Reaction 48Ca+208Pb: the capture-fission cross-sections and the mass-energy distributions of fragments above and deep below the Coulomb barrier

E. V. Prokhorova; E. A. Cherepanov; M. G. Itkis; N. A. Kondratiev; E. M. Kozulin; L. Krupa; Yu. Ts. Oganessian; V. V. Pashkevich; I. V. Pokrovsky; A. Ya. Rusanov

arXiv · nucl-ex/0309021

Reaction 48Ca+208Pb: the capture-fission cross-sections and the mass-energy distributions of fragments above and deep below the Coulomb barrier

E. V. Prokhorova·E. A. Cherepanov·M. G. Itkis·N. A. Kondratiev·E. M. Kozulin·L. Krupa·Yu. Ts. Oganessian·V. V. Pashkevich·I. V. Pokrovsky·A. Ya. Rusanov

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Abstract

The capture-fission cross-sections in an energy range of 206-242 MeV of 48Ca-projectiles and mass-energy distributions (MEDs) of reaction products in an energy range of 211-242 MeV have been measured in the 48Ca+208Pb reaction using the double-arm time-of-flight spectrometer CORSET. The MEDs of fragments for heated fission were shown to consist of two components. One component, which is due to classical fusion-fission, is associated with the symmetric fission of the 256No compound nucleus. The other component, which appears as ''shoulders'', is associated with the quasi-fission process and can be named ''quasi-fission shoulders''. Those quasi-fission shoulders enclose light fragments whose masses are 60-90 a.m.u. The total kinetic energy (TKE) of the fragments that belong to the shoulders is higher than the value expected for a classical fusion-fission process. We have come to the conclusion that in quasi-fission, spherical shells with Z=28 and N=50 play a great role. It has also been demonstrated that the properties of the MEDs of fragments formally agree with a well-known hypothesis of two independent fission modes; in this case the modes are normal fusion-fission and quasi-fission processes. A high-energetic Super-Short mode of classical fission has been found at low excitation energies in the mass range of heavy fragments M = 130-135 and TKE = 233 MeV; however the yield associated with this mode is small.

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E. V. Prokhorova, E. A. Cherepanov, M. G. Itkis, N. A. Kondratiev, E. M. Kozulin, L. Krupa, Yu. Ts. Oganessian, V. V. Pashkevich, I. V. Pokrovsky, A. Ya. Rusanov. 2003-09-29. Reaction 48Ca+208Pb: the capture-fission cross-sections and the mass-energy distributions of fragments above and deep below the Coulomb barrier. https://arxiv.org/abs/nucl-ex/0309021

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