The Unusual Energy-dependence of Be-10/Be-9 Ratio in Cosmic Rays

Recently, Lipari [1] has analyzed the dependence of the ratio Be – 10 / Be – 9 in cosmic rays over the energy interval 0.5 GeV to about 12 GeV per nucleon and concludes that the ratio increases significantly more slowly than expected due to the relativistic time-dilatation of the lifetime of Be – 10. This finding was based on the model in which the spallation of C, O and other heavier nuclei in the collisions with gas in the interstellar medium is exclusively responsible for the production the Be nuclei and the residence-time of cosmic rays in the ISM decreases with energy. We have analyzed the same data assuming that the sources of cosmic rays are spatially and temporally discrete, and a substantial part of the spallation of cosmic rays occurs in the sources before they leak into the ISM. We assume that the residence time of cosmic rays in the sources in energy-dependent, but their subsequent leakage from the Galaxy is independent of energy up to considerably higher energies ~ PeV. In the latter model the isotopic ratio of Be is nearly consistent with the expectations of relativity.