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Beryllium isotopic composition and Galactic cosmic ray propagation
High Energy Astrophysical Phenomena · Submitted 27 Apr 2022
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim In this work we discuss the average survival probability that can be inferred from the preliminary AMS02 data, adopting publically available models of the nuclear fragmentation cross sections, and interpret the results in the framework of a simple diffusion model, This study shows that the effects of decay decrease more slowly than the predictions, resulting in an average cosmic ray age that increases with energy.
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The isotopic composition of beryllium nuclei and its energy dependence encode information of fundamental importance about the propagation of cosmic rays in the Galaxy. The effects of decay on the spectrum of the unstable beryllium--10 isotope can be described introducing the average survival probability $P_{\rm surv} (E_0)$ that can inferred from measurements of the isotopic ratio Be10/Be9 if one has sufficiently good knowledge of the nuclear fragmentation cross sections that determine the isotopic composition of beryllium nuclei at injection. The average survival probability can then be interpreted in terms of propagation parameters, such as the cosmic ray average age, adopting a theoretical framework for Galactic propagation. Recently the AMS02 Collaboration has presented preliminary measurements of the beryllium isotopic composition that extend the observations to a broad energy range ($E_0 \simeq 0.7$-12 GeV/n) with small errors. In this work we discuss the average survival probability that can be inferred from the preliminary AMS02 data, adopting publically available models of the nuclear fragmentation cross sections, and interpret the results in the framework of a simple diffusion model, This study shows that the effects of decay decrease more slowly than the predictions, resulting in an average cosmic ray age that increases with energy. An alternative possibility is that the cosmic ray age distribution is broader than in the models that are now commonly accepted, suggesting that the Galactic confinement volume has a non trivial structure and is formed by an inner halo contained in an extended one.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The isotopic composition of beryllium nuclei and its energy dependence encode information of fundamental importance about the propagation of cosmic rays in the Galaxy. | background 1.00 | 0.04 | 0.03 | asserted 0.99 |
| s1 | The effects of decay on the spectrum of the unstable beryllium--10 isotope can be described introducing the average survival probability $P_{\rm surv} (E_0)$ that can inferred from measurements of the isotopic ratio Be10/Be9 if one has sufficiently good knowledge of the nuclear fragmentation cross sections that determine the isotopic composition of beryllium nuclei at injection. | background 0.60 | 0.09 | 0.04 | asserted 0.83 |
| s2 | The average survival probability can then be interpreted in terms of propagation parameters, such as the cosmic ray average age, adopting a theoretical framework for Galactic propagation. | background 0.80 | 0.08 | 0.04 | asserted 0.76 |
| s3 | Recently the AMS02 Collaboration has presented preliminary measurements of the beryllium isotopic composition that extend the observations to a broad energy range ($E_0 \simeq 0.7$-12 GeV/n) with small errors. | background 0.90 | 0.05 | 0.02 | asserted 1.00 |
| s4 | In this work we discuss the average survival probability that can be inferred from the preliminary AMS02 data, adopting publically available models of the nuclear fragmentation cross sections, and interpret the results in the framework of a simple diffusion model, This study shows that the effects of decay decrease more slowly than the predictions, resulting in an average cosmic ray age that increases with energy. | contribution 0.56 | 0.93 | 0.88 | asserted 1.00 |
| s5 | An alternative possibility is that the cosmic ray age distribution is broader than in the models that are now commonly accepted, suggesting that the Galactic confinement volume has a non trivial structure and is formed by an inner halo contained in an extended one. | interpretation 1.00 | 0.17 | 0.09 | hedged possibility 0.97 |
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The paper
Original abstract
The isotopic composition of beryllium nuclei and its energy dependence encode information of fundamental importance about the propagation of cosmic rays in the Galaxy. The effects of decay on the spectrum of the unstable beryllium--10 isotope can be described introducing the average survival probability $P_{\rm surv} (E_0)$ that can inferred from measurements of the isotopic ratio Be10/Be9 if one has sufficiently good knowledge of the nuclear fragmentation cross sections that determine the isotopic composition of beryllium nuclei at injection. The average survival probability can then be interpreted in terms of propagation parameters, such as the cosmic ray average age, adopting a theoretical framework for Galactic propagation. Recently the AMS02 Collaboration has presented preliminary measurements of the beryllium isotopic composition that extend the observations to a broad energy range ($E_0 \simeq 0.7$-12 GeV/n) with small errors. In this work we discuss the average survival probability that can be inferred from the preliminary AMS02 data, adopting publically available models of the nuclear fragmentation cross sections, and interpret the results in the framework of a simple diffusion model, This study shows that the effects of decay decrease more slowly than the predictions, resulting in an average cosmic ray age that increases with energy. An alternative possibility is that the cosmic ray age distribution is broader than in the models that are now commonly accepted, suggesting that the Galactic confinement volume has a non trivial structure and is formed by an inner halo contained in an extended one.
