Effects of electron screening on the 3He(d, p)4He low-energy cross sections

Engstler, S.; Krauß, A.; Neldner, K.; Rolfs, C.; Schröder, U.; Langanke, K.

doi:10.1016/0370-2693(88)90003-2

Cited by 151 publications

(137 citation statements)

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“…Although the absolute cross section was measured at very low energy (Engstler et al 1988;Kwon et al 1989;Engstler et al 1992), experimental data below 100 keV could not be used to determine the bare nucleus S(E) dependence for a center-of-mass energy approaching zero, since it is affected by the electron screening. Thus a polynomial expansion S b = a+bE+cE 2 +dE 3 was used to fit the data for both atomic and molecular targets above 100 keV in order to extrapolate the behavior of the bare nucleus S b (E) factor to the lower energy region.…”

Section: Experimental Results On the 6 Li(pα) 3 Hementioning

confidence: 99%

“…The direct 6 Li(p,α) 3 He reaction was performed using a proton beam and a 6 Li solid target, as well as a 6 Li beam and a H 2 gas target (Engstler et al 1988;Kwon et al 1989;Engstler et al 1992). Although the absolute cross section was measured at very low energy (Engstler et al 1988;Kwon et al 1989;Engstler et al 1992), experimental data below 100 keV could not be used to determine the bare nucleus S(E) dependence for a center-of-mass energy approaching zero, since it is affected by the electron screening.…”

Section: Experimental Results On the 6 Li(pα) 3 Hementioning

confidence: 99%

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Trojan Horse estimate of bare nucleus astrophysical S(E)-factor for the $\mathsf{^{6}}$Li(p,α)$^{\mathsf{3}}$He reaction and its astrophysical implications

Pizzone

Туміно

Degl’Innocenti

et al. 2005

A&A

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Abstract.The 6 Li(p, α) 3 He bare nucleus cross-section at astrophysical energies has been indirectly measured in the framework of the Trojan-Horse Method, finding an agreement within the experimental errors with the results of data extrapolations from direct methods. This result is thus an independent check of the extrapolation method used until now. The method of measure is recalled and the results are shown with particular attention to the bare cross section value at the Gamow energy. The quoted agreement between direct and indirect methods is discussed in the context of the surface lithium abundances in stars. It is shown that the problem of stellar lithium abundances is not at the nuclear physics level but it is an astrophysics problem that requires improvements in our knowledge of the mixing mechanisms, the reduction of the uncertainties on the other (nonnuclear) physical inputs, and more precise observational data.

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Section: Experimental Results On the 6 Li(pα) 3 Hementioning

confidence: 99%

Section: Experimental Results On the 6 Li(pα) 3 Hementioning

confidence: 99%

Trojan Horse estimate of bare nucleus astrophysical S(E)-factor for the $\mathsf{^{6}}$Li(p,α)$^{\mathsf{3}}$He reaction and its astrophysical implications

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Туміно

Degl’Innocenti

et al. 2005

A&A

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“…We will not develop the screening theory from first principles but refer the reader to the established literature on this subject (e.g., Salpeter 1954;Dewitt et al 1973;Graboske et al 1973;Itoh et al 1979;Ichimaru & Utsumi 1984;Brown & Sawyer 1997;Bravo & García-Senz 1999;Yakovlev et al 2006, to name but a few). For a handful of reactions, screening has been investigated experimentally (e.g., Engstler et al 1988;Rolfs & Somorjai 1995;Chen et al 2004;Gatu Johnson et al 2017). We use Gaussian cgs units throughout this section.…”

