Reduction of fusion and reaction cross sections at near-barrier energies

Abstract

We investigate three of the most frequently used methods to reduce fusion and total reaction excitation functions. For this purpose, we apply them in two situations. First, we consider theoretical cross sections obtained by single-channel calculations based on standard optical potentials. In this case, the cross sections are not influenced by any particular nuclear property. Thus, the method is successful if the cross sections for different systems are about the same. In the case of fusion excitation functions, we found that the fusion function method works very well, being much better than the other two methods. Regarding total reaction excitation functions, none of the methods is satisfactory. Their reduced reaction cross sections maintain a strong dependence on the atomic and mass numbers of the collision partners. However, they perform reasonably well when compared to similar systems. Next, we use the three methods to reduce experimental fusion and reaction cross sections for many systems, over a broad mass range. Our conclusions are consistent with the ones reached for our theoretical cross sections, resulting from single-channel calculations. That is, the fusion function method is the best for fusion data, whereas none of the three methods works for total reaction.