The α decay of α recoil collected sources of ${}^{223}\mathrm{Fr}$ was studied using a purified ${}^{227}\mathrm{Ac}$ source. Five α groups were observed whereas previously only one was reported. Multipolarities and energies of the γ transitions between the ${}^{219}\mathrm{At}$ levels were observed for the first time which allowed spins and parities to be assigned to the levels. The systematics of the levels of ${}^{215}\mathrm{At},$ ${}^{217}\mathrm{At},$ and ${}^{219}\mathrm{At}$ show a strong similarity, but with decreasing level energies with increasing mass. The levels in ${}^{219}\mathrm{At}$ are interpreted in terms of the shell model configurations $\pi {(h}_{9/2}{)}^3\nu {(g}_{9/2}{)}^{-2}$ and $\pi {(h}_{9/2}{)}^2{f}_{7/2}\nu {(g}_{9/2}{)}^{-2}.$ Although there is no evidence of parity doublets in ${}^{215}\mathrm{At},$ ${}^{217}\mathrm{At},$ and ${}^{219}\mathrm{At},$ some of their configurations are shown to be very closely related to the quadrupole-octupole deformed ground states of ${}^{219}\mathrm{Fr},$ ${}^{221}\mathrm{Fr},$ and ${}^{223}\mathrm{Fr},$ respectively.

• Received 24 October 2000

DOI:https://doi.org/10.1103/PhysRevC.64.034310