A1 Refereed original research article in a scientific journal
Precision Measurement of the Helium Flux in Primary Cosmic Rays of Rigidities 1.9 GV to 3 TV with the Alpha Magnetic Spectrometer on the International Space Station
Authors: Aguilar M, Aisa D, Alpat B, Alvino A, Ambrosi G, Andeen K, Arruda L, Attig N, Azzarello P, Bachlechner A, Barao F, Barrau A, Barrin L, Bartoloni A, Basara L, Battarbee M, Battiston R, Bazo J, Becker U, Behlmann M, Beischer B, Berdugo J, Bertucci B, Bindi V, Bizzaglia S, Bizzarri M, Boella G, de Boer W, Bollweg K, Bonnivard V, Borgia B, Borsini S, Boschini MJ, Bourquin M, Burger J, Cadoux F, Cai XD, Capell M, Caroff S, Casaus J, Castellini G, Cernuda I, Cerreta D, Cervelli F, Chae MJ, Chang YH, Chen AI, Chen GM, Chen H, Chen HS, Cheng L, Chou HY, Choumilov E, Choutko V, Chung CH, Clark C, Clavero R, Coignet G, Consolandi C, Contin A, Corti C, Gil EC, Coste B, Creus W, Crispoltoni M, Cui Z, Dai YM, Delgado C, Della Torre S, Demirkoz MB, Derome L, Di Falco S, Di Masso L, Dimiccoli F, Diaz C, von Doetinchem P, Donnini F, Duranti M, D'Urso D, Egorov A, Eline A, Eppling FJ, Eronen T, Fan YY, Farnesini L, Feng J, Fiandrini E, Fiasson A, Finch E, Fisher P, Formato V, Galaktionov Y, Gallucci G, Garcia B, Garcia-Lopez R, Gargiulo C, Gast H, Gebauer I, Gervasi M, Ghelfi A, Giovacchini F, Goglov P, Gong J, Goy C, Grabski V, Grandi D, Graziani M, Guandalini C, Guerri I, Guo KH, Haas D, Habiby M, Haino S, Han KC, He ZH, Heil M, Hoffman J, Huang ZC, Huh C, Incagli M, Ionica M, Jang WY, Jinchi H, Kanishev K, Kim GN, Kim KS, Kirn T, Korkmaz MA, Kossakowski R, Kounina O, Kounine A, Koutsenko V, Krafczyk MS, La Vacca G, Laudi E, Laurenti G, Lazzizzera I, Lebedev A, Lee HT, Lee SC, Leluc C, Li HL, Li JQ, Li JQ, Li Q, Li Q, Li TX, Li W, Li Y, Li ZH, Li ZY, Lim S, Lin CH, Lipari P, Lippert T, Liu D, Liu H, Liu H, Lolli M, Lomtadze T, Lu MJ, Lu SQ, Lu YS, Luebelsmeyer K, Luo F, Luo JZ, Lv SS, Majka R, Mana C, Marin J, Martin T, Martinez G, Masi N, Maurin D, Menchaca-Rocha A, Meng Q, Mo DC, Morescalchi L, Mott P, Muller M, Nelson T, Ni JQ, Nikonov N, Nozzoli F, Nunes P, Obermeier A, Oliva A, Orcinha M, Palmonari F, Palomares C, Paniccia M, Papi A, Pauluzzi M, Pedreschi E, Pensotti S, Pereira R, Picot-Clemente N, Pilo F, Piluso A, Pizzolotto C, Plyaskin V, Pohl M, Poireau V, Putze A, Quadrani L, Qi XM, Qin X, Qu ZY, Raiha T, Rancoita PG, Rapin D, Ricol JS, Rodriguez I, Rosier-Lees S, Rozhkov A, Rozza D, Sagdeev R, Sandweiss J, Saouter P, Schael S, Schmidt SM, von Dratzig AS, Schwering G, Scolieri G, Seo ES, Shan BS, Shan YH, Shi JY, Shi XY, Shi YM, Siedenburg T, Son D, Song JW, Spada F, Spinella F, Sun W, Sun WH, Tacconi M, Tang CP, Tang XW, Tang ZC, Tao L, Tescaro D, Ting SCC, Ting SM, Tomassetti N, Torsti J, Turkoglu C, Urban T, Vagelli V, Valente E, Vannini C, Valtonen E, Vaurynovich S, Vecchi M, Velasco M, Vialle JP, Vitale V, Vitillo S, Wang LQ, Wang NH, Wang QL, Wang RS, Wang X, Wang ZX, Weng ZL, Whitman K, Wienkenhover J, Willenbrock M, Wu H, Wu X, Xia X, Xie M, Xie S, Xiong RQ, Xu NS, Xu W, Yan Q, Yang J, Yang M, Yang Y, Ye QH, Yi H, Yu YJ, Yu ZQ, Zeissler S, Zhang C, Zhang JH, Zhang MT, Zhang SD, Zhang SW, Zhang XB, Zhang Z, Zheng ZM, Zhuang HL, Zhukov V, Zichichi A, Zimmermann N, Zuccon P
Publisher: Amer Physical Soc
Publication year: 2015
Journal: Physical Review Letters
Journal name in source: PHYSICAL REVIEW LETTERS
Journal acronym: Phys Rev Lett
Article number: ARTN 211101
Volume: 115
Issue: 21
Number of pages: 9
ISSN: 0031-9007
DOI: https://doi.org/10.1103/PhysRevLett.115.211101
Web address : http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.211101#fulltext#fulltext
Knowledge of the precise rigidity dependence of the helium flux is important in understanding the origin, acceleration, and propagation of cosmic rays. A precise measurement of the helium flux in primary cosmic rays with rigidity (momentum/charge) from 1.9 GV to 3 TV based on 50 million events is presented and compared to the proton flux. The detailed variation with rigidity of the helium flux spectral index is presented for the first time. The spectral index progressively hardens at rigidities larger than 100 GV. The rigidity dependence of the helium flux spectral index is similar to that of the proton spectral index though the magnitudes are different. Remarkably, the spectral index of the proton to helium flux ratio increases with rigidity up to 45 GV and then becomes constant; the flux ratio above 45 GV is well described by a single power law.
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