Neutron inelastic scattering in natural Pb as a background in neutrinoless double-beta decay experiments

Inelastic neutron scattering on Pb isotopes can result in γ rays near the signature endpoint energy in a number of ββ isotopes. In particular, there are γ-ray transitions in 206Pb and 207Pb that might produce energy deposits at the 76Ge Qββ in Ge detectors used for 0νββ searches. The levels that produce these γ rays can be excited by n,n'γ reactions, but the cross sections are small and previously unmeasured. The cross section on natPb to produce the 2041-keV γ ray from 206Pb is measured to be 3.1 ± 0.6 (stat.) ± 0.3 (syst.) mb at ∼ 9.6 MeV. The cross section on natPb to produce the 3062-keV γ ray from 207Pb is measured to be 4.3 ± 0.8 (stat.) ± 0.4 (syst.) mb at the same energy. We place upper limits on the cross sections for exciting some other levels in Pb that have transition energies corresponding to Qββ in orhter ββ isotopes.