Electromagnetic transition properties and isospin excitation in the cross-conjugate nuclei 44Ti and 52Fe

The interacting boson model with isospin (IBM-3) is applied to study the band structure and electromagnetic transition properties of the low-lying states in the cross-conjugate nuclei ⁴⁴Ti and ⁵²Fe. The isospin excitation states with T=0, 1 and 2 are identified and compared with available data. The E2 and M1 matrix elements for the low-lying states have been investigated. According to this study, the 2₃⁺ state is the lowest mixed symmetry state in the cross-conjugate nuclei ⁴⁴Ti and ⁵²Fe. The excitation energy of the second 0₂⁺ and 2₂⁺ states with T=0 in the nucleus ⁵²Fe are identified. The agreement between the model calculations and data is reasonably good.     

原子核结构研究的一些进展

简述在最近几年中原子核结构研究中的一些新的进展.原子核的超对称性在1980年提出,1999年在奇奇核中得到检验.在原子核结构的代数模型中,玻色子模型中的弱集体性困难最近得到解决,在八极振动中,代数模型给出了大量的电磁跃迁的解析表达式,对于实验研究十分方便,¹⁵⁸Gd是目前最好的八极振动核.在原子核的壳模型中蒙特卡罗壳模型,投影壳模型有较大进展.最后对今后原子核结构的发展作出展望.     

Isospin structure in 68Ge

The interacting boson model-3(IBM-3) has been used to study the low-energy level structure and electromagnetic transitions of 68Ge nucleus. The main components of the wave function for some states are also analyzed respectively. The theoretical calculations are in agreement with experimental data, and the 68Ge is in transition from U(5) to SU(3).     

Low-lying spectra and E2 transition rates in 160-170Er isotopes in the interaction boson model

Spectra and E2 transition rates for the ^160-170Er isotopes are studied in the framework of the interaction boson model. A schematic Hamiltonian able to describe their spectra and B(E2) transition is used. It is found that the ^160-170Er isotopes are in the transition from the vibrational limit to rotational limit.     

Mixed symmetry states and electromagnetic transition in the N=Z nucleus ^28Si

The interacting boson model with isospin （IBM-3） has been used to study mixed symmetry states and electromagnetic transitions at low-lying states for a ^28Si nucleus. The theoretical calculations show that the 24^＋ state is the lowest mixed symmetry state in ^28Si and the 43＋ state is also a mixed symmetry state.     

164—182Hf核的低能谱和电磁跃迁的相互作用玻色子模型

采用相互作用玻色子模型研究了^164—182Hf偶偶核的低能谱和电磁跃迁, 应用一个U(5)→SU(3)简化哈密顿量很好的描述它们的低能谱和电磁跃迁过渡. 结果表明^164—182Hf同位素核基本上属于U(5)→SU(3)的过渡核.     

原子核形状演变的又一个特征指标E0跃迁及对102—110Pd偶偶核的应用

利用相互作用玻色子模型分别在U(5)—SU(3)和U(5)—O(6)描述下研究了^102—110Pd偶偶核的电单极跃迁.研究表明,这些偶偶Pd核能够用U(5)—SU(3)更好地描述.     

Critical behaviour in nuclear structure from spherical to axially symmetric deformed shape in IBM

To compare with the predictions of the transitional dynamical symmetry X(5) proposed by Iachello (2001 Phys. Rev. Lett. 87 052502), the critical behaviours of U(5)--SU(3) are studied in the space of two control parameters in the interacting boson model (IBM). A simple-shaped phased diagram has been presented. It is found that X(5) predictions cannot be exactly reproduced by our calculations and that the best agreement is close to the calculations with boson numbers N = 11 and 12. By comparing with experimental data on X(5)-like nuclei, we find that X(5) predictions and IBM calculations can reproduce the energy ratios and E2 transition ones.     

A～130区域核晕带的形状变化和共存

利用最近提出的E-GOS理论分析方法, 对A～130质量区域的核进行了分析研究, 发现该区域的核基本上处于U(5)→SU(3)过渡区域, ^124—130Ba核更接近于O(6)核.     

140-162Gd核的低能谱和电磁跃迁的相互作用玻色子模型

采用相互作用玻色子模型研究了140-162Gd偶偶核的低能谱和电磁跃迁,应用一个U(5)→SU(3)的简化哈密顿量很好地描述它们的低能谱和电磁跃迁过渡.结果表明140-162Gd同位素核基本上属于U(5)→SU(3)的过渡核.