Low-lying collective states in neutron-rich oxygen isotopes via proton scattering

Proton elastic and inelastic scattering angular distributions to the 2(1)() and the 3(1)(-) states for the neutron-rich nucleus O-20 were measured wi th a secondary beam using the MUST silicon strip detector array. Data for O -18 were also obtained for comparison. A phenomenological analysis has been used to deduce the deformation parameters beta(p,p), for the collective ex citations, Matter and transition densities were generated from self-consist ent QRPA calculations. DWBA calculations using microscopic optical potentia ls obtained with these densities and the JLM interaction are compared to th e data. The isovector character of the 2(1)(+) state in O-20 is confirmed a nd predictions are discussed for the properties of the heavier neutron-rich oxygen isotopes. (C) 2000 Elsevier Science B.V. All rights reserved.