skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Potential Energy of Heavy Nuclear System in Low-energy Fusion-fission Processes

Abstract

The problem of description of low-energy nuclear dynamics and derivation of multi-dimensional potential energy surface depending on several collective degrees of freedom is discussed. Multi-dimensional adiabatic potential is constructed basing on extended version of the two-center shell model. It has correct asymptotic value and height of the Coulomb barrier in the entrance channel (fusion) and appropriate behavior in the exit one, giving required mass and energy distributions of reaction products and fission fragments. Explicit time-dependence of the driving potential was introduced in order to take into account difference of diabatic and adiabatic regimes of motion of nuclear system at above-barrier energies and also difference of nuclear shapes in fusion and fission channels (neck formation). Derived driving potential is proposed to be used for unified analysis of the processes of deep-inelastic scattering, fusion and fission at low-energy collisions of heavy ions.

Authors:
; ; ;  [1];  [2]
  1. Flerov Laboratory of Nuclear Reactions, JINR, Dubna, Moscow region (Russian Federation)
  2. Frankfurt Institute for Advanced Studies, J. W. Goethe-Universitaet Frankfurt am Main (Germany)
Publication Date:
OSTI Identifier:
21061812
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 912; Journal Issue: 1; Conference: International symposium on exotic nuclei, Khanty-Mansiysk (Russian Federation), 17-22 Jul 2006; Other Information: DOI: 10.1063/1.2746606; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ASYMPTOTIC SOLUTIONS; COULOMB FIELD; DEEP INELASTIC HEAVY ION REACTIONS; DEEP INELASTIC SCATTERING; DEGREES OF FREEDOM; ENERGY SPECTRA; FISSION; FISSION FRAGMENTS; HEAVY ION FUSION REACTIONS; POTENTIAL ENERGY; POTENTIALS; SHELL MODELS; TIME DEPENDENCE

Citation Formats

Karpov, A. V., Zagrebaev, V. I., Aritomo, Y., Naumenko, M. A., and Greiner, W. Potential Energy of Heavy Nuclear System in Low-energy Fusion-fission Processes. United States: N. p., 2007. Web. doi:10.1063/1.2746606.
Karpov, A. V., Zagrebaev, V. I., Aritomo, Y., Naumenko, M. A., & Greiner, W. Potential Energy of Heavy Nuclear System in Low-energy Fusion-fission Processes. United States. doi:10.1063/1.2746606.
Karpov, A. V., Zagrebaev, V. I., Aritomo, Y., Naumenko, M. A., and Greiner, W. Tue . "Potential Energy of Heavy Nuclear System in Low-energy Fusion-fission Processes". United States. doi:10.1063/1.2746606.
@article{osti_21061812,
title = {Potential Energy of Heavy Nuclear System in Low-energy Fusion-fission Processes},
author = {Karpov, A. V. and Zagrebaev, V. I. and Aritomo, Y. and Naumenko, M. A. and Greiner, W.},
abstractNote = {The problem of description of low-energy nuclear dynamics and derivation of multi-dimensional potential energy surface depending on several collective degrees of freedom is discussed. Multi-dimensional adiabatic potential is constructed basing on extended version of the two-center shell model. It has correct asymptotic value and height of the Coulomb barrier in the entrance channel (fusion) and appropriate behavior in the exit one, giving required mass and energy distributions of reaction products and fission fragments. Explicit time-dependence of the driving potential was introduced in order to take into account difference of diabatic and adiabatic regimes of motion of nuclear system at above-barrier energies and also difference of nuclear shapes in fusion and fission channels (neck formation). Derived driving potential is proposed to be used for unified analysis of the processes of deep-inelastic scattering, fusion and fission at low-energy collisions of heavy ions.},
doi = {10.1063/1.2746606},
journal = {AIP Conference Proceedings},
number = 1,
volume = 912,
place = {United States},
year = {Tue May 22 00:00:00 EDT 2007},
month = {Tue May 22 00:00:00 EDT 2007}
}
  • A realistic microscopically-based quantum approach to the competition between fusion and quasi-fission in a heavy fusing system is applied to several reactions leading to 256No. Fusion and quasi-fission are described in terms of a diffusion process of nuclear shapes through a dynamical collective potential energy landscape which is initially diabatic and gradually becomes adiabatic. The microscopic ingredients of the theory are obtained with a realistic two-center shell model based on Woods-Saxon potentials. The results indicate that (i) the diabatic effects play a very important role in the onset of fusion hindrance for heavy systems, and (ii) very asymmetric reactions inducedmore » by closed shell nuclei seem to be the best suited to synthesize the heaviest compound nuclei.« less
  • A new approach is proposed for a unified description of strongly coupled deep-inelastic (DI) scattering, fusion, fission, and quasi-fission (QF) processes of heavy ion collisions. A unified driving-potential and a unified set of dynamic Langevin-type equations of motion are used in this approach. This makes it possible to perform a full (continuous) time analysis of the evolution of heavy nuclear systems, starting from the approaching stage, moving up to the formation of the compound nucleus or emerging into two final fragments. The calculated mass, charge, energy and angular distributions of the reaction products agree well with the corresponding experimental datamore » for heavy and superheavy nuclear systems. Collisions of very heavy nuclei (such as 238U+248Cm) are investigated as an alternative way for production of superheavy elements. Large charge and mass transfer was found in these reactions due to the inverse (anti-symmetrizing) quasi-fission process leading to formation of surviving superheavy long-lived neutron-rich nuclei.« less
  • A theory of the competition between fusion and quasifission in a heavy fusing system is proposed, which is based on a master equation and the two-center shell model. Fusion and quasifission arise from a diffusion process in an ensemble of nuclear shapes, each of which evolves toward the thermal equilibrium. The fusing system moves on a dynamical (time-dependent) collective potential energy surface that is initially diabatic and gradually becomes adiabatic. Calculations for several reactions leading to {sup 256}No are performed within a simplified two-dimensional model. Among other important conclusions, the results indicate that (i) the diabatic effects play a verymore » important role in the onset of fusion hindrance for heavy systems and (ii) very asymmetric reactions induced by closed-shell nuclei seem to be the best suited to synthesize the heaviest compound nuclei.« less
  • We develop a unified nuclear potential for the description of large-scale nuclear collective motion and find that it satisfactorily reproduces experimental data for heavy-ion elastic scattering, fusion, fission, and ground-state masses. Obtained by generalizing the modified liquid-drop model so that two semi-infinite slabs of constant-density nuclear matter have minimum energy at zero separation, this potential is given in terms of a double volume integral of a Yukawa-plus-exponential folding function. For heavy nuclear systems the resulting heavy-ion interaction potential is similar to the proximity potential of Swiatecki and co-workers. However, for light nuclear systems our potential lies slightly below the proximitymore » potential at all nuclear separations. For heavy nuclei fission barriers calculated with our Yukawa-plus-exponential model are similar to those calculated with the liquid-drop model. However, for light nuclei the finite range of the nuclear force and the diffuse nuclear surface lower the fission barriers relative to those calculated with the liquid-drop model. Use of a Wigner term proportional to absolute value (N - Z)/A in the nuclear mass formula resolves the major part of the anomaly between nuclear radii derived from elastic electron scattering on the one hand and from ground-state masses and fission-barrier heights on the other.« less