Largely deformed states of $^{13}$B

Abstract

The excited states of $^{13}$B were studied with a method of antisymmetrized molecular dynamics(AMD). The theoretical results suggest that the intruder states with large deformations construct the rotational bands, $K^\pi=3/2^-$ and $K^\pi=1/2^+$, starting from 5 MeV and 8 MeV, respectively. The neutron structure of the $K^\pi=3/2^-$ is analogous to the intruder ground state of $^{12}$Be. In the predicted $K^\pi=1/2^+$ band, we found very exotic structure with a proton intruder configuration. This proton intruder state has a larger deformation than superdeformation. The band-head $1/2^+$ state is assigned to the $1/2^+$(4.83 MeV), which was experimentally suggested to be the proton intruder state because of the strong production via the proton-transfer to the $^{12}$Be($0^+$) state in the $^4$He($^{12}$Be,$^{13}$B$\gamma$)$X$ experiments.