Photonuclear channel of 7Be production in the Earth’s atmosphere

Measurements of average values of cross sections for the A(γ,X)7Be photonuclear reactions on nitrogen, oxygen, and carbon of natural isotopic composition were performed in the energy range from the threshold to 90 MeV. On the basis of the measured cross sections for 7Be photoproduction and on the basis of the results obtained by simulating the nuclear-electromagnetic cascade in the Earth’s atmosphere, the contribution of the photonuclear mechanism to the production of the cosmogenic radioisotope 7Be in the atmosphere and its latitude dependence were investigated for the first time. It is shown that the contribution of the photonuclear mechanism is commensurate with the contribution of the proton and neutron mechanisms of 7Be production in the atmosphere and that the inclusion of this mechanism is mandatory in analyzing the accumulation and transfer of 7Be in the planetary boundary layer.