g玻色子对100Pd核高自旋态能谱的影响

Effect of g-Boson on Spectra of HighSpin States in 100Pd Nucleus

  • 摘要: 以新近的实验单粒子能量为输入,应用唯象sdgIBM理论的两种微观实现——微观sdgIBM-2方案和sdgIBM-Fmax方案,仔细研究100Pd的核能谱和B(E2)跃迁。计算结果表明:sdgIBM-2方案成功地再现了100Pd核的较复杂的基态带和γ带的高角动量态能谱以及已知的B(E2)跃迁,其再现角动量达Jπ=16+Ex≈7.00 MeV,比通常IBM理论再现的Jπ=6+~8+Ex≈2.00 MeV高出很多;指认直到16+的yrast态都是基态,很可能目前观测到的yrast带中根本就不存在玻色子破对后的准粒子态。理论分析和数值计算进一步表明,为了能在IBM理论框架下描述好核的高角动量基态,需要平权地引入g玻色子,以便提供较强的十六极对相互作用,抵抗住高速转动下玻色子的破对趋势。用g玻色子数为0~3的弱耦合sdgIBM-Fmax方案的计算结果对此作了进一步说明。按照微观sdgIBM2方案,解释了实验上3个14+态的异常:14+1态是由于1个中子g玻色子在转变为中子d玻色子的量子相变中辐射出1对光子的结果,14+2是16+1态退耦的中间态,而14+3是真正的基态。

     

    Abstract: By using a microscopic sdgIBM-2 approach which is the accomplishment of the phenomenological sdgIBM theory and the experimental single-particle energies, the levels of the more complex ground-state band and the high-angular momentum states of γ-band on 100Pd nucleus are successfully reproduced. The groundstate band and γ-band are described well up to Jπ=16+ and Ex≈7 00 MeV, and that is larger than that Jπ=6+-8+, Ex≈2 00 MeV can be successfully reproduced in IBM theory. It has been proved that its yrast states up to the 16+ state are ground states, there may not exist any broken pair quasi-particle state by boson in yrast states. Theoretical analysis and numerical calculation show that to describe successfully spectra on 100Pd nucleus underthe boson approach in IBM theory, it is impossible that the g-boson has been not considered in one. According to the microscopic sdgIBM-2 approach, the 14+1 state is understood as a result that a neutron g-boson transites into a neutron d-boson and a pair of photos is radiated at same time, and the 14+2 state is the decoupling state of the 16+1 state, while the 14+3 state is the actual ground state.

     

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