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arXiv 1402.0306nucl-thnucl-ex
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张量优化壳层模型计算~ 8Be的壳层和α团簇结构

Shell and alpha cluster structures in 8Be with tensor-optimized shell model

Takayuki Myo, Atsushi Umeya, Kaori Horii, Hiroshi Toki, Kiyomi Ikeda

摘要:

利用张量优化壳层模型(TOSM)研究了8 Be基态和激发态的壳层和α团簇结构。在TOSM中,张量关联在包含高动量分量的2 p2 h组态的全空间中被优化。短程相关用酉相关算子方法(UCOM)处理。我们采用基于裸核子-核子相互作用AV 8 $^\prime$的有效相互作用。8Be态由两组基态和高激发态组成,它们的同位旋T=0和T=1。结果表明,基态的张量贡献比高激发态强,基态的动能和中心贡献几乎是4 He值的两倍.这些功能表明两个α集群的8Be的基态。我们还估计的相关能量的$α$聚类使用的α聚类模型。在高激发态,TOSM计算的光谱再现了实验的能级顺序和各能级的相对能量。这种一致性表明,这些状态可以被解释为壳状状态。与使用明尼苏达有效相互作用而不使用张量力的结果相比,发现能级顺序对张量力的存在敏感。研究还发现,T=0态的张量贡献比T=1态的强,这与张量力的态依赖性是一致的.

英文摘要:

We study the shell and alpha cluster structures in the ground and excited states of 8Be in terms of the tensor-optimized shell model (TOSM). In TOSM, the tensor correlation is optimized in the full space of 2p2h configurations involving high-momentum components. The short-range correlation is treated with the unitary correlation operator method (UCOM). We use the effective interaction based on the bare nucleon-nucleon interaction AV8$^\prime$. The 8Be states consist of two groups of ground band states and highly excited states with the isospin T=0 and T=1. It is found that the tensor contributions of the ground band states are stronger than the highly excited states and that the kinetic energies and the central contributions of the ground band states are almost twice the 4He values. These features suggest two-alpha clustering for the ground band states in 8Be. We also estimate the correlation energy of the $α$ clustering using the alpha cluster model. In the highly excited states, the calculated spectrum in TOSM reproduces the experimental level order and the relative energies of each level. This agreement suggests that those states can be interpreted as shell-like states. The level order is found to be sensitive to the presence of the tensor force in comparison with the results using the Minnesota effective interaction without the tensor force. It is also found that the tensor contributions in the T=0 states are stronger than the T=1 states, which is consistent with the state dependence of the tensor force.

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