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.

An anomalous positron abundance in cosmic rays with energies 1.5-100 GeV / O. Adriani;G. C. Barbarino;G. A. Bazilevskaya;R. Bellotti;M. Boezio;E. A. Bogomolov;L. Bonechi;M. Bongi;V. Bonvicini;S. Bottai;A. Bruno;F. Cafagna;D. Campana;P. Carlson;M. Casolino;G. Castellini;M. P. De Pascale;G. D. Rosa;N. D. Simone;V. D. Felice;A. M. Galper;L. Grishantseva;P. Hofverberg;S. V. Koldashov;S. Y. Krutkov;A. N. Kvashnin;A. Leonov;V. Malvezzi;L. Marcelli;W. Menn;V. V. Mikhailov;E. Mocchiutti;S. Orsi;G. Osteria;P. Papini;M. Pearce;P. Picozza;M. Ricci;S. B. Ricciarini;M. Simon;R. Sparvoli;P. Spillantini;Y. I. Stozhkov;A. Vacchi;E. Vannuccini;G. Vasilyev;S. A. Voronov;Y. T. Yurkin;G. Zampa;N. Zampa;V. G. Zverev. - In: NATURE. - ISSN 0028-0836. - STAMPA. - 458:(2009), pp. 607-609. [10.1038/nature07942]

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

ADRIANI, OSCAR;BONECHI, LORENZO;BONGI, MASSIMO;SPILLANTINI, PIERO;
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.
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O. Adriani;G. C. Barbarino;G. A. Bazilevskaya;R. Bellotti;M. Boezio;E. A. Bogomolov;L. Bonechi;M. Bongi;V. Bonvicini;S. Bottai;A. Bruno;F. Cafagna;D. Campana;P. Carlson;M. Casolino;G. Castellini;M. P. De Pascale;G. D. Rosa;N. D. Simone;V. D. Felice;A. M. Galper;L. Grishantseva;P. Hofverberg;S. V. Koldashov;S. Y. Krutkov;A. N. Kvashnin;A. Leonov;V. Malvezzi;L. Marcelli;W. Menn;V. V. Mikhailov;E. Mocchiutti;S. Orsi;G. Osteria;P. Papini;M. Pearce;P. Picozza;M. Ricci;S. B. Ricciarini;M. Simon;R. Sparvoli;P. Spillantini;Y. I. Stozhkov;A. Vacchi;E. Vannuccini;G. Vasilyev;S. A. Voronov;Y. T. Yurkin;G. Zampa;N. Zampa;V. G. Zverev
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2158/394360
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