Complete and incomplete fusion cross sections for ${}^6\mathrm{Li}$ $+$ ${}^{159}\mathrm{Tb}$ have been measured at energies around the Coulomb barrier by the $\gamma$-ray method. The measurements show that the complete fusion cross sections at above-barrier energies are suppressed by $~$34% compared to coupled-channel calculations. A comparison of the complete fusion cross sections at above-barrier energies with the existing data for ${}^{11,10}\mathrm{B}$ $+$ ${}^{159}\mathrm{Tb}$ and ${}^7\mathrm{Li}$ $+$ ${}^{159}\mathrm{Tb}$ shows that the extent of suppression is correlated with the $\alpha$ separation energies of the projectiles. It has been argued that the Dy isotopes produced in the reaction ${}^6\mathrm{Li}$ $+$ ${}^{159}\mathrm{Tb}$ at below-barrier energies are primarily due to the $d$ transfer to unbound states of ${}^{159}\mathrm{Tb}$, while both transfer and incomplete fusion processes contribute at above-barrier energies.

• Received 5 May 2011

DOI:https://doi.org/10.1103/PhysRevC.83.064606