Antiproton Flux, Antiproton to Proton Flux Ratio, and Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station.
A precision measurement by AMS of the antiproton flux and the antiproton to proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV is presented based on 3.49x10^{5} antiproton events and 2.42x10^{9} proton events. The fluxes and flux ratios of charged elementary particles in cosmic rays are also presented. In the absolute rigidity range ~60 to ~500 GV, the antiproton p[over proton p, and positron e^ fluxes are found to have nearly identical rigidity dependence and the electron e^ flux exhibits a different rigidity dependence. Below 60 GV, the (p[over /p) (p[over /e^ and (p/e^ flux ratios each reaches a maximum. From ~60 to ~500 GV, the (p[over /p) (p[over /e^ and (p/e^ flux ratios show no rigidity dependence. These are new observations of the properties of elementary particles in the cosmos.
Physical review letters