The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
S. G. Kadmensky - One of the best experts on this subject based on the ideXlab platform.
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Sequential character of low-energy ternary and quaternary Nuclear Fission
Physics of Atomic Nuclei, 2016Co-Authors: S. G. Kadmensky, A. O. BulychevAbstract:An analysis of low-energy true ternary (quaternary) Nuclear Fission leads to the conclusion that these Fission modes have a sequential two-step (three-step) character such that the emission of a third particle (third and fourth particles) and the separation of Fission fragments occur at distinctly different instants, in contrast to the simultaneous emergence of all Fission products in the case of onestep ternary (quaternary) Fission. This conclusion relies on the following arguments. First, the emission of a third particle (third and fourth particles) from a fissile nucleus is due to a nonevaporative mechanism associated with a nonadiabatic character of the collective deformation motion of this nucleus at the stages preceding its scission. Second, the axial symmetry of the deformed fissile compound nucleus and the direction of its symmetry axis both remain unchanged at all stages of ternary (quaternary) Fission. This circumstancemakes it possible to explain themechanism of the appearance of observed anisotropies and T — odd asymmeries in the angular distributions of products of ternary (quaternary) Nuclear Fission. Third, the T —odd asymmetry discovered experimentally in ternary Nuclear Fission induced by cold polarized neutrons obeys the T —invariance condition only in the case of a sequential two-step (three-step) character of true ternary (quaternary) Nuclear Fission. At the same time, this asymmetry is not a T —invariant quantity in the case of the simultaneous emission of products of true ternary (quaternary) Nuclear Fission from the fissile compound nucleus.
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Interference effects in Nuclear Fission
Bulletin of the Russian Academy of Sciences: Physics, 2007Co-Authors: S. G. Kadmensky, L. V. TitovaAbstract:Various interference effects governing the character of angular distributions of binary and ternary Nuclear Fission products and P-odd, P-even, and T-odd asymmetries in these angular distributions have been studied within the quantum theory of spontaneous and low-energy induced Nuclear Fission.
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Quantum description of quaternary Nuclear Fission
Bulletin of the Russian Academy of Sciences: Physics, 2007Co-Authors: S. G. Kadmensky, O. V. SmolyanskyAbstract:The quantum theory of binary and ternary Fission is generalized to the case of recently observed quaternary Nuclear Fission. Formulas for the amplitudes of partial Fission widths and angular and energy distributions of quaternary Fission products are derived with allowance for strong channel coupling. The nonevaporation mechanism for formation of light particles is used to explain the experimentally observed decrease in the probability for emission of light particles (α, α), (α, t), and (t, t) as compared with the product of emission probabilities for the same particles in ternary Fission. It is concluded that in quaternary Fission, as in ternary Fission, light particles escape from the neck of the Fissioning nucleus much earlier than scission of the nucleus into heavy fragments occurs.
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Quantum and thermodynamical characteristics of Nuclear Fission and generalized model of the nucleus
Physica Scripta, 2006Co-Authors: S. G. KadmenskyAbstract:We describe several quantum and thermodynamical characteristics of different Nuclear Fission stages based on the generalized model of the nucleus.
Mireia Piera - One of the best experts on this subject based on the ideXlab platform.
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Sustainability issues in the development of Nuclear Fission energy
Energy Conversion and Management, 2010Co-Authors: Mireia PieraAbstract:Abstract A review is made of the ongoing lines of R&D in the field on Nuclear Fission and potential alternatives based on specific features of some types of reactors. This Nuclear perspective is confronted with a proposal on sustainability criteria for the Nuclear Fission field. This proposal stems from an analysis of the main drawbacks of Nuclear Fission, notably those related to security, safety and environment. On the other hand, it is pointed out that Nuclear Fission is a sound and proven CO2-free source of energy, with an outstanding maturity in its current stage of commercial development, and with an enormous potential to undergo new phases of industrial developments by exploiting very appealing features of the Nuclear phenomenology, which deserve further research, under the guidance of sustainability concepts and criteria.
G.f. Bertsch - One of the best experts on this subject based on the ideXlab platform.
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a schematic reaction theory model for Nuclear Fission
arXiv: Nuclear Theory, 2019Co-Authors: G.f. BertschAbstract:The K-matrix formalism is applied to a schematic model for Nuclear Fission. The purpose is to explore the dependence of observables on the assumptions made about the configuration space and nucleon interaction in the Hamiltonian of the fissile nucleus. As expected, branching ratios in induced Fission are found to depend sensitively on the character of the residual interaction, whether it is pairing in form or taken from a random ensemble. On the other hand, the branching ratio is not much affected by the presence of additional configurations that do not introduce new Fission paths.
