The cross sections for single-neutron removal from the very neutron-rich nucleus Ne31 on Pb and C targets have been measured at 230MeV/nucleon using the RIBF facility at RIKEN. The deduced large Coulomb breakup cross section of 540(70) mb is indicative of a soft E1 excitation. Comparison with direct-breakup model calculations suggests that the valence neutron of Ne31 occupies a low-ρ orbital (most probably 2p3/2) with a small separation energy (Sn□0.8MeV), instead of being predominantly in the 1f7/2 orbital as expected from the conventional shell ordering. These findings suggest that Ne31 is the heaviest halo system known.
ASJC Scopus subject areas
- Physics and Astronomy(all)