近质子数Z=50原子核磁转动和反磁转动的理论研究和实验探索

Since phenomena of nuclear magnetic rotation (MR) and antimagnetic rotation (AMR) were discovered, the study on these novel nuclear rotations has been the frontiers of nuclear structure for several decades. The present project will combine research status of nuclear magnetic moment and the working foundation of applicant and corresponding research group, to study the relevant problems of magnetic rotation and antimagnetic rotation in mass region around proton number Z=50. The main contents include: theoretically, based on the multi-particle-multi-hole particle-rotor model (PRM) and titled axis cranking covariant density functional theory (TAC-CDFT), to systematically study nuclear magnetic rotation bands of isotopes with similar level structure and same intrinsic configuration, investigate the effects of competition between shear mechanism and collective rotation of core, interpret the transition from electric rotation mode to magnetic rotation mode, and explore the g-factor as the indicator of magnetic rotation. In addition，the TAC-CDFT with angular momentum projection will be established and applied to describe the MR and AMR as well as to explore the quantum effects of rotational symmetry restoration. Experimentally, populating high-spin states in 104Cd (or 106In) and completing the level structure via fusion-evaporation reaction, to explore the possible antimagnetic rotation band, and the systematics also will be performed for the present mass region as well. It’s expected to deepen the knowledge of nuclear magnetic rotation and antimagnetic rotation, improve their description and widen the understanding of nuclear rotation.

自从原子核磁转动和反磁转动现象被发现以来，对这种新奇转动模式的研究一直是核结构的前沿和热点。本课题将结合当前国内外研究现状，以及申请人和所在课题组的工作基础，对近质子数Z=50核区原子核磁和反磁转动相关问题开展研究。主要研究内容包含：理论上基于多粒子多空穴组态的粒子转子模型和倾斜轴推转的协变密度泛函理论，系统研究同位素链原子核中具有相似能级结构和相同内禀组态的磁转动带，深入理解剪刀机制和核芯集体转动模式的竞争带来的影响以及电磁转动模式转变现象，探讨g因子作为磁转动带的判据。同时发展包含角动量投影的倾斜轴推转协变密度泛函理论，探讨转动对称性恢复带来的量子效应。实验上利用熔合蒸发反应布居104Cd、106In高自旋态，探索可能存在的反磁转动带，并对该核区谱学性质特别是反磁转动进行系统学研究。通过本项目的研究，将深化对磁转动和反磁转动现象的认识，改善对其的描述，拓宽对原子核转动现象的理解。

本项目主要对近质子数Z=50核区原子核磁转动和反磁转动以及相关的磁偶极双带、磁偶极矩开展研究。系统研究了核素图上所有理想磁转动带的转动特征，发现能量振荡参数S(I)均明显表现出随自旋增加而变大的共有特性，并与理论描述相符。同时讨论同中异位素103Rh、105Ag和107In中的同组态磁偶极带，自旋振荡参数能清晰展示质子数近Z=50原子核中手征转动到磁转动机制的转变，表现出集体转动和剪刀机制转动模式的竞争。开展113In、109In和109Ag的高自旋实验，完善了相关的能级纲图。通过对比早期的实验结果和系统学讨论，以及倾斜轴推转的相对论平均场理论计算，在113In中发现一条新的候选反磁转动带和磁转动带，109In中发现一条候选反磁转动带，109Ag中发现一条新的磁转动带和一条类订书机模式的磁偶极带，拓展了Z=50核区附近磁转动和反磁转动原子核的边界。同时针对125,127,129,131Cs原子核实验磁偶极双带组态指定的不确定，从角动量顺排、电磁跃迁性质出发分析更新之前指定的组态。还结合相对论平均场理论和倾斜轴推转的相对论平均场理论计算，支持手征双带解释。建议120I为A ∼ 130核区“手性原子核岛”边界。最后发展了描述形变原子核磁矩的相对论平均场理论，很好地描述奇质子核 23,25,27,29,31,33Al 的基态磁矩和自旋，解释基态源于质子内禀态 5/2[202]上的转动耦合结构。