A fundamental nuclear process - complete fusion of two nuclei - is analyzed. This process has been much investigated over the past years, however, the mechanism of the compound nucleus formation still remains an open question. The author and his colleagues proposed a basically new approach to the interpretation and description of the complete fusion process - the dinuclear system concept (DNSC). The concept is based on the information about the interaction of nuclei in deep inelastic collisions which was obtained in the study of deep inelastic transfer reactions. According to the DNSC, the process of fusion of nuclei includes a dinuclear system formation on the capture stage and a subsequent systems evolution to the compound nucleus via nucleon transfer from a light nucleus to a heavy one. The DNSC revealed two important peculiarities in the complete fusion of massive nuclei: the existence of the potential barrier on the way to the compound nucleus formation and the competition between complete fusion and quasi-fission channels. The DNSC and models based on it made it possible to describe the main characteristics of nuclear reactions used for the synthesis of transactinide and superheavy elements. The DNSC revealed the dominant role of quasi-fission in the cold synthesis of superheavy elements. It permitted calculations of the optimal value of the compound nucleus excitation energy and showed that symmetrical nuclear reactions are not promising for the synthesis of superheavy elements. It also allowed us to reveal the effect of the a-particle quasi-emission, unknown before. On the whole the DNSC gives the most realistic idea about the mechanism of the compound nucleus formation in reactions with heavy ions. For the first time a review of theoretical models for nuclear fusion is given, and the nucleus-nucleus potentials used in these models are discussed.

PDF (1.65 Mb)