A model for explaining fusion suppression using the classical trajectory method

Abstract

A two-dimensional classical trajectory model is used to explain the projectile breakup and above-barrier fusion suppression for the reactions 6Li+209Bi, 6Li+152Sm and 6Li+144Sm. To obtain the initial conditions of the equations of motion, a simplified model of the 6Li nucleus has been developed. Numerical solutions of the equations lead to the classification of orbits into breakup and no-breakup trajectories. The breakup fraction is studied as a function of the impact parameter. Using quantum mechanical arguments, the cut-off impact parameter for fusion is determined by proposing a sharp cut-off model which assumes that there is an angular momentum limit to fusion. We introduce a simple formula for the explanation of fusion suppression, according to which fusion suppression is given by the average of the breakup fractions evaluated at impact parameters ranging from head-on collision up to the cut-off impact parameter. We find that there is excellent agreement between the experimental fusion cross section (σexp) and the calculated fusion cross section (σcal) for the systems studied.