Quasi-elastic scattering excitation functions at backward angles and near b
arrier energies for the systems C-12,C-13+Pd-105,Pd-106 have been measured.
The first derivative of the cross sections with respect to the energy was
determined. The purpose of this work is to evaluate if such derivative is a
good representation of the barrier distribution involved in the fusion pro
cess. The results are analyzed considering that the characteristics of the
barrier distribution depend on the effective Q-values.