Extended ^9Li+n+n Three-Body Model of ^<11>Li with a Pairing Correlation in ^9Li

概要

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We investigate the binding mechanism of ^<11>Li on the basis of an extended three-body model of ^9Li+n+n. In the model, we take into account the pairing correlation of p-shell neutrons in ^9Li, in addition to that of valence neutrons outside the ^9Li nucleus, and solve the coupled-channel two- and three-body problems of ^<10>Li and ^<11>Li, respectively. The results show that the degrees of freedom of the pairing correlation in ^9Li play an important role in the structure of ^<10>Li and ^<11>Li. In ^<10>Li,the pairing correlation in ^9Li produces a so-called pairing-blocking effect due to the presence of a valence neutron, which causes the s-and p-wave neutron orbits to become energetically degenerate. In ^<11>Li, contrastingly, the pairing-blocking effect is overwhelmed by the core-n interaction due to the two degrees of freedom of the two valence neutrons surrounding ^9Li, and as a result, the ground state is dominated by the p-shell closed configuration and does not exhibit spatial extension with a large r.m.s. radius. These results indicate that the pairing correlation is realized differently in odd- and even-neutron systems of ^<10>Li and ^<11>Li. In addition, we further improve the tail part of the ^9Li-n interaction, which yields reasonable reproductions of the observed large r.m.s. radius in ^<11>Li.
理論物理学刊行会の論文
2002-07-25