In the framework of the symplectic extension of the interacting vector boson model a good description of the first excited positive and negative parity bands of the nuclei in the rare earth and the actinide region is achieved. The bands investigated in the model are extended to very high angular momenta as a result of their consideration as “yrast” bands with respect to the symplectic classification of the basis states. The analysis of the eigenvalues of the model Hamiltonian reveals the presence of an interaction between these bands. Due to this interaction the $\Delta L=1$ staggering effect between the energies of the states of two bands is also reproduced including the “beat” patterns.

• Received 25 September 2003

DOI:https://doi.org/10.1103/PhysRevC.69.014305