多核子转移反应中自旋分布的微观描述
Microscopic description of spin distributions in multinucleon tranfer reactions
- Institute of Science Tokyo（东京科学大学）
- University of Tsukuba（筑波大学）
- RIKEN Nishina Center（理化学研究所西村中心）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文通过三维TDHF计算结合粒子数与角动量投影，首次微观描述了多核子转移反应产物的自旋分布，发现其可由单粒子态角动量组合解释，并随转移核子数增加趋于热平衡分布。
AI中文摘要：
背景：近年来，裂变碎片中自旋分布的产生引起了广泛关注，其机制随着微观理论的精细描述而逐渐清晰。相比之下，反应产物中自旋分布的微观起源在很大程度上仍未得到探索。方法：利用Skyrme SLy5能量密度泛函，在质心能量约为128.54 MeV的$^{40}\ ext{Ca} + {}^{124}\ ext{Sn}$反应中，对多核子转移过程进行了三维TDHF计算。为了获得每个转移道中的自旋分布，对反应产物同时进行了粒子数投影（PNP）和角动量投影（AMP）。结果：通过对碰撞后的TDHF波函数进行PNP+AMP，计算了类弹碎片（PLFs）的自旋相关转移截面。从结果中我们发现，从TDHF波函数可以获得丰富的自旋分布。对于单核子添加和移除道，计算得到的自旋值与$pf$壳和$sd$壳中单粒子态的自旋值分别吻合良好。此外，对于少数核子转移道，我们表明所获得的自旋分布可以很好地由这些单粒子态的总角动量组合来解释。进一步地，随着转移核子数的增加，我们发现计算得到的自旋分布呈现出光滑的单峰形状，并带有长尾，作为$J$的函数，这类似于热平衡碎片经验自旋分布。还对$^{240}$Pu的感生裂变进行了探索性计算，获得了与多核子转移反应相似的结果。（因arXiv字数限制而缩短）
英文摘要：
Background: The generation of spin distributions in fission fragments has attracted substantial interest in recent years and its mechanism is becoming clear alongside the refined description with microscopic theories. In contrast, the microscopic origin of spin distributions in reaction products remain largely unexplored. Methods: Three-dimensional TDHF calculations are performed for multinucleon transfer processes in the $^{40}\text{Ca} + {}^{124}\text{Sn}$ reaction at $E_{\text{c.m.}} \simeq 128.54\,\text{MeV}$ using the Skyrme SLy5 energy density functional. To obtain spin distributions in each transfer channel, the particle-number projection (PNP) and the angular-momentum projection (AMP) are simultaneously achieved for a reaction product. Results: By performing PNP+AMP for TDHF wave functions after collisions, spin-dependent transfer cross sections are calculated for projectile-like fragments (PLFs). From the results, we find that abundant spin distributions can be obtained from the TDHF wave functions. For one-nucleon addition and removal channels, the calculated spin values agree well with those of single-particle states in the $pf$- and $sd$-shell, respectively. Moreover, for a-few-nucleon transfer channels, we show that the obtained spin distributions can be well explained by combinations of total angular momenta of those single-particle states. Furthermore, as the number of transferred nucleons increases, we find that the calculated spin distributions exhibit a smooth singly-peaked shape with a long tail as a function of $J$, which resembles that of empirical spin distributions for thermally equilibrated fragments. An exploratory calculation for induced fission of $^{240}$Pu is also carried out, obtaining similar results as in multinucleon transfer reactions. (shorted due to the arXiv's word limit)
