Energy features of fissile nuclei at the scission point for various fission modes
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CLEI Theory
Energy Features of Fissile Nuclei at the Scission Point for Various Fission Modes Yu. N. Koblik* , V. P. Pikul, G. A. Abdullaeva** , A. P. Morozov, and A. F. Nebesniy Institute of Nuclear Physics, Uzbek Academy of Sciences, pos. Ulughbek, Tashkent, 100214 Republic of Uzbekistan Received January 14, 2013
Abstract—Mass-spectroscopic data on the yields of heavy products originating from the thermal-neutroninduced fission of 235 U nuclei are presented over broad ranges of mass numbers A (125 A 155), kinetic energies Ek (40 Ek 80 MeV), and effective ion charges z ∗ (18 z ∗ 29). The potential energy of a fissile system at the scission point is analyzed with allowance for the positions of the minima that correspond to the most probable ways of separation of the system for the standard (S2) and superasymmetric (S3) fission modes. DOI: 10.1134/S106377881401013X
1. INTRODUCTION
spectroscopic data on the yields of heavy fragments originating from the thermal-neutron-induced fission of 235 U nuclei in broad ranges of mass numbers A (125 A 155), kinetic energies Ek (40 Ek 80 MeV), and effective ion charges z ∗ (18 z ∗ 29). Taking into account the positions of the minima corresponding to the most probable partitions of the fissile system being considered, we analyze the potential energy of this system at the scission point for the standard (S2) and superasymmetric (S3) fission modes.
In the case of low-energy fission, experimental information is satisfactorily interpreted on the basis of a number of models, including the model of equilibrium at the scission point [1], the droplet model [2], and the two-center shell model [3]. However, none of these models has so far provided a comprehensive picture of the fission process. In view of this, it is of interest to perform a detailed analysis of various facets of the nuclear fission process as a dynamical phenomenon that involves almost all of the degrees of freedom of fissile nuclei. A feature common to processes associated with fission is that, at the scission point, Coulomb and surface forces compensate each other, so that it is the shell structure of the fissioning nucleus and final-state nuclei appearing as fission fragments that determines primarily the dynamics of the fission process. For want of a theory that would be able to describe the dynamics of nuclear fission from the saddle to the scission point, there naturally arises the need for investigating in detail this phenomenon by experimental and theoretical means of nuclear physics. Previously, we studied some properties of fissile nuclear systems, such as the shape of a nucleus in a prescission state for various combinations of fission-fragment pairs and the most probable charge of nascent fragments with allowance for shell corrections and pair interactions depending on the deformation parameters and kinetic energies of fission fragments [4–8]. In this article, we present new mass* **
2. EXPERIMENTAL CONDITIONS AND RESULTS OF THE MEASUREMENTS The measurements of the yields of fragments originating from t
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