Evaporation residue cross sections for ${}^{124,126,127,128}\mathrm{Sn}+{}^{64}\mathrm{Ni}$ and ${}^{132}\mathrm{Sn}+{}^{58}\mathrm{Ni}$ have been measured to study the effects of neutron excess in neutron-rich radioactive nuclei on the fusion probability. A comparison of the reduced evaporation residue cross sections for ${}^{126}\mathrm{Sn}+{}^{64}\mathrm{Ni}$ and ${}^{132}\mathrm{Sn}+{}^{58}\mathrm{Ni}$, which make the same compound nucleus, shows that the fusion probability is indistinguishable for reactions involving the same atomic elements, Sn and Ni, but different isotope combinations. For the reactions with ${}^{64}$Ni, the fusion probability does not decrease with increasing neutron excess in Sn, contrary to the result of the stable beam $\mathrm{Sn}+\mathrm{Zr}$ measurement.

• Received 29 September 2011

DOI:https://doi.org/10.1103/PhysRevC.85.031601