N/Z equilibration in damped collisions induced by E/A = 8. 5 MeV /sup 58/Ni and /sup 64/Ni on /sup 238/U

Nuclide distributions have been measured for damped collision products formed in the reaction of E/A = 8.5 MeV /sup 58/Ni and /sup 64/Ni ions with /sup 238/U. The data demonstrate that in these very asymmetric systems the evolution of the nucleon-exchange process as a function of energy loss depends strongly on the N/Z value of the projectile and the corresponding gradient in the potential-energy surface. Comparison of the data with transport model calculations shows qualitative agreement with the N and Z centroids, variances, and correlation coefficients. However, absolute discrepancies exist which suggest the need for improvement in the model.