The generation velocities of the cosmic ray produced 32P and 33P in the atmosphere

The effective cross-sections of the 32P and 33P generation in the atmosphere are calculated by the Rudstam and Silberger-Tsao methods. When comparing theoretical and experimental data it was found that the measured ratios of the phosphorus isotope concentrations in the surface air frequently disagree with the theoretically calculated ones. This disagreement may be explained by the presence of phosphorus radioisotopes of artificial origin in the atmosphere, by the secondary dust arrival to the filter and by the fractionation of carriers