Excitation functions for complete fusion of ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ + ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ + ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$, and ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$ + ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$ have been determined over a range of energies from just above to well below the fusion barrier. The response of these excitation functions to the addition of valence neutrons is found to be surprisingly complex. We suggest that at least part of the observed variations may be due to dynamic, single-particle effects.

• Received 14 May 1980

DOI:https://doi.org/10.1103/PhysRevLett.45.1472