Observation of isomeric decays and the high spin states in doubly-odd 208Fr

Abstract

Neutron deficient isotopes of Francium (Z=87, N ∼ 121 − 123) as excited nuclei were produced in the fusionevaporation reaction: 197 Au ( 16 O, xn) 213−x Fr 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 208 Fr nuclei, identified from the known sequence of ground state transitions, were observed. The half lives of the E γ = 194(2) keV isomeric transition, known from earlier observations, was measured to be T 1/2 = 233(18) ns. A second isomeric transition at E γ = 383(2) keV and T 1/2 = 33(7) ns was also found. The measured half lives were compared with the corresponding single particle estimates, based on a the level scheme obtained from the experiment.