Measurement of cosmic-ray low-energy antiproton spectrum with the first   BESS-Polar Antarctic flight
  The BESS-Polar spectrometer had its first successful balloon flight over Antarctica in December 2004. During the 8.5-day long-duration flight, almost 0.9 billion events were recorded and 1,520 antiprotons were detected in the energy range 0.1-4.2 GeV. In this paper, we report the antiproton spectrum obtained, discuss the origin of cosmic-ray antiprotons, and use antiprotons to probe the effect of charge sign dependent drift in the solar modulation. 
K. Abe, H. Fuke, S. Haino, T. Hams, A. Itazaki, K. C. Kim, T.   Kumazawa, M. H. Lee, Y. Makida, S. Matsuda, K. Matsumoto, J....