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Neutrinos from the primary proton–proton fusion process in the Sun

Nature volume 512, pages 383386 (28 August 2014) | Download Citation

Abstract

In the core of the Sun, energy is released through sequences of nuclear reactions that convert hydrogen into helium. The primary reaction is thought to be the fusion of two protons with the emission of a low-energy neutrino. These so-called pp neutrinos constitute nearly the entirety of the solar neutrino flux, vastly outnumbering those emitted in the reactions that follow. Although solar neutrinos from secondary processes have been observed, proving the nuclear origin of the Sun’s energy and contributing to the discovery of neutrino oscillations, those from proton–proton fusion have hitherto eluded direct detection. Here we report spectral observations of pp neutrinos, demonstrating that about 99 per cent of the power of the Sun, 3.84 × 1033 ergs per second, is generated by the proton–proton fusion process.

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Acknowledgements

The Borexino program is made possible by funding from the INFN (Italy); the NSF (USA); the BMBF, DFG and MPG (Germany); the JINR; the RFBR, RSC and NRC Kurchatov Institute (Russia); and the NCN (Poland). We acknowledge the support of the Laboratori Nazionali del Gran Sasso (Italy).

Author information

Affiliations

  1. Dipartimento di Fisica, Università degli Studi e INFN, 20133 Milano, Italy.

    • G. Bellini
    • , B. Caccianiga
    • , D. D’Angelo
    • , M. Giammarchi
    • , P. Lombardi
    • , L. Ludhova
    • , E. Meroni
    • , L. Miramonti
    • , G. Ranucci
    •  & A. Re
  2. Chemical Engineering Department, Princeton University, Princeton, New Jersey 08544, USA.

    • J. Benziger
  3. Institut für Experimentalphysik, Universität Hamburg, 22761 Hamburg, Germany.

    • D. Bick
    • , C. Hagner
    •  & M. Meyer
  4. INFN Laboratori Nazionali del Gran Sasso, 67100 Assergi, Italy.

    • G. Bonfini
    • , P. Cavalcante
    • , K. Fomenko
    • , F. Gabriele
    • , S. Gazzana
    • , Aldo Ianni
    • , M. Laubenstein
    • , F. Lombardi
    • , M. Montuschi
    • , A. Razeto
    • , N. Rossi
    • , Y. Suvorov
    •  & R. Tartaglia
  5. Physics Department, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.

    • D. Bravo
    • , S. Manecki
    • , L. Papp
    •  & R. B. Vogelaar
  6. Physics Department, University of Massachusetts, Amherst, Massachusetts 01003, USA.

    • L. Cadonati
    • , K. Otis
    •  & A. Pocar
  7. Physics Department, Princeton University, Princeton, New Jersey 08544, USA.

    • F. Calaprice
    • , A. Chavarria
    • , C. Galbiati
    • , A. Goretti
    • , Andrea Ianni
    • , P. Mosteiro
    • , R. Saldanha
    •  & A. Wright
  8. Gran Sasso Science Institute (INFN), 67100 L’Aquila, Italy.

    • F. Calaprice
    •  & S. Marcocci
  9. Dipartimento di Fisica, Università degli Studi e INFN, 16146 Genova, Italy.

    • A. Caminata
    • , C. Ghiano
    • , S. Marcocci
    • , M. Pallavicini
    • , L. Perasso
    • , C. Salvo
    • , G. Testera
    •  & S. Zavatarelli
  10. Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, 119234 Moscow, Russia.

    • A. Chepurnov
    •  & M. Gromov
  11. Department of Physics, University of Houston, Houston, Texas 77204, USA.

    • S. Davini
    • , A. Empl
    • , E. Hungerford
    •  & G. Korga
  12. St Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.

    • A. Derbin
    •  & V. Muratova
  13. NRC Kurchatov Institute, 123182 Moscow, Russia.

    • A. Etenko
    • , E. Litvinovich
    • , G. Lukyanchenko
    • , I. Machulin
    • , M. Skorokhvatov
    • , S. Sukhotin
    •  & Y. Suvorov
  14. National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409 Moscow, Russia.

    • A. Etenko
    • , E. Litvinovich
    • , I. Machulin
    •  & M. Skorokhvatov
  15. Joint Institute for Nuclear Research, 141980 Dubna, Russia.

    • K. Fomenko
    • , D. Korablev
    • , O. Smirnov
    • , A. Sotnikov
    •  & O. Zaimidoroga
  16. APC, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 75205 Paris Cedex 13, France.

    • D. Franco
    • , D. Kryn
    • , M. Obolensky
    •  & D. Vignaud
  17. Physik-Department and Excellence Cluster Universe, Technische Universität München, 85748 Garching, Germany.

    • M. Göger-Neff
    • , T. Lewke
    • , Q. Meindl
    • , L. Oberauer
    • , L. Papp
    • , S. Schönert
    •  & F. von Feilitzsch
  18. Kiev Institute for Nuclear Research, 03680 Kiev, Ukraine.

    • V. Kobychev
  19. Department of Physics, Technische Universität Dresden, 01062 Dresden, Germany.

    • B. Lehnert
    •  & K. Zuber
  20. Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany.

    • W. Maneschg
    •  & H. Simgen
  21. M. Smoluchowski Institute of Physics, Jagiellonian University, 30059 Krakow, Poland.

    • M. Misiaszek
    • , M. Wojcik
    •  & G. Zuzel
  22. Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi e INFN, 06123 Perugia, Italy.

    • F. Ortica
    •  & A. Romani
  23. Physics and Astronomy Department, University of California Los Angeles (UCLA), Los Angeles, California 90095, USA.

    • Y. Suvorov
    •  & H. Wang
  24. Institut für Physik, Johannes Gutenberg Universität Mainz, 55122 Mainz, Germany.

    • J. Winter
    •  & M. Wurm

Consortia

  1. Borexino Collaboration

Authors

    Contributions

    The Borexino detector was designed, constructed and commissioned by the Borexino Collaboration over the span of more than 15 years. The Borexino Collaboration sets the science goals. Scintillator purification and handling, source calibration campaigns, PMT and electronics operations, signal processing and data acquisition, Monte Carlo simulations of the detector, and data analyses were performed by Borexino Collaboration members, who also discussed and approved the scientific results. The manuscript was prepared by a subgroup of authors appointed by the collaboration and subject to an internal collaboration-wide review process. All authors reviewed and approved the final version of the manuscript.

    Competing interests

    The author declare no competing financial interests.

    Corresponding author

    Correspondence to O. Smirnov.

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    DOI

    https://doi.org/10.1038/nature13702

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