First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5-350 GeV

Aguilar, M; Alberti, G; Alpat, B; Alvino, A; Ambrosi, G; Andeen, K; Anderhub, H; Arruda, L; Azzarello, P; Bachlechner, A; Barao, F; Baret, B; Barrau, A; Barrin, L; Bartoloni, A; Basara, L; Basili, A; Batalha, L; Bates, J; Battiston, R; Bazo, J; Becker, R; Becker, U; Behlmann, M; Beischer, B; Berdugo, J; Berges, P; Bertucci, B; Bigongiari, G; Biland, A; Bindi, V; Bizzaglia, S; Boella, G; de Boer, W; Bollweg, K; Bolmont, J; Borgia,; Borsini, B; S,; Boschini, M; Boudoul, G; Bourquin, M; Brun, P; Buenerd, M; Burger, J; Burger, W; Cadoux, F; Cai, X; Capell, M; Casadei, D; Casaus, J; Cascioli, V; Castellini, G; Cernuda, I; Cervelli, F; Chae, M; Chang, Y; Chen, A; Chen, C; Chen, H; Cheng, G; Chen, H; Cheng, L; Chernoplyiokov, N; Chikanian, A; Choumilov, E; Choutko, V; Chung, C; Clark, C; Clavero, R; Coignet, G; Commichau, V; Consolandi, C; Contin, A; Corti, C; Dios, M; Costado Coste, B; Crespo, D; Cui, Z; Dai, M; Delgado, C; Della Torre, S; Demirkoz, B; Dennett, P; Derome, L; Di Falco, S; Diao, X; Diago, A; Djambazov, L; Diaz, C; von Doetinchem, P; Wj, D; Dubois, J; Duperay, R; Duranti, M; D'Urso, D; Egorov, A; Eline, A; Eppling, F; Eronen, T; van Es, J; Esser, H; Falvard, A; Fiandrini, E; Fiasson, A; Finch, E; Fisher, P; Flood, K; Foglio, R; Fohey, M; Fopp, S; Fouque, N; Galaktionov, Y; Gallilee, M; Gallin Martel, L; Gallucci, G; Garcia, B; Garcia, J; Garcia Lopez, R; Garcia Tabares, L; Gargiulo, C; Gast, H; Gebauer, I; Gentile, S; Gervasi, M; Gillard, W; Giovacchini, F; Girard, L; Goglov, P; Gong, J; Goy Henningsen, C; Grandi, D; Graziani, M; Grechko, A; Gross, A; Guerri, I; de la Guia, C; Guo, K; Habiby, M; Haino, S; Hauler, F; Zh, H; Heil, M; Heilig, J; Hermel, R; Hofer, H; Huang, Z; Hungerford, W; Incagli, M; Ionica, M; Jacholkowska, A; Jang, W; Jinchi, H; Jongmanns, M; Journet, L; Jungermann, L; Karpinski, W; Kim, G; Kim, K; Kirn, T; Kossakowski, R; Koulemzine, A; Kounina, O; Kounine, A; Koutsenko, V; Krafczyk, M; Laudi, E; Laurenti, G; Lauritzen, C; Lebedev, A; Lee, M; Lee, S; Leluc, C; Vargas, H; Lepareur, V; Jq, L; Li, Q; Tx, L; Li, W; Zh, L; Lipari, P; Lin, C; Liu, D; Liu, H; Lomtadze, T; Ys, L; Lucidi, S; Luebelsmeyer, K; Luo, J; Lustermann, W; Lv, S; Madsen, J; Majka, R; Malinin, A; Mana, C; Marin, J; Martin, T; Martinez, G; Masciocchi, F; Masi, N; Maurin, D; Mcinturff, A; Mcintyre, P; Menchaca Rocha, A; Meng, Q; Menichelli, M; Mereu, I; Millinger, M; Dc, M; Molina, M; Mott, P; Mujunen, A; Natale, S; Nemeth, P; Jq, N; Nikonov, N; Nozzoli, F; Nunes, P; Obermeier, A; Oh, S; Oliva, A; Palmonari, F; Palomares, C; Paniccia, M; Papi, A; Park, W; Pauluzzi, M; Pauss, F; Pauw, A; Pedreschi, E; Pensotti, S; Pereira, R; Perrin, E; Pessina, G; Pierschel, G; Pilo, F; Piluso, A; Pizzolotto, C; Plyaskin, V; Pochon, J; Pohl, M; Poireau, V; Porter, S; Pouxe, J; Putze, A; Quadrani, L; Xn, Q; Rancoita, P; Rapin, D; Ren, Z; Ricol, J; Riihonen, E; Rodriguez, I; Roeser, U; Rosier Lees, S; Rossi, L; Rozhkov, A; Rozza, D; Sabellek, A; Sagdeev, R; Sandweiss, J; Santos, B; Saouter, P; Sarchioni, M; Schael, S; Schinzel, D; Schmanau, M; Schwering, G; von Dratzig, A; Scolieri, G; Seo, E; Shan, B; Shi, J; Shi, Y; Siedenburg, T; Siedling, R; Son, D; Spada, F; Spinella, F; Steuer, M; Stiff, K; Sun, W; Sun, W; Sun, X; Tacconi, M; Tang, C; Tang, X; Tang, Z; Tao, L; Tassan Viol, J; Ting, S; Ting, S; Titus, C; Tomassetti, N; Toral, F; Torsti, J; Tsai, J; Tutt, J; Ulbricht, J; Urban, T; Vagelli, V; Valente, E; Vannini, C; Valtonen, E; Trevino, M; Vaurynovich, S; Vecchi, M; Vergain, M; Verlaat, B; Vescovi, C; Vialle, J; Viertel, G; Volpini, G; Wang, D; Wang, N; Wang, Q; Wang, R; Wang, X; Wang, Z; Wallraff, W; Weng, Z; Willenbrock, M; Wlochal, M; Wu, H; Ky, W; Zs, W; Xiao, W; Xie, S; Xiong, R; Xin, G; Ns, X; Xu, W; Yan, Q; Yang, J; Yang, M; Qh, Y; Yi, H; Yj, Y; Zq, Y; Zeissler, S; Zhang, J; Zhang, Z; Zhang, M; Zheng, Z; Zhuang, H; Zhukov, V; Zichichi, A; Zuccon, P; Zurbach, C

doi:10.1103/PhysRevLett.110.141102

A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8×106 positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to ∼250 GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena. © 2013 American Physical Society.

Aguilar, M., Alberti, G., Alpat, B., Alvino, A., Ambrosi, G., Andeen, K., et al. (2013). First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5-350 GeV. PHYSICAL REVIEW LETTERS, 110(14) [10.1103/PhysRevLett.110.141102].