The activation cross sections for production of ${}^{51}\mathrm{Cr}$, ${}^{52,54,56}\mathrm{Mn}$, ${}^{59}\mathrm{Fe}$, and ${}^{55,56,57,58}\mathrm{Co}$ radioisotopes in deuteron-induced reactions on natural Fe were measured at deuteron energies up to 20 MeV. Then, within an extended analysis of deuteron interactions with ${}^{\mathrm{nat}}$Fe, all processes from elastic scattering until the evaporation from fully equilibrated compound system have been taken into account. Following the available elastic-scattering data analysis that supports the deuteron optical potential for reaction cross sections calculations, increased attention is paid especially to the breakup (BU) mechanism and direct reactions (DR). The deuteron activation cross-section analysis is completed by consideration of the preequilibrium and compound-nucleus contributions, corrected for decrease of the total reaction cross section due to the leakage of the initial deuteron flux towards BU and DR processes. The overall agreement of the measured data and model calculations validates the description of nuclear mechanisms taken into account, particularly the strong effects of direct interactions that have still not been appropriately considered within previous deuteron activation evaluations.

The muon charge ratio of the lateral muon density distributions in single EAS is studied by simulations, in context of recent proposals to measure this observable in coincidence with EAS observations. While effects of the hadronic interaction do not lead to significant differences of the total μ+ and μ− content, the differences of the azimuthal variation of the muon densities of opposite charges and the azimuthal variation of the muon charge ratio appear to be very much pronounced, dependent on the direction of EAS incidence. This is due to the influence of the geomagnetic field which induces related effects in radio emission from extended air showers.