Effects of target nuclear excitations on fusion reactions

Abstract

In this work we analyse fusion cross-section (σF ) in different projectile target systems. Collision systems can result in different reactions such as elastic/ inelastic scattering, fu sion and fission reactions to name a few. In this paper, we will be doing a systematic study of light projectile collision, medium projectile collisions and heavy projectile collisions. To this end we should be able to relate fusion cross-section to the size of the projectile. Fu sion analysis has played a major role in synthesis of super heavy elements and simulations of supersonic reactions. To understand the fusion analysis, we first take into account the state of no internal excitations of the collision partners (spherical collision). In this case, the target orientation and the radial distance between colliding nuclei are the factors of which σF is dependent on. We analyse how the target orientation affects the Coulomb potential which significantly gives us the effect on fusion. Secondly, we look at the case of deformed target nucleus. The target deformations consid ered in this paper include rotational deformation, vibrational deformations and neutron transfer reactions. The full-coupled channel program (CCFULL) is used to couple the rotational excitations to the radial part. With this program, we are able to analyse how each deformation parameter affects fusion cross-section. We can also make sense of fusion at energies below and around the Coulomb barrier. The barrier distribution calculations gives us a great insight of how each deformation parameter lowers the barrier and at which energy regions. For vibrational coupling calculations, the cross-section can be compared to that of rotational coupling and spherical collisions in order to see which parameters enhance fusion the most and at which energies. In the case of neutron transfer reactions, we analyse how the Q-value relates to fusion enhancement. For each system where neutron transfer was considered, we look at the possibility and comparison of +1neu tron,+2neutrons and +3neutrons transfer channels. We further look into details how the fusion barrier distribution data relates to the cross-sections. For quantitative analysis in this work, the systems investigated were:

6,7Li projectiles with 28Si, 64 Zn, 152 Sm, 198 Pt & 209Bi targets

40Ca projectile with 62,64Ni, 96 Zr, 194 Pt & 238U targets