A definition of scission points and consequences on some fission distributionsL. Bonneau1, P. Quentin1, 2 and I.N. Mikhailov3, 4
1 Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
2 Centre d'Études Nucléaires de Bordeaux-Gradignan, Université Bordeaux 1, CNRS/IN2P3, Chemin du Solarium, BP. 120, 33175 Gradignan Cedex, France
3 Bogoliubov Laboratory of Theoretical Physics, JINR Dubna, 141980 Dubna, Moscow region, Russia
4 Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, CNRS/IN2P3-Université Paris XI, 91406 Orsay-Campus, France
Published online: 21 May 2008
A quantitative definition of scission points occurring in a fission process at low energy (spontaneous or induced by low-energy neutron, γ, charged particle) is proposed. It is based on the concept of a negligible nuclear mutual energy versus its Coulomb counterpart. Practical ways by which one may approximately, albeit mostly in a microscopic fashion (à la Skyrme-Hartree-Fock-BCS), calculate the total energy at scission and their mutual energy parts is presented in a limited yet relevant collective variable space. For a given fragmentation, we present some modeling of the probability for the fissioning system to lie at a given point in the fragment deformation space. From this probability, one deduces the distributions of total fragment-deformation, excitation or Coulomb energies for a given couple of fragments. To yield these distributions some approximations are made and discussed on the sharing of the energy gained in the descent towards scission between kinetic and excitation energies. Some calculational results using the SkM* Skyrme effective interaction and related to the spontaneous fission of the 252Cf nucleus are shown for given fragmentations. As an example, results for the angular momentum distributions in primary fission fragments is compared with available data.
© CEA 2008