nucl-th digest · May 26, 2017

[Submitted on 25 May 2017]

Tetrahedral $4 α$ and $^{12} C + α$ cluster structures in $^{16}$ O

We have investigated structures of the ground and excited states of $^{16} O$ with the method of variation after spin-parity projection in the antisymmetrized molecular dynamics model combined with the generator coordinate method of $^{12} C + α$ cluster. The calculation reasonably reproduces the experimental energy spectra, $E 2$ , $E 3$ , $E 4$ , $I S 1$ transitions, and $α$ -decay properties. The formation of 4 $α$ clusters has been confirmed from nucleon degrees of freedom in the AMD model without assuming existence of any clusters. They form "tetrahedral" $4 α$ - and $^{12} C + α$ -cluster structures. The $^{12} C + α$ structure constructs the $K^{π} = 0^{+}$ band consisting of the $0_{2}^{+}$ , $2_{1}^{+}$ , and $4_{1}^{+}$ states and the $K^{π} = 0^{-}$ band of the $1_{2}^{-}$ , $3_{2}^{-}$ , and $5_{1}^{-}$ states. The $0_{1}^{+}$ , $3_{1}^{-}$ , and $4_{2}^{+}$ states are assigned to the ground band constructed from the tetrahedral 4 $α$ structure. The $0_{1}^{+}$ and $3_{1}^{-}$ are approximately interpreted as $T_{d}$ band members with the ideal tetrahedral configuration. The ground state $4 α$ correlation plays an important role in enhancement of the $E 3$ transition strength to the $3_{1}^{-}$ . The $4_{2}^{+}$ state is not the ideal $T_{d}$ member but constructed from a distorted tetrahedral $4 α$ structure. Moreover, significant state mixing of the tetrahedral $4 α$ and $^{12} C + α$ cluster structures occurs between $4_{1}^{+}$ and $4_{2}^{+}$ states, indicating that the $T_{d}$ configuration of $4 α$ is rather fragile at $J^{π} = 4^{+}$ .

Comments:: 12 pages, 7 figures
Subjects:: Nuclear Theory (nucl-th)
arXiv:: 1705.09097 [pdf]

PRC(2017)·21 citations

Friday·May 26, 2017

Tetrahedral $4 α$ and $^{12} C + α$ cluster structures in $^{16}$ O

Experimental status of the nuclear spin scissors mode

Affiliations

Tetrahedral 4α and 12C+α cluster structures in 16O

Experimental status of the nuclear spin scissors mode

Affiliations

Tetrahedral $4 α$ and $^{12} C + α$ cluster structures in $^{16}$ O