PARTICLE PLUS OCTUPOLE M2-E3 ISOMERS AND HIGH-SPIN PARTICLE-HOLE STATES IN TB-147 AND TB-148

The level structures of the N=82 and N=83 nuclei147Tb and148Tb have been studied by means of (α, 8 n) and (α,7 n) reactions induced by 68 to 110 MeV α particle bombardments of151Eu targets. In-beam conversion electron measurements have established that isomers with T1/2=4.8(6)ns in147Tb and T1/2=22(1)ns in148Tb decay by M2+E3 transitions to the ground states. The measured B(E3) values show that the isomeric states arise from the coupling of the valence nucleon(s) to the146Gd core octupole. Particlephonon coupling in these nuclei and in the one-neutron nucleus147Gd is discussed and compared with well known cases involving the208Pb core. The higher lying yrast states in the two Tb nuclei are described as shell-model particle-hole excitations using empirical single particle energies and nucleon-nucleon interactions. © 1979 Springer-Verlag.