SUMMARY
In this research, the effect of changing the values of the diffusion parameter on the semi-elastic scattering ( ) and distribution (D) calculations for (SC) and (CC) have been studied. Three values were taken from the diffusion for each system parameter. It is assumed that the nuclear potential has a Woods-Saxon form, which is indicated by the surface diffuseness, potential depth, and radius parameters for (25Mg + 90Zr), (28Si + (120Sn ,150Nd) Systems. The chi-square (?2) is applied to compare the best-fitted value of the diffuseness parameter between the theoretical calculations and the experimental data. According to the results of (?2 ), we noticed that some systems achieved a good match between the theoretical calculations and experimental data of semi-elastic scattering ( ) and the distribution calculations at the standard value of the diffusion parameter (a0=0.63 ) or at a value higher and lower than the standard value. In the case of (SC ) the best fit was at a value less than the standard value of the diffusivity parameter but in the case of (CC ), the fit was better at a value higher than the standard value of the diffusivity parameter because the potential barrier in the (SC ) is single, while in (CC ) calculations it is multiple.