Fragment properties of fragmenting heavy nuclei produced in central and semi-peripheral collisions

TL;DR

This study compares fragment properties from central and semi-peripheral nuclear collisions, revealing differences in collective energy and fragmentation patterns, and proposes a method to select similar sources for analysis.

Contribution

It introduces a method to select comparable quasi-projectile sources and analyzes the role of collective energy in fragmentation differences.

Findings

Weak radial collective energy in quasi-projectile sources is from thermal pressure.

Fused systems show higher fragment multiplicity and more symmetric fragmentation.

Expansion after compression influences the collective energy and fragmentation behavior.

Abstract

Fragment properties of hot fragmenting sources of similar sizes produced in central and semi-peripheral collisions are compared in the excitation energy range 5-10 AMeV. For semi-peripheral collisions a method for selecting compact quasi-projectiles sources in velocity space similar to those of fused systems (central collisions) is proposed. The two major results are related to collective energy. The weak radial collective energy observed for quasi-projectile sources is shown to originate from thermal pressure only. The larger fragment multiplicity observed for fused systems and their more symmetric fragmentation are related to the extra radial collective energy due to expansion following a compression phase during central collisions. A first attempt to locate where the different sources break in the phase diagram is proposed.