Derivation of the age distributions of cosmic rays in a Galaxy with a convective halo
Abstract
A model of cosmic ray propagation in the Galaxy is considered in which the sources are uniformly distributed in the disk. The cosmic rays diffuse into a halo where diffusion is combined with outward convection. The propagation equation has been solved analytically to give the distributions of total age and diskage, and the surviving fraction of radioactive ^{10}Be, ƒ_{s}, in terms of 4 propagation parameters. A knowledge of the grammage, X, traversed by cosmic rays and of ƒ_{s} sets lower limits, but no upper limits, to the mean age of cosmic rays at the earth and the extent of the halo. Provided that ƒ_{s} ≲ 1/3 an upper limit of ∼16 km s^{1} to the outward convection velocity in the halo is set by the value of X.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 February 1980
 Bibcode:
 1980A&A....82..110F
 Keywords:

 Astronomical Models;
 Beryllium 10;
 Cosmic Rays;
 Galactic Radiation;
 Milky Way Galaxy;
 Radiation Distribution;
 Chronology;
 Convection;
 Diffusion Coefficient;
 Halos;
 Space Radiation