Investigation of the role of shell structure in quasi-fission mass distributions

TL;DR

This study systematically measures quasi-fission mass distributions in heavy-ion collisions, revealing the influence of shell structure and deformation on the fission process, and introduces a new analysis framework for comparison.

Contribution

It presents a novel framework for analyzing mass-ratio distributions that directly relates to shell effects, independent of traditional assumptions.

Findings

Quasi-fission mass distributions depend on target deformation and fissility.

Shell structure influences the mass asymmetry in quasi-fission.

The new analysis method aligns quasi-fission trends with low-energy actinide fission.

Abstract

Systematic measurements of mass-ratio distributions for fission following collisions of $^{48}$Ti projectiles with even-even target nuclei from $^{144}$Sm to $^{208}$Pb have been made at sub-barrier energies. They show the presence of quasifission, and depend strongly on target nucleus deformation and the fissility of the composite nucleus. A new framework to analyse systematic mass-ratio measurements allows direct comparison with the trends expected from shell structure, independent of assumptions or fits. This indicates that quasi-fission mass distributions show trends consistent with low energy mass-asymmetric fission of the same actinide elements.