Formula for calculating partial cross sections for nuclear reactions of nuclei with<i>E≳</i>200 MeV/nucleon in hydrogen targets

Webber, W. R.; Kish, J. C.; Schrier, D. A.

doi:10.1103/physrevc.41.566

Cited by 114 publications

(67 citation statements)

References 11 publications

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“…2D histograms of the relative differences between various semi-empirical models currently used to calculate the production cross-sections σ b→a . Our reference model is Webber et al (2003) (Webber 03), and we compare it to the parameterisations from Webber et al (1990) (Webber 93), Webber et al (1998) (Webber 98) and Silberberg et al (1998) (S&T 00). The charges of the parent and child nuclei are given on the vertical and horizontal axes, respectively.…”

Section: Cross-section Modellingmentioning

confidence: 99%

“…Multiplying σ b→B by a factor κ while rescaling σ B Notes. The reference model used in our calculations of the fluxes is adapted from Webber et al (2003) (Webber 03) and is compared to previous releases by Webber et al (1990) (Webber 93) and Webber et al (1998) (Webber 98) as well as to the work from Silberberg et al (1998) (S&T 00). The dominant production channels, which involve the stable isotopes of carbon, nitrogen, and oxygen, are listed in boldface.…”

Section: Cross-section Modellingmentioning

confidence: 99%

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Theoretical uncertainties in extracting cosmic-ray diffusion parameters: the boron-to-carbon ratio

Génolini

Putze

Salati

et al. 2015

A&A

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Context. PAMELA and, more recently, AMS-02, are ushering us into a new era of greatly reduced statistical uncertainties in experimental measurements of cosmic-ray fluxes. In particular, new determinations of traditional diagnostic tools such as the boron-tocarbon ratio (B/C) are expected to significantly reduce errors on cosmic-ray diffusion parameters, with important implications for astroparticle physics, ranging from inferring primary source spectra to indirect dark matter searches. Aims. It is timely to stress, however, that the conclusions obtained crucially depend on the framework in which the data are interpreted as well as on some nuclear input parameters. We aim at assessing the theoretical uncertainties affecting the outcome, with models as simple as possible while still retaining the key dependencies. Methods. We compared different semi-analytical, two-zone model descriptions of cosmic-ray transport in the Galaxy: infinite slab(1D), cylindrical symmetry (2D) with homogeneous sources, cylindrical symmetry (2D) with inhomogeneous source distribution. We tested for the effect of a primary source contamination in the boron flux by parametrically altering its flux. We also tested for nuclear cross-section uncertainties. All hypotheses were compared by χ 2 minimisation techniques to preliminary results from AMS-02. Results. We find that the main theoretical bias on the determination of the diffusion coefficient index δ (up to a factor two) is represented by the assumption that no injection of boron takes place at the source. The next most important uncertainty is represented by cross-section uncertainties, which reach ±20% in δ. As a comparison, nuclear uncertainties are more important than the shift in the best-fit when introducing a convective wind of velocity 30 km s −1 , with respect to a pure diffusive baseline model. Perhaps surprisingly, homogeneous 1D vs. 2D performances are similar in determining diffusion parameters. An inhomogeneous source distribution marginally alters the central value of the diffusion coefficient normalisation (at the 10%, 1σ level). However, the index of the diffusion coefficient δ is basically unaltered, as well as the goodness of fit. Conclusions. Our study suggests that, differently for instance from the leptonic case, realistic modelling of the geometry of the Galaxy and of the source distribution are of minor importance to correctly reproduce B/C data at high energies and thus, to a large extent, for the extraction of diffusion parameters. The ansatz on the lack of primary injection of boron represents the most serious bias and requires multi-messenger studies to be addressed. If this uncertainty could be lifted, nuclear uncertainties would still represent a serious concern; they degrade the systematic error on the inferred parameters to the 20% level, or three times the estimated experimental sensitivity. To reduce this, a new nuclear cross-section measurement campaign might be required.

