Rigidity dependence of cosmic ray escape length in the Galaxy obtained from a comparison of proton and iron spectra in the range 3-3000 GV

TL;DR

This study analyzes cosmic ray spectra data to determine how the escape length varies with rigidity, revealing a change at high energies that may indicate different source compositions.

Contribution

It provides the first detailed measurement of the rigidity dependence of cosmic ray escape length using proton and iron spectra data across a wide energy range.

Findings

Escape length follows R^(-0.47) dependence at lower rigidities.

A change in behavior occurs at R > 300 GV, suggesting source composition variation.

Results align with secondary/primary nuclei ratio estimates.

Abstract

The simple leaky-box model of propagation of cosmic rays in the Galaxy is quite suitable for handling data on cosmic ray nuclei energy spectra and composition at E ? 1 GeV [1,2]. In the leakybox model a full information about cosmic ray propagation in Galaxy is compressed to the single parameter - escape length, Xe, characterizing mean grams of a matter passed by cosmic rays from sources to the Earth. In this paper we analyze the world data on proton and iron cosmic ray spectra collected in the past (HEAO, CRN et al.) and in series of recent electronic experiments (ATIC, CREAM, MS, BESS, Tracer et al.) and obtain the rigidity dependence of escape length, Xe(R) = R^(-0.47\pm-0.03), from the measured rigidity dependence of the protons/iron ratio. It quite agrees with the one stimated in standard manner from the secondary/primary nuclei ratio. But at R > 300 GV the behavior of Xe(R)distinctly changes, that can (variant of explanation)point out to the change of proton/iron ratio in cosmic ray sources.