Entrance-channel effects in the population of superdeformed bands

In order to investigate whether entrance-channel effects influence the production of superdeformed nuclei, we have measured the yield of the yrast superdeformed band in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Dy}$ populated via nearly mass-symmetric ${(}^{82}$Se${+}^{74}$Ge) and mass-asymmetric ${(}^{48}$Ca${+}^{108}$Pd, ${}_{}{}^{36}{}_{}{}^{}\mathrm{S}$ ${+}^{120}$Sn) fusion reactions leading to the same compound nucleus at similar excitation energies and angular momenta. Large differences in the relative intensity of the band compared with the total yield of the nucleus are observed in the various reactions. This effect indicates that the competition between fission and neutron evaporation is affected by the mode of formation of the fusing system.