Low-lying 2(+) states in neutron-rich oxygen isotopes in quasiparticle random phase approximation

The properties of the low-lying, collective 2(1)(+) states in neutron-rich oxygen isotopes are investigated in the framework of self-consistent micros copic models with effective Skyrme interactions. In RPA the excitation ener gies E-2I(+) can be well described but the transition probabilities are muc h too small as compared to experiment. Pairing correlations are then accoun ted for by performing quasiparticle RPA calculations. This improves conside rably the predictions of B(E2) values and it enables one to calculate more reliably the ratios M-n/M-p of neutron-to-proton transition amplitudes. A s atisfactory agreement with the existing experimental values of M-n/M-p is o btained. (C) 2000 Elsevier Science B.V. All rights reserved.