Abstract
The structure of C has been investigated using high-energy (around 240 MeV/nucleon) one- and two-neutron removal reactions on a carbon target. Measurements were made of the inclusive cross sections and momentum distributions for the charged residues. Narrow momentum distributions were observed for one-neutron removal from C and C and two-neutron removal from C. Two-neutron removal from C resulted in a relatively broad momentum distribution. The results are compared with eikonal-model calculations combined with shell-model structure information. The neutron removal cross sections and associated momentum distributions are calculated for transitions to both the particle-bound and particle-unbound final states. The calculations take into account the population of the mass reaction residues C and, following one-neutron emission after one-neutron removal, the mass two-neutron removal residues C. The smaller contributions of direct two-neutron removal, that populate the C residues in a single step, are also computed. The data and calculations are shown to be in good overall agreement and consistent with the predicted shell-model ground-state configurations and one-neutron overlaps with low-lying states in C. These suggest significant valence neutron configurations in both C and C. The results for C strongly support the picture of C as a two-neutron halo nucleus with a dominant ground-state configuration.
- Received 30 November 2011
DOI:https://doi.org/10.1103/PhysRevC.86.054604
©2012 American Physical Society