Neutron rich Carbon and Oxygen isotopes with an odd number of neutrons

TL;DR

This paper models odd neutron-rich isotopes of carbon and oxygen as a core plus one neutron, calculating energy modifications due to neutron-phonon couplings, successfully reproducing experimental shell inversion phenomena in carbon isotopes.

Contribution

It introduces a coupling model between neutrons and collective phonons to explain shell inversion in neutron-rich isotopes, aligning well with experimental data.

Findings

Reproduces shell inversion in carbon isotopes up to $^{19}$C.

Accurately predicts energies close to experimental values.

Shows large but non-inverting corrections in oxygen isotopes.

Abstract

We describe odd isotopes as formed of a core plus one neutron. We have calculated the modification of single neutron energies brought by couplings of the neutron with collective $2^+$ phonons in the cores. The results reproduce very well the inversion of $2s$ and $1d_{5/2}$ shells in carbon isotopes up to $^{19}$C while in oxygen isotopes the correction is also large but do not show any inversion in agreement with experiments. The calculated energies are close to the experimental ones in both series of isotopes except in $^{21}$C for the $2s$ state for which our coupling is too weak.