Impact of pairing and neutron-excess on suppression of the above-barrier fusion cross-section in 19O + 12C

Abstract

Fusion excitation functions for ¹⁹O and ¹⁹F + ¹²C were simultaneously measured along with ²⁰O + ¹²C using the active-target detector MuSIC@Indiana. Examination of the cross-section just above the barrier reveals a significant suppression of fusion for the ¹⁹O + ¹²C system starting at E${}_{c.m.}\sim$12 MeV. This suppression is not simply due to the reduced binding of the unpaired neutron in ¹⁹O as ¹⁷O + ¹²C does not exhibit the same sharp suppression of the fusion cross-section. Multiple mean-field models are used as a reference to understand the measured fusion excitation functions.