Evaluation of the fission cross-section within the multi-modal fission approach for 235U(n,f)

Vlăducă, G.; Tudora, Anabella; Hambsch, F.‐J.; Oberstedt, S.; Ruskov, I.

doi:10.1016/s0375-9474(03)00911-4

Cited by 14 publications

(14 citation statements)

References 9 publications

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“…We observed [16,17,20,[26][27][28][29][30][31][32] and other authors too (like as Refs. [33][34][35][36][37][38]), that the fission barriers obtained by cross-section data analysis also exhibit Z, A-dependence.…”

Section: Nucleus Symmetry At the Barrier Deformationssupporting

confidence: 63%

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Inner barrier shape symmetries in 237Np neutron data evaluation up to 40 MeV incident energy

et al. 2006

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Section: Nucleus Symmetry At the Barrier Deformationssupporting

confidence: 63%

“…[24] predicting that the inner barrier of U nuclei with A 236 is axially symmetric with the inner barrier height (V A ) less than the height of the outer barrier (V B ). The same A tr value of 236 was obtained by cross-section data analysis [27,33] and is given in the data bases RIPL-1,2 [38].…”

Section: Nucleus Symmetry At the Barrier Deformationsmentioning

confidence: 99%

Inner barrier shape symmetries in 237Np neutron data evaluation up to 40 MeV incident energy

et al. 2006

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“…(We do not consider the appreciably larger value found for symmetric fission in Ref. [123], which has a very low yield.) However, Fig.…”

Section: H Spontaneous Fissionmentioning

confidence: 93%

“…Therefore, the relative population of the different fission valleys is much less sensitive to the magnitudes of the shell effects in the different fission valleys than the spontaneous-fission half-life is to the ground-state shell effect. A simple estimate for this sensitivity is given by the Hill-Wheeler formula, using the ω value of the outer barrier, which is in the order of 0.7 MeV [57,123]. (We do not consider the appreciably larger value found for symmetric fission in Ref.…”

Section: H Spontaneous Fissionmentioning

confidence: 99%

General Description of Fission Observables: GEF Model Code

Schmidt

Jurado

Amouroux

et al. 2016

Nuclear Data Sheets

444

421

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The GEF ("GEneral description of Fission observables") model code is documented. It describes the observables for spontaneous fission, neutron-induced fission and, more generally, for fission of a compound nucleus from any other entrance channel, with given excitation energy and angular momentum. The GEF model is applicable for a wide range of isotopes from Z = 80 to Z = 112 and beyond, up to excitation energies of about 100 MeV. The results of the GEF model are compared with fission barriers, fission probabilities, fission-fragment mass-and nuclide distributions, isomeric ratios, total kinetic energies, and prompt-neutron and prompt-gamma yields and energy spectra from neutron-induced and spontaneous fission. Derived properties of delayed neutrons and decay heat are also considered.The GEF model is based on a general approach to nuclear fission that explains a great part of the complex appearance of fission observables on the basis of fundamental laws of physics and general properties of microscopic systems and mathematical objects. The topographic theorem is used to estimate the fission-barrier heights from theoretical macroscopic saddle-point and ground-state masses and experimental ground-state masses. Motivated by the theoretically predicted early localisation of nucleonic wave functions in a necked-in shape, the properties of the relevant fragment shells are extracted. These are used to determine the depths and the widths of the fission valleys corresponding to the different fission channels and to describe the fission-fragment distributions and deformations at scission by a statistical approach. A modified composite nuclear-level-density formula is proposed. It respects some features in the superfluid regime that are in accordance with new experimental findings and with theoretical expectations. These are a constant-temperature behaviour that is consistent with a considerably increased heat capacity and an increased pairing condensation energy that is consistent with the collective enhancement of the level density. The exchange of excitation energy and nucleons between the nascent fragments on the way from saddle to scission is estimated according to statistical mechanics. As a result, excitation energy and unpaired nucleons are predominantly transferred to the heavy fragment in the superfluid regime. This description reproduces some rather peculiar observed features of the prompt-neutron multiplicities and of the even-odd effect in fission-fragment Z distributions. For completeness, some conventional descriptions are used for calculating pre-equilibrium emission, fission probabilities and statistical emission of neutrons and gamma radiation from the excited fragments. Preference is given to simple models that can also be applied to exotic nuclei compared to more sophisticated models that need precise empirical input of nuclear properties, e.g. spectroscopic information.The approach reveals a high degree of regularity and provides a considerable insight into the physics of the fission process. Fission obs...

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“…The compound nucleus (CN) mechanism is treated within the statistical model with sub-barrier effects using the STATIS code, in the version including the extended fission model in the frame of the multi-modal fission concept [10] in case of 238 U. This extended theory of the statistical model including the competition with three fission modes is described in detail in previous papers (see for instance Ref.…”

Section: Introductionmentioning

confidence: 99%

Modelling of reaction cross sections and prompt neutron emission

Hambsch¹,

Tudora

Oberstedt³

2010

EPJ Web of Conferences

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Abstract. Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra) as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides ( 238 U(n, f) and 237 Np(n, f)) both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.

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Evaluation of the fission cross-section within the multi-modal fission approach for 235U(n,f)

Cited by 14 publications

References 9 publications

Inner barrier shape symmetries in 237Np neutron data evaluation up to 40 MeV incident energy

Inner barrier shape symmetries in 237Np neutron data evaluation up to 40 MeV incident energy

General Description of Fission Observables: GEF Model Code

Modelling of reaction cross sections and prompt neutron emission

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