Role of ${}^{28}\mathrm{Si}$ excitations in the sub-barrier fusion of ${}^{28}\mathrm{Si}{+}^{120}\mathrm{Sn}$

Fusion cross sections were measured for the systems ${}^{16}\mathrm{O}$ and ${}^{28}\mathrm{Si}{+}^{120}\mathrm{Sn}$ in order to understand the role of specific channels involved in sub-barrier fusion. Fusion cross sections were measured by direct detection of the evaporation residues. Extracted fusion barrier distributions were analyzed using the exact coupled-channel code CCFULL as well as the simplified code CCMOD. These calculations show that the observed fusion barrier distribution for the Si+Sn system is reproduced only if the rotational excitation in ${}^{28}\mathrm{Si}$ is taken into account.