Yrast states in vibrational nuclei

First, a phenomenological analysis of anharmonic vibrational spectra with emphasis on high-angular-momentum states is presented; the resulting energies E(N,I) of nuclear states are tabulated (N = number of phonons, I = state angular momentum). Then a rotational description of high-angular-momentum states in vibrational nuclei is given, dealing with the transformed Hamiltonian, which more clearly exhibits the properties and shapes of the states. The transformation is to the usual β, γ and ω variables and links the notions familiar for deformed nuclei to the problem of vibrational nuclei. (A.H.)