Neutron-Induced Partial $\gamma$-ray Cross-Section Measurements on Cu, Ge and Pb

In high-precision low-statistic measurements such as those carried out in deep underground low-background environments, naturally-occurring radiation can obscure the region of interest. For example, energetic neutrons produced from natural radioactivity or muon-induced reactions will interact with the experimental apparatus producing a continuous background. A survey of neutron-induced $\gamma$-ray transitions in $^{nat}$Cu, enriched $^{76}$Ge, and $^{nat}$Pb from 150-4000 keV was carried out at TUNL using pulsed mono-energetic neutron beams, with an emphasis on the region around 2039 keV where the $0\nu\beta\beta$ decay peak of $^{76}$Ge is expected to appear. Transitions at 2041, 2615, and 3062 keV in the shielding materials of Pb and Cu may either directly interfere with the $^{76}$Ge $0\nu\beta\beta$ peak at 2039 keV or may produce nearby escape peaks. The rates at which these background peaks occur are needed to determine whether events due to $0\nu\beta\beta$ decay are observed and whether neutrinos are indeed their own anti-particles.