Analysis of contribution of direct and exchange mechanisms in reaction cross-section 11B(α,t)12C

The aim of present work is the analysis of the experimental obtained differential reaction cross-section 11B(α,t)12C, at E α=50 MeV on three level of final nucleus 12C: ground and excited 12C(0+, 7,65 MeV) and 12C(4+, 14,08 MeV). In experimental angle distribution the appreciable ascent of cross-section at largest angles is detected. It is conditioned by manifestation of target nucleus cluster structure. According to concerned energy the reaction 11B(α,t)12C may be occurred both on direct mechanisms and statistical mechanism of compound nucleus in Hauser-Feshbach approximation. As the shape of experimental spectra evidences the prevalent contribution of direct mechanisms (availability of oscillations, ascent at front angles), in the first place the contribution of mechanisms of disruption and heavy cluster exchange in angular distribution are considered. For calculation the software code FRESCO based on coupled channels method with final interaction radius is used. The uniqueness of reactions is that the mechanisms of disruption and exchange act separately because of selection rules: the state 12C(4+, 14,08 MeV) can be generated consequently of heavy cluster exchange only, its contribution to reaction on levels of 12C with zero moment is negligible. Specified circumstance allows the independent selection wave function parameters and determination of spectroscopic multipliers of 12C nucleus in ground state and excited state.