Work

Dynamical properties and secondary decay effects of projectile fragmentations in Sn124,Sn107+Sn120 collisions at 600 MeV/nucleon

Year: 2018

Type: article

Abstract: Background: Projectile fragmentation is a well-established technique to produce rare isotope beams, but its underlying physical processes are not fully known.Purpose: We devote ourselves to studying the dynamical properties and secondary decay effects of projectile fragmentations in $^{124}\mathrm{Sn}, ^{107}\mathrm{Sn}+^{120}\mathrm{Sn}$ collisions at 600 MeV/nucleon.Method: The formation of the projectile spectator and the fragmentation process are studied with the isospin-dependent quantum molecular dynamics (IQMD) model. The minimum spanning tree algorithm and the ratio of parallel to transverse quantities are applied to distinguish the equilibrated projectile spectator during the dynamics evolution. The influence of secondary decay on fragmentation observables is investigated by comparing the calculations with and without the statistical code gemini. The validity of the theoretical approach is tested by comparing the calculated product yields with the experimental results of the ALADIN Collaboration for the studied reactions.Results: The general correlation of an increasing excitation energy with a decreasing mass of the spectator system is found for collisions with impact parameter of $b=5$--10 fm. The nucleon evaporation of the prefragments reduces the multiplicity of intermediate-mass fragments, but does not change their dependence on the isospin of the projectile. The sequential decay also leads to narrower isotope distributions. Switching to gemini at a higher excitation energy results in slightly narrower isotope distributions. With the gemini code, in which the nuclear masses with shell and pairing corrections are adopted, the calculations can rather generally reproduce the data of the isotope distributions and mean neutron-to-proton ratios of the light fragments.Conclusion: By permitting only evaporation in gemini, the IQMD+gemini model is able to reproduce the main features of projectile fragmentation in the studied Sn+Sn reactions.

Source: Physical Review C

DOI: 10.1103/physrevc.98.014610

Authors: Jun Su, W. Trautmann, Long Zhu, Wen-Jie Xie, Feng-Shou Zhang