Odd-spin yrast states as multiple quadrupole-phonon excitations

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 21+ state can be measured from E2-branching ratios of the 31+ state. These data show a high correlation to the 21+ Q-phonon purity deduced from the E2-decay of 2+ states.