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Decay widths at the scission point in Nuclear Fission.
arXiv: Nuclear Theory, 2019Co-Authors: G.f. Bertsch, L. M. RobledoAbstract:An outstanding problem in the theory of Nuclear Fission is understanding the Hamiltonian dynamics at the scission point. Here we apply the Generator Coordinate Method to calculate decay widths for pre-scission configurations into the two-fragment continuum. Transitions that are allowed under diabatic dynamics can have widths up to several MeV. For non-diabatic decays through the pairing interaction, typical widths to a specific final state channel are 2-3 orders of magnitude smaller. The nucleus U-236 is taken as a representative example in the calculations.
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Nuclear Fission as resonance-mediated conductance
arXiv: Nuclear Theory, 2014Co-Authors: G.f. BertschAbstract:For 75 years the theory of Nuclear Fission has been based on the existence of a collective coordinate associated with the Nuclear shape, an assumption required by the Bohr-Wheeler formula as well as by the R-matrix theory of Fission. We show that it is also possible to formulate the theory without the help of collective coordinates. In the new formulation, Fission is facilitated by individual states in the barrier region rather than channels over the barrier. In a certain limit the theory reduces to a formula closely related to the formula for electronic conductance through resonant tunneling states. In contrast, conduction through channels gives rise to a staircase excitation function that is well-known in nanoscale electronics but has never been seen in Nuclear Fission.
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Nuclear Fission with diffusive dynamics.
Physical review. C Nuclear physics, 1992Co-Authors: D. Cha, G.f. BertschAbstract:We investigate the dynamics of Nuclear Fission, assuming purely diffusive motion up to the saddle point. The resulting Smoluchowski equation is solved for conditions appropriate to the {sup 16}O+{sup 142}Nd{r arrow}{sup 158}Er reaction at 207 MeV. The solution is characterized by an equilibration time {tau}{sub 0} for the system to reach steady state, and the Fission decay rate in steady state, {Lambda}. We find that the equilibration time {tau}{sub 0} plays a very small role in determining the number of prescission neutrons. The diffusion coefficient extracted from the experimental data is larger than the theoretical in the work of Bush, Bertsch, and Brown by a factor of 5--11.
O. A. Yuminov - One of the best experts on this subject based on the ideXlab platform.
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Stochastic model of tilting mode in Nuclear Fission
Physics of Atomic Nuclei, 2006Co-Authors: D. O. Eremenko, V. A. Drozdov, M. H. Eslamizadex, O. V. Fotina, S. Yu. Platonov, O. A. YuminovAbstract:A model of induced Nuclear Fission was developed with consideration of thermodynamically fluctuating orientation degree of freedom (tilting) of deformed nuclei. This model was applied to analysis of the experimental angular anisotropy of Fission fragments in the 16O + 232Th, 238U, 248Cm, 208Pb, 209Bi; 12C + 236U; 19F + 208Pb; and 11B + 237Np reactions. Information on the equilibrating time of the tilting mode was obtained.
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Stochastic model of the tilting mode in Nuclear Fission
AIP Conference Proceedings, 2004Co-Authors: V. A. Drozdov, D. O. Eremenko, O. V. Fotina, S. Yu. Platonov, O. A. YuminovAbstract:A model of induced Nuclear Fission is developed with consideration of thermodynamically fluctuating orientational degree of freedom of deformed nuclei. This model was applied in analysis of the experimental angular anisotropy of Fission fragments in the 16O + 232Th, 238U and 248Cm reactions at the oxygen energies from 90 to 160 MeV. Information on the equlibrating time of the orientational mode was obtained.
Sakir Ayik - One of the best experts on this subject based on the ideXlab platform.
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Nuclear Fission with a Langevin equation
Nuclear Physics A, 1993Co-Authors: David Boilley, E. Suraud, Abe Yasuhisa, Sakir AyikAbstract:Abstract A microscopically derived Langevin equation is applied to thermally induced Nuclear Fission. An important memory effect is pointed out and discussed. A strong friction coefficient, estimated from microscopic quantities, tends to decrease the stationary limit of the Fission rate and to increase the transient time. The calculations are performed with a collective mass depending on the collective variable and with a constant mass. Fission rates calculated at different temperatures are shown and compared with previous available results.
