A study on the transition between seniority-type and collective excitations in 204Po and 206Po

Low-lying yrast states in 204Po and 206Po have been investigated by the γ-γ fast timing technique with LaBr3(Ce) detectors. Excited states of these nuclei were populated in the 197Au(11B,4n) and the 198Pt(12C,4n) fusion-evaporation reactions, respectively, at the FN-Tandem Facility at the University of Cologne. The lifetimes of the 4+1 states in both nuclei were measured, along with an upper limit for the 2+1 state in 204Po. The preliminary results are discussed in the scope of the systematic behavior of the transition strengths between yrast states in polonium isotopes