Theoretical Study of Projectile Fragmentations in Relativistic Heavy-Ion Reactions

R Ogul,W Trautmann,H Imal,A Ergun,A S Botvina,N Buyukcizmeci,R Schwengner,K Zuber

doi:10.1051/epjconf/20159302022

Abstract

We have investigated and interpreted the production cross sections and isotopic distributions of projectile-like residues in the reactions 124 Sn + 124 Sn and 112 Sn + 112 Sn at an incident beam energy of 1 GeV/nucleon measured with the FRS fragment separator at the GSI laboratory. For the interpretation of the data, calculations within the statistical multifragmentation model (SMM) for an ensemble of excited sources were performed with ensemble parameters. The possible modification of symmetry energy parameter, in the multifragmentation region at the low density and hot freeze-out environment, is studied. It is reconfirmed that a significant reduction of the symmetry energy term is found necessary to reproduce experimental results at these conditions. We have also found a decreasing trend of the symmetry energy for large neutron-rich fragments of low excitation energy which is interpreted as a nuclear-structure effect.

Highlights

Nuclear multifragmentation has similarity to the collapse and explosions of massive stars
On the other hand we have demonstrated in our previous works [4, 5], that in order to reproduce the N/Z values, the isoscaling parameters and isotope content of fragments observed in the ALADIN and MSU experimental data, one needs a considerable reduction of the fragment symmetry energy
The correlations between the production cross section and charge of the final fragments are shown in Fig.1 together with the experimental results, which we extract by summing up isotope yields given in the tables of Ref. [2]

Summary

Introduction

Nuclear multifragmentation has similarity to the collapse and explosions of massive stars. On the other hand we have demonstrated in our previous works [4, 5], that in order to reproduce the N/Z values, the isoscaling parameters and isotope content of fragments observed in the ALADIN and MSU experimental data, one needs a considerable reduction of the fragment symmetry energy. In this short presentation, we show the results of the analysis of the symmetry energy with the new data on the projectile fragmentation at 1 GeV/nucleon. The symmetry energy represents the main model parameter governing the mean N/Z values, the isoscaling parameters, and the isotopic composition of the fragment yields

Charge and Isotopic Distribution

Conclusions