Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10695259 | Advances in Space Research | 2005 | 7 Pages |
Abstract
The Balloon Borne Experiment with a Superconducting Spectrometer (BESS) has measured the energy spectrum of cosmic-ray antiprotons between 0.18 and 4.20 GeV in eight flights between 1993 and 2002. Above about 1 GeV, models in which antiprotons are secondary products of the interactions of primary cosmic rays with the interstellar gas agree with the BESS antiproton spectrum. Below 1 GeV, the data show a possible excess antiproton flux compared to secondary model predictions, suggesting the presence of an additional source of antiprotons. The antiproton/proton ratios measured between 1993 and 1999, during the Sun's positive-polarity phase, are consistent with simple models of solar modulation. However, results from the 2000 flight, following the solar magnetic field reversal, show a sudden increase in the antiproton/proton ratio and tend to favor a charge-sign-dependent drift model. To extend BESS measurements to lower energies, an evolutionary instrument, BESS-Polar, is under construction for polar flight in 2004.
Keywords
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Space and Planetary Science
Authors
J.W. Mitchell, K. Abe, K. Anraku, Y. Asaoka, M. Fujikawa, H. Fuke, S. Haino, T. Hams, N. Ikeda, M. Imori, A. Itazaki, K. Izumi, M.H. Lee, T. Maeno, Y. Makida, S. Matsuda, N. Matsui, T. Matsukawa, K. Yoshimura,