Interactions of Heavy Nuclei, Kr, Xe and Ho, in Light Targets

Over the past few years, we have been analyzing the HEAO-3 measurements of the abundances of ultra-heavy cosmic ray nuclei (Z>26) at earth. In order to interpret these abundances in terms of a source composition, allowance must be made for the propagation of the nuclei in the interstellar medium. Vital to any calculation of the propagation is a knowledge of the total and partial interaction cross sections for these heavy nuclei on hydrogen. Until recently, data on such reactions have been scarce, and we have relied on the semiempirical formalism of Silberberg and Tsao to predict the partial cross sections. However, now that relativistic heavy ion beams are available at the LBL Bevalac, some of the cross sections of interest can be measured at energies close to those of the cosmic ray nuclei being observed.