Improvement of Calculations of Cross Sections and Cosmic-Ray Propagation

Abstract

The cosmic-ray experiments on the HEAO-3 satellite provide unprecedented data, both in terms of the number of events and in elemental resolution. The two experiments together have yielded measurements all the way from lithium to uranium. Our partial cross section calculations have a standard deviation of ~ 30 per cent; higher precision is desirable now for the analysis of the high-quality experimental results on relative abundances and energy spectra of elements. We have collected data on cross section measurements of the last five years, in order to explore the existence of systematic deviations in our equations and parameters for calculating cross sections. During the first phase of this work, we have emphasized the development of an empirical formula for total inelastic cross sections. The results of this investigation (both on total and partial inelastic cross sections) will be presented, and the effects on the calculation of cosmic-ray abundances will be discussed. In particular, the discrepancy between earlier propagation calculations and measurements of the secondary/primary ratio (6l ≤ Z ≤ 75)/(76 ≤ Z ≤ 83) is appreciably reduced.