Effects of Odd-$Z$ Projectiles on Fusion-Evaporation Cross Sections

The production of nuclides near the $N=$126 shell in the $^{45}$Sc $+ \quad^{159}$Tb, $^{162}$Dy reactions has been studied at Texas A{\&}M University using the MARS spectrometer. Previously measured 4n exit channel cross sections for the $^{48}$Ca, $^{50}$Ti $+ \quad^{159}$Tb and $^{48}$Ca $+ \quad^{162}$Dy reactions have exhibited enhanced fission probabilities in the de-excitation of the compound nucleus due to collective enhancements to the fission level density. The current research intends to study the change in the evaporation residue cross sections when odd-$Z$ projectiles react with the same targets. The maximum 4n cross sections of the $^{45}$Sc $+$ $^{159}$Tb, $^{162}$Dy reactions were 2 $\mu $b, and 4 $\mu $b respectively, and these data are several orders of magnitude smaller than both theoretical predictions and the experimental data for the $^{48}$Ca and $^{50}$Ti reactions discussed above. This can be explained by collective enhancements as well as the relative neutron deficiency of $^{45}$Sc compared to $^{48}$Ca and $^{50}$Ti. This talk will discuss theoretical models of evaporation residue cross sections, and will discuss the latest results on excitation functions for odd-$Z$ projectiles reacting with lanthanide targets. This work may also have relevance to the production of superheavy elements with Z \textgreater\ 118.