Section: Electron Screeningmentioning

confidence: 99%

SkyNet: A Modular Nuclear Reaction Network Library

Lippuner

Roberts

2017

ApJS

129

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Almost all of the elements heavier than hydrogen that are present in our solar system were produced by nuclear burning processes either in the early universe or at some point in the life cycle of stars. In all of these environments, there are dozens to thousands of nuclear species that interact with each other to produce successively heavier elements. In this paper, we present SkyNet, a new general-purpose nuclear reaction network that evolves the abundances of nuclear species under the influence of nuclear reactions. SkyNet can be used to compute the nucleosynthesis evolution in all astrophysical scenarios where nucleosynthesis occurs. SkyNet is free and open source, and aims to be easy to use and flexible. Any list of isotopes can be evolved, and SkyNet supports different types of nuclear reactions. SkyNet is modular so that new or existing physics, like nuclear reactions or equations of state, can easily be added or modified. Here, we present in detail the physics implemented in SkyNet with a focus on a self-consistent transition to and from nuclear statistical equilibrium to non-equilibrium nuclear burning, our implementation of electron screening, and coupling of the network to an equation of state. We also present comprehensive code tests and comparisons with existing nuclear reaction networks. We find that SkyNet agrees with published results and other codes to an accuracy of a few percent. Discrepancies, where they exist, can be traced to differences in the physics implementations.

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“…and U e 49) and the corresponding uncertainty is 50) where δS i is the internal uncertainty and δS e is the external uncertainty, and have the same form as eqs. 5.43 and 5.44:…”

Section: Results For S B (E)mentioning

confidence: 99%

Experimental study of proton-induced nuclear reactions in^6,7Li

Cruz

Luís

Fonseca

et al. 2007

J. Phys. G: Nucl. Part. Phys.

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for converting on the lathe, my blueprints into pieces for the target chamber, and for his valuable help in mechanical issues.Jorge Rocha for doing the lithium implantations and for helping with his expertise in vacuum technology.Eng. Hugo Marques and Prof. Dr. Orlando Teodoro for taking the SIMS and XPS spectra and helping me in the analysis. Palavras chaveLítio primordial, reacções nucleares induzidas por partículas carregadas, secção eficaz, factor astrofísico S , distribuições angulares, blindagem electrónica, modelo de Debye. AbstractThis work presents the results of the experimental study of proton induced nuclear reactions in lithium, namely the He reactions were measured concurrently with seven and four targets, respectively. These targets were produced in order to obtain adequate and stable lithium depth profiles.In metallic environments, the measured electron screening potential energies are much higher than the predictions of atomic-physics models. The Debye screening model applied to the metallic conduction electrons is able to explain these high values. It is a simple model, but also very robust. Concerning primordial nucleosynthesis and stellar evolution models, these v vi results are very important as they show that laboratory measurements are well controlled, and the model inputs from these cross sections are therefore correct.

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Effects of electron screening on the 3He(d, p)4He low-energy cross sections

Cited by 151 publications

References 5 publications

Trojan Horse estimate of bare nucleus astrophysical S(E)-factor for the $\mathsf{^{6}}$Li(p,α)$^{\mathsf{3}}$He reaction and its astrophysical implications

Trojan Horse estimate of bare nucleus astrophysical S(E)-factor for the $\mathsf{^{6}}$Li(p,α)$^{\mathsf{3}}$He reaction and its astrophysical implications

SkyNet: A Modular Nuclear Reaction Network Library

Experimental study of proton-induced nuclear reactions in^6,7Li

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Effects of electron screening on the 3He(d, p)4He low-energy cross sections

Cited by 151 publications

References 5 publications

Trojan Horse estimate of bare nucleus astrophysical S(E)-factor for the $\mathsf{^{6}}$Li(p,α)$^{\mathsf{3}}$He reaction and its astrophysical implications

Trojan Horse estimate of bare nucleus astrophysical S(E)-factor for the $\mathsf{^{6}}$Li(p,α)$^{\mathsf{3}}$He reaction and its astrophysical implications

SkyNet: A Modular Nuclear Reaction Network Library

Experimental study of proton-induced nuclear reactions in6,7Li

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Experimental study of proton-induced nuclear reactions in^6,7Li