Abstract
The cross sections for single-neutron removal from the very neutron-rich nucleus on Pb and C targets have been measured at using the RIBF facility at RIKEN. The deduced large Coulomb breakup cross section of 540(70) mb is indicative of a soft excitation. Comparison with direct-breakup model calculations suggests that the valence neutron of occupies a low- orbital (most probably ) with a small separation energy (), instead of being predominantly in the orbital as expected from the conventional shell ordering. These findings suggest that is the heaviest halo system known.
- Received 9 July 2009
DOI:https://doi.org/10.1103/PhysRevLett.103.262501
©2009 American Physical Society