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자연과학대학
물리학전공
Journal papers
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Cosmic-ray proton and helium spectra from the first cream flight
Title
Cosmic-ray proton and helium spectra from the first cream flight
Authors
Yoon Y.S.
;
Ahn H.S.
;
Allison P.S.
;
Bagliesi M.G.
;
Beatty J.J.
;
Bigongiari G.
;
Boyle P.J.
;
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.
;
Malinine A.
;
Marrocchesi P.S.
;
Minnick S.A.
;
Mognet S.I.
;
Nam S.
;
Nutter S.
;
Park I.H.
;
Park N.H.
;
Seo E.S.
;
Sina R.
;
Swordy S.
;
Wakely S.P.
;
Wu J.
;
Yang J.
;
Zei R.
;
Zinn S.Y.
Ewha Authors
양종만
;
박일흥
SCOPUS Author ID
양종만
; 박일흥
Issue Date
2011
Journal Title
Astrophysical Journal Letters
ISSN
2041-8205
Citation
Astrophysical Journal Letters vol. 728, no. 2
Indexed
SCI; SCIE; SCOPUS
Document Type
Article
Abstract
Cosmic-ray proton and helium spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass experiment flown for 42 days in Antarctica in the 2004-2005 austral summer season. High-energy cosmic-ray data were collected at an average altitude of ∼38.5 km with an average atmospheric overburden of ∼3.9 g cm-2. Individual elements are clearly separated with a charge resolution of ∼0.15 e (in charge units) and ∼0.2 e for protons and helium nuclei, respectively. The measured spectra at the top of the atmosphere are represented by power laws with a spectral index of -2.66 ± 0.02 for protons from 2.5 TeV to 250 TeV and -2.58 ± 0.02 for helium nuclei from 630 GeV nucleon-1 to 63 TeV nucleon -1. They are harder than previous measurements at a few tens of GeV nucleon-1. The helium flux is higher than that expected from the extrapolation of the power law fitted to the lower-energy data. The relative abundance of protons to helium nuclei is 9.1 ± 0.5 for the range from 2.5 TeV nucleon-1 to 63 TeV nucleon-1. This ratio is considerably smaller than the previous measurements at a few tens of GeV nucleon-1. © 2011. The American Astronomical Society. All rights reserved. Printed in the U.S.A.
DOI
10.1088/0004-637X/728/2/122
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