核子与锂-7反应中的散射与产氚机制研究

The study of the nucleon-scattering and triton-production mechanism in nucleon induced reactions on 7Li and the obtainment of the corresponding nuclear data are of great significance in the physical design of some fusion and fission devices, and are also helpful for the understanding of the nucleosynthesis of lithium element in the early Universe. 7Li is a weakly-bound nucleus and the intermediate production in nucleon induced reactions on 7Li contains some unstable nuclei, which leads difficulties to the analysis of the reactions. In this project, the breakup reactions, n(p)+7Li→n’(p’)+7Li*→n’(p’)+α+t, are studied in the framework of the continuum discretized coupled channels method, and the contribution and effect of the breakup channel are analyzed quantitatively. The breakup continuum states of 7Li are truncated and discretized to finite number of discrete states by the pseudostate method. The diagonal and coupling potentials between nucleon and 7Li are obtained by folding the complex Jeukenne-Lejeune-Mahaux (JLM) effective nucleon-nucleon interaction with the transition densities between the corresponding bound and discretized states. The other triton production channels, n(p)+7Li→t+5He(5Li)→t+n’(p’)+α, are studied by the distorted-wave Born approximation theory and sequential decay model. The neutron total cross section, proton reaction cross section, nucleon scattering spectra and the double differential cross sections of emitted nucleon and triton will be obtained, and the contribution of the two reaction mechanism to the triton production will be discussed.

核子与锂-7反应的散射与产氚机制及相应的反应数据，对一些聚变和裂变能源装置的物理设计十分关键，对解决核天体物理中的锂疑难问题也有重要的应用价值。锂-7是弱束缚轻核且反应的中间产物有不稳定核，因此核子与锂-7反应的理论研究十分困难。本项目以连续态离散化耦合道方法为基础，研究核子与锂-7的破裂反应：n(p)+7Li→n’(p’)+7Li*→n’(p’)+α+t，从而定量分析破裂道的贡献与影响。通过赝态方法对锂-7的破裂连续态进行离散化。利用7Li内部各态的波函数对JLM核子-核子相互作用进行折叠得到核子与7Li之间的中心势和耦合势。利用DWBA理论和顺次衰变模型分析另一个产氚道：n(p)+7Li→t+5He(5Li)→t+n’(p’)+α。预言150 MeV以下核子与7Li反应的中子总截面、质子总反应截面、弹性和非弹角分布和出射氚的截面、双微分截面等。厘清不同反应机制对产氚的贡献。

锂是氘氚聚变堆中的产氚元素，也是一种高强度中子源的靶材料，还是熔盐堆中熔盐的一种元素成分。研究核子与锂-7反应的散射与产氚机制并定量地获得相应的核数据，对这些聚变和裂变能源装置的物理设计十分关键。锂-7是弱束缚轻核且反应的中间产物中有不稳定核，这给理论研究核子与锂-7的反应带来了困难。本项目以连续态离散化耦合道方法为基础，研究了核子与锂-7的破裂反应：n(p)+7Li→n’(p’)+7Li*→n’(p’)+α+t, 从而定量分析了破裂道的贡献与影响。用唯象方法研究了α-t的相互作用势，利用动量箱方法(momentum-bin method)和赝态方法(pseudostate method)对锂-7的破裂连续态进行了离散化，考虑了7Li内部的s、p、d、f、g、h分波，并最终选用了赝态方法。利用微观方法，用7Li内部各离散态的波函数对JLM核子-核子相互作用进行折叠得到核子与7Li之间的中心势和耦合势。通过分析7Li内部s、p、d、f、g、h分波对各物理量的贡献和收敛性给出了7Li内部离散化相对波函数的轨道角动量的截断值。研究了对应于7Li内部各角动量分波的破裂道的耦合效应。利用扭曲波玻恩近似理论、末态相互作用理论和顺次衰变模型分析了另一个产氚道：n(p)+7Li→t+5He(5Li)→t+n’(p’)+α。最终给出了核子与7Li反应的总截面、总反应截面、弹散角分布、非弹角分布和出射核子与氚的双微分截面等。厘清了这两种不同的反应机制对产氚的贡献。. 共发表了SCI文章3篇。.