Sub-barrier fusion of weakly bound ${}^6\mathrm{Li}$ with ${}^{58}\mathrm{Ni}$

Evaporation-proton yields were measured for the fusion of the weakly bound nucleus ${}^6\mathrm{Li}$ on a ${}^{58}\mathrm{Ni}$ target at six near- or sub-barrier bombarding energies. Effects of the one-neutron transfer reaction were estimated and corrections made. Total-fusion cross sections were deduced using calculated proton multiplicities. The resulting fusion excitation function shows a considerable enhancement with respect to calculations for a bare potential. Inelastic couplings are estimated to have insignificant effects on such fusion. The sum of total fusion plus one-neutron transfer cross sections nearly saturates the total reaction cross section in the energy region measured. Comparison with previous results appropriately scaled for the ${}^6\mathrm{Li}+({}^{59}\mathrm{Co}, {}^{64}\mathrm{Ni}, {}^{64}\mathrm{Zn})$ systems shows good consistency except for some data spread at the lower energies.

Figure 1

Mixed secondary beam spectrum, obtained with a detector temporarily placed at the target position with the beam rate lowered by 3 orders of magnitude.

Figure 2

Proton angular distribution obtained with the backward telescopes for each bombarding energy. The curves correspond to pace2 calculations fitting the data.

Figure 3

Fusion excitation function obtained in the present work for the ${}^6\mathrm{Li}+{}^{58}\mathrm{Ni}$ system. Also shown are the respective total reaction cross sections from Ref. [23], as well as results from BPM calculations and respective CC results, as described in the text. The dash-dotted line indicates that the sum ${\sigma }_{\text{fus}}+{\sigma }_{\text{ntr}}$, where ${\sigma }_{\text{ntr}}$ represents a DWBA calculation for one-neutron transfer, nearly saturates ${\sigma }_R$.

Figure 4

Comparison of reduced fusion data for ${}^6\mathrm{Li}$ projectiles with targets of ${}^{58}\mathrm{Ni}$ (present work), ${}^{59}\mathrm{Co}$ [4], ${}^{64}\mathrm{Ni}$ [60], and ${}^{64}\mathrm{Zn}$ [11]. Error bars are shown only if larger than symbol size. The curve corresponds to the UFF [Eq. (3)].

Figure 5

Same as Fig. 4 but extended to include the full energy region where data have been measured.