Role of the cluster structure of 7Li in the dynamics of fragment capture

Exclusive measurements of prompt γ-rays from the heavy-residues with various light charged particles in the 7Li + 198Pt system, at an energy near the Coulomb barrier (E/Vb∼1.6) are reported. Recent dynamic classical trajectory calculations, constrained by the measured fusion, α- and t-capture cross-sections have been used to explain the excitation energy dependence of the residue cross-sections. These calculations distinctly illustrate a two-step process, breakup followed by fusion, in case of the capture of t and α clusters; whereas for He6+p and He5+d configurations, massive transfer is inferred to be the dominant mechanism. The present work clearly demonstrates the role played by the cluster structures of 7Li in understanding the reaction dynamics at energies around the Coulomb barrier.