Role of positive transfer Q values in fusion cross sections for O-18+ W-182,W-184,W-186 reactions

Background: The relevance of including channel coupling effects in the form of target deformation and vibration in fusion reactions has been well established. Many reactions with positive Q values for neutron transfer show enhancement in sub-barrier fusion cross sections. However, there are exceptions to these cases. Purpose: We aim to make a comprehensive list of factors influencing the sub-barrier fusion enhancement in systems with neutron transfer channels having positive Q values. Method: Evaporation residue cross sections were measured for O-18+W-182,W-184,W-186 reactions in the energy range 68-104 MeV in the laboratory frame, using a recoil mass spectrometer. Results: Inclusion of deformation of target and projectile low-level excitations in the coupled channels calcula- tions - explains the measured fusion excitation functions of O-18+W-182,W-184 ,W-186 reactions. Conclusions: Considering that all the targets have similar deformation, and comparing with O-16+W-182,W-184,W-186 reactions having negative 2n transfer Q values, we can conclude that the positive Q values of neutron transfer - channels have no effect on the observed fusion cross sections of O-18+W-182,W-184,W-186 reactions.