Constraints for stellar electron-capture rates on 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Kr</mml:mi><mml:mprescripts /><mml:none /><mml:mn>86</mml:mn></mml:mmultiscripts></mml:math>
 via the 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>Kr</mml:mi><mml:mprescripts /><mml:none /><mml:mn>86</mml:mn></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mi>t</mml:mi><mml:mo>,</mml:mo><mml:mmultiscripts><mml:mi>He</mml:mi><mml:m

Titus, R.; Ney, E. M.; Zegers, R. G. T.; Bazin, D.; Belarge, J.; Bender, P. C.; Brown, B. A.; Campbell, C. M.; Elman, B.; Engel, J.; Gade, A.; Gao, B. S.; Kwan, E.; Lipschutz, S.; Longfellow, B.; Lunderberg, E.; Mijatović, T.; Noji, S.; Pereira, J.; Schmitt, J.; Sullivan, Chris; Weißhaar, D.; Zamora, J. C.

doi:10.1103/physrevc.100.045805

Cited by 16 publications

(27 citation statements)

References 74 publications

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“…The rates, indicated by dashed lines, have been calculated from the ground-state GT + distribution. The shaded bands represent the results based on the experimental GT + data [392,393] where β λμ are deformation parameters. Besides β 20 corresponding to the elongation of the whole nucleus along its symmetry axis, other shape degrees of freedom also play a crucial role during the fission process [394][395][396][397][398][399][400][401][402][403][404][405][406][407][408][409][410][411][412].…”

Section: Fission Barriersmentioning

confidence: 99%

Self-consistent methods for structure and production of heavy and superheavy nuclei

et al. 2021

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Self-consistent methods for the structure of heavy and superheavy nuclei are reviewed. The construction and application of energy-density functionals are discussed. The relationship between the self-consistent methods and microscopic-macroscopic approaches is considered on the mean-field level. The extraction of single-particle potentials from the energy-density functional is described. The isotopic dependence of nucleon distributions and its influence on the nucleus-nucleus interaction is analyzed. As a new additional condition we introduce that the energy-density functional must describe the heights of the Coulomb barriers in nucleusnucleus interaction potentials, thus imposing constraints on the properties of the functional at low matter densities. The self-consistent methods are applied to describe the quasiparticle structure, cluster radioactivity, and fission of the heaviest nuclei. These methods are used to predict the probabilities of β-delayed multi-neutron emission and half-lives of β-decays and electron captures in heavy and superheavy nuclei. The predicted properties of superheavy nuclei are used to estimate the production cross-sections of superheavy nuclei in complete fusion reactions. Contents

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Section: Fission Barriersmentioning

confidence: 99%

Self-consistent methods for structure and production of heavy and superheavy nuclei

et al. 2021

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“…Here, we extend the work of Ref. [44] by accounting for the temperature dependence of the Gamow-Teller strength with the FT-QRPA.…”

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confidence: 86%

“…So far, no EC rate tables from finite-temperature microscopic calculations cover the region of interest for the collapse phase of CCSN, along N =50 near 78 Ni, here referred to as the "diamond region". The first extensive calculations in this region were performed with a hybrid model [30], but only for a subset of the nuclei of interest, or with a QRPA model [44] for all nuclei in the diamond region but without considering temperature-dependent effects. Recently, few finite-temperature calculations [16,17] were performed on selected nuclei in the region of interest.…”

Section: Introductionmentioning

confidence: 99%

“…This functional was fit with an effective axial vector coupling of g A = 1.0, and was also used for the electron capture calculations in Ref. [44]. In that work, the FAM was used to compute Gamow-Teller strength functions at zero temperature with an artificial Lorentzian width of 0.25 MeV.…”

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confidence: 99%

“…We make several adjustments to the calculations performed in Ref. [44] to accommodate finite temperature. Odd nuclei in the present work are treated by constraining the finite-temperature Hartree-Fock-Bogoliubov (FT-HFB) [56] ensembles to have the desired odd particle number on average.…”

