Preequilibrium neutron emission in central and peripheral heavy-ion collisions

Preequilibrium neutron emission is observed in central and peripheral collisions of Ho + Ne at 11, 14.6, and 20.1 MeV/μ, and in central collisions of Ho + C at 25 MeV/μ contributing approximately 5 to 15% to the total neutron multiplicity. The present data are compared to inclusive and exclusive experiments on charged-particle emission. Predictions by the Fermi-jet model are seen to be inconsistent with the high-energy neutron component observed for the Ho + Ne and Ho + C reactions, while the exciton model provides a satisfactory reproduction of the data. Asymptotic temperatures of projectile-like fragments produced in the reaction Ho + Ne at 14.6 and 20.1 MeV/μ are found to be larger than those of the corresponding targetlike reaction partners