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 mediumspin states with spins 4–8 kh 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 T12 = 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 T12 = 3.6(2) ns. The systematic features of even-A Po isotopes, including excitation energies and transition rates, are discussed.