Complete fusion excitation functions for 11,10 B+ 159 Tb have been measured at energies around the respective Coulomb barriers, and the existing complete fusion measurements for 7 Li+ 159 Tb have been extended to higher energies. The measurements show significant reduction of complete fusion cross sections at above-barrier energies for both the reactions, 10 B+ 159 Tb and 7 Li+ 159 Tb, when compared to those for 11 B+ 159 Tb. The comparison shows that the extent of suppression of complete fusion cross sections is correlated with the α-separation energies of the projectiles. Also, the two reactions, 10 B+ 159 Tb and 7 Li+ 159 Tb were found to produce incomplete fusion products at energies near the respective Coulomb barriers, with the α-particle emitting channel being the favoured incomplete fusion process in both the cases.PACS number(s): 24.10. Eq, 25.70.Jj, 25.70.Pj, 25.70.Mn, 27.70.+q

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Complete and incomplete fusion cross sections for 6 Li + 159 Tb have been measured at energies around the Coulomb barrier by the γ -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 B + 159 Tb and 7 Li + 159 Tb shows that the extent of suppression is correlated with the α separation energies of the projectiles. It has been argued that the Dy isotopes produced in the reaction 6 Li + 159 Tb at below-barrier energies are primarily due to the d transfer to unbound states of 159 Tb, while both transfer and incomplete fusion processes contribute at above-barrier energies.

Abstract. Fusion excitation functions are measured for the system 6 Li+ 28 Si using the characteristic γ-ray method, encompassing both the sub-barrier and above barrier regions, viz., E lab = 7-24 MeV. Two separate experiments were performed, one for the above barrier region (E lab = 11-24 MeV) and another for the below barrier region (E lab = 7-10 MeV). The results were compared with our previously measured fusion cross section for the 7 Li+ 28 Si system. We observed enhancement of fusion cross section at sub-barrier regions for both 6 Li and 7 Li, but yield was substantially larger for 6 Li. However, for well above barrier regions, similar type of suppression was identified for both the systems.PACS. PACS-key 25.60.Pj; 25.70.Gh

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