The Relationship between the Bohr Collective Model and the Interacting Boson Model

Abstract

The Bohr-Mottelson collective model¹ has been very successful in describing the quadrupole collective degrees of freedom of heavy nuclei. As we have seen from this workshop, the interacting boson model (IBM) has also been successful in describing similar data.² At first glance these models seem very different. The former treats the nucleus as a rotating and vibrating liquid drop with quadrupole degrees of freedom. The latter describes the lowlying collective states of heavy nuclei by assuming that only the collective J = 0 (monopole) and J = 2 (quadrupole) pairs of valence fermions outside of closed shells play the dominant role in these states. The purpose of this talk is to make a connection between these two models. The important concept in making that connection is that of the intrinsic state for the IBM. Before discussing the intrinsic state, we give a short review of the Bohr-Mottelson model.