Low-lying single-particle structure of 17C and the N = 14 sub-shell closure

TL;DR

This study investigates the single-particle structure of 17C, revealing the absence of the N=14 sub-shell closure and identifying a potential one-neutron halo state through transfer reaction experiments and theoretical comparisons.

Contribution

It provides the first experimental analysis of 17C's single-particle states, confirming shell model predictions and challenging the existence of the N=14 sub-shell closure.

Findings

Confirmed spin-parity assignments for excited states

Provided evidence against N=14 sub-shell closure

Identified a potential one-neutron halo state

Abstract

The first investigation of the single-particle structure of the bound states of 17C, via the d(16C, p) transfer reaction, has been undertaken. The measured angular distributions confirm the spin-parity assignments of 1/2+ and 5/2+ for the excited states located at 217 and 335 keV, respectively. The spectroscopic factors deduced for these states exhibit a marked single-particle character, in agreement with shell model and particle-core model calculations, and combined with their near degeneracy in energy provide clear evidence for the absence of the N = 14 sub-shell closure. The very small spectroscopic factor found for the 3/2+ ground state is consistent with theoretical predictions and indicates that the {\nu}1d3/2 strength is carried by unbound states. With a dominant l = 0 valence neutron configuration and a very low separation energy, the 1/2+ excited state is a one-neutron halo candidate.