γproduction and neutron inelastic scattering cross sections for76Ge

Abstract

The 2040.7-keV $\ensuremath{\gamma}$ ray from the 69th excited state of ${}^{76}$Ge was investigated in the interest of Ge-based double-$\ensuremath{\beta}$-decay experiments like the Germanium Detector Array (GERDA) experiment. The predicted transition could interfere with valid $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ events at 2039.0 keV, creating false signals in large-volume ${}^{76}$Ge enriched detectors. The measurement was performed with the Gamma Array for Inelastic Neutron Scattering (GAINS) at the Geel Electron Linear Accelerator (GELINA) white neutron source, using the ($n$,${n}^{\ensuremath{'}}$$\ensuremath{\gamma}$) technique and focusing on the strongest $\ensuremath{\gamma}$ rays originating from the level. Upper limits obtained for the production cross section of the 2040.7-keV $\ensuremath{\gamma}$ ray showed no possible influence on GERDA data. Additional analysis of the data yielded high-resolution cross sections for the low-lying states of ${}^{76}$Ge and related $\ensuremath{\gamma}$ rays, improving the accuracy and extending existing data for five transitions and five levels. The inelastic scattering cross section for ${}^{76}$Ge was determined for incident neutron energies up to 2.23 MeV, significantly increasing the energy range for which experimental data are available. Comparisons with model calculations using the talys code are presented indicating that accounting for the recently established asymmetric rotor structure should lead to an improved description of the data.