Production and Decay of the Ge(1/2) Metastable State in a Low-Background Germanium Detector

The Ge(1/2) metastable states decay with a very characteristic signature which allow them to be tagged event-by-event. Studies were performed using data taken with a high-purity germanium detector in a low-background laboratory near a nuclear power reactor core where ν̄e-flux was 6.4× 10 12 cms. The measured average and equilibrium production rates of Ge(1/2) were (8.7± 0.4) and (6.7± 0.3) kgday, respectively. The production channels were studied and identified. By studying the difference in the production of Ge(1/2) between the reactor ON and OFF spectra, the limiting sensitivities at the range of ∼ 10 − 10 cm for the cross-sections of neutrino-induced nuclear transitions were derived. The dominant background are due to β-decays of cosmic-ray induced Ga. The prospects of enhancing the sensitivities at underground locations are discussed. PACS numbers: 14.60.Lm, 13.15.+g, 5.30.Pt.