Subbarrier nucleon transfer: Doorway to heavy-ion fusion

Nucleon-transfer cross sections have been measured at subbarrier energies in collisions between Sn target nuclei and light (16,18O) and heavy (58Ni) projectile nuclei. Large differences in cross sections correlate directly with the subbarrier fusion enhancement, suggesting nucleon transfer as an important doorway to fusion with a direct dependence on the overall transfer strengths. Simple two-level mixing considerations support this picture.