Coexistence of covalent superdeformation and molecular resonances in an unbound region of 12Be.
The generalized two-center cluster model, which can treat static structures and dynamical reactions in excited states, is applied to the light neutron-rich system, 12Be=alpha+alpha+4N. We discuss the change of the neutrons' configuration around two alpha cores from the covalent structure to the ionic one. We show that, in the unbound region above particle-decay thresholds, the ionic configurations appear as the molecular resonances of alpha+8He, 6He+6He, and 5He+7He. A new type of superdeformation is possible, and we find here a covalent superdeformation with a hybrid configuration of both the covalent and ionic structures. The excitation of these exotic structures through the two-neutron transfer reaction is also discussed.
RIKEN Nishina Center for Accelerator-Based Science, RIKEN, Wako, 351-0198, Saitama, Japan.
M
M
Ito
N
N
Itagaki
H
H
Sakurai
K
K
Ikeda