Excited states in neutron rich boron isotopes

Abstract

New experimental results on in-beam gamma spectroscopy of neutron rich boron isotopes are presented for 17B and its neutron removal fragments 14,15B, after scattering with a H2 target. A gamma transition for 17B is observed at 1089±15keV. The fragment 15B is observed abundantly associated with a gamma transition of 1336±10keV. This suggests for the first time a core-excited structure for 17B thereby providing a new insight into its structure. Observations for 12,14B are also presented. The data set provides a useful systematic study of first excited states of neutron rich boron isotopes showing the dramatic drop in excitation energy beyond N=8.