Near-barrier Fusion Evaporation and Fission of 28Si+174Yb and 32S+170Er

Dongxi Wang,Xinxing Xu,Feng Yang,Nanru Ma,Huiming Jia,Pengfei Bao,Huanqiao Zhang,Lei Yang,Lijie Sun,Chengjian Lin

doi:10.1051/epjconf/201716300063

Abstract

Fusion evaporation residues and fission fragments have been measured, respectively, at energies around the Coulomb barrier for the 28 Si+ 174 Yb and 32 S+ 170 Er systems forming the same compound nucleus 202 Po. The excitation function of fusion evaporation, fission as well as capture reactions were deduced. Coupled-channels analyses reveal that couplings to the deformations of targets and the two-phonon states of projectiles contribute much to the enhancement of capture cross sections at sub-barrier energies. The mass and total kinetic energy of fission fragments were deduced by the time-difference method assuming full momentum transfer in a two-body kinematics. The mass-energy and mass-angle distributions were obtained and no obvious quasi-fission components were observed in this bombarding energy range. Further, mass distributions of fission fragments were fitted to extract their widths. Results show that the mass widths decrease monotonically with decreasing energy, but might start to increase when E c.m. / V B < 0.95 for both systems.

Highlights

Heavy-ion induced fusion-fission reactions at energies around the Coulomb barrier have attracted much attention [1, 2], due to many degrees of freedom involved in the interaction processes
It is expected that the deformation [3], vibrational state [4] and transfer channel [5,6,7] may be involved in the capture reaction
An additional way to distinguish fission fragments from the scattered projectile and recoiled nuclei is to exploit the difference in the reaction kinematics

Summary

Introduction

Heavy-ion induced fusion-fission reactions at energies around the Coulomb barrier have attracted much attention [1, 2], due to many degrees of freedom involved in the interaction processes. The system can go to fission via some equilibrium or non-equilibrium processes, such as complete fusion-fission, pre-equilibrium fission [8], quasi-fission [9] and fast fission [10,11,12]. These processes may strongly depend on some factors of the entrance channel, for example, deformations of projectile and target, the mass asymmetry, and so on. Comprehensive research on fusion-fission reactions can cast useful light on the understanding of heavy ion induced reactions

Methods

Results

Conclusion