Microscopic and nonadiabatic Schrödinger equation derived from the generator coordinate method based on zero- and two-quasiparticle states

Bernard, R.; Goutte, Héloϊse; Gogny, D.; Younes, W.

doi:10.1103/physrevc.84.044308

Cited by 77 publications

(72 citation statements)

References 46 publications

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“…Dissipation of the collective motion into internal excitations also plays a key role to understand the excitation energy and kinetic energy sharing during fragments separation [16]. Understanding this dissipation requires to include many-body states beyond the adiabatic limit [17]. It is yet unclear how the pre-scission neutron and proton emissions can be incorporated in the TDGCM.…”

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confidence: 99%

Microscopic Phase-Space Exploration Modeling ofFm258Spontaneous Fission

2017

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We show that the total kinetic energy (TKE) of nuclei after the spontaneous fission of 258 Fm can be well reproduced using simple assumptions on the quantum collective phase-space explored by the nucleus after passing the fission barrier. Assuming energy conservation and phase-space exploration according to the stochastic mean-field approach, a set of initial densities is generated. Each density is then evolved in time using the nuclear time-dependent density-functional theory with pairing. This approach goes beyond mean-field by allowing spontaneous symmetry breaking as well as a wider dynamical phase-space exploration leading to larger fluctuations in collective space. The total kinetic energy and mass distributions are calculated. New information on the fission process: fluctuations in scission time, strong correlation between TKE and collective deformation as well as pre-scission particle emission, are obtained. We conclude that fluctuations of TKE and mass are triggered by quantum fluctuations.PACS numbers: 21.60. Jz, 24.75.+i, 25.85.Ca, 27.90.+b The dynamical modeling of a nuclear Fermi quantum droplet that spontaneously breaks into two pieces represents one of the most exciting challenges of nuclear physics today. Beside its description, a deeper microscopic understanding of spontaneous fission (SF) is of great importance to form the heaviest elements at the frontier of the nuclear chart [1][2][3] or to further improve our knowledge about the competition between the r-process and fission during the primordial nucleosynthesis [4]. Motivated also by its importance in nuclear energy production, intensive experimental efforts have been made to accumulate precise measurements [5][6][7][8][9]. In recent years, an increasing effort was made to remove empirical ingredients that are employed in macroscopic modeling of fission and use microscopic theories [10,11]. The nuclear Density Functional Theory (DFT) is a suitable starting point to describe some aspects related to the large amplitude collective motion (LACM). A minimal information obtained from DFT is the adiabatic collective energy landscape [11]. One challenge to describe spontaneous fission (SF) is the necessity to explicitly treat the evolution as a quantum dynamic in collective space. Progresses have been made with the Time-Dependent Generator Coordinate Method (TDGCM) [12][13][14]. This theory by treating quantally collective degrees of freedom (DOF) is promising. However, the adiabatic assumption often made becomes critical especially close to scission [15]. Dissipation of the collective motion into internal excitations also plays a key role to understand the excitation energy and kinetic energy sharing during fragments separation [16]. Understanding this dissipation requires to include many-body states beyond the adiabatic limit [17]. It is yet unclear how the pre-scission neutron and proton emissions can be incorporated in the TDGCM.The nuclear time-dependent DFT (TDDFT) overcomes some of these limitations. With recently developed symmetry unrest...

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Microscopic Phase-Space Exploration Modeling ofFm258Spontaneous Fission

2017

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“…The extent to which this assumption is valid is currently being studied at LLNL and elsewhere using collective-intrinsic coupling formalisms [23] and temperature-dependent HFB calculations. These energy-dependent calculations are not expected to drastically alter the results given the relatively low neutron energies considered here (E n ≤ 5MeV), but the effects on the yields as a function of E n should nevertheless be explored.…”

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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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“…III D 1. Intrinsic dissipation could be represented by multi-qp excitations and may be estimated in extensions of the GCM framework [106]. It does not seem unreasonable to estimate that between 5 and 15 MeV of energy could be dissipated when combining both collective and intrinsic sources of dissipation.…”

Section: E Fragment Interaction Energy and Kinetic Energymentioning

confidence: 99%

Description of induced nuclear fission with Skyrme energy functionals: Static potential energy surfaces and fission fragment properties

et al. 2014

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Eighty years after its experimental discovery, a description of induced nuclear fission based solely on the interactions between neutrons and protons and quantum many-body methods still poses formidable challenges. The goal of this paper is to contribute to the development of a predictive microscopic framework for the accurate calculation of static properties of fission fragments for hot fission and thermal or slow neutrons. To this end, we focus on the 239 Pu(n,f) reaction and employ nuclear density functional theory with Skyrme energy densities. Potential energy surfaces are computed at the Hartree-Fock-Bogoliubov approximation with up to five collective variables. We find that the triaxial degree of freedom plays an important role, both near the fission barrier and at scission. The impact of the parameterization of the Skyrme energy density and the role of pairing correlations on deformation properties from the ground-state up to scission are also quantified. We introduce a general template for the quantitative description of fission fragment properties. It is based on the careful analysis of scission configurations, using both advanced topological methods and recently proposed quantum many-body techniques. We conclude that an accurate prediction of fission fragment properties at low incident neutron energies, although technologically demanding, should be within the reach of current nuclear density functional theory.

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Microscopic and nonadiabatic Schrödinger equation derived from the generator coordinate method based on zero- and two-quasiparticle states

Cited by 77 publications

References 46 publications

Microscopic Phase-Space Exploration Modeling ofFm258Spontaneous Fission

Microscopic Phase-Space Exploration Modeling ofFm258Spontaneous Fission

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

Description of induced nuclear fission with Skyrme energy functionals: Static potential energy surfaces and fission fragment properties

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