The transfer reaction¹¹B(¹³N,¹²C)¹²C

Summary

The transfer reaction¹¹B(¹³N,¹²C)¹²C^* has been investigated at the two laboratory energiesE _lab =45 MeV andE _lab =29.5 MeV. Particle-γ and particleparticle coincidences have been measured. The coincidence between a heavy ion and the 15.1 MeV γ-ray emitted from¹²C^* shows transition to the¹²C_gs +¹²C^* _15.1 and¹²C^* _4.44 +¹²C^* _15.1 exit channels. These indicate the mixed ground-state structure of¹³N. DWBA calculations have also been performed. Analysis of particle-particle coincidence data revealed the presence of transfer channels also to unbound states of¹²C such as¹²C_gs +¹²C^* (E^* >7.64 MeV) and¹²C^* _4.44 +¹²C^* (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 from¹¹B(¹³N,¹²C^*)¹²C^* reaction. An enhancement in the six-α cross-section is observed at an excitation energy for the compound nucleus²⁴Mg close to the 46 MeV resonances observed in¹²C +¹²C inelastic scattering. These six-alphas events are generated mostly from the break-up of¹²C(3^- ₁) +¹²C(3^- ₁) and therefore seems not to be associated with the six-alphas chain state.