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How the literature uses it
4 arXiv papers cite this in 7 sentences
Papers citing it · 5 sentences without a confident label
Compares with it 1 paper
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Note that our analytical fit expression in this figure (see red line) shares the same form but different parameters with [ref] , reflecting that our small-halo geometry approximates to — but does not exactly reproduce — the 1D diffusion model result.
Galactic Cosmic Ray Transport in the Giant Circumgalactic Medium Halo · Cosmic ray age distribution · 1.00
Cites it as support 1 paper
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The giant-halo picture is potentially supported by [ref] , who found that preliminary AMS-02 $^10Be / ^9Be$ data favor a broader CR age distribution and a more extended galactic confinement volume.
Galactic Cosmic Ray Transport in the Giant Circumgalactic Medium Halo · Cosmic ray age distribution · 0.99
What it cites · 20 sentences without a confident label
Uses the method or tool of 4 papers
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Fig. [ref] shows an estimate of the average survival probability obtained from the isotopic ratios measured by AMS02 and ISOMAX correcting for solar modulations (for the FFA potential $V = 0.5$ GV) and for the difference in injection rates using the parametrisation of the fragmentation cross sections of Evoli et al. [ref] and of GALPROP [ref] .
Galactic cosmic rays after the AMS-02 observations · Isotopic ratio at injection · 0.93
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One parametrization is presented in Evoli et al. in [ref] , while the other is taken from the numerical code GALPROP [ref] .
Production and propagation of cosmic-ray positrons and electrons · Isotopic ratio at injection · 0.81
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One parametrization is presented in Evoli et al. in [ref] , while the other is taken from the numerical code GALPROP [ref] .
Propagation of cosmic-ray nucleons in the Galaxy · Isotopic ratio at injection · 0.81
Uses data or values from 2 papers
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Using the Evoli et al. cross section model [ref] the isotopic ratio at prodiuction grows from a value $R_0 ≃0.59$ at for $E_0 ≃1$ GeV to an asymptotic value $R_0 ≃0.81$ at asymptotic value of order 0.80 at high energy.
Galactic cosmic rays after the AMS-02 observations · Outlook · 0.96
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In the numerical work performed below we will also use $Z_disk ≃0.15$ kpc and $n_disk ≃1$ cm$^-3$ with a composition (following Ferriere [ref] ) formed by 0.9 hydrogen, 0.0875 helium and 0.0125 metals.
The Interstellar Environment of our Galaxy · The “Minimal Diffusion Model” · 0.99
Cites as background 4 papers
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An alternative possibility [ref] is that the nuclei are generated by collisions inside or in the vicinity of CR accelerators.
The origin of the spectral intensities of cosmic-ray positrons · Average survival probability for a purely magnetic propagation · 0.89
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An alternative possibility [ref] is that the nuclei are generated by collisions inside or in the vicinity of CR accelerators.
Interpretation of the cosmic ray positron and antiproton fluxes · Average survival probability for a purely magnetic propagation · 0.89
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An alternative possibility [ref] is that the nuclei are generated by collisions inside or in the vicinity of CR accelerators.
The spectral shapes of the fluxes of electrons and positrons and the average residence time of cosmic rays in the Galaxy · Average survival probability for a purely magnetic propagation · 0.89
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