Angular momentum transfer in the reactions induced by 166 MeVNe20onCu63

A study has been made of the energy, angular, and charge distribution of products emitted in the reaction of 166-MeV ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ ions with ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$. The first three moments of the $\gamma$-ray multiplicity distribution and the out-of-plane $\gamma$-ray angular correlations have been measured in coincidence with the projectile-like fragments. Relaxation times of 2.6 × ${10}^{-22\mathrm{}}$ s for energy dissipation, 4.1 × ${10}^{-22\mathrm{}}$ s for angular momentum transfer, and a charge diffusion coefficient of 0.58 × ${10}^{22}$ ${\mathrm{}\left(\mathrm{charge}\mathrm{units}\right)\mathrm{}}^2$ ${\mathrm{s}}^{-1\mathrm{}}$ have been deduced from these data. A small $\gamma$-ray anisotropy and a large width of the multiplicity distribution have been observed. These are interpreted in terms of a random component of transferred angular momentum whose magnitude is comparable to that of the aligned component induced by tangential friction. Thermal excitation of collective modes of motion in the equilibrated dinuclear complex can account quantitatively for these experimental results. Other mechanisms for the generation of a random component of angular momentum are also possible.