Upper limit on the antihelium flux in primary cosmic rays

A. G. Mayorov, A. M. Galper, O. Adriani, G. A. Bazilevskaya, G. Barbarino, R. Bellotti, M. Boezio, E. A. Bogomolov, V. Bonvicini, M. Bongi, L. Bonechi, S. V. Borisov, S. Bottai, A. Bruno, S. Vacci, E. Vannuccini, G. I. Vasiliev, S. A. Voronov, Y. Wu, I. A. DanilchenkoW. Gillard, G. Jerse, G. Zampa, N. Zampa, V. G. Zverev, M. Casolino, D. Campana, R. Carbone, A. V. Karelin, P. Carlson, G. Castellini, F. Cafagna, A. N. Kvashnin, S. V. Koldashov, S. A. Koldobsky, S. Yu Krutkov, A. A. Leonov, V. V. Malakhov, V. Malvezzi, L. Marcelli, W. Menn, V. V. Mikhailov, E. Mocchiutti, N. Mori, N. V. Nikonov, G. Osteria, S. Pizzolotto, P. Papini, M. P. De Pascale, P. Picozza, M. Pearce, M. Ricci, S. Ricciarini, M. F. Runtso, M. Simon, N. De Simone, R. Sparvoli, P. Spillantini, Yu I. Stozhkov, V. Di Felice, Yu T. Yurkin

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Abstract

The explanation of the observed baryon asymmetry, i.e., the almost complete absence of antimatter in the visible part of the universe, is one of the most important problems in cosmology. The real asymmetry value can be determined by direct measurements of the fluxes of antinuclei with charges {pipe}Z{pipe} ≥ 2 in primary cosmic rays near the Earth. The results of the search for antihelium using data from the PAMELA experiment obtained from June 2006 to December 2009 are presented. No events with a charge of -2 have been detected in the rigidity range of 0.6-600 GV. An upper limit on the antihelium/helium flux ratio has been presented as a function of the energy. An integral upper level of 4.7 × 10-7 is the lowest limit at rigidities above 14 GV.

Original languageEnglish
Pages (from-to)628-631
Number of pages4
JournalJETP Letters
Volume93
Issue number11
DOIs
StatePublished - Aug 2011
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by the Space Council, Russian Academy of Sciences; Russian Federal Space Agency Roscosmos; Progress State Research and Pro duction Space Center; Scientific Center for Operative Monitoring of the Earth; Italian Space Agency; Ger man Aerospace Center; Swiss National Space Coun cil; and Swiss Research Council.

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