Precision measurement of cosmic-ray antiproton spectrum

The energy spectrum of cosmic-ray antiprotons ((p) over bar's) has been measured in the range 0.18-3.56 GeV, based on 458 (p) over bar's collected by BESS in a recent solar-minimum period. We have detected for the first time a characteristic peak at 2 GeV of (p) over bar's originating from cosmic-ray interactions with the interstellar gas. The peak spectrum is reproduced by theoretical calculations, implying that the propagation models are basically correct and that different cosmic-ray species undergo a universal propagation. Future BESS data with still higher statistics will allow us to study the solar modulation and the propagation in detail and to search for primary (p) over bar components.