Variations of Cosmogenic Radionuclide Production Rates in Chondrites of Known Orbits

Abstract

The results of multiyear investigations of cosmogenic radionuclide production rates along the orbits of 42 chondrites that fell to the Earth between 1959 and 2016 are presented. They constitute a long set of homogeneous data, statistical smoothing of which demonstrates some main regularities of the distribution and variation of the galactic cosmic rays (GCR) with energy >100 MeV in the internal (<5 AU) heliosphere. This set is exclusive, and it has timeless importance for all the future investigations of the magneto-hydrodynamic peculiarities of the GCR solar modulation mechanism. Analysis of the ²⁶Al contents in ten chondrites of known orbits allowed us to find the spatial profile of the GCR intensity (E > 100 MeV), averaged over a 1 My in the internal heliosphere, testifying to continual development and dissipation of a layer of the solar wind magnetic irregularities, which efficiently modulates cosmic radiation. It suggests constancy of the magneto-hydrodynamic environment in the Solar System for at least the last million years.