Particle-number projection method in time-dependent Hartree-Fock theory: Properties of reaction products

Sekizawa, Kazuyuki; Yabana, Kazuhiro

doi:10.1103/physrevc.90.064614

Cited by 57 publications

(53 citation statements)

References 28 publications

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“…The Hartree-Fock approximation and its time-dependent generalization, the time-dependent Hartree-Fock theory, have provided a possible means to study the diverse phenomena observed in low energy nuclear physics [41,42]. In general modern TDHF calculations provide a useful foundation for a fully microscopic many-body description of large amplitude collective motion including collective surface vibrations and giant resonances [48][49][50][51][52][53][54][55][56][57][58][59][60][61] nuclear reactions in the vicinity of the Coulomb barrier, such as fusion [36,39,[62][63][64][65][66][67][68][69], deepinelastic reactions and transfer [70][71][72][73][74][75][76], and dynamics of (quasi)fission fragments [33,[43][44][45][46][47].…”

Section: Formalism a Tdhf And Dc-tdhf Approachesmentioning

confidence: 99%

Shape evolution and collective dynamics of quasifission in the time-dependent Hartree-Fock approach

2015

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Background: At energies near the Coulomb barrier, capture reactions in heavy-ion collisions result either in fusion or in quasifission. The former produces a compound nucleus in statistical equilibrium, while the second leads to a reseparation of the fragments after partial mass equilibration without formation of a compound nucleus. Extracting the compound nucleus formation probability is crucial to predict superheavy-element formation crosssections. It requires a good knowledge of the fragment angular distribution which itself depends on quantities such as moments of inertia and excitation energies which have so far been somewhat arbitrary for the quasifission contribution.Purpose: Our main goal is to utlize the time-dependent Hartee-Fock (TDHF) approach to extract ingredients of the formula used in the analysis of experimental angular distributions. These include the moment-of-inertia and temperature.Methods: We investigate the evolution of the nuclear density in TDHF calculations leading to quasifission. We study the dependence of the relevant quantities on various initial conditions of the reaction process.Results: The evolution of the moment of inertia is clearly non-trivial and depends strongly on the characteristics of the collision. The temperature rises quickly when the kinetic energy is transformed into internal excitation. Then, it rises slowly during mass transfer.Conclusions: Fully microscopic theories are useful to predict the complex evolution of quantities required in macroscopic models of quasifission.

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Section: Formalism a Tdhf And Dc-tdhf Approachesmentioning

confidence: 99%

Shape evolution and collective dynamics of quasifission in the time-dependent Hartree-Fock approach

2015

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“…It is also possible to compute the probability to form a fragment with a given number of nucleons [27][28][29][30][31][32], but the resulting fragment mass and charge distributions are often underestimated in dissipative collisions [33,34]. Much effort has been done to improve the standard mean-field approximation by incorporating the fluctuation mechanism into the description.…”

Section: Introductionmentioning

confidence: 99%

Multinucleon transfer in central collisions of U238+U238

et al. 2017

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Quantal diffusion mechanism of nucleon exchange is studied in the central collisions of 238 U + 238 U in the framework of the stochastic mean-field (SMF) approach. For bombarding energies considered in this work, the di-nuclear structure is maintained during the collision. Hence, it is possible to describe nucleon exchange as a diffusion process for mass and charge asymmetry. Quantal neutron and proton diffusion coefficients, including memory effects, are extracted from the SMF approach and the primary fragment distributions are calculated.

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“…For instance, a simple proxy to the dissipation can be obtained in TDHF from the total kinetic energy loss [105] and from the number of emitted nucleons [106]. More advanced techniques to extract the energy dissipated into excitation energies include a macroscopic reduction procedure [107], the density-constrained TDHF approach [108], and a more general application of the particle number projection technique [109].…”

Section: Role Of Transfermentioning

confidence: 99%

Dynamical effects in fusion with exotic nuclei

2016

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Background:Reactions with stable beams have demonstrated a strong interplay between nuclear structure and fusion. Exotic beam facilities open new perspectives to understand the impact of neutron skin, large isospin, and weak binding energies on fusion. Microscopic theories of fusion are required to guide future experiments.Purpose: To investigate new effects of exotic structures and dynamics in near-barrier fusion with exotic nuclei.Method: Microscopic approaches based on the Hartree-Fock (HF) mean-field theory are used for studying fusion barriers in 40−54 Ca+ 116 Sn reactions for even isotopes. Bare potential barriers are obtained assuming frozen HF ground-state densities. Dynamical effects on the barrier are accounted for in time-dependent Hartree-Fock (TDHF) calculations of the collisions. Vibrational couplings are studied in the coupled-channel framework and near-barrier nucleon transfer is investigated with TDHF calculations.Results: The development of a neutron skin in exotic calcium isotopes strongly lowers the bare potential barrier. However, this static effect is not apparent when dynamical effects are included. On the contrary, a fusion hindrance is observed in TDHF calculations with the most neutron rich calcium isotopes which cannot be explained by vibrational couplings. Transfer reactions are also important in these systems due to charge equilibration processes.Conclusions: Despite its impact on the bare potential, the neutron skin is not seen as playing an important role in the fusion dynamics. However, the charge transfer with exotic projectiles could lead to an increase of the Coulomb repulsion between the fragments, suppressing fusion. The effect of transfer and dissipative mechanisms on fusion with exotic nuclei deserve further studies.

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Particle-number projection method in time-dependent Hartree-Fock theory: Properties of reaction products

Cited by 57 publications

References 28 publications

Shape evolution and collective dynamics of quasifission in the time-dependent Hartree-Fock approach

Shape evolution and collective dynamics of quasifission in the time-dependent Hartree-Fock approach

Multinucleon transfer in central collisions of U238+U238

Dynamical effects in fusion with exotic nuclei

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