Recoil of products from reactions of20,22Ne withNb93at 100 and 142 MeV

Abstract

The recoil properties of thirty-five nuclides produced in reactions of 100 and 142 MeV $^{20}\mathrm{Ne}$ and $^{22}\mathrm{Ne}$ with $^{93}\mathrm{Nb}$ have been measured. A thick-target/thick-catcher technique was used, with the foils mounted at 45\ifmmode^\circ\else\textdegree\fi{} to the beam axis so as to provide information on the transverse as well as the longitudinal momentum transfer. Relationships have been derived to extract values, from the resulting data, for the average longitudinal component of recoil velocity and the average recoil angle. The experimental results show, in almost all cases, mean recoil velocities less than the compound nuclear velocity. For products with near-target mass, transverse momentum transfers greater than those along the axis were observed. For heavier products, the momentum transfer increases with the product mass. The results from the $^{22}\mathrm{induced}$ reactions are significantly different from those of $^{20}\mathrm{Ne}$. The results are interpreted mainly in terms of two competing mechanisms: complete fusion/evaporation and a class of process involving varying degrees of mass transfer between projectile and target.