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confidence: 99%

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Finite-temperature electron-capture rates for neutron-rich nuclei around N=50 and effects on core-collapse supernovae simulations

Giraud,

Ney,

Ravlić

et al. 2021

Preprint

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The temperature dependence of stellar electron-capture (EC) rates is investigated, with a focus on nuclei around N = 50, just above Z = 28, which play an important role during the collapse phase of core-collapse supernovae (CCSN). Two new microscopic calculations of stellar EC rates are obtained from a relativistic and a non-relativistic finite-temperature quasiparticle random-phase approximation approaches, for a conventional grid of temperatures and densities. In both approaches, EC rates due to Gamow-Teller transitions are included. In the relativistic calculation contributions from first-forbidden transitions are also included, and add strongly to the EC rates. The new EC rates are compared with large-scale shell model calculations for the specific case of 86 Kr, providing insight into the finite-temperature effects on the EC rates. At relevant thermodynamic conditions for core-collapse, the discrepancies between the different calculations of this work are within about one order of magnitude. Numerical simulations of CCSN are performed with the spherically-symmetric GR1D simulation code to quantify the impact of such differences on the dynamics of the collapse. These simulations also include EC rates based on two parametrized approximations. A comparison of the neutrino luminosities and enclosed mass at core bounce shows that differences between simulations with different sets of EC rates are relatively small (≈ 5%), suggesting that the EC rates used as inputs for these simulations have become well constrained.

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Electron capture in stars

2021

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Electron capture on nuclei plays an essential role in the dynamics of several astrophysical objects, including core-collapse and thermonuclear supernovae, the crust of accreting neutron stars in binary systems and the final core evolution of intermediate-mass stars. In these astrophysical objects, the capture occurs at finite temperatures and densities, at which the electrons form a degenerate relativistic electron gas. The capture rates can be derived from perturbation theory, where allowed nuclear transitions [Gamow–Teller (GT) transitions] dominate, except at the higher temperatures achieved in core-collapse supernovae, where forbidden transitions also contribute significantly to the capture rates. There has been decisive progress in recent years in measuring GT strength distributions using novel experimental techniques based on charge-exchange reactions. These measurements not only provide data for the GT distributions of ground states for many relevant nuclei, but also serve as valuable constraints for nuclear models which are needed to derive the capture rates for the many nuclei for which no data yet exist. In particular, models are needed to evaluate stellar capture rates at finite temperatures, where capture can also occur on nuclei in thermally excited states. There has also been significant progress in recent years in the modeling of stellar capture rates. This has been made possible by advances in nuclear many-body models as well as in computer soft- and hardware. Specifically, to derive reliable capture rates for core-collapse supernovae, a dedicated strategy has been developed based on a hierarchy of nuclear models specifically adapted to the abundant nuclei and astrophysical conditions present under various collapse conditions. In particular, for the challenging conditions where the electron chemical potential and the nuclear Q values are of the same order, large-scale shell-model diagonalization calculations have proved to be an appropriate tool to derive stellar capture rates, often validated by experimental data. Such situations are relevant in the early stage of the core collapse of massive stars, for the nucleosynthesis of thermonuclear supernovae, and for the final evolution of the cores of intermediate-mass stars involving nuclei in the mass range A ∼ 20–65. This manuscript reviews the experimental and theoretical progress recently achieved in deriving stellar electron capture rates. It also discusses the impact these improved rates have on our understanding of the various astrophysical objects.

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Constraints for stellar electron-capture rates on Kr86 via the Kr86(t,He

Cited by 16 publications

References 74 publications

Self-consistent methods for structure and production of heavy and superheavy nuclei

Self-consistent methods for structure and production of heavy and superheavy nuclei

Finite-temperature electron-capture rates for neutron-rich nuclei around N=50 and effects on core-collapse supernovae simulations

Electron capture in stars

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