Results from the study of the β decays of ${}^{40,42}\mathrm{S}$ and ${}^{43}\mathrm{Cl}$, produced in the fragmentation of a 70-MeV/nucleon ${}^{48}\mathrm{Ca}$ beam, are presented. The half-lives for ${}^{42}\mathrm{S}$ and ${}^{43}\mathrm{Cl}$ have been measured to be $1.03\pm 0.03$ s and $3.13\pm 0.09$ s, respectively. On the basis of γ-ray singles and $\gamma \gamma$ coincidence data, decay schemes for each of these decays have been established. Only subtle changes in low-energy nuclear structure, including switching of the order of the $2^{-}$ and $3^{-}$ states in the odd-odd Cl isotopes, were observed when passing the midpoint of the $\nu f_{7/2}$ subshell. These results agree well with previous shell-model calculations using restricted model spaces suggesting that deformation and shell-breaking effects in the midshell region are small. However, excitations across the $N=20$ shell gap are important to explain the low-lying positive parity states.

• Received 2 February 2006

DOI:https://doi.org/10.1103/PhysRevC.73.044318