Mass-energy distribution of fragments from the fission of excited nuclei within three-dimensional Langevin dynamics

Nadtochy, P. N.; Карпов, А. В.; Vanin, D. V.; Адеев, Г. Д.

doi:10.1134/1.1378876

Cited by 5 publications

(3 citation statements)

References 21 publications

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“…These studies began considering the dynamics of fission with two-dimensional models of the nuclear shape [24][25][26]. Around 2000, three-dimensional Langevin equations began to be considered by various groups [27][28][29]. Later, some three-dimensional modeling was extended by including an additional angular orientation degree of freedom [30].…”

Section: Introductionmentioning

confidence: 99%

Langevin model of low-energy fission

Sierk

2017

Phys. Rev. C

109

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Background: Since the earliest days of fission, stochastic models have been used to describe and model the process. For a quarter century, numerical solutions of Langevin equations have been used to model fission of highly excited nuclei, where microscopic potential-energy effects have been neglected. Purpose: In this paper I present a Langevin model for the fission of nuclei with low to medium excitation energies, for which microscopic effects in the potential energy cannot be ignored. Method: I solve Langevin equations in a five-dimensional space of nuclear deformations. The macroscopicmicroscopic potential energy from a global nuclear structure model well benchmarked to nuclear masses is tabulated on a mesh of approximately 10 7 points in this deformation space. The potential is defined continuously inside the mesh boundaries by use of a moving five-dimensional cubic spline approximation. Because of reflection symmetry, the effective mesh is nearly twice this size. For the inertia, I use a (possibly scaled) approximation to the inertia tensor defined by irrotational flow. A phenomenological dissipation tensor related to one-body dissipation is used. A normal-mode analysis of the dynamical system at the saddle point, and the assumption of quasi-equilibrium, provide distributions of initial conditions appropriate to low excitation energies, and is extended to model spontaneous fission. A dynamical model of post-scission fragment motion including dynamical deformations and separation allows the calculation of final mass and kinetic-energy distributions, along with other interesting quantities. Results: The model makes quantitative predictions for fragment mass and kinetic-energy yields, some of which are very close to measured ones. Varying the energy of the incident neutron for induced fission allows the prediction of energy dependences of fragment yields and average kinetic energies. With a simple approximation for spontaneous fission starting conditions, quantitative predictions are made for some observables which are close to measurements. Conclusions: This model is able to reproduce several mass and energy yield observables with a small number of physical parameters, some of which do not need to be varied after benchmarking to 235 U(n,f) to predict results for other fissioning isotopes.

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Section: Introductionmentioning

confidence: 99%

Langevin model of low-energy fission

Sierk

2017

Phys. Rev. C

109

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“…This model has been developed in many branches, such as the Gaussian model [3,4] and modified scission point models [6][7][8][9][10][11][12][13]. The time-dependent model has been significantly developed by Randrup [14][15][16] and others [17][18][19][20][21][22] to predict the shape of mass yields (symmetric or asymmetric modes). Because all of them have sophisticated computations, a systematic method is needed to evaluate the mass distribution of fission fragments in an easy way.…”

Section: Introductionmentioning

confidence: 99%

Deformation Parameters and Collective Temperature Changes in Photofission Mass Yields of Actinides Within the Systematic Statistical Scission Point Model

Kaldiani

2021

Front. Phys.

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The photofission fragment mass yields of actinides are evaluated using a systematic statistical scission point model. In this model, all energies at the scission point are presented as a linear function of the mass numbers of fission fragments. The mass yields are calculated with a new approximated relative probability for each complementary fragment. The agreement with the experimental data is quite good, especially with a collective temperature Tcol of 2 MeV at intermediate excitation energy and Tcol = 1 MeV for spontaneous fission. This indicates that the collective temperature is greater than the value obtained by the initial excitation energy. The generalized superfluid model is applied for calculating the fragment temperature. The deformation parameters of fission fragments have been obtained by fitting the calculated results with the experimental values. This indicates that the deformation parameters decrease with increasing excitation energy. Also, these parameters decrease for fissioning systems with odd mass numbers.

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“…These models have been developed in many branches, such as the Gaussian model [3][4][5] and the modified scission point models [7][8][9][10][11][12]. Recently, the time-dependent model has been significantly developed by Randrup [14][15][16] and some researchers [17][18][19][20][21] to evaluate the mass yields of pre-actinides and actinides. However, recent models have sophisticated computations, which indicate the need for a systematic method to more easily evaluate the mass yields of fission fragments.…”

Section: Introductionmentioning

confidence: 99%

Deformation parameter changes in fission mass yields within the systematic statistical scission-point model

Kaldiani¹

2021

Commun. Theor. Phys.

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The fission fragment mass-yields are evaluated for pre-actinide and actinide isotopes using a systematic statistical scission point model. The total potential energy of the fissioning systems at the scission point is presented in approximate relations as functions of mass numbers, deformation parameters and the temperature of complementary fission fragments. The collective temperature, T coll, and the temperature of fission fragments, T i , are separated and the effect of collective temperature on mass yields results is investigated. The fragment temperature has been calculated with the generalized superfluid model. The sum of deformation parameters of complementary fission fragments has been obtained by fitting the calculated results with the experimental data. To investigate the transitions between symmetric and asymmetric modes mass yields for pre-actinide and heavy actinides are calculated with this model. The transition from asymmetric to symmetric fission is well reproduced using this systematic statistical scission point model. The calculated results are in good agreement with the experimental data with T coll = 2 MeV at intermediate excitation energy and with T coll = 1 MeV for spontaneous fission. Despite the Langevin model, in the scission point model, a constraint on the deformation parameters of fission fragments has little effect on the results of the mass yield.

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Mass-energy distribution of fragments from the fission of excited nuclei within three-dimensional Langevin dynamics

Cited by 5 publications

References 21 publications

Langevin model of low-energy fission

Langevin model of low-energy fission

Deformation Parameters and Collective Temperature Changes in Photofission Mass Yields of Actinides Within the Systematic Statistical Scission Point Model

Deformation parameter changes in fission mass yields within the systematic statistical scission-point model

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