Low- and medium-spin states in 204Po

Abstract

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 J π = 13 − and E exc = 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 J π = 8 + isomer was remeasured to T 1 2 = 158(2) ns , the J π = 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 T 1 2 = 3.6(2) ns . The systematic features of even- A Po isotopes, including excitation energies and transition rates, are discussed.