Abstract
Neutron-deficient astatine and francium nuclei were produced in the reaction ${}^{30}\mathrm{Si}+{}^{181}\mathrm{Ta}\ensuremath{\rightarrow}{}^{211}{\mathrm{Fr}}^{*}$ at 152 MeV. The evaporation residues from this very fissile system were selected with the HERCULES-II detector system and residue-gated $\ensuremath{\gamma}$ rays were measured with Gammasphere. Excited states were observed for the first time in $^{205,207}\mathrm{Fr}$, as well as sequences of low-energy transitions between high-spin states in $^{204}\mathrm{At}$ and $^{206}\mathrm{Fr}$. These latter structures have properties similar to those associated with magnetic rotation (shears bands) in lead nuclei. Comparisons with established shears bands are presented and prospects for the magnetic-rotation phenomenon near the predicted $N=120$ ``magic'' number are explored.
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