Fast-neutron-induced potential background near the Q value of neutrinoless double- β decay of Ge 76

The $^{76}\mathrm{Ge}$(n,p)$^{76}\mathrm{Ga}$ reaction and the subsequent $\ensuremath{\beta}$ decay of $^{76}\mathrm{Ga}$ to $^{76}\mathrm{Ge}$ has been used to excite the 3951.89-keV state of $^{76}\mathrm{Ge}$, which decays by the emission of a 2040.70-keV $\ensuremath{\gamma}$ ray. Using high-purity germanium detectors, the associated pulse-height signal may be undistinguishable from the potential signal produced in neutrinoless double-$\ensuremath{\beta}$ decay of $^{76}\mathrm{Ge}$ with its $Q$ value of 2039.0 keV. At 20-MeV neutron energy the production cross section of the 2040.70-keV $\ensuremath{\gamma}$ ray is approximately 0.1 mb.