Strong Angular Momentum Effects in Near-Barrier Fusion Reactions

Abstract

Cross sections and $\ensuremath{\gamma}$-ray multiplicities have been measured for neutron evaporation channels in the reactions $^{16}\mathrm{O}$ + $^{144}\mathrm{Nd}$, $^{37}\mathrm{Cl}$ + $^{123}\mathrm{Sb}$, $^{64}\mathrm{Ni}$ + $^{96}\mathrm{Zr}$, and $^{80}\mathrm{Se}$ + $^{80}\mathrm{Se}$ leading to the compound system $^{160}\mathrm{Er}$ at common excitation energies. In the near-barrier energy regime average angular momentum transfers depend dramatically on the asymmetry of the entrance channel. The results are interpreted in terms of the ground-state zero-point vibrations.