Total reaction and transfer cross sections for 11B+9Be and 13C+9Be reactions at low energies

The total reaction cross sections for 11B+9Be and 13C+9Be have been measured by the total γ-ray yield method over the energy intervals Esub(c.m.)=1.4-4.4 MeV and Esub(c.m.)=2.0-5.2 MeV, respectively. The cross sections for the neutron transfer reactions 11B(9Be, 8Be)12B, leading to the 12B 0.953 and 1.674 MeV states, and 13C(9Be, 8Be)14C, leading to the 14C 6.094, 6.728 and 6.902 MeV states, have been obtained from the yields of the characteristic γ-rays. The α-transfer reaction 11B(9Be, 5He)15N, leading to many unresolved 15N states, has been observed with large cross section. There is, however, no evidence for the 13C(9Be, 5He)17O transfer process in the 17O+nα channels. This different behaviour of the 11B+9Be and 13C+9Be system seems to indicate that the α-transfer reaction at sub-barrier energies is not a direct transfer process, and that it probably occurs via molecular state formation. (orig.)