Role of positive transfer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Q</mml:mi></mml:math> values in fusion cross sections for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi mathvariant="normal">O</mml:mi><mml:mprescripts/><mml:none/><mml:mn>18</mml:mn></mml:mmultiscripts><mml:mo>+</mml:mo><mml:mmultiscripts><mml:mi mathvariant="normal">W</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>182</mml:mn><mml:mo>,</mml:mo><mml:mn>184</mml:mn><mml:mo>,</mml:mo><mml:mn>186</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> reactions
P. Jisha, A. M. Vinodkumar, S. Sanila, K. Arjun, B. R. S. Babu, J. Gehlot, S. Nath, N. Madhavan, Rohan Biswas, A. Parihari, A. Vinayak, Amritraj Mahato, E. Prasad, A. C. Visakh
Abstract
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 $^{18}\mathrm{O}+^{182,184,186}\mathrm{W}$ 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 calculations explains the measured fusion excitation functions of $^{18}\mathrm{O}+^{182,184,186}\mathrm{W}$ reactions.Conclusions: Considering that all the targets have similar deformation, and comparing with $^{16}\mathrm{O}+^{182,184,186}\mathrm{W}$ 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 $^{18}\mathrm{O}+^{182,184,186}\mathrm{W}$ reactions.