Measurement ofC12,O16, andFe56charge changing cross sections in helium at high energy, comparison with cross sections in hydrogen, and application to cosmic-ray propagation

We present measurements of the spallation cross sections of carbon, oxygen, and iron in helium and hydrogen, at beam energies from 540 to 1600 MeV/nucleon, performed by exposing liquid helium, ${\mathrm{CH}}_2$, and C targets. Charge changing cross sections are reported for fragments down to Ne for Fe+α and Fe+p reactions, and down to B for O+α, O+p, C+α, and C+p reactions. α- to p-induced cross section ratios (${\sigma }_{\alpha }$/${\sigma }_{\mathrm{p}}$) are determined at the same energy per nucleon. From these measurements an empirical formula for the ${\sigma }_{\alpha }$/${\sigma }_{\mathrm{p}}$ ratios is derived, and is found in good agreement with available isotopic cross sections data from radioactivity and radiochemical techniques. These results are applied to the propagation of heavy charged cosmic rays in an interstellar medium with an helium to hydrogen abundance ratio of 0.10. It is shown that the Sc–Mn/Fe ratio prediction is decreased relative to the B/C ratio when compared to propagation calculations in a pure hydrogen interstellar medium.