Systematic continuum-discretized coupled-channels calculations of total fusion for Li6 with targets Si28, Co59, Zr96, Pt198 , and Bi209 : Effect of resonance states

Abstract

Continuum discretized coupled-channel (CDCC) calculations of total fusion cross sections for reactions induced by the weakly bound nucleus $^{6}\mathrm{Li}$ with targets $^{28}\mathrm{Si}, ^{59}\mathrm{Co}, ^{96}\mathrm{Zr}, ^{198}\mathrm{Pt}$, and $^{209}\mathrm{Bi}$ at energies around the Coulomb barrier are presented. In the cluster structure frame of $^{6}\mathrm{Li}\ensuremath{\rightarrow}\ensuremath{\alpha}+d$, short-range absorption potentials are considered for the interactions between the $\ensuremath{\alpha}$ and $d$ fragments with the targets. The effect of resonance ($l=2, {J}^{\ensuremath{\pi}}={3}^{+},{2}^{+},{1}^{+}$) and nonresonance states of $^{6}\mathrm{Li}$ on fusion is studied by using two approaches: (1) by omitting the resonance states from the full discretized CDCC breakup space and (2) by considering only the resonance subspace. A systematic analysis of the effect on fusion from resonance breakup couplings is carried out from light to heavy mass targets. Among other things, it is found that resonance breakup states produce strong repulsive polarization potentials that lead to fusion suppression. Couplings from nonresonance states give place to weak repulsive potentials at high energies; however, these become attractive for the heavier targets at low energies.