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Discrepant hardening observed in cosmic-ray elemental spectra

Title
Discrepant hardening observed in cosmic-ray elemental spectra
Authors
Ahn H.S.Allison P.Bagliesi M.G.Beatty J.J.Bigongiari G.Childers J.T.Conklin N.B.Coutu S.Duvernois M.A.Ganel O.Han J.H.Jeon J.A.Kim K.C.Lee M.H.Lutz L.Maestro P.Malinin A.Marrocchesi P.S.Minnick S.Mognet S.I.Nam J.Nam S.Nutter S.L.Park I.H.Park N.H.Seo E.S.Sina R.Wu J.Yang J.Yoon Y.S.Zei R.Zinn S.Y.
Ewha Authors
양종만박일흥남신우
SCOPUS Author ID
양종만scopus
Issue Date
2010
Journal Title
Astrophysical Journal Letters
ISSN
2041-8205JCR Link
Citation
vol. 714, no. 1 PART 2, pp. L89 - L93
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
The balloon-borne Cosmic Ray Energetics And Mass experiment launched five times from Antarctica has achieved a cumulative flight duration of about 156 days above 99.5% of the atmosphere. The instrument is configured with complementary and redundant particle detectors designed to extend direct measurements of cosmic-ray composition to the highest energies practical with balloon flights. All elements from protons to iron nuclei are separated with excellent charge resolution. Here, we report results from the first two flights of ∼70 days, which indicate hardening of the elemental spectra above ∼ 200 GeV/nucleon and a spectral difference between the two most abundant species, protons and helium nuclei. These results challenge the view that cosmic-ray spectra are simple power laws below the so-called knee at ∼1015 eV. This discrepant hardening may result from a relatively nearby source, or it could represent spectral concavity caused by interactions of cosmic rays with the accelerating shock. Other possible explanations should also be investigated. © 2010. The American Astronomical Society. All rights reserved..
DOI
10.1088/2041-8205/714/1/L89
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자연과학대학 > 물리학전공 > Journal papers
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