Neutron inelastic scattering processes as a background for double-β decay experiments

We investigate several Pb(n,n'γ) and Ge(n,n'γ) reactions. We measure {γ}-ray production from Pb(n,n'γ) reactions that can be a significant background for double-{β} decay experiments which use lead as a massive inner shield. Particularly worrisome for Ge-based double-{β} decay experiments are the 2041-keV and 3062-keV {γ} rays produced via Pb(n,n'γ). The former is very close to the ⁷⁶Ge double-{β} decay endpoint energy and the latter has a double escape peak energy near the endpoint. We discuss the implications of these {γ} rays on past and future double-{β} decay experiments and estimate the cross section to excite the level that produces the 3062-keV {γ} ray. Excitation {γ}-ray lines from Ge(n,n'γ) reactions are also observed. We consider the contribution of such backgrounds and their impact on the sensitivity of next-generation searches for neutrinoless double-{β} decay using enriched germanium detectors.