Phys. Rev. Lett.
102,
051101
(2009)
[5 pages]
New Measurement of the Antiproton-to-Proton Flux Ratio up to 100 GeV in the Cosmic Radiation
O. Adriani et al. PAMELA Collaboration
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O. Adriani1,2, G. C. Barbarino3,4, G. A. Bazilevskaya5, R. Bellotti6,7, M. Boezio8, E. A. Bogomolov9, L. Bonechi1,2, M. Bongi2, V. Bonvicini8, S. Bottai2, A. Bruno6,7, F. Cafagna7, D. Campana4, P. Carlson10, M. Casolino11, G. Castellini12, M. P. De Pascale11,13, G. De Rosa4, D. Fedele1,2, A. M. Galper14, L. Grishantseva14, P. Hofverberg10, A. Leonov14, S. V. Koldashov14, S. Y. Krutkov9, A. N. Kvashnin5, V. Malvezzi11, L. Marcelli11, W. Menn15, V. V. Mikhailov14, M. Minori11, E. Mocchiutti8, M. Nagni11, S. Orsi10, G. Osteria4, P. Papini2, M. Pearce10, P. Picozza11,13, M. Ricci16, S. B. Ricciarini2, M. Simon15, R. Sparvoli11,13, P. Spillantini1,2, Y. I. Stozhkov5, E. Taddei1,2, A. Vacchi8, E. Vannuccini2, G. Vasilyev9, S. A. Voronov14, Y. T. Yurkin14, G. Zampa8, N. Zampa8, and V. G. Zverev14 (PAMELA Collaboration)
1Physics Department of University of Florence, I-50019 Sesto Fiorentino, Florence, Italy 2INFN, Sezione di Florence, I-50019 Sesto Fiorentino, Florence, Italy 3Physics Department of University of Naples “Federico II”, I-80126 Naples, Italy 4INFN, Sezione di Naples, I-80126 Naples, Italy 5Lebedev Physical Institute, RU-119991 Moscow, Russia 6Physics Department of University of Bari, I-70126 Bari, Italy 7INFN, Sezione di Bari, I-70126 Bari, Italy 8INFN, Sezione di Trieste, I-34012 Trieste, Italy 9Ioffe Physical Technical Institute, RU-194021 St. Petersburg, Russia 10Royal Institute of Technology (KTH), Department of Physics, SE-10691 Stockholm, Sweden 11INFN, Sezione di Rome “Tor Vergata”, I-00133 Rome, Italy 12IFAC, I-50019 Sesto Fiorentino, Florence, Italy 13Physics Department of University of Rome “Tor Vergata”, I-00133 Rome, Italy 14Moscow Engineering and Physics Institute, RU-11540 Moscow, Russia 15Physics Department of Universität Siegen, D-57068 Siegen, Germany 16INFN, Laboratori Nazionali di Frascati, I-00044 Frascati, Italy

Received 13 September 2008; revised 21 November 2008; published 2 February 2009
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Physics
Viewpoint
A new measurement of the cosmic-ray antiproton-to-proton flux ratio between 1 and 100 GeV is presented. The results were obtained with the PAMELA experiment, which was launched into low-Earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. During 500 days of data collection a total of about 1000 antiprotons have been identified, including 100 above an energy of 20 GeV. The high-energy results are a tenfold improvement in statistics with respect to all previously published data. The data follow the trend expected from secondary production calculations and significantly constrain contributions from exotic sources, e.g., dark matter particle annihilations.
© 2009 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.102.051101
DOI:
10.1103/PhysRevLett.102.051101
PACS:
96.50.sb, 95.35.+d, 95.55.Vj
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