Investigation of the quasifission process by theoretical analysis of experimental data of fissionlike reaction products

TL;DR

This paper analyzes experimental data on fissionlike fragments to understand the quasifission process, which impacts the synthesis of superheavy elements, by examining various reaction mechanisms and their dependence on entrance channel characteristics.

Contribution

It provides a theoretical analysis of experimental data across multiple reactions to clarify the role of quasifission and other processes in fissionlike fragment production, especially in superheavy element synthesis.

Findings

Quasifission significantly affects fusion hindrance in superheavy element formation.

The study identifies key reaction parameters influencing the quasifission process.

Results include determination of evaporation residue cross sections and effective fission barriers.

Abstract

The fusion excitation function is the important quantity in planning experiments for the synthesis of superheavy elements. Its values seem to be determined by the experimental study of the hindrance to complete fusion by the observation of mass, angular and energy distributions of the fissionlike fragments. There is ambiguity in establishment of the reaction mechanism leading to the observed binary fissionlike fragments. The fissionlike fragments can be produced in the quasifission, fast fission, and fusion-fission processes which have overlapping in the mass (angular, kinetic energy) distributions of fragments. The branching ratio between quasifission and complete fusion strongly depends on the characteristics of the entrance channel. In this paper we consider a wide set of reactions (with different mass asymmetry and mass symmetry parameters) with the aim to explain the role played by many quantities on the reaction mechanisms. We also present the results of study of the $^{48}$Ca+$^{249}$Bk reaction used to synthesize superheavy nuclei with Z = 117 by the determination of the evaporation residue cross sections and the effective fission barriers $<B_{\rm f}>$ of excited nuclei formed along the de-excitation cascade of the compound nucleus.