6Li excitation above the breakup threshold in the 6Li+208Pb system at Coulomb barrier energies

The excitation energy of the 6Li+208Pb system has been studied at several energies around the Coulomb barrier with a large solid angle detector array. The α + d/6Li∗ excitation above the breakup threshold (Sd = 1.475 MeV) has been deduced from the invariant mass of the α + d system. All the collected data show a similar behaviour: the cross sections are peaked at around 1 MeV above the threshold and they have an exponential decay on the high energy side, suggesting a direct breakup process. A Monte‐Carlo simulation of the whole reaction mechanism has been performed in order to check the validity of data analysis procedure and to study the influence of the set‐up geometry onto the experimental results. Two different theoretical approaches, the former based on fully quantum mechanical Coupled Channel calculations and the latter based on simpler semi‐classical calculations, treating the relative motion of the α + d cluster structure along a classical trajectory, reproduce both in shape and absolute value the experimental excitation energy distributions.