Study On The Kinetic Energy Distribution Of Fragments After Thermal Neutron-induced Fission Of ²³⁵U And ²³⁹Pu Based On Dinuclear And Statistical Model

Since the development of nuclear fission,it has played a vital role in the fields of nuclear energy,national defense,nuclear technology and cutting-edge scientific research,and has affected human production and life.As we all know,the fission energy mainly comes from the kinetic energy of the fragment induced by the neutron-induced fission reaction?accounting for more than 85%of the entire fission energy?.²³⁵U and ²³⁹Pu are widely used in nuclear fuels as fissile actinide nuclei,especially thermal neutron-induced fission of ²³⁵U and ²³⁹Pu,because their fission cross-section is very large?A few orders of magnitude beyond the incident neutron-induced fission cross-section of MeV?.It is a key nuclide for experimental and theoretical research.Therefore,it is very necessary to study the kinetic energy distribution of fragments after thermal neutron-induced fission of ²³⁵U and ²³⁹Pu,which not only has practical application value,but also helps to deeply understand the academic problem of fission mechanism.This paper takes the generation and evolution process of paired fission initial fragments as the research object,and proposes a dinuclear and statistical model:?1?Assume that the fission core is stretched along the axis of symmetry until it breaks into two initial fission fragments;?2?The kinetic energy of the fragments after fracture is mainly provided by Coulomb repulsion.After strictly performing the six-dimensional integration operation and ignoring the higher-order terms,an analytical representation of the Coulomb repulsion interaction of the pair of large deformation fragments is given;?3?By mining some common characteristics of observable measurements after fission?such as fragment mass distribution,average fragment total kinetic energy distribution,fragment charge distribution,instant neutron number,instant neutron kinetic energy,average gamma energy,etc.?.The deformation representation of large deformation fragments and a set of universal deformation parameters are given;?4?Through the given deformation parameters,the distance between the initial fragment and the centroid is derived,and the average total kinetic energy distribution ???and the average kinetic energy distribution ???are given.Taking the thermal neutron-initiated two fission systems ²³⁵U and ²³⁹Pu as examples,the average total kinetic energy distribution and average kinetic energy distribution of the fragments of the two fission systems were obtained consistently.In addition,the average prompt neutron number,average prompt neutron kinetic energy,and average?energy of the fragmented fission fragments were preliminarily discussed,which laid a foundation for further research on the fission mechanism.