Mechanism of the 11B($\alpha$α,t)12C reaction at an energy of 40 MeV, role of exchange processes and collective excitations

Abstract

The differential cross sections of triton from the 11B($\alpha$,t) reaction with transitions to the ground (0+) and excited states of the 12C nucleus at $ E_{x} = 4.44$ MeV (2+), 7.65 MeV (0+), 9.64 MeV (3-) and 14.08 MeV (4+) have been measured at an $\alpha$-particles energy of 40 MeV. Analysis of the measured angular distributions was carried out in the framework of the coupled reaction channels method considering the contribution of the 8Be cluster exchange mechanism. It is shown that the direct mechanism with proton transfer dominates at an energy of 40 MeV, and the heavy particle transfer is noticeable only at large angles. An exception is the transition to the 14.08 MeV (4+) state, which is possible only by the transfer of the 8Be cluster. It is established that the couplings between the excited states of 12C, arising from the nonsphericity of the nucleus, have little effect on the $ (\alpha, t)$ reaction cross sections in the forward hemisphere, but strongly affect the cross sections at large angles.