丰中子轻核同位旋结构和形状相变的理论研究

Abundant changes on nuclear structure are found and studied on the light neutron-rich nuclei region which lies between the β stability line and the neutron drip line. The development of radioactive nuclear beam technologies accumulates plentiful experimental data，and it provides proper conditions for researches on light neutron-rich nuclei far from stability line. In this work，the isospin-dependent interacting boson model，the self-consistent relativistic angular momentum projected shell model and the self-consistent shell-model-like approach in the framework of relativistic mean field theory are used to study systematicly some typical isotope chains in the light neutron-rich nuclei region. Isospin structure,nuclear deformation evolution,the magic number in light nuclei region and isospin-dependent shell effect on the light neutron-rich nuclei region are studied further owing to calculations of electromagnet transitions,low excited energy levels,binding energy,neutron separation energy,single-particle energy level and the quadrupole deformation, and so on. Researches on phenomenological and microscopic theories make further understandings of isospin effect and dynamical symmetry in the light neutron-rich nuclei region as well as verify and extends the appilications of these theoretical models.

丰中子轻核区域具有丰富的核结构变化，这主要由于在β稳定线和中子滴线之间，存在大量核素，而大部分不稳定核处于丰中子一侧。随着放射性核束技术的发展，涌现出大量实验数据,为远离稳定线的丰中子轻核结构性质的研究创造了有利条件和机遇。本工作将使用含同位旋效应的相互作用玻色子模型、相对论自洽角动量投影壳模型和在自洽的相对论平均场理论框架下严格保持粒子数守恒的类壳模型对丰中子轻核区的多个典型同位素链进行系统研究,通过对电磁跃迁、低激发能谱、结合能、中子分离能、单粒子能级和四极形变等的计算，深入研究丰中子轻核的同位旋结构性质、原子核形变演化、轻核区的幻数结构和壳效应随同位旋的演化规律。通过对该核区的唯象和微观理论研究,加深对丰中子轻核区原子核同位旋效应和动力学对称性的认识，检验现有模型理论，扩展它们的应用。

本项目分别使用相互作用玻色子模型对丰中子轻核区部分典型核素进行了理论研究,分别计算了丰中子轻核22Ne ,88-90Mo,72-84kr同位素链的电磁跃迁、低激发能谱、同位旋激发态、低能混合对称态、波函数的主要成分,并对电四极跃迁和磁偶极跃的同位旋标量和同位旋矢量部分进行了深入的研究,给出了部分能级的波函数成分分析，讨论了同位素链的动力学对称性变化和形状相变随控制参量的演化规律。使用自洽的相对论平均场理论框架下严格保持粒子数守恒的类壳模型（RMF+SLAP）对19-40Mg同位素链的结合能、中子分离能、单粒子能级和四极形变进行了理论计算并与实验比较。优化了轴形变尼尔逊平均场加邻近轨道对力模型的近似角动量投影方法,并对Mg同位素链进行了理论计算。通过对该核区的唯象和微观理论研究,加深了对丰中子轻核区原子核同位旋效应和动力学对称性的认识，检验了所使用的理论模型，扩展它们的应用,进一步深化了对丰中子轻核结构的理解和认识。