High spin states and isomeric decays in doubly-odd 208Fr

Neutron deficient isotopes of francium (Z=87, N∼121–123) as excited nuclei were produced in the fusion–evaporation reaction: 197Au(16O, xn) 213 − xFr at 100 MeV. The γ rays from the residues were observed through the high sensitivity Germanium Clover detector array INGA. The decay of the high spin states and the isomeric states of the doubly-odd 208Fr nuclei, identified from the known sequence of ground state transitions, were observed. The half-lives of the Eγ=194(2)keV isomeric transition, known from earlier observations, was measured to be T1/2=233(18)ns. A second isomeric transition at Eγ=383(2)keV and T1/2=33(7)ns was also found. The measured half-lives were compared with the corresponding single particle estimates, based on the level scheme obtained from the experiment.