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, Papini P, Pearce M, Picozza P, Ricci M, Ricciarini S B, Simon M, Sparvoli R, Spillantini P, Stozhkov Y I, Vacchi A, Vannuccini E, Vasilyev G, Voronov S A, Yurkin Y T, Zampa G, Zampa N, Zverev V G
University of Florence, Department of Physics, Via Sansone 1, I-50019 Sesto Fiorentino, Florence, Italy.
Nature. 2009 Apr 2;458(7238):607-9. 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, which is referred to as a 'secondary source'. Positrons might also originate in objects such as pulsars and microquasars or through dark matter annihilation, which would be 'primary sources'. Previous statistically limited measurements 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.
反粒子在宇宙射线中占比很小，已知它们是在宇宙射线原子核与星际介质中的原子相互作用时产生的，这种相互作用被称为“次级源”。正电子也可能起源于脉冲星和微类星体等天体，或者通过暗物质湮灭产生，这将是“初级源”。先前对正电子与电子通量之比的统计测量有限，这些测量结果被解释为正电子存在初级源的证据，在300至600 GeV能量之间的总电子 + 正电子通量增加也被如此解释（参考文献8）。在此，我们报告了在1.5 - 100 GeV能量范围内对正电子份额的测量。我们发现，在该范围的大部分区域，正电子份额急剧增加，其方式似乎与次级源完全不一致。因此，我们得出结论，必须存在一个初级源，无论是天体物理对象还是暗物质湮灭。
