The transfer reaction B-11(N-13,C-12)C-12

The transfer reaction B-11(N-13,C-12)C-12* has been investigated at the two laboratory energies E-lab = 45 MeV and E-lab = 29.5 MeV. Particle-gamma and particle-particle coincidences have been measured. The coincidence between a heavy ion and the 15.1 MeV gamma-ray emitted from C-12* shows transition to the C-12(gs) + C-12*(15.1) and C-12*(4.44) + C-12*(15.1) exit channels. These indicate the mixed ground-state structure of N-13. DWBA calculations have also been performed. Analysis of particle-particle coincidence data revealed the presence of transfer channels also to unbound states of C-12 such as C-12(gs) + C-12* (E* > 7.64 MeV) and C-12*(4.44) + C-12* (E* >7.64 MeV). The angular distributions have been extracted for these two channels. Six-alpha-particle events have also been analyzed. Some of these events have been identified as coming from B-11(N-13,C-12*)C-12* reaction. An enhancement in the six-alpha cross-section is observed at an excitation energy for the compound nucleus Mg-24 close to the 46 MeV resonances observed in C-12+C-12 inelastic scattering. These six-alphas events are generated mostly from the break-up of C-12(3(1)(-))+(12) C(3(1)(-)) and therefore seems not to be associated with the six-alphas chain state.