Effect of ${}^6\mathrm{Li}$ resonances on near-barrier elastic scattering involving ${}^{28}\mathrm{Si}$ and ${}^{58}\mathrm{Ni}$ target nuclei

Calculations of elastic scattering angular distributions for reactions of the weakly bound projectile ${}^6\mathrm{Li}$ with targets ${}^{28}\mathrm{Si}$ and ${}^{58}\mathrm{Ni}$ at energies just above the Coulomb barrier are performed with the continuum-discretized coupled-channel calculation method. Ground, resonant, and nonresonant continuum states of ${}^6\mathrm{Li}$ are included in the convergent calculations. The effect of the resonances on elastic scattering angular distributions is studied, in an original procedure, by excluding from the continuum space those states corresponding to the resonances. When the resonances of ${}^6\mathrm{Li}$ are considered, the calculated elastic scattering angular distributions are in good agreement with the measurements. The exclusion of the resonances, unexpectedly, has a very small effect at the energies studied. Calculation of the polarization potentials associated with the resonances show that they have a repulsive character at the long range region, where scattering occurs. It is also confirmed that couplings to continuum states of ${}^6\mathrm{Li}$ are essential to achieve agreement with the data.

Figure 1

Elastic scattering angular distributions for ${}^6\mathrm{Li}$ + ${}^{28}\mathrm{Si}$. See text for details.

Figure 2

Polarization potentials associated with couplings to the whole discrete space of ${}^6\mathrm{Li}$ (solid lines) and without resonance space (dashed lines).

Figure 3

Elastic scattering angular distribution calculation for ${}^6\mathrm{Li}$ + ${}^{28}\mathrm{Si}$ at $E_{\mathrm{lab}}=99$ MeV and corresponding polarization potentials with and without resonances.

Figure 4

Elastic scattering angular distributions for ${}^6\mathrm{Li}$ + ${}^{58}\mathrm{Ni}$. See text for details.

Figure 5

Polarization potentials associated with couplings to the whole discrete space of ${}^6\mathrm{Li}$ (solid lines) and without resonance space (dashed lines). See text for details.

Figure 6

Elastic scattering angular distribution calculation for ${}^6\mathrm{Li}$ + ${}^{58}\mathrm{Ni}$ at $E_{\mathrm{lab}}=99$ MeV and corresponding polarization potentials with and without resonances.