He jishu (Mar 2023)
Cluster emission in massive transfer reactions based on dinuclear system model
Abstract
BackgroundThe pre-equilibrium cluster manifests the nuclear structure and reaction dynamics of collision system. The systematical investigation of cluster emission in transfer reactions is of significance in deep understanding of the synthesis of superheavy nuclei, shell evolution, new isotope production, etc.PurposeThe dynamics of pre-equilibrium cluster in a few of nucleon transfer reaction has been described by theoretical model, such as exciton model, cluster model. However, the cluster emission in massive transfer is very complicated because of the emission mechanism associated with the structure properties and also the dynamical process.MethodsIn this work, the pre-equilibrium cluster emission in massive transfer reaction has been systematically investigated within the dinuclear system model. The model has been successfully used for describing the massive fusion reaction and multi-nucleon transfer dynamics. The nucleon exchange and energy dissipation take place once the dinuclear system is formed. The nucleon transfer between the binary fragments is governed by the single-particle Hamiltonian and proceeds around the Fermi surface formed by the dinuclear system. The master equation is used for the nucleon transfer dynamics and the relative motion energy dissipation is taken into account. The dynamics of neutron, proton, deuteron, triton, 3He, 4He, 6,7Li and 8,9Be in collisions of 12C+209Bi, 40Ca+208Pb and 48Ca+238U near Coulomb barrier energies is analyzed, i.e., temporal evolution of production rate, kinetic energy spectra and angular distribution.ResultsIt is found that the emission probability of 4He is the same magnitude of proton emission and several orders larger than the one of 3He. Both the nuclear structure and dynamical effects influence the pre-equilibrium cluster production.ConclusionsThe pre-equilibrium clusters are emitted from the 'projectile-like' and 'target-like' fragments and the angular distributions manifest the similar trends. The kinetic energy spectra of clusters are shown as the Boltzmann distribution. The method is also extended to the cluster emission in weakly bound nuclei induced reactions by considering the preformation factor for the cluster construction.
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