Proton Distribution Radii of $^{16--24}\mathrm{O}$: Signatures of New Shell Closures and Neutron Skin

Proton Distribution Radii of ${}^{16 - 24}O$ : Signatures of New Shell Closures and Neutron Skin

S. Kaur et al.

Phys. Rev. Lett. 129, 142502 – Published 28 September 2022

Abstract

The root mean square radii of the proton density distribution in ${}^{16 - 24}O$ derived from measurements of charge changing cross sections with a carbon target at $\sim 900 A MeV$ together with the matter radii portray thick neutron skin for ${}^{22 - 24}O$ despite ${}^{22, 24}O$ being doubly magic. Imprints of the shell closures at $N = 14$ and 16 are reflected in local minima of their proton radii that provide evidence for the tensor interaction causing them. The radii agree with ab initio calculations employing the chiral ${NNLO}_{sat}$ interaction, though skin thickness predictions are challenged. Shell model predictions agree well with the data.