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, B.; Borsini, S.; Boschini, M. J.; Boudoul, G.; Bourquin, M.; Brun, P.; Buénerd, M.; Burger, J.; Burger, W.; Cadoux, F.; Cai, X. D.; Capell, M.; Casadei, D.; Casaus, J.; Cascioli, V.; Castellini, G.; Cernuda, I.; Cervelli, F.; Chae, M. J.; Chang, Y. H.; Chen, A. I.; Chen, C. R.; Chen, H.; Cheng, G. M.; Chen, H. S.; Cheng, L.; Chernoplyiokov, N.; Chikanian, A.; Choumilov, E.; Choutko, V.; Chung, C. H.; Clark, C.; Clavero, R.; Coignet, G.; Commichau, V.; Consolandi, C.; Contin, A.; Corti, C.; Costado-Dios, M. T.; Coste, B.; Crespo, D.; Cui, Z.; Dai, M.; Delgado, C.; Della Torre, S.; Demirkoz, B.; Dennett, P.; Derome, L.; Di Falco, S.; Diao, X. H.; Diago, A.; Djambazov, L.; Díaz, C.; von Doetinchem, P.; Du, W. J.; Dubois, J. M.; Duperay, R.; Duranti, M.; D'Urso, D.; Egorov, A.; Eline, A.; Eppling, F. J.; Eronen, T.; van Es, J. et al.
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Physical Review Letters, vol. 110, Issue 14, id. 141102

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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 ˜250GeV, 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.
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Particle Astrophysics

The MAGIC Collaboration is integrated by 20 research institutes and university departments from Armenia, Bulgaria, Finland, Germany, Italy, Poland, Spain, Switzerland and USA. The collaboration comprises two 17m diameter telescopes, located at the Roque de los Muchachos Observatory, designed to measure the Cherenkov radiation associated with

García López