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.

Adriani, O., Barbarino, G., Bazilevskaya, G., Bellotti, R., Boezio, M., Bogomolov, E., et al. (2009). An anomalous positron abundance in cosmic rays with energies 1.5–100 GeV. NATURE, 458(7238), 607-609 [10.1038/nature07942].

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

DE PASCALE, MARIA PIA;MALVEZZI, VALERIA;PICOZZA, PIERGIORGIO;SPARVOLI, ROBERTA;
2009

Abstract

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.
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore FIS/04 - Fisica Nucleare e Subnucleare
English
Con Impact Factor ISI
Adriani, O., Barbarino, G., Bazilevskaya, G., Bellotti, R., Boezio, M., Bogomolov, E., et al. (2009). An anomalous positron abundance in cosmic rays with energies 1.5–100 GeV. NATURE, 458(7238), 607-609 [10.1038/nature07942].
Adriani, O; Barbarino, G; Bazilevskaya, G; Bellotti, R; Boezio, M; Bogomolov, E; Bonechi, L; Bongi, M; Bonvicini, V; Bottai, S; Bruno, A; Cafagna, F; Campana, D; Carlson, P; Casolino, M; Castellini, G; DE PASCALE, Mp; De Rosa, G; De Simone, N; Di Felice, V; Galper, A; Grishantseva, L; Hofverberg, P; Koldashov, S; Krutkov, S; Kvashnin, A; Leonov, A; Malvezzi, V; Marcelli, L; Menn, W; Mikhailov, V; Mocchiutti, E; Orsi, S; Osteria, G; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S; Simon, M; Sparvoli, R; Spillantini, P; Stozhkov, Y; Vacchi, A; Vannuccini, E; Vasilyev, G; Voronov, S; Yurkin, Y; Zampa, G; Zampa, N; Zverev, V
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/55486
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