有限玻色子系统中的激发态量子相变

为了探讨原子核系统中存在激发态量子相变的可能性,在相互作用玻色子模型框架下对有限玻色子系统中的激发态量子相变现象进行唯象分析,特别是针对角动量和有限N效应如何影响U（5）-SU（3）和SU（3）-O（6）过渡区中的激发态量子相变行为进行了系统研究。结果表明,低角动量振动谱中的激发态量子相变特征在现实玻色子数情况下可以很好地保持,但随着角动量增加相变特征逐渐消失。In this work, a phenomenological analysis of the excited-state quantum phase transitions (ESQPTs) in the finite-N boson system has been carried out within the interacting boson model in order to reveal the possibility of finding ESQPTs in nuclear systems. Particularly, the angular momentum and finite-N effects on the ESQPTs in the U(5)-SU(3) and SU(3)-O(6) transitional regions have been systematically investigated. The results indicate that the main features of ESQPTs can be well preserved even at a realistic boson number for small angular momentum but will gradually disappear as the angular momentum increases.     

轴对称奇A核系统的强耦合临界点对称性

鉴于临界点对称性方法在描述原子核形状相变中的成功应用,在强耦合方案下对原有描述偶偶核球形到长椭形状相变的临界点对称性模型X（n）（n=3,4,5）进行扩展,据此建立描述轴对称奇A核系统的SX（n）临界点对称性。通过对X（n）模型与SX（n）模型的转动谱结构进行对比分析,揭示了SX（n）临界点模型的动力学结构受模型维数n的影响较小且更接近刚性转子的模型特征,这些模型特征进一步通过检验过渡区核素150,151,152,153Sm以及172,173,174,175Os中的相关转动带结构得到了初步证实。In view of the successful application of the methods based on critical point symmetries (CPSs) in nuclear shape phase transitions, the new CPSs named SX(n) are established in this work for axially-symmetric odd-A nuclei through extending the original X(n) CPSs with n=3,4,5, which were used to describe the spherical to prolate shape phase transitions in even-even nuclei, in the strong-coupling scheme. By comparing the spectral structures in between the X(n) and the SX(n) CPSs, it is revealed that the dynamical structures of SX(n) are closer to the rigid rotor and less changed with the model dimension in comparison with X(n). Moreover, these features of SX(n) are preliminarily verified by checking the rotational structures of 150,151,152,153Sm and 172,173,174,175Os nuclei.