Studies of the O-16(Be-9, alpha(7)Be)C-14 and Li-7(Be-9, alpha(7)Li)He-5 reactions at E-beam = 70 MeV have been performed using resonant particle spectroscopy techniques. The C-11 excited states decaying into alpha+Be-7(gs) are observed at 8.65, 9.85, 10.7 and 12.1 MeV as well as possible states at 12.6 and 13.4 MeV This result is the first observation of a-decay for excited states above 9 MeV The alpha+Li-7(gs) decay of B-11 excited states at 9.2, 10.3, 10.55, 11.2, (11.4), 11.8, 12.5, (13.0), 13.1, (14.0), 14.35, (17.4) and (18.6) MeV is observed. The decay processes are used to indicate the possible three-centre 2alpha+He-3(H-3) cluster structure of observed states. Two rotational bands corresponding to very deformed structures are suggested for the positive-parity states. Excitations of some observed T = 1/2 resonances coincide with the energies of T = 3/2 states which are the isobaric analogs of the lowest Be-11 states. Some of these states may have mixed isospin. (C) 2004 Elsevier B.V. All rights reserved.
- Li-7(Be-9,alpha Li-7), E=70 MeV
- NUCLEAR REACTIONS O-16(Be-9,alpha Be-7), E=70 MeV