Possible shears bands in {sup 204}At and {sup 206}Fr, and identification of excited states in {sup 205,207}Fr

Neutron-deficient astatine and francium nuclei were produced in the reaction {sup 30}Si+{sup 181}Ta{yields}{sup 211}Fr* at 152 MeV. The evaporation residues from this very fissile system were selected with the HERCULES-II detector system and residue-gated {gamma} rays were measured with Gammasphere. Excited states were observed for the first time in {sup 205,207}Fr, as well as sequences of low-energy transitions between high-spin states in {sup 204}At and {sup 206}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.