Proton to helium ratio in cosmic rays: analysis of the PAMELA data

Abstract

In our previous papers we proposed an anomalous diffusion model for solution of the knee problem in the primary cosmic-rays spectrum and explanation of different values of spectral exponent of protons and other nuclei at wide energy region. The anomaly results from large free paths (Levy flights) of particles between magnetic domains. The physical arguments and the calculations indicate that the bulk of observed cosmic rays with energy 108 – 1010 eV is formed by numerous distant (r > 1 kpc) sources. It means that the contribution of these sources to the observed flux may be evaluated in the framework of the steady-state approach (JG). The contribution of the nearby (r < 1 kpc) relatively young (t < 105 yrs) sources defines the spectrum in the high energy region and provides the knee (JL). Consequently the cosmic rays intensity from all galactic sources for some group of nuclei consists of local JL and global JG components.We show that in the framework of our anomalous diffusion model with two-component representation of CR intensity the behavior of proton to helium ratio observed by PAMELA can be reproduced.