Level Structure ofBi208as Observed at High Resolution with theBi209

Abstract

The Bi m (d,t)Bi 208 reaction has been studied at a bombarding energy of 12 MeV with a high-resolution magnetic spectrograph. A ground-state Q value of -1.201±0.005 MeV was measured. Excited states were observed at 0.063, 0.513, 0.605, 0.634, 0.651, 0.890, 0.929, 0.963, 1.074, 1.098, 2.349, 2.394, and 2.417 MeV. The angular-distribution data taken separate the hi2pzi<T l states from the hvufs^1 states. Spin assignments based on the observed cross sections of the levels are given. In particular, the ground state and first excited state are assigned / = 5 and J=4, respectively. The resulting interpretation is in good agreement with the Bi 208 calculations by Kim and Rasmussen. * Work performed under the auspices of the U. S. Atomic Energy Commission. 1

Proton-Particle, Neutron-Hole Multiplets in BI208

“…Spin assignments made in this way for the 1-9, 5-9, and 3-9 multiplets 4 agree with measurements of Erskine. 5 Those multiplets, as well as the 7-9 one observed here for the first time, agree very well with the shell-model calculations of Kim and Rasmussen, 6 given in Table I. For the 13-9 multiplet, the states are weak and not so clearly resolved.…”

Proton-neutron interaction near closed shells

“…In particular, the spectrum of 208 Bi was extensively studied through pick-up and stripping reactions and several proton-neutron hole multiplets were identified [5,6]. The pattern exhibited by the observed multiplets was well reproduced by the shell-model calculations of Ref.…”

“…The particle-hole multiplets in 208 Bi were long ago found to exhibit a peculiar behavior [5,6], namely the states with the minimum and maximum J have the highest excitation energy, while the state with next to highest J is the lowest one. As mentioned in the Introduction, the results of the shell-model calculations of Ref.…”

“…To place this study in its proper perspective, it should be mentioned that the particle-hole multiplets in the 208 Pb region were the subject of great theoretical and experimental interest [5,6,7,8] some thirty-five years ago. In particular, the spectrum of 208 Bi was extensively studied through pick-up and stripping reactions and several proton-neutron hole multiplets were identified [5,6]. The pattern exhibited by the observed multiplets was well reproduced by the shell-model calculations of Ref.…”