Measurement of cosmic-ray proton, antiproton and muon spectra was carried out at mountain altitude. We observed 2 x 10^5 protons and 10^2 antiprotons in a kinetic energy region of 0.25 -- 3.3 GeV. Zenith-angle dependence of proton fluxes was obtained. Atmospheric muon spectra were measured simultaneously. The observed antiproton spectrum showed some deviation from theoretical predictions particularly in a low energy region.
Download