Fast-neutron activation of long-lived nuclides in natural Pb

We measured the production of the long-lived nuclides 207Bi, 202Pb, and 194Hg in a sample of natural Pb due to high-energy neutron interactions using a neutron beam at the Los Alamos Neutron Science Center. The activated sample was counted by a HPGe detector to measure the amount of radioactive nuclides present. These nuclides are critical in understanding potential backgrounds in low background experiments utilizing large amounts of Pb shielding due to cosmogenic neutron interactions in the Pb while residing on the Earth's surface. By scaling the LANSCE neutron flux to a cosmic neutron flux, we measure the sea level cosmic ray production rates of 8.0 ± 1.3 atoms/kg/day of 194Hg, 120 ± 25 atoms/kg/day 202Pb, and <0.17 ± 0.04 atoms/kg/day 207Bi.