The processes of fusion-fission and quasi-fission of superheavy nuclei

Иткис, М. Г.; Bogachev, A. A.; Itkis, I. M.; Kliman, J.; Knyazheva, G. N.; Kondratiev, N. A.; Козулин, Э. М.; Крупа, Л.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Прохорова, Е. В.; Rusanov, A. Ya.

doi:10.1016/j.nuclphysa.2006.12.026

Cited by 83 publications

(66 citation statements)

References 13 publications

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“…The main problem is the dynamical evolution of the multidimensional di-nuclear system leading to equilibration in all possible degrees of freedom, which is still not describable despite developments in modern theory and computing. Therefore, P CN is often extrapolated from the experimental observations of the nuclear reaction studies [26]. In the earlier studies, where mostly the light particles/ions were used as a projectile, the quasi-fission probability was shown to be negligible.…”

Section: The Cross Sections Of the Fusion-evaporation Reactionsmentioning

confidence: 99%

The cross sections of fusion-evaporation reactions: the most promising route to superheavy elements beyond Z=118

Khuyagbaatar

2017

EPJ Web Conf.

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Abstract. The synthesis of superheavy elements beyond oganesson (Og), which has atomic number Z = 118, is currently one of the main topics in nuclear physics. An absence of sufficient amounts of target material with atomic numbers heavier than californium (Z = 98) forces the use of projectiles heavier than 48 Ca (Z = 20), which has been successfully used for the discoveries of elements with Z = 114 − 118 in complete fusion reactions. Experimental cross sections of 48 Ca with actinide targets behave very differently to "cold" and "hot" fusion-evaporation reactions, where doubly-magic lead and deformed actinides are used as targets, respectively. The known cross sections of these reactions have been analysed compared to calculated fission barriers. It has been suggested that observed discrepancies between the cross sections of 48 Ca-induced and other fusionevaporation reactions originate from the shell structure of the compound nucleus, which lies in the island of the stability. Besides scarcely known data on other reactions involving heavier projectiles, the most promising projectile for the synthesis of the elements beyond Og seems to be 50 Ti. However, detailed studies of 50 Ti, 54 Cr, 58 Fe and 64 Ni-induced reactions are necessary to be performed in order to fully understand the complexities of superheavy element formation.

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Section: The Cross Sections Of the Fusion-evaporation Reactionsmentioning

confidence: 99%

The cross sections of fusion-evaporation reactions: the most promising route to superheavy elements beyond Z=118

Khuyagbaatar

2017

EPJ Web Conf.

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“…In reactions using actinide target nuclei, quasifission and fusion-fission generate fragments with different mass asymmetry. Quasifission shows an asymmetric mass distribution with fragments in the vicinity of the doubly closed shell nuclei 208 Pb and 78 Ni, whereas fusion-fission shows a symmetric distribution [4][5][6][7][8][9]. The measured fission spectra contain information on fusion and/or quasifission.…”

Section: Introductionmentioning

confidence: 92%

Fusion probabilities in the reactions40,48Ca+238U at energies around the Coulomb barrier

et al. 2012

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Fission cross sections and fission fragment mass distributions were measured in the reactions of 40 Ca + 238 U and 48 Ca + 238 U at energies around the Coulomb barrier. Fusion probabilities were calculated based on the fluctuation dissipation model. The measured mass distributions for both reactions showed an asymmetric shape at low incident energies, whereas the distribution changed to a flat shape at higher energies. The variation of the mass distribution is explained by a change of the ratio between fusion and quasifission with nuclear orientation. The calculation reproduced the mass distributions and their energy dependence. The trajectories for fusion-fission were used to determine the fusion probability. Fusion probabilities for both reactions are identical as function of the center-of-mass energy (E c.m. ), but they differ when plotted as function of the excitation energy (E * ). Evaporation residue cross sections were calculated for the reaction 48 Ca + 238 U using a statistical model and the obtained fusion cross sections as input values. The results are compared to experimental data.

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“…Thus it is difficult to unambiguously separate quasi-fission and fusionfission, though ingenious fitting procedures have been developed [1]. However, as noted, quasi-fission and fusionfission occur at different stages of evolution of the composite system, which is reflected in the difference in their average timescales.…”

Section: Introductionmentioning

confidence: 99%