Theory of nuclear fission

Schunck, N.; Regnier, David

doi:10.1016/j.ppnp.2022.103963

Cited by 60 publications

(12 citation statements)

References 472 publications

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“…A good representation of PES is usually obtained by imposing quadrupole Q 20 (cigar shape) and octupole Q 30 (pear shape) moments, while leaving free the higher multipole moments in an energy minimisation procedure [20,21]. PES are generated by constraining the quadrupole moment…”

Section: Constrained Hartree-fock-bogoliubov Calculationsmentioning

confidence: 99%

“…Note that, although collective inertia is calculated (see Appendix C), it is not used in the path calculation. Several definitions of scission have been used by different groups (see discussion in [21]). Here, it is assumed that scission is achieved when the spatial density in the neck becomes lower than 0.08 fm −3 (approximatively half the nuclear saturation density).…”

Section: Definitions Of the Fission Path Of Scission And Of The Pre-f...mentioning

confidence: 99%

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Hartree–Fock–Bogoliubov study of quantum shell effects on the path to fission in $$^{180}$$Hg, $$^{236}$$U and $$^{256}$$Fm

2023

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Quantum shell effects stabilising fission fragments with various shapes have been invoked as a factor determining the distribution of nucleons between the fragments at scission. Shell effects also induce asymmetric shapes in the nucleus on its way to fission well before the final fragments are (pre)formed. These shell effects are studied in fission of $$^{180}$$ 180 Hg, $$^{236}$$ 236 U and $$^{256}$$ 256 Fm with constrained Hartree-Fock-Bogoliubov calculations using the D1S parametrisation of the Gogny interaction. Strutinsky shell energy correction and single-particle energy level density near the Fermi surface are computed. Several neutron and proton shell effects are identified as drivers towards asymmetric fission. Shell effects are also used to identify the preformation of the fragments in the later stage of fission.

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Section: Constrained Hartree-fock-bogoliubov Calculationsmentioning

confidence: 99%

Section: Definitions Of the Fission Path Of Scission And Of The Pre-f...mentioning

confidence: 99%

Hartree–Fock–Bogoliubov study of quantum shell effects on the path to fission in $$^{180}$$Hg, $$^{236}$$U and $$^{256}$$Fm

2023

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“…Self-consistent approaches based on the nuclear DFT have recently demonstrated that a microscopic description has a potential for both qualitative and quantitative description of fission data [6,[23][24][25][26][27]. In the DFT framework, the wave functions along the fission path are generally determined by the minimization of the energy of the nucleus within a given set of constraints and assumed symmetries.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional potential energy surface for fission of $^{236}$U within covariant density functional theory

Zhou¹,

Li²,

Chen³

et al. 2023

Preprint

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We have calculated the three-dimensional potential energy surface (PES) for the fission of compound nucleus 236 U using the covariant density functional theory with constraints on the axial quadrupole and octupole deformations (β2, β3) as well as the nucleon number in the neck qN . By considering the additonal degree of freedom qN , coexistence of the elongated and compact fission modes is predicted for 0.9 β3 1.3. Remarkably, the PES becomes very shallow across a large range of quadrupole and octupole deformations for small qN , and consequently, the scission line in (β2, β3) plane will extend to a shallow band, which leads to a fluctuation for the estimated total kinetic energies by several to ten MeV and for the fragment masses by several to about ten nucleons.

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“…Modeling fission, in general, implies four stages: (i) the definition of the initial conditions of the system, (ii) its dynamical evolution, and rearrangement in specific configurations of fragment pairs with corresponding probabilities, (iii) the (fast) prompt de-excitation of the excited fragments, and (iv) the (slow) decay towards β-stability of those fragments which are radioactive. The recent review by Schunck and Regnier [1] gives an excellent panorama on contemporary fission theories, and further details about foundations can be found in the textbook by Krappe and Pomorski [2]. In spontaneous and low-energy (mostly induced by neutrons) fission, the initial conditions are well defined.…”

Section: Introductionmentioning

confidence: 99%

“…The last decade has seen the tremendous development of microscopic, self-consistent models. Unfortunately, quantitative description remains limited so far, and computing time makes systematic calculations impossible even at super computers [1]. Transport models within the macroscopic-microscopic approach have been established as a very good alternative.…”

Section: Introductionmentioning

confidence: 99%

Fourier-over-Spheroid shape parametrization applied to nuclear fission dynamics

Pomorski,

Nerlo-Pomorska,

Schmitt

et al. 2023

Preprint

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We propose a new, rapidly convergent, the so-called Fourier over Spheroid (FoS), shape parametrization to model fission of heavy nuclei. Four collective coordinates are used to characterize the shape of the fissioning system, being its elongation, left-right asymmetry, neck size, and non-axiality. The potential energy landscape is computed within the macroscopic-microscopic approach, on the top of which the multi-dimensional Langevin equation is solved to describe the dynamics. Charge equilibration at scission and de-excitation of the primary fragments after scission are further considered. The model gives access to a wide variety of observables, including fission fragments mass, charge, and kinetic energy yields, fragment mean N/Z and post-scission neutron multiplicities, and importantly, their correlations. The latter are crucial to unravel the complexity of the fission process. The parameters of the model were tuned to reproduce experimental observation from thermal neutron-induced fission of 235 U, and next used to discuss the transition from the asymmetric to symmetric fission along the Fm isotopic chain.

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Theory of nuclear fission

Cited by 60 publications

References 472 publications

Hartree–Fock–Bogoliubov study of quantum shell effects on the path to fission in $$^{180}$$Hg, $$^{236}$$U and $$^{256}$$Fm

Hartree–Fock–Bogoliubov study of quantum shell effects on the path to fission in $$^{180}$$Hg, $$^{236}$$U and $$^{256}$$Fm

Three-dimensional potential energy surface for fission of $^{236}$U within covariant density functional theory

Fourier-over-Spheroid shape parametrization applied to nuclear fission dynamics

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