Dynamic treatment of ternary fission

Abstract

The new dynamic model of light charged particle (LCP) formation in ternary fission is presented. The model is based on the assumption that light particles are formed as a result of two random neck ruptures during the time interval about one single-particle period. The connection of the final stage of ternary fission and of the saddle point descent stage was obtained in the framework of the density moments method. The analysis of LCP formation has shown that LCP mass and charge distributions are strongly governed by statistical nucleon exchange in the LCP-light fragment double system. New semiclassical expressions for the calculations of LCP yields and relative ternary fission probability are given. The results of calculations are in satisfactory agreement with the experimental data.

Ternary-fission mass distribution ofCf252: A level-density approach

“…To study ternary fission, a phenomenological shell model using the harmonic oscillator potential with a spin-orbit term and 2 corrections was developed by Degheidy et al [5]. Rubchenya et al [6] employed a new dynamic model by assuming that light particles are formed as a result of two random neck ruptures. Sǎndulescu et al [7,8], with the help of a coplanar three-body cluster model, investigated ternary fission by calculating the relative isotopic yield and by finding the existence of long-life tri-nuclear molecules.…”

Nucleation and cluster formation in low-density nucleonic matter: A mechanism for ternary fission

“…The discovery of "long range alpha accompanied fission" in 1946 [11] and later experiments demonstrated the existence of a large range of light isotopes with characteristics similar to those of the long range alphas [7][8][9][10]. Considerable theoretical and experimental effort has been directed towards understanding this type of ternary fission [1][2][3][4][5][6][7][8][9][10][12][13][14][15].…”

“…Although fission processes inherently involve an important collective dynamics, the ternary isotope data indicate that statistical considerations also play a major role in the determination of the observed yields. As a result, models which are primarily based on dynamic considerations [1,3,14], on statistical considerations [1,12] and on both [1,15] have been employed in attempts to reproduce the observed yields. These previous efforts have treated the problem by emphasizing the dominance of one of the following: neck instabilities and rupture [14], barrier penetration of pre-formed clusters [15] or formation of fragments from interacting nucleons in the fission neck region [12].…”

“…As a result, models which are primarily based on dynamic considerations [1,3,14], on statistical considerations [1,12] and on both [1,15] have been employed in attempts to reproduce the observed yields. These previous efforts have treated the problem by emphasizing the dominance of one of the following: neck instabilities and rupture [14], barrier penetration of pre-formed clusters [15] or formation of fragments from interacting nucleons in the fission neck region [12]. However, these models have had only limited success and have been unable to explain such key experimental results as the high yield of scission tritons relative to scission protons [1,2,16] and the non-observation of 3 He [1,2,8,9].…”

An Evaporation-Based Model of Thermal Neutron Induced Ternary Fission of Plutonium

“…However, the initial suggestion of Halpern has not been used to obtain a quantitative description of ternary fission, and many other dynamical models have been developed. These include models involving an extension of the theory of particle emission from actinide ground states to a rapidly evolving system in the last phase of the fission process [11], double-neck rupture [12], models where α particles inside the neck region gain energy from the average timedependent potential of a fissioning system [13,14], and other dynamical models reviewed in ref. [6].…”