂变碎片蒸发出的（n，xnf）裂变前中子能谱和裂变后中子能谱的叠加而得到的，这两种能谱作为蒸发能谱的表达式。讨论了（n，xnf）裂变中子能谱对PFNS计算的贡献。结果表明，（n，nf）或（n，2nf）反应中的一个或两个中子的发射影响PFNS的形状，（n，xnf）裂变通道的中子能谱比（n，f）裂变通道的中子能谱软。此外，多机会裂变成分的分析表明，第二次机会裂变占主导地位的PFNS与入射中子能量为14.7兆电子伏，而第一次机会裂变占主导地位的7兆电子伏的情况。
Calculations of prompt fission neutron spectra (PFNS) from the 235U(n, f) reaction were performed with a semi-empirical method for En = 7.0 and 14.7 MeV neutron energies. The total PFNS were obtained as a superposition of (n,xnf) pre-fission neutron spectra and post-fission spectra of neutrons which were evaporated from fission fragments, and these two kinds of spectra were taken as an expression of the evaporation spectrum. The contributions of (n,xnf) fission neutron spectra on the calculated PFNS were discussed. The results show that emission of one or two neutrons in the (n,nf) or (n,2nf) reactions influences the PFNS shape, and the neutron spectra of the (n,xnf) fission-channel are soft compared with the neutron spectra of the (n,f) fission channel. In addition, analysis of the multiple-chance fission component showed that second-chance fission dominates the PFNS with an incident neutron energy of 14.7 MeV whereas first-chance fission dominates the 7 MeV case.