Competition between collective and non collective excitation modes at high spin in 124Ba

High-spin states in124Ba were investigated in two experiments using the 64Ni(64Ni,4n)124Ba reaction at three different beam energies. In-beam γ-ray coincidences were measured with the Euroball and Gammasphere detector arrays. In the experiment with Euroball, the CsI detector array Diamant was employed to discriminate against charged-particle channels. Six new rotational bands were observed in 124Ba, and previously known bands were extended to higher spins. One of the bands shows a transition from collective to non collective behaviour at high spins. Configuration assignments are suggested on the basis of comparison with cranked shell model and cranked Nilsson-Strutinsky calculations.