Temperatures, energies, and degree of thermal equilibration of fragments in damped nuclear reactions

Abstract

Experimental neutron multiplicities and spectral slope parameters are compared with evaporation calculations for the damped $^{165}$Ho${+\mathrm{}}^{56}$Fe reaction as a function of ${E}_{\mathrm{loss}}$ for different degrees of energy relaxation of the dinuclear system. These calculations indicate that the popular direct interpretation of the slope parameters in terms of the nuclear temperature of the emitter is poorly justified. Detailed comparisons for two different primary reaction fragment distributions show that the energy partition of the primary fragments is energy-loss dependent and, for small energy losses, far from thermal equilibrium. For ${E}_{\mathrm{loss}<100}$ MeV, the ratio ${E}_{L}$(Fe-like)/${E}_{H}$(Ho-like)>0.5 and for ${E}_{\mathrm{loss}=150}$ MeV, this ratio is given by ${A}_{L}$/${A}_{H}$.