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Precision Measurement of the Boron to Carbon Flux Ratio in Cosmic Rays from 1.9 GV to 2.6 TV with the Alpha Magnetic Spectrometer on the International Space Station

M. Aguilar et al. (AMS Collaboration)
Phys. Rev. Lett. 117, 231102 – Published 28 November 2016
Physics logo See Focus story: More Hints of Exotic Cosmic-Ray Origin
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Abstract

Knowledge of the rigidity dependence of the boron to carbon flux ratio (B/C) is important in understanding the propagation of cosmic rays. The precise measurement of the B/C ratio from 1.9 GV to 2.6 TV, based on 2.3 million boron and 8.3 million carbon nuclei collected by AMS during the first 5 years of operation, is presented. The detailed variation with rigidity of the B/C spectral index is reported for the first time. The B/C ratio does not show any significant structures in contrast to many cosmic ray models that require such structures at high rigidities. Remarkably, above 65 GV, the B/C ratio is well described by a single power law RΔ with index Δ=0.333±0.014(fit)±0.005(syst), in good agreement with the Kolmogorov theory of turbulence which predicts Δ=1/3 asymptotically.

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  • Received 5 October 2016

DOI:https://doi.org/10.1103/PhysRevLett.117.231102

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & Astrophysics

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More Hints of Exotic Cosmic-Ray Origin

Published 28 November 2016

New Space Station data support a straightforward model of cosmic-ray propagation through the Galaxy but also add to previous signs of undiscovered cosmic-ray sources such as dark matter.

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Vol. 117, Iss. 23 — 2 December 2016

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