裂变碎片的微观自旋-宇称分布
Microscopic Spin-Parity Distributions of Fission Fragments
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中文总结 AI 辅助
研究热中子诱发²³⁹Pu裂变中碎片的自旋-宇称分布，在含时Hartree-Fock-Bogoliubov框架内同时投影角动量、粒子数和宇称，发现动力学对破裂影响宇称分布，结果与统计退激模型假设不同，对碎片衰变建模有潜在意义。
中文摘要 AI 辅助
近期微观研究探讨了裂变碎片自旋分布的各种特征，但其宇称分布大多未被探索。本文在含时Hartree-Fock-Bogoliubov框架内，首次对角动量、粒子数和宇称进行同时投影，完整刻画了裂变碎片的自旋-宇称内容。利用Gogny和Skyrme能量密度泛函对热中子诱发的²³⁹Pu裂变进行计算。发现裂变过程中的动力学对破裂使大量非自然宇称态布居，并产生非零自旋投影K的成分。宇称内容取决于碎片的质量数奇偶性，奇质量核呈现明显的宇称交错，奇偶核倾向负宇称。这些结果表明碎片的宇称分布可能与统计退激模型中通常假设的等概率分配有显著差异，对碎片衰变建模有潜在影响。
英文摘要
Recent microscopic studies have investigated various features of the spin distributions of fission fragments, but their parity distributions remain largely unexplored. In this Letter, we provide a complete characterization of the spin--parity content of fission fragments within a time-dependent Hartree-Fock-Bogoliubov framework, performing for the first time simultaneous projections on angular momentum, particle number, and parity. Calculations are carried out for the thermal neutron-induced fission of $^{239}$Pu using both the Gogny and Skyrme energy density functionals. We find that dynamical pair breaking during fission populates a significant fraction of unnatural-parity states and generates components with non-zero spin projections $K$. The parity content is found to depend on the number parity of the fragments, with odd-mass nuclei exhibiting pronounced parity staggering and odd-odd nuclei favoring negative parity. These results show that the parity distribution of fragments can depart significantly from the equiprobable partition commonly assumed in statistical de-excitation models, with potential implications for the modeling of fragment decay.
