High-Spin States in204Bi and the Question of Many-Nucleon Configuration Mixing

The properties of high-spin levels in 204Bi have been studied using conventional in-beam γ-ray and conversion-electron spectroscopy on the products of the reactions 205Tl(α, 5n) 204Bi and 203Tl(α, 3n) 204Bi. The yrast cascade is followed to a 19+ level at 3808 keV and several non-yrast levels in the spin interval J = 9-16 are reported. The energies of the levels in 204Bi were calculated within the shell-model frame of multi-nucleon states, and the agreement is found to be good. A previously reported T1/2 = 1 ms isomeric state is shown to have a main configuration πh9/2ν(j-2)0+(i13/2-2)12+f5/2-1 and a spin-parity 17+. The configuration mixing for the neutron-hole components of the wave funct…