Measurement of the Secondary Radionuclides10Be,26Al,36Cl,54Mn, and14C and Implications for the Galactic Cosmic‐Ray Age

Yanasak, N. E.; Wiedenbeck, M. E.; Mewaldt, R. A.; Davis, A. J.; Cummings, A. C.; George, Jimin; Leske, R. A.; Stone, E. C.; Christian, E. R.; Rosenvinge, T. T. von; Binns, W. R.; Hink, P. L.; Israel, M. H.

doi:10.1086/323842

Cited by 235 publications

(205 citation statements)

References 72 publications

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“…9: 2σ bands of the 10 Be/ 9 Be ratios for different propagation models. The observational data are from: Ulysses [51], ACE [14], Voyager [52], IMP [53], ISEE-3 [53], and ISOMAX [54].…”

Section: Discussionmentioning

confidence: 99%

Propagation of cosmic rays in the AMS-02 era

et al. 2017

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In this work we use the newly reported Boron-to-Carbon ratio (B/C) from AMS-02 and the time-dependent proton fluxes from PAMELA and AMS-02 to constrain the source and propagation parameters of cosmic rays in the Milky Way. A linear correlation of the solar modulation parameter with solar activities is assumed to account for the time-varying cosmic ray fluxes. A comprehensive set of propagation models, with/without reacceleration or convection, have been discussed and compared. We find that only the models with reacceleration can selfconsistently fit both the proton and B/C data. The rigidity dependence slope of the diffusion coefficient, δ, is found to be about 0.38 − 0.50 for the diffusion-reacceleration models. The plain diffusion and diffusionconvection models fit the data poorly. We compare different model predictions of the positron and antiproton fluxes with the data. We find that the diffusion-reacceleration models over-produce low energy positrons, while non-reacceleration models give better fit to the data. As for antiprotons, reacceleration models tend to underpredict low energy antiproton fluxes, unless a phenomenological modification of the velocity-dependence of the diffusion coefficient is applied. Our results suggest that there could be important differences of the propagation for nuclei and leptons, in either the Milky Way or the solar heliosphere.PACS numbers: 95.35.+d,96.50.S-

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“…9: 2σ bands of the 10 Be/ 9 Be ratios for different propagation models. The observational data are from: Ulysses [51], ACE [14], Voyager [52], IMP [53], ISEE-3 [53], and ISOMAX [54].…”

Section: Discussionmentioning

confidence: 99%

Propagation of cosmic rays in the AMS-02 era

et al. 2017

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“…For 10 Be/ 9 Be, the data are taken from balloon flights (Hagen et al 1977;Buffington et al 1978;Webber & Kish 1979), including the ISOMAX balloon-borne instrument (Hams et al 2004), and from the IMP-7/8 (Garcia-Munoz et al 1977), ISEE-3 (Wiedenbeck & Greiner 1980), Ulysses (Connell 1998), Voyager (Lukasiak et al 1999), and ACE spacecrafts (Yanasak et al 2001). For 26 Al/ 27 Al, the data consist of a series of balloon flights (Webber 1982), and the ISEE-3 (Wiedenbeck 1983), Voyager (Lukasiak et al 1994), Ulysses , and ACE spacecrafts (Yanasak et al 2001).…”

Section: D2 Isotopic and Elemental Ratios Of Radioactive Speciesmentioning

confidence: 99%

“…For 26 Al/ 27 Al, the data consist of a series of balloon flights (Webber 1982), and the ISEE-3 (Wiedenbeck 1983), Voyager (Lukasiak et al 1994), Ulysses , and ACE spacecrafts (Yanasak et al 2001). For 36 Cl/Cl, the data are from the CRISIS balloon (Young et al 1981), and from the Ulysses ) and ACE (Yanasak et al 2001) spacecrafts.…”

Section: D2 Isotopic and Elemental Ratios Of Radioactive Speciesmentioning

confidence: 99%

A Markov Chain Monte Carlo technique to sample transport and source parameters of Galactic cosmic rays

