Preequilibrium cluster emission in massive transfer reactions near Coulomb barrier energy
Abstract
Within the framework of the dinuclear system model, the preequilibrium emission of neutron, proton, deuteron, triton, 3He, α, 6Li, 7Li, 8Be and 9Be in the transfer reactions of 12C + 209Bi, 40,48Ca+238U, 238U+238U and 238U+248Cm has been systematically investigated. The production rate, kinetic energy spectra and emission angular distribution are calculated. It is found that the preequilibrium emission mechanism is associated with the reaction system and beam energy. The preequilibrium cross sections of proton, deuteron, triton and alpha are comparable in magnitude. The reaction with 40Ca is favorable for the cluster emission in comparison with 48Ca on 238U at the near barrier energy. A broad angular distribution of the preequilibrium cluster is found in the heavy systems 238U+238U and 238U+248Cm.