Structure study of typical light hypernuclei

The structure study has been extended to some typical hypernuclei; sub(Λ)13C, sub(Λ)21Ne, sub(Λ)16O, sub(Λ)17O, and sub(Λ)18O. The structure of the low-lying states in sub(Λ)13C was investigated by the microscopic 3α + Λ cluster model which can take into account the effect of the dynamical coupling between the Λ particle motion and the two kinds of characteristic nuclear structures, namely, the shell-model-like structure and the loosely-coupled 3α cluster atructure. Secondly, a detailed spectroscopic analysis of the sub(Λ)21Ne hypernucleus has been carried out by solving the microscopic α + 16O + Λ three-cluster problem. The obtained wave functions were used to evaluate B(E2)'s, inter-cluster distances, reduced width amplitudes and S2-factors for the two-body decays. The basic ingredients of the present description of sub(Λ)21Ne are that the α + 16O model nicely describes the k sub(π) = O1+, O1-, and O2+ rotational bands of 20Ne and that the Λ particle is allowed to move in a wide space consisting of the O sub(s), O sub(p) and (1SOd) states. Detailed discussions are made on the interplays among the Λ-particle and nuclear collective motions. Finally, the shell model framework was applied to analyze the sub(Λ)sup(16,17,18)O hypernuclear structures. The elimination of the nuclear CM spuriosity is stressed to be essentially important to describe the core nuclear energy levels. It is also predicted that future observations of the (K-, π-) angular distribution offer some information on new hypernuclear energy levels. (Aoki, K.)