R-matrix analysis of the3He(n, p)3H and7Be(n, p)7Li reactions

Adahchour, Abderrahim; Descouvemont, Pierre

doi:10.1088/0954-3899/29/2/315

Cited by 34 publications

(42 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5 In addition, the data show evidence for two peaks that correspond to the (unresolved) 3 + states at 19.07 and 19.24 MeV and to the 3 + resonance at 21.5 MeV. The reaction rate has been determined by R-matrix fits to the experimental data with uncertainties ∼ 1% [3,21]. More refined theoretical approaches based on modern coupled-channel effective field theory lead essentially to the same conclusion [22].…”

Section: Treatment Of Nuclear Cross-sectionsmentioning

confidence: 74%

The cosmological⁷Li problem from a nuclear physics perspective

Broggini

Canton

Fiorentini

et al. 2012

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

Abstract. The primordial abundance of 7 Li as predicted by Big Bang Nucleosynthesis (BBN) is more than a factor 2 larger than what has been observed in metal-poor halo stars. Herein, we analyze the possibility that this discrepancy originates from incorrect assumptions about the nuclear reaction cross sections relevant for BBN. To do this, we introduce an efficient method to calculate the changes in the 7 Li abundance produced by arbitrary (temperature dependent) modifications of the nuclear reaction rates. Then, considering that 7 Li is mainly produced from 7 Be via the electron capture process 7 Be + e − → 7 Li + ν e , we assess the impact of the various channels of 7 Be destruction. Differently from previous analysis, we consider the role of unknown resonances by using a complete formalism which takes into account the effect of Coulomb and centrifugal barrier penetration and that does not rely on the use of the narrow-resonance approximation. As a result of this, the possibility of a nuclear physics solution to the 7 Li problem is significantly suppressed. Given the present experimental and theoretical constraints, it is unlikely that the 7 Be + n destruction rate is underestimated by the 2.5 factor required to solve the problem. We exclude, moreover, that resonant destruction in the channels 7 Be + t and 7 Be + 3 He can explain the 7 Li puzzle. New unknown resonances in 7 Be + d and 7 Be + α could potentially produce significant effects. Recent experimental results have ruled out such a possibility for 7 Be + d. On the other hand, for the 7 Be + α channel very favorable conditions are required. The possible existence of a partially suitable resonant level in 11 C is studied in the framework of a coupled-channel model and the possibility of a direct measurement is considered.

show abstract

Section: Treatment Of Nuclear Cross-sectionsmentioning

confidence: 74%

The cosmological⁷Li problem from a nuclear physics perspective

Broggini

Canton

Fiorentini

et al. 2012

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

show abstract

“…Despite its large cross section, experimental measurements are very hard because 7 Be is radioactive and the inverse reaction, which could be used together with detailed balance, can lead to excited states in 7 Be. A R-matrix analysis of the existing experimental data using four partial waves yields the nearly constant, σE 1/2 5.8 MeV 1/2 .b, at thermal energies [101].…”

Section: Bbn Of Elements Up To Berylliummentioning

confidence: 98%

“…A study performed in Refs. [80,81] argue for preferring theoretical calculations [82,83,84,85] [100,101]. The cross section for this reaction near the threshold is strongly influenced by a 0 + s-wave resonance in 4 He.…”

Section: Bbn Of Elements Up To Berylliummentioning

confidence: 99%

Frontiers in nuclear astrophysics

Bertulani

Kajino

2016

Progress in Particle and Nuclear Physics

109

View full text Add to dashboard Cite

The synthesis of nuclei in diverse cosmic scenarios is reviewed, with a summary of the basic concepts involved before a discussion of the current status in each case is made. We review the physics of the early universe, the proton to neutron ratio influence in the observed helium abundance, reaction networks, the formation of elements up to beryllium, the inhomogeneous Big Bang model, and the Big Bang nucleosynthesis constraints on cosmological models. Attention is paid to element production in stars, together with the details of the pp chain, the pp reaction, 3 He formation and destruction, electron capture on 7 Be, the importance of 8 B formation and its relation to solar neutrinos, and neutrino oscillations. Nucleosynthesis in massive stars is also reviewed, with focus on the CNO cycle and its hot companion cycle, the rp-process, triple-α capture, and red giants and AGB stars. The stellar burning of carbon, neon, oxygen, and silicon is presented in a separate section, as well as the slow and rapid nucleon capture processes and the importance of medium modifications due to electrons also for pycnonuclear reactions. The nucleosynthesis in cataclysmic events such as in novae, X-ray bursters and in core-collapse supernovae, the role of neutrinos, and the supernova radioactivity and light-curve is further discussed, as well as the structure of neutron stars and its equation of state. A brief review of the element composition found in cosmic rays is made in the end.

show abstract

“…typically yielding a resonance with E x = 18.9 MeV and Γ ≈ 100 keV, although there is disagreement on the width. Most strikingly, an analysis of 7 Li(p, n 0 ) and 7 Be(n, p 0 ) data finds Γ = 1634 keV [82], based on a prescription whereby the sum of the Γ c equals Γ.…”

Section: Resonance Structurementioning

confidence: 99%

New broadBe8nuclear resonances

Page¹

2005

Phys. Rev. C

View full text Add to dashboard Cite

R-matrix analysis of the³He(n, p)³H and⁷Be(n, p)⁷Li reactions

Cited by 34 publications

References 34 publications

The cosmological⁷Li problem from a nuclear physics perspective

The cosmological⁷Li problem from a nuclear physics perspective

Frontiers in nuclear astrophysics

New broadBe8nuclear resonances

Contact Info

Product

Resources

About

R-matrix analysis of the3He(n, p)3H and7Be(n, p)7Li reactions

Cited by 34 publications

References 34 publications

The cosmological7Li problem from a nuclear physics perspective

The cosmological7Li problem from a nuclear physics perspective

Frontiers in nuclear astrophysics

New broadBe8nuclear resonances

Contact Info

Product

Resources

About

R-matrix analysis of the³He(n, p)³H and⁷Be(n, p)⁷Li reactions

The cosmological⁷Li problem from a nuclear physics perspective

The cosmological⁷Li problem from a nuclear physics perspective