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

TL;DR

This study investigates how the cluster structure of $^7$Li influences reaction mechanisms such as breakup, fusion, and transfer in near-barrier collisions with $^{198}$Pt, using experimental measurements and classical trajectory calculations.

Contribution

It provides new insights into the role of $^7$Li's cluster structure in reaction dynamics, supported by combined experimental and theoretical analysis.

Findings

Breakup followed by fusion dominates for $t$ and $\alpha$ capture.

Massive transfer is the main mechanism for $^{6}$He + $p$ and $^{5}$He + $d$ configurations.

Cluster structure significantly affects reaction pathways at Coulomb barrier energies.

Abstract

Exclusive measurements of prompt $\gamma$-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, $\alpha$ 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 $\alpha$ 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.