(Multi-)nucleon transfer in the reactions 16O, 332S + 208Pb

Abstract

A detailed analysis of the projectile-like fragments detected at backward angles in the reactions 16O,32S+208Pb at energies below the fusion barrier is presented. Excitation functions corresponding to nucleon transfer with ΔZ = 1 and ΔZ = 2 were extracted, indicating surprisingly large absolute transfer probabilities at sub-barrier energies. A comparison of 2p transfer probabilities with time-dependent Hartree-Fock calculations suggests strong pairing correlations between the two protons. Excitation energies in the projectile-like fragments up to ~ 15MeV for the 16 O and ~ 25MeV for 32S-induced reactions show the population of highly excited states in the residual nuclei, and indicate substantial dissipation of kinetic energy. A new phenomenological framework explores the effect of energy dissipation through these highly inelastic (large excitation energies) and complex (correlated few-nucleon transfer) processes on the probability for fusion in the reaction 16o+208Pb. Preliminary results show that the suppression of fusion at energies above the barrier in this reaction can be explained within the new framework.