.
The fission fragments mass-yield of
236
U is obtained by an approximate solution of the eigenvalue problem of the collective Hamiltonian that describes the dynamics of the fission process whose ...degrees of freedom are: the fission (elongation), the neck and mass-asymmetry modes. The macroscopic-microscopic method is used to evaluate the potential energy surface. The macroscopic energy part is calculated using the liquid drop model and the microscopic corrections are obtained using a Woods-Saxon single-particle levels. The four-dimensional modified Cassini ovals shape parametrization is used to describe the shape of the fissioning nucleus. The mass tensor is taken within a cranking-type approximation. The final fragment mass distribution is obtained by weighting the adiabatic density distribution in the collective space with the neck-dependent fission probability. The neck degree of freedom is found to play a significant role in determining the final fragment mass distribution.
Shape isomers in Pt, Hg and Pb isotopes with N≤126 Pomorski, K.; Nerlo-Pomorska, B.; Dobrowolski, A. ...
The European physical journal. A, Hadrons and nuclei,
2020/4, Volume:
56, Issue:
4
Journal Article
Peer reviewed
Open access
Deformation-energy surfaces of 54 even-even isotopes of Pt, Hg and Pb nuclei with neutron numbers up to 126 are investigated within a macroscopic-microscopic model based on the Lublin-Strasbourg-Drop ...macroscopic energy and shell plus pairing-energy corrections obtained from a Yukawa-folded mean-field potential at the desired deformation. A new, rapidly converging Fourier shape parametrization is used to describe nuclear shapes. The stability of shape isomeric states with respect to non-axial and higher-order deformations is investigated.
The fission-fragment mass and total kinetic energy (TKE) distributions are evaluated in a quantum mechanical framework using elongation, mass asymmetry, neck degree of freedom as the relevant ...collective parameters in the Fourier shape parametrization recently developed by us. The potential energy surfaces (PES) are calculated within the macroscopic-microscopic model based on the Lublin-Strasbourg Drop (LSD), the Yukawa-folded (YF) single-particle potential and a monopole pairing force. The PES are presented and analysed in detail for even-even Plutonium isotopes with
A
= 236–246. They reveal deep asymmetric valleys. The fission-fragment mass and TKE distributions are obtained from the ground state of a collective Hamiltonian computed within the Born-Oppenheimer approximation, in the WKB approach by introducing a neck-dependent fission probability. The calculated mass and total kinetic energy distributions are found in good agreement with the data.
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A certain number of yet unknown super- and hyper-deformed shape isomeric states are predicted in even-even nuclei of the region between Pt and Ra, using the macroscopic-microscopic model based on ...the Lublin Strasbourg Drop for the macroscopic energy and shell plus pairing corrections evaluated through the Yukawa-folded mean-field potential for the microscopic part. A new, rapidly converging shape parametrization is used to describe the vast range of nuclear deformations between the ground and the fission isomeric states up to near the scission configuration. Quadrupole moments are evaluated in the local minima and turn out to be in good agreement with the experimental data wherever available.
An innovative parametrization of nuclear shapes, based on a Fourier expansion of the square distance from the surface of the nucleus to the symmetry axis is introduced. Surface, curvature and Coulomb ...energy coefficients of a charged liquid drop, that determine the semiclassical nuclear energy, are evaluated within this shape parametrization, together with the wall-friction and the irrotational-flow mass tensors. These transport coefficients are important ingredients of many nuclear models describing nuclear structure and dynamics. A numerical code allowing for the determination of all these quantities for a huge variety of nuclear shapes is made available to the interested user.
Program title: inerfric
Program Files doi:http://dx.doi.org/10.17632/gtvbc8b7sw.1
Licensing provisions: GPLv3
Programming language: Fortran
Nature of problem: The inertia tensor evaluated in the hydrodynamical model using the Werner–Wheeler approximation generalized to nonaxial shapes is evaluated, together with the friction tensor using the wall formula, and the shape functions that define the liquid-drop energy in terms of surface, curvature, Coulomb and congruence energy. For the description of the fission process, the mass ratio of the nascent fission fragments and their centre-of-mass distance is also evaluated together with the quadrupole moment and the moments of inertia for rotation of the deformed shape.
Solution method: All these quantities are evaluated in our new rapidly converging Fourier shape parametrization, able to describe a huge variety of nuclear shapes, simply by reading in the (up to 7) shape parameters determining in an unambiguous way the nuclear deformation and corresponding for the (4) principal parameters to the nuclear elongation, left–right asymmetry, non axiality and neck degree of freedom, the remaining 3 allowing, if necessary, to optimize the evaluation of the asymmetry and neck degrees of freedom.
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