Role of input angular momentum and target deformation on the incomplete-fusion dynamics in the O16+Sm154 system at ELab=6.1 MeV/nucleon

Abstract

Spin distributions of nine evaporation residues $^{164}\mathrm{Yb}(xn)$, $^{163}\mathrm{Tm}(pxn)$, $^{168,167}\mathrm{Er}(2pxn)$, $^{163\ensuremath{-}161}\mathrm{Ho}(\ensuremath{\alpha}pxn)$, $^{164}\mathrm{Dy}\phantom{\rule{0.16em}{0ex}}(\ensuremath{\alpha}2pxn)$, and $^{160}\mathrm{Dy}(2\ensuremath{\alpha}xn)$ produced through complete- and incomplete-fusion reactions have been measured in the system $^{16}\mathrm{O}+^{154}\mathrm{Sm}$ at projectile energy $=6.1\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}/\mathrm{nucleon}$ using the in-beam charged-particle ($Z=1,2$)--\ensuremath{\gamma}-ray coincidence technique. The results indicate the occurrence of incomplete fusion involving the breakup of $^{16}\mathrm{O}$ into $^{4}\mathrm{He}+^{12}\mathrm{C}$ and/or $^{8}\mathrm{Be}+^{8}\mathrm{Be}$ followed by fusion of one of the fragments with target nucleus $^{154}\mathrm{Sm}$. The pattern of measured spin distributions of the evaporation residues produced through complete and incomplete fusion are found to be entirely different from each other. It has been observed from these present results that the mean input angular momentum for the evaporation residues produced through complete fusion is relatively lower than that of evaporation residues produced through incomplete-fusion reactions. The pattern of feeding intensity of evaporation residues populated through complete- and incomplete-fusion reactions has also been studied. The evaporation residues populated through complete-fusion channels are strongly fed over a broad spin range and widely populated, while evaporation residues populated through incomplete-fusion reactions are found to have narrow range feeding only for high spin states. Comparison of present results with earlier data suggests that the value of mean input angular momentum is relatively higher for a deformed target and more mass asymmetric system than that of a spherical target and less mass asymmetric system by using the same projectile and the same energy. Thus, present results indicate that the incomplete-fusion reactions not only depend on the mass asymmetry of the system, but also depend on the deformation of the target.