The sub-barrier capture (fusion) reactions $^{ 32}$S+$^{ 90,94,96}$Zr, $^{ 36}$S+$^{ 90,96}$Zr, $^{ 40}$Ca+$^{ 90,94,96}$Zr, and $^{ 48}$Ca+$^{ 90,96}$Zr with positive and negative $Q$-values for neutron transfer are studied within the quantum diffusion approach and the universal fusion function representation. For these systems, the s-wave capture probabilities are extracted from the experimental excitation functions and are also analyzed. Different effects of the positive $Q_{ xn}$-value neutron transfer in the fusion enhancement are revealed in the relatively close reactions $^{ 32}$S+$^{ 94,96}$Zr and $^{ 40}$Ca+$^{ 94,96}$Zr.
Categories: nucl-th