Measurement of cosmic-ray low-energy antiproton spectrum with the first BESS-Polar Antarctic flight

Understand

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.