Isospin dependence of projectile-like fragment production at intermediate energies

TL;DR

This study investigates how the isospin of projectile nuclei affects fragment production in intermediate energy nuclear reactions, revealing that isospin dependence diminishes in central collisions and distributions are similar for symmetric nuclei.

Contribution

It provides a detailed analysis of isospin effects on projectile fragmentation using the statistical abrasion-ablation model and compares with experimental data.

Findings

Isospin dependence decreases in central collisions.

Fragment distribution shapes are similar for symmetric projectiles.

Similar proton and neutron densities explain distribution similarities.

Abstract

The cross sections of fragments produced in 140 $A$ MeV $^{40,48}$Ca + $^9$Be and $^{58,64}$Ni + $^9$Be reactions are calculated by the statistical abration-ablation(SAA) model and compared to the experimental results measured at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The fragment isotopic and isotonic cross section distributions of $^{40}$Ca and $^{48}$Ca, $^{58}$Ni and $^{64}$Ni, $^{40}$Ca and $^{58}$Ni, and $^{48}$Ca and $^{64}$Ni are compared and the isospin dependence of the projectile fragmentation is studied. It is found that the isospin dependence decreases and disappears in the central collisions. The shapes of the fragment isotopic and isotonic cross section distributions are found to be very similar for symmetric projectile nuclei. The shapes of the fragment isotopic and isotonic distributions of different asymmetric projectiles produced in peripheral reactions are found very similar. The similarity of the distributions are related to the similar proton and neutron density distributions inside the nucleus in framework of the SAA model.