EVOLUTION OF COSMIC-RAYS IN THE EARLY GALAXY

We calculate the variation of the cosmic-ray spectra at early Galactic epochs arising from dynamical evolution of the halo. In particular, we highlight the maximum effect such modified spectra can have on light isotope production in the early Galaxy, assuming a widely adopted spallation model. We find that spectra evolution alone can only maintain the linear Be versus Z relationship, observed at low Z, over the limited metallicity range Z(i)/4 - Z(i), where Z(i) marks the onset of linearity. At the very least, this indicates that nonlinearity in the Be abundance should be apparent at [Fe/H] less-than-or-similar-to -3, providing an observational test within the grasp of current techniques.