Analyzing Cosmic Ray Spectral Features Using Numerical Methods

Recent high-precision measurements of cosmic rays from space and balloon-borne experiments have revealed multiple spectral features. A hardening around ~200 GV has been observed in primary nuclei and their secondaries. Additionally, a softening of the proton spectrum at ~10 TV and the helium spectrum at a few tens TV has been observed, along with a positron excess above ~25 GeV. To investigate the cause of these features, we utilized GALPROP v57, a cosmic ray propagation code. A diffusion model that incorporates reacceleration and convection effects was employed as a base model. The parameter optimization module from GALPROP v57, utilizing the minimization library MINUIT2, was applied to obtain the best fit to experimental data. Three scenarios were explored for the hardening: one involving a diffusion break, another with injection spectra breaks, and one with a combination of both. For fitting the softening in proton and helium spectra, we considered an additional source break. To address the positron excess, a charge-symmetric primary positron source was introduced. The results for elemental spectra and ratios, along with the all-particle spectrum, will be compared to compiled cosmic ray data. Implications of these features will also be discussed.