Average Eeective-interaction Strength of Rst Nucleon-nucleon Collision in Multistep Reactions

E ective NN -interaction strength V 0 averaged along the trajectory of the incident nucleon, for the rst NN collision, is obtained with respect to both the nuclear density and the rst NN -collision probability. Good agreement is found between the average strengths obtained with the Hartree-Fock potential plus the dispersive component and by using the parametrization based on the Brueckner-Hartree-Fock nuclear matter calculations. The nuclear-density dependence of the e ective NN interaction may account for the low-energy phenomenological V0 values. The e ect of using V 0 values within the multistep direct (MSD) reaction formalism is shown.