Yrast states up to $(6^{+})$ in the neutron-rich ${}^{40}\mathrm{S}$ nucleus have been studied using binary grazing reactions produced by the interaction of a $215$ MeV beam of ${}^{36}\mathrm{S}$ ions with a thin ${}^{208}\mathrm{Pb}$ target. The novel experimental setup that combines the large acceptance magnetic spectrometer, PRISMA, and the high-efficiency $\gamma$-ray detection array, CLARA, was used. A new $\gamma$-ray transition at an energy of $1572$ keV was observed and tentatively assigned to the $(6^{+})\to (4^{+})$ transition. A comparison of experimental observations and the results of large-scale $0\hslash \omega$ $\mathit{sd}-\mathit{pf}$ shell-model calculations indicates that one- and two-proton excitations from the $2s_{1/2}$ to the $1d_{3/2}$ orbitals play an important role in reproducing the ${}^{40}\mathrm{S}$ yrast level structure and the published $B(E2;0_{\mathrm{g}.\mathrm{s}.}^{+}\to 2_1^{+})$ value. The structure of the yrast states of the even-$A$ isotopes of sulfur is interpreted in terms of the configurations of valence protons and neutrons within the context of large-scale $0\hslash \omega$ $\mathit{sd}-\mathit{pf}$ shell-model calculations.

• Received 21 December 2009

DOI:https://doi.org/10.1103/PhysRevC.81.054305