The r-Process in Supernovae: Impact of New Microscopic Mass Formulas

The astrophysical origin of $r$-process nuclei remains a long-standing mystery. Although some astrophysical scenarios show some promise, many uncertainties involved in both the astrophysical conditions and in the nuclear properties far from the $\beta$-stability have inhibited us from understanding the nature of the $r$-process. The purpose of the present paper is to examine the effects of the newly-derived microscopic Hartree-Fock-Bogoliubov (HFB) mass formulas on the $r$-process nucleosynthesis and analyse to what extent a solar-like $r$-abundance distribution can be obtained. The $r$-process calculations with the HFB-2 mass formula are performed, adopting the parametrized model of the prompt explosion from a collapsing O-Ne-Mg core for the physical conditions and compared with the results obtained with the HFB-7 and droplet-type mass formulas. Due to its weak shell effect at the neutron magic numbers in the neutron-rich region, the microscopic mass formulas (HFB-2 and HFB-7) give rise to a spread of the abundance distribution in the vicinity of the $r$-process peaks ($A = 130$ and 195). While this effect resolves the large underproduction at $A \approx 115$ and 140 obtained with droplet-type mass formulas, large deviations compared to the solar pattern are found near the third $r$-process peak. It is shown that a solar-like $r$-process pattern can be obtained if the dynamical timescales of the outgoing mass trajectories are increased by a factor of about 2-3, or if the $\beta$-decay rates are systematically increased by the same factor.Comment: 22 pages, 12 figures, accepted for publication in ApJ, some color figures converted to B&W due to size constraint

CMS physics technical design report : Addendum on high density QCD with heavy ions

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Improved nuclear predictions of relevance to the r-process of nucleosynthesis

Doctorat en sciences, Spécialisation physiqueinfo:eu-repo/semantics/nonPublishe

La physique nucléaire en astrophysique

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Large-scale Skyrme-Hartree-Fock calculations of fission barriers in a multi-dimensional space

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Hartree-Fock-Bogoliubov fission barriers with skyrme forces adjusted on masses

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Microscopic HFB fission barriers for r-process nucleosynthesis calculations

New systematic calculations of fission barriers are performed in the 3-dimensional deformation space using the constrained Skyrme-Hartree-Fock-Bogoliubov (SHFB) plus Particle-Number Projection method. The BSk8 Skyrme force, fitted to the full set of more than 2000 experimentally known masses, is used. The energy surfaces are analysed using the flooding method, a necessary tool if more than two dimensions are spanned. The SHFB outer fission barriers are compared with experimental data. The reflection asymmetry is shown to play a significant role in the Z ≈ 94 open-shell region. Extrapolations in the neutron-rich region can differ with the previous compilations of fission barriers. © 2005 Elsevier B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Fission barriers from a microscopic model

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Microscopic dipole strength predictions for neutron capture rates

Large-scale QRPA calculations of the E1-strength are performed on top of HFB calculations in order to derive the radiative neutron capture cross sections for the whole nuclear chart. The spreading width of the GDR is taken into account by analogy with the second-RPA (SRPA) method. It is shown that the present model allows to constrain the effective nucleon-nucleon interaction with the GDR data and to provide quantitative predictions of dipole strengths.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Microscopic calculations of spontaneous fission half-lives and neutron-induced fission cross sections

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