Three-dimensional Langevin calculations of fission fragment mass-energy distribution from excited compound nuclei

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

doi:10.1103/physrevc.63.054610

Cited by 161 publications

(163 citation statements)

References 61 publications

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“…While it has been quite well established that dissipation is rather strong in the large-distortion range [9,10,11,2], the situation is still unclear in the small-deformation regime [12,13,14,15,16]. One of the reasons for the vivid debates concerning the strength of nuclear dissipation is the large amount of complex side effects entering into the description of the fission mechanism, in particular in fusion-fission experiments, which often induce large angular momenta and deformations.…”

Section: Experimental Approachmentioning

confidence: 99%

Conditions for the manifestation of transient effects in fission

et al. 2005

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Abstract:We examine the manifestation of transient effects in fission by analysing experimental data where fission is induced by peripheral heavy-ion collisions at relativistic energies. Available total nuclear fission cross sections of 238 U at 1⋅A GeV on gold and uranium targets are compared with a nuclear-reaction code, where transient effects in fission are modelled using different approximations to the numerical time-dependent fission-decay width: a new analytical description based on the solution of the Fokker-Planck equation and two widely used but less realistic descriptions, a step function and an exponential-like function. The experimental data are only reproduced when transient effects are considered. The deduced value of the dissipation strength β depends strongly on the approximation applied for the time-dependent fission-decay width and is estimated to be of the order of 2·10 21 s -1. A careful analysis sheds severe doubts on the use of the exponential-like in-growth function largely used in the past. Finally, we discuss which should be the characteristics of experimental observables to be most sensitive to transient effects in fission.

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Section: Experimental Approachmentioning

confidence: 99%

Conditions for the manifestation of transient effects in fission

et al. 2005

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“…Other, semi-classical, approaches have been used to calculate fission-fragment properties. We note in particular the full Langevin calculations of the Omsk group [9,10,11], and more recently the Brownian-motion approach of Randrup et al [12,13]. We have preferred to adopt the microscopic approach for the present work because, although it is far more technically and conceptually challenging, this approach incorporates the tenets of quantum mechanics from the start, such as the non-locality of the nuclear wave function and exchange terms in the Hamiltonian of the system.…”

Section: Introductionmentioning

confidence: 99%

Fragment Yields Calculated in a Time-Dependent Microscopic Theory of Fission

Younes¹,

Gogny²

2012

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Pre-neutron fragment-yield distributions are calculated for the 235 U(n, f ) and 239 Pu(n, f ) reactions using a time-dependent fully microscopic approach. These yields are calculated as a function of incident neutron energy from thermal to 5 MeV. We show that our calculations are in good agreement with experimental results, and competitive in accuracy with more phenomenological approaches. Further improvements to future calculations of these yields are discussed.

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“…[21,22]. These types of simulations continue [17][18][19]. They employ two or three shape degrees of freedom, macroscopic potential energies, fluid dynamic inertias, and more recent calculations usually use some form of one-body dissipation.…”

Section: Introductionmentioning

confidence: 99%

Fission-fragment mass distributions from strongly damped shape evolution

2011

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Random walks on five-dimensional potential-energy surfaces were recently found to yield fissionfragment mass distributions that are in remarkable agreement with experimental data. Within the framework of the Smoluchowski equation of motion, which is appropriate for highly dissipative evolutions, we discuss the physical justification for that treatment and investigate the sensitivity of the resulting mass yields to a variety of model ingredients, including in particular the dimensionality and discretization of the shape space and the structure of the dissipation tensor. The mass yields are found to be relatively robust, suggesting that the simple random walk presents a useful calculational tool. Quantitatively refined results can be obtained by including physically plausible forms of the dissipation, which amounts to simulating the Brownian shape motion in an anisotropic medium.

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Three-dimensional Langevin calculations of fission fragment mass-energy distribution from excited compound nuclei

Cited by 161 publications

References 61 publications

Conditions for the manifestation of transient effects in fission

Conditions for the manifestation of transient effects in fission

Fragment Yields Calculated in a Time-Dependent Microscopic Theory of Fission

Fission-fragment mass distributions from strongly damped shape evolution

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