Nucleo-synthesis of cosmic-ray nuclei

Among explanations for the differences between the solar composition and that of cosmic rays at the sources, two of the principal models have assumed, respectively, that the makeup of cosmic rays is largely determined by 1) a selective injection process that depends on ionization potentials or ionization cross sections, or 2) explosive nucleosynthesis. Our estimate of the source abundance of nitrogen has been reduced on the basis of recent cross section measurements; it agrees with hypothesis (2), though a combination of the two mechanisms is also allowable. A list is presented of nuclides suitable for exploring the processes of C-, O-, and Si-burning in cosmic ray sources. (orig.)