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

作者：Adriani O; Barbarino G C; Bazilevskaya G A; Bellotti R; Boezio M; Bogomolov E A; Bonechi L; Bongi M; Bonvicini V; Bottai S; Bruno A; Cafagna F; Campana D; Carlson P; Casolino M; Castellini G; De Pascale M P; De Rosa G; De Simone N; Di Felice V; Galper A M; Grishantseva L; Hofverberg P; Koldashov S V; Krutkov S Y; Kvashnin A N; Leonov A; Malvezzi V; Marcelli L; Menn W; Mikhailov V V; Mocchiutti E; Orsi S; Osteria G

来源：Nature, 2009, 458(7238): 607-609.

DOI：10.1038/nature07942

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 medium(1), which is referred to as a 'secondary source'. Positrons might also originate in objects such as pulsars(2) and microquasars(3) or through dark matter annihilation(4), which would be 'primary sources'. Previous statistically limited measurements(5-7) 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 overmuch 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.

• 出版日期2009-4-2