Inverse quasifission in the reactions Gd 156,160 + W 186

Background: Low-energy multinucleon transfer reactions may be used for production of new neutron-enriched heavy nuclei. Purpose: Our aim is to investigate the influence of proton (Z=82) and neutron (N=82, 126) shells as well as orientation effects on the formation of reaction products in the inverse quasifission process in the reactions 156,160Gd + 186W. Methods: Mass, energy, and angular distributions of primary binary fragments formed in the reactions 156Gd+186W at an energy of 878 MeV, and 160Gd+186W at 860 and 935 MeV, have been measured using the double-arm time-of-flight spectrometer CORSET at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions (FLNR) at the Joint Institute for Nuclear Research (JINR), Dubna. Results: Enhancement in the yield of products with masses 200–215 u has been found for both reactions. The cross sections of the formation of trans-target fragments with masses around 208 u are found to be about 10μb at the Coulomb barrier energy and reach the level of 0.5 mb at the energy above the barrier for side-to-side collision. Conclusions: The enhanced yield of products with masses heavier than the target mass confirms the important role of the closed shells at Z=82 and N=82, 126 in the inverse quasifission process in low-energy damped collisions. The orientation effect caused by the strong deformation of colliding nuclei can result in a gain in the yield of heavy target-like fragments.