On the yrast two proton-two neutron hole states in²⁰⁸Po

Abstract

High-spin levels in²⁰⁸Po, populated in the²⁰⁸Pb(α,4n)-reaction, were studied usingα-particles in the energy region 41–51 MeV. The energies of levels above the 6⁺ level have an uncertainty of about 10 keV due to the fact that the 8⁺→6⁺ transition has not been observed so far, but this transition has previously been established to be converted neither in theK-shell nor in theL-shells. It was found that the yrast cascade ofγ-rays from a 19⁺ level at 5896+ε keV feeds levels of lower spin which all can be explained as originating from two proton-two neutron hole configurations. In the higher part of the cascade it is mainly the neutron holes which change their configuration, while the lower part of the cascade is dominated by changes in the proton configuration. The yrast levels in the angular momentum regionJ=8–19 vary practically linearly with energy in the region 1.5–6 MeV. No isomeric traps were found above the 11⁻ level at 2699+ε keV.