Odd-spin yrast states as multiple quadrupole-phonon excitations

Abstract

The wavefunctions of the lowest odd spin positive parity yrast states in the IBA are shown to be nearly pure multiple quadrupole-phonon excitations even outside the three dynamical symmetries. The empirical data for collective nuclei with 30≤ Z≤80 confirm these predictions. The quadrupole-phonon purity of the 2 1 + state can be measured from E2-branching ratios of the 3 1 + state. These data show a high correlation to the 2 1 + Q-phonon purity deduced from the E2-decay of 2 + states.