New development for galactic cosmic-ray propagation

We have developed a new model and a corresponding computer code to study cosmic ray propagation and interactions. The model depends on the expansion of the time backward stochastic solution of the general diffusion transport equation [4] starting from an observer position to solve a group of diffusion transport equations each of which represents a particular element or isotope of cosmic ray nuclei. In this paper we are focusing on key abundace ratios such as B/C, sub-Fe/Fe. The effect of inhomogeneousity in the interstellar medium is investigated. The contribution of certain cosmic ray nuclei to the production of other nuclei is addressed.