New Region of Deformation: The Neutron-Rich Sulfur Isotopes

Abstract

The energies and $B({E2;0\mathrm{}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}^{+}\to 2_1^{+})$ values for the lowest $J^{\pi }{=2\mathrm{}}^{+}$ states in the neutron-rich radioactive nuclei ${}^{38,40,42}\mathrm{S}$ and ${}^{44,46}\mathrm{Ar}$ were measured via intermediate-energy Coulomb excitation. The results for ${}^{40,42}\mathrm{S}$ provide the first evidence of moderate deformation near $N=28\mathrm{}$, while the effects of the $N=28\mathrm{}$ shell closure persist in the $Z=18\mathrm{}$ nucleus ${}^{46}\mathrm{Ar}$.