Adriani 2009 PAMELA对高能正电子电子的观测

主要内容:
正电子数/(正电子数+电子数)的数值在这一阶段开始上升

精彩摘抄:


文章信息:

Letter

Nature 458, 607-609 (2 April 2009) | doi:10.1038/nature07942; Received 28 October 2008; Accepted 6 February 2009

An anomalous positron abundance in cosmic rays with energies 1.5–100 GeV

O. Adriani^1,2, G. C. Barbarino^3,4, G. A. Bazilevskaya⁵, R. Bellotti^6,7, M. Boezio⁸, E. A. Bogomolov⁹, L. Bonechi^1,2, M. Bongi², V. Bonvicini⁸, S. Bottai², A. Bruno^6,7, F. Cafagna⁷, D. Campana⁴, P. Carlson¹⁰, M. Casolino¹¹, G. Castellini¹², M. P. De Pascale^11,13, G. De Rosa⁴, N. De Simone^11,13, V. Di Felice^11,13, A. M. Galper¹⁴, L. Grishantseva¹⁴, P. Hofverberg¹⁰, S. V. Koldashov¹⁴, S. Y. Krutkov⁹, A. N. Kvashnin⁵, A. Leonov¹⁴, V. Malvezzi¹¹, L. Marcelli¹¹, W. Menn¹⁵, V. V. Mikhailov¹⁴, E. Mocchiutti⁸, S. Orsi^10,11, G. Osteria⁴, P. Papini², M. Pearce¹⁶, P. Picozza^11,13, M. Ricci¹⁷, S. B. Ricciarini², M. Simon¹⁵, R. Sparvoli^11,13, P. Spillantini^1,2, Y. I. Stozhkov⁵, A. Vacchi⁸, E. Vannuccini², G. Vasilyev⁹, S. A. Voronov¹⁴, Y. T. Yurkin¹⁴, G. Zampa⁸, N. Zampa⁸ & V. G. Zverev¹⁴

1. University of Florence, Department of Physics, Via Sansone 1, I-50019 Sesto Fiorentino, Florence, Italy
2. I...

Correspondence to: P. Picozza^11,13 Correspondence and requests for materials should be addressed to P.P. (Email: Piergiorgio.Picozza@roma2.infn.it).

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Antiparticles account for a small fraction of cosmic rays and are known to be produced in interactions between cosmic-ray nuclei and atoms in the interstellar medium¹, which is referred to as a 'secondary source'. Positrons might also originate in objects such as pulsars² and microquasars³ or through dark matter annihilation⁴, which would be 'primary sources'. Previous statistically limited measurements^{5, 6, 7} of the ratio of positron and electron fluxes have been interpreted as evidence for a primary source for the positrons, as has an increase in the total electron+positron flux at energies between 300 and 600 GeV (ref. 8). Here we report a measurement of the positron fraction in the energy range 1.5–100 GeV. We find that the positron fraction increases sharply over much of that range, in a way that appears to be completely inconsistent with secondary sources. We therefore conclude that a primary source, be it an astrophysical object or dark matter annihilation, is necessary.