Why does neutron transfer play different roles in sub-barrier fusion reactions ${}^{32}$S+${}^{94,96}$Zr and ${}^{40}$Ca+${}^{94,96}$Zr?

Abstract

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.

Comments: 17 pages, 6 figures, submitted in PRC