Decay of ${}_{}{}^{160}{}_{}{}^{}\mathrm{Er}_{}^{\mathrm{*}}{}_{}{}^{}$ in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{144}$Nd and ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$${+}^{96}$Zr fusion reactions

The population of evaporation residue entry states in the decay of the compound nucleus ${}_{}{}^{160}{}_{}{}^{}\mathrm{Er}_{}^{\mathrm{*}}{}_{}{}^{}$(54 MeV) is investigated in a cross-bombardment employing the reactions ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{144}$Nd and ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$${+}^{96}$Zr. Evaporation residue cross sections and entry state γ-ray fold distributions of the dominant exit channels were obtained for each reaction, using a 4π γ-ray detection system. An entrance-channel dependence of the γ-ray fold distributions of the xn products is observed. This effect is described successfully by the statistical model making use of compound nucleus angular momentum distributions obtained with a fusion model that provides a good description of the bombarding energy dependence of fusion data for both reactions. In accordance with recent findings on the decay of ${}_{}{}^{164}{}_{}{}^{}\mathrm{Yb}_{}^{\mathrm{*}}{}_{}{}^{}$, it is suggested that the observed differences in the population of the dominant exit channels originate from the primary spin distributions rather than a possible dependence of the compound nucleus decay on the formation mode.