The ultraheavy cosmic rays: Propagation and selective acceleration

Results of calculations of ultraheavy cosmic ray propagation are examined in the light of recent observations and theoretical advances with the objective of distinguishing the effects of propagation from nucleosynthesis and preferential acceleration. The results presented here have been calculated by the method described in Margolis (1983), with elements from iron (Z = 26) to uranium (Z = 92) combined in a single calculation. The source abundances of Anders and Ebihara (1982) have been used as a reference composition. It is shown, in particular, that the relative abundances of Sr and Ba are substantially increased by using the modified ionization potential dependence (MIPD) compared with solar abundances and the first ionization potential dependence (FIPD) model. In contrast, Pb shows similar enhancements in both FIPD and MIPD models.