Cross sections for 68 Ge production in natural- and enriched-germanium targets irradiated with protons of energy 100 MeV and background in experiments devoted to searches for the 2 β 0 ν decay of 76 Ge

The rate of 68 Ge production at sea level under the effect of the nuclear component of cosmic rays is calculated. The calculation is based on the experimental values of the cross sections for 68 Ge production in natural- and enriched-germanium targets (enrichment in 76 Ge) irradiated with high-energy protons. The background from the decays of 68 Ge can be a serious problem in new-generation experiments devoted to searches for the 2 β 0 ν decay of 76 Ge.