Evolution of the decay mechanisms in central collisions of $Xe$ + $Sn$ from $E/A$ = 8 to 29 $MeV$

TL;DR

This study investigates the decay mechanisms in central Xe+Sn collisions across a range of energies, revealing how the system evolves from emission to breakup or residue formation, with detailed analysis of light charged particles and decay channels.

Contribution

It provides a detailed experimental analysis of decay mechanisms and energy spectra in Xe+Sn collisions, highlighting the evolution of decay modes with energy and the sequence of particle emissions.

Findings

Maximum fusion cross section at 18-20 MeV per nucleon

Most evaporative light charged particles precede fission and breakup

Quantitative estimates of primary emission processes

Abstract

Collisions of Xe+Sn at beam energies of $E/A$ = 8 to 29 $MeV$ and leading to fusion-like heavy residues are studied using the $4\pi$ INDRA multidetector. The fusion cross section was measured and shows a maximum at $E/A$ = 18-20 $MeV$. A decomposition into four exit-channels consisting of the number of heavy fragments produced in central collisions has been made. Their relative yields are measured as a function of the incident beam energy. The energy spectra of light charged particles (LCP) in coincidence with the fragments of each exit-channel have been analyzed. They reveal that a composite system is formed, it is highly excited and first decays by emitting light particles and then may breakup into 2- or many- fragments or survives as an evaporative residue. A quantitative estimation of this primary emission is given and compared to the secondary decay of the fragments. These analyses indicate that most of the evaporative LCP precede not only fission but also breakup into several fragments.