Low- and medium-spin states in 204Po

Excited states in 204Po were populated in the reaction 204Pb(3He,3n) at beam energies 23.0 and 27.6 MeV. The subsequent de-excitation was studied using in-beam spectroscopic methods including γ-ray excitation function, γ-ray angular distribution, γ-RF timing, conversion-electron and γγ coincidence measurements. Yrast states up to Jπ=13- and Eexc = 3440 keV, and medium-spin states with spins 4-8 ℎ and energies in the range 2.0-2.5 MeV were observed. The half-life of the previously reported Jπ=8+ isomer was remeasured to T1/2=158(2) ns, the Jπ=9- state at 2227 keV was observed to have a half-life of 15.6(5) ns, and the half-life of the yrast 11- state at 2621 keV was determined to be T1/2=3.6(2) ns. The systematic features of even-A Po isotopes, including excitation energies and transition rates, are discussed. (orig.)