Putze

Derome

Maurin

2010

A&A

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191

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Context. Ongoing measurements of the cosmic radiation (nuclear, electronic, and γ-ray) are providing additional insight into cosmicray physics. A comprehensive picture of these data relies on an accurate determination of the transport and source parameters of propagation models. Aims. A Markov Chain Monte Carlo method is used to obtain these parameters in a diffusion model. By measuring the B/C ratio and radioactive cosmic-ray clocks, we calculate their probability density functions, placing special emphasis on the halo size L of the Galaxy and the local underdense bubble of size r h . We also derive the mean, best-fit model parameters and 68% confidence level for the various parameters, and the envelopes of other quantities. Methods. The analysis relies on the USINE code for propagation and on a Markov Chain Monte Carlo technique previously developed by ourselves for the parameter determination. Results. The B/C analysis leads to a most probable diffusion slope δ = 0.86 +0.04 −0.04 for diffusion, convection, and reacceleration, or δ = 0.234 +0.006 −0.005 for diffusion and reacceleration. As found in previous studies, the B/C best-fit model favours the first configuration, hence pointing to a high value for δ. These results do not depend on L, and we provide simple functions to rescale the value of the transport parameters to any L. A combined fit on B/C and the isotopic ratios ( 10 Be/ 9 Be, 26 Al/ 27 Al, 36 Cl/Cl) leads to L = 8 +8 −7 kpc and r h = 120 +20 −20 pc for the best-fit model. This value for r h is consistent with direct measurements of the local interstallar medium. For the model with diffusion and reacceleration, L = 4 +1 −1 kpc and r h = 3 +70 −3 pc (consistent with zero). We vary δ, because its value is still disputed. For the model with Galactic winds, we find that between δ = 0.2 and 0.9, L varies from O(0) to O(2) if r h is forced to be 0, but it otherwise varies from O(0) to O(1) (with r h ∼ 100 pc for all δ > ∼ 0.3). The results from the elemental ratios Be/B, Al/Mg, and Cl/Ar do not allow independent checks of this picture because these data are not precise enough. Conclusions. We showed the potential and usefulness of the Markov Chain Monte Carlo technique in the analysis of cosmic-ray measurements in diffusion models. The size of the diffusive halo depends crucially on the value of the diffusion slope δ, and also on the presence/absence of the local underdensity damping effect on radioactive nuclei. More precise data from ongoing experiments are expected to clarify this issue.

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“…The idea is to measure the suppression of the flux of an unstable nuclear isotope such as beryllium-10 (T 1/2 1.51 ± 0.04 Myr) relative to the flux of a stable isotope such as beryllium-9. For example, the CRIS collaboration aboard the ACE spacecraft [9] has measured a isotopic ratio 10 Be/ 9 Be of order 0.11-0.12 for nuclei with E kin 70-150 MeV per nucleon, and interpreted the measurement, on the basis of a steady state leaky-box model, to obtain a residence time T age = 15.0 ± 1.6 Myr. At higher energy the dependence on the Galactic propagation model becomes less important [12].…”

Section: Secondary Nucleimentioning

confidence: 99%

Gamma ray and antiparticles ($e^+$ and $\overline{p}$) as tools to study the propagation of cosmic rays in the Galaxy

Lipari¹

2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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The spectra of cosmic rays observed at the Earth are determined by the properties of their sources and by the properties of their propagation in the Galaxy. Disentangling the source and propagation effects is a problem of central importance for cosmic ray astrophysics. To address this problem, the study of the fluxes of antiparticles (e + and p) and of the diffuse Galactic flux of γ can be a very powerful tool, because it is expected that the dominant mechanism of production is identical for all three components, namely the creation of the particles as secondary products in the interactions of primary cosmic rays. In this case, the shape and relative size of the source spectra for the three particles is reasonably well known. Folding the inclusive hadronic cross section with the (power law) energy distribution of the primary particles one obtains secondary source spectra that for E 20 GeV, in good approximation, are also of power law form, with the same spectral index of the primary particles. The predicted ratios at production are e + /p 2 and γ/e + 5. The observed spectra of e + , p and γ are power laws with spectral indices α e + α p α γ 2.7-2.8, with an observed ratio e + /p 2, equal to the ratio at production. These results suggests that the propagation effects for charged particles have only a weak energy dependence, and are approximately equal for e + and p. This implies that the total energy losses for e ± during propagation in the Galaxy is negligible, and therefore that the cosmic ray Galactic residence time is sufficiently short. An intriguing possibility is that a marked softening of the energy spectrum of the flux of (e + + e − ) observed by the Cherenkov telescopes at E ≈ 0.9 TeV is the manifestation of the critical energy where the energy losses of e ∓ becomes important. This assumption determines the Galactic residence time as of order T age (1 TeV) ≈ 1 Myr. A comparison of the fluxes of antiparticles and the diffuse Galactic γ flux allows then to estimate the effective cosmic ray confinement volume as V CR 300 kpc 3 . These tentative conclusions are in potential conflict with common interpretations of the fluxes of secondary nuclei (such as lithium, beryllium and boron) and require significant production of secondary nuclei inside or near the accelerators. Models where the cosmic ray confinement time is significantly longer than 1 Myr require a new hard source of positrons in the Galaxy, that must be fine tuned in spectral shape and absolute normalization. The implications of this puzzle are of profound importance for high energy astrophysics and the modeling of the cosmic ray accelerators.

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Measurement of the Secondary Radionuclides¹⁰Be,²⁶Al,³⁶Cl,⁵⁴Mn, and¹⁴C and Implications for the Galactic Cosmic‐Ray Age

Cited by 235 publications

References 72 publications

Propagation of cosmic rays in the AMS-02 era

Propagation of cosmic rays in the AMS-02 era

A Markov Chain Monte Carlo technique to sample transport and source parameters of Galactic cosmic rays

Gamma ray and antiparticles ($e^+$ and $\overline{p}$) as tools to study the propagation of cosmic rays in the Galaxy

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