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Section: Cross-section Modellingmentioning

confidence: 99%

Section: Cross-section Modellingmentioning

confidence: 99%

Theoretical uncertainties in extracting cosmic-ray diffusion parameters: the boron-to-carbon ratio

Génolini

Putze

Salati

et al. 2015

A&A

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“…Namely, since h d is the half-thickness of the (assumed infinitesimal) gaseous disk, and 2 h d q 0,α is the rate of injection in the disk of the Galaxy per unit surface. The total cross section for spallation and the cross sections for the individual channels of spallation of a heavier element to a lighter element (σ α →α ) have been taken from Webber et al (1990Webber et al ( , 2003. As stressed above, for the sake of a meaningful comparison with data, it is important to take the stable isotopes of all elements into account.…”

Section: Self-generated Versus Pre-existing Waves and Cr Transportmentioning

confidence: 99%

Nonlinear cosmic ray Galactic transport in the light of AMS-02 and Voyager data

Aloisio

Blasi

Serpico

2015

A&A

115

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Context. Features in the spectra of primary cosmic rays (CRs) provide invaluable information on the propagation of these particles in the Galaxy. In the rigidity region around a few hundred GV, these features have been measured in the proton and helium spectra by the PAMELA experiment and later confirmed with a higher significance by AMS-02. We investigate the implications of these data sets for the scenario in which CRs propagate under the action of self-generated waves. Aims. We show that the recent data on the spectrum of protons and helium nuclei as collected with AMS-02 and Voyager are in very good agreement with the predictions of a model in which the transport of Galactic CRs is regulated by self-generated waves. We also study the implications of the scenario for the boron-to-carbon ratio: although a good overall agreement is found, at high energy we find marginal support for a (quasi) energy independent contribution from the grammage, which we argue may come from the sources themselves. Methods. The transport equation for both primary and secondary nuclei is solved together with an equation for the evolution of the self-generated waves and a background of pre-existing waves. The solution for this system of nonlinear equations is found with an iterative method elaborated by the same authors in a previous work on this topic. Results. A break in the spectra of all nuclei is found at a rigidity of a few hundred GV, as a result of a transition from self-generated waves to pre-existing waves with a Kolmogorov power spectrum. Neither the slope of the diffusion coefficient, nor its normalization are free parameters. Moreover, at rigidities below a few GV, CRs are predicted to be advected with the self-generated waves at the local Alfvén speed. This effect, predicted in our previous work, provides an excellent fit to the Voyager data on the proton and helium spectra at low energies, providing additional support to the model.

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“…Among them, the most up-to-date are W03 (Webber et al 2003) and GAL09 (from the GALPROP code 1 ). The former is based on the semiempirical approach of Webber and coworkers, initiated in the 90's (Webber et al 1990). The latter set takes advantage of the former approach, renormalising some cross-sections to selected data.…”

Section: Using Different Sets Of Fragmentation Cross-sectionsmentioning

confidence: 99%

Systematic uncertainties on the cosmic-ray transport parameters

Maurin

Putze

Derome

2010

A&A

117

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Context. The B/C ratio is used in cosmic-ray physics to constrain the transport parameters. However, from the same set of data, the various published values show a puzzling large scatter of these parameters. Aims. We investigate the impact of using different inputs (gas density and hydrogen fraction in the Galactic disc, source spectral shape, low-energy dependence of the diffusion coefficient, and nuclear fragmentation cross-sections) on the best-fit values of the transport parameters. We quantify the systematics produced when varying these inputs, and compare them to statistical uncertainties. We discuss the consequences for the slope of the diffusion coefficient δ. Methods. The analysis relies on the propagation code USINE interfaced with the Minuit minimisation routines. Results. We find the typical systematic uncertainties to be greater than the statistical ones. The several published values of δ (from 0.3 to 0.8) can be recovered when varying the low-energy shape of the diffusion coefficient and the convective wind strength. Models including a convective wind are characterised by δ 0.6, which cannot be reconciled with the expected theoretical values (1/3 and 1/2). However, from a statistical point of view (χ 2 analysis), models with both reacceleration and convection -hence large δ -are favoured. The next favoured models in line yield δ, which can be accommodated with 1/3 and 1/2, but require a strong upturn of the diffusion coefficient at low energy (and no convection). Conclusions. To date, using the best statistical tools, the transport parameter determination is still plagued by many unknowns at low energy (∼GeV/n). To disentangle all these configurations, measurements of the B/C ratio at TeV/n energies and/or combination with other secondary-to-primary ratios is necessary.

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Formula for calculating partial cross sections for nuclear reactions of nuclei withE≳200 MeV/nucleon in hydrogen targets

Cited by 114 publications

References 11 publications

Theoretical uncertainties in extracting cosmic-ray diffusion parameters: the boron-to-carbon ratio

Theoretical uncertainties in extracting cosmic-ray diffusion parameters: the boron-to-carbon ratio

Nonlinear cosmic ray Galactic transport in the light of AMS-02 and Voyager data

Systematic uncertainties on the cosmic-ray transport parameters

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