Present status of coupled-channels calculations for heavy-ion subbarrier fusion reactions

K Hagino,J.M Yao,V Greco,C Spitaleri,F Rizzo,M La Cognata,S Pirrone

doi:10.1051/epjconf/201611708003

Abstract

The coupled-channels method has been a standard tool in analyzing heavy-ion fusion reactions at energies around the Coulomb barrier. We investigate three simplifications usually adopted in the coupled-channels calculations. These are i) the exclusion of non-collective excitations, ii) the assumption of coordinate independent coupling strengths, and iii) the harmonic oscillator approximation for multi-phonon excitations. In connection to the last point, we propose a novel microscopic method based on the beyond-mean-field approach in order to take into account the anharmonic effects of collective vibrations.

Highlights

The field of heavy-ion subbarrier fusion reactions started in the late ’70s, when a large enhancement of fusion cross sections was experimentally discovered with respect to the prediction of a simple potential model [1]
The coupled-channels approach has been a standard tool in the field of heavy-ion subbarrier fusion reactions
By explicitly including many non-collective excitations, we have demonstrated that they smear the barrier distribution for 20Ne + 92Zr system while the effect is much smaller for the 20Ne + 90Zr system

Summary

Introduction

The field of heavy-ion subbarrier fusion reactions started in the late ’70s, when a large enhancement of fusion cross sections was experimentally discovered with respect to the prediction of a simple potential model [1]. Even though the potential model works well for light systems, such as 14N+12C, it has turned out that it largely underestimates fusion cross sections for heavier systems, such as 16O+154Sm, at energies below the Coulomb barrier. It has been well recognized that this large enhancement of subbarrier fusion cross sections is caused by the couplings of the relative motion between the colliding nuclei to several nuclear intrinsic degrees of freedom, such as low-lying collective excitations in the colliding nuclei as well as several nucleon transfer processes [1,2,3,4]. We shall investigate the validity of each of these assumptions

Role of non-collective excitations

Coordinate dependent coupling strength and deep subbarrier fusion hindrance

Summary