Role of the cluster structure of ${}^7$Li in the dynamics of fragment capture

Abstract

Exclusive measurements of prompt ${\hat{I}}^3$-rays from the heavy-residues with various light charged particles in the ${}^7$Li + ${}^{198}$Pt system, at an energy near the Coulomb barrier (E/$V_b$ $\sim$ 1.6) are reported. Recent dynamic classical trajectory calculations, constrained by the measured fusion, $\hat{I}\pm$ 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 $\hat{I}\pm$ clusters; whereas for ${}^6$He + $p$ and ${}^5$He + $d$ configurations, massive transfer is inferred to be the dominant mechanism. The present work clearly demonstrates the role played by the cluster structures of ${}^7$Li in understanding the reaction dynamics at energies around the Coulomb barrier.

6 pages, 4 figures, Accepted for publication in Phys. Letts. B