Dinuclear systems in complete fusion reactions
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nuclear Systems in Complete Fusion Reactions G. G. Adamiana, b, N. V. Antonenkoa, and A. S. Zubova a
Joint Institute for Nuclear Research, Dubna, Moscow oblast, Russia bInstitute of Nuclear Physics, Tashkent, Uzbekistan email: [email protected]
Abstract—Formation and evolution of dinuclear systems in reactions of complete fusion are considered. Based on the dinuclear system concept, the process of compound nucleus formation is studied. Arguments confirming the validity of this concept are given. The main problems of describing the complete fusion in adi abatic approximation are listed. Calculations of evaporation residue cross sections in complete fusion reac tions leading to formation of superheavy nuclei are shown. Isotopic trends of the cross sections of heavy nuclei formation in complete fusion reactions are considered. DOI: 10.1134/S1063779614050025
I. INTRODUCTION Dinuclear Systems in Nuclear Reactions Discovery and investigation of deep inelastic trans fer reactions (DITRs) [1–4], in which a total dissipa tion of kinetic energy of collision occurs, made it pos sible to find a new approach to a mechanism of two nuclei interaction. The dinuclear system (DNS) that forms in these reactions participates simultaneously in two nuclear processes. It evolves in coordinate of mass (charge) asymmetry and at the same time may break down into two fragments from all intermediate config urations. Studying the charge, mass, and energy distri butions of DITR products for different escape angles, which corresponds to different lifetimes of a DNS, it is possible to gain a complete impression of regularities of its evolution [1–6]. The DITRs were successfully applied to producing isotopes of nuclei far from the stability line. Yields of products and basic characteris tics of these reactions are well explained by the DNS evolution within the microscopic transport approach [7] to the DNS dynamics description. The information obtained in DITR investigation was used for disclosure of the mechanism of com pound nucleus formation [8]. It has been found that the underlying mechanism of the process of complete fusion of nuclei is formation of a DNS and its evolu tion in the direction of the mass (charge) asymmetry growth. This approach to describing the process of complete fusion of nuclei was called the dinuclear sys tem concept (DNS concept) [9–11]. Based on this concept, a model of nuclear fusion (DNS model) was proposed and developed that made it possible for the first time to take into account the competition between the complete fusion and quasifission, to explain a large set of experimental data, and to make a number of successful predictions [12–19].
The analysis carried out within DNS concept has shown that a process of complete fusion of nuclei includes both dynamic and static phases. A stage of capture of an incident nucleus by a target nucleus with creation of the excited DNS proceeds mainly as a dynamic process, whereas the DNS evolution to the compound nucleus obeys statistical regularities. Thus, a pro
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