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

Abstract

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 3.49 x 10(5) antiproton events and 2.42 x 10(9) proton events. The fluxes and flux ratios of charged elementary particles in cosmic rays are also presented. In the absolute rigidity range similar to 60 to similar to 500 GV, the antiproton (p) over bar, 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 bar /p), ((p) over bar /e(+)), and (p/e(+)) flux ratios each reaches a maximum. From similar to 60 to similar to 500 GV, the ((p) over bar /p), ((p) over bar /e(+)), and (p/e(+)) flux ratios show no rigidity dependence. These are new observations of the properties of elementary particles in the cosmos.