Excitation energy division in the quasielastic region from reactions of 12 MeV/nucleon 48Ti with 150Nd.

Abstract

Internal excitation of projectile-like fragments and target-like fragments was investigated for the system 12 MeV/nucleon $^{48}$Ti${+\mathrm{}}^{150}$Nd, by measuring the discrete \ensuremath{\gamma} rays emitted by both fragments in coincidence with the charge-separated projectile-like fragments. Two quasielastic exit channels of the projectile-like fragments were studied: Z=20 and Z=22. Characteristic \ensuremath{\gamma} rays were used to determine the average masses of products, after separation and neutron evaporation, as a function of kinetic energy loss. Our results show that the mass-to-charge equilibration occurs quickly for the Z=20 exit channel, but is slower for the Z=22 channel. Comparison between the average masses of products with the masses calculated using the statistical model show that the excitation energy is divided approximately equally between the projectile-like and the target-like fragments for the Z=20 exit channel. The excitation energy appears to be divided equally up to \ensuremath{\sim}105 MeV of the kinetic energy loss corresponding to \ensuremath{\sim}36% of kinetic energy damping. This result is consistent with predictions made by the stochastic nucleon-exchange models for a small kinetic energy loss.