Decay of 160Er* in 16O+144Nd and 64Ni+96Zr fusion reactions.

Abstract

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 \ensuremath{\gamma}-ray fold distributions of the dominant exit channels were obtained for each reaction, using a 4\ensuremath{\pi} \ensuremath{\gamma}-ray detection system. An entrance-channel dependence of the \ensuremath{\gamma}-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.