Production and decay of the 73Ge*(1/2−) metastable state in a low-background germanium detector

The 73Ge*(1/2−) metastable state decays with a very characteristic signature which allows it 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 the -flux was . The measured average and equilibrium production rates of 73Ge*(1/2−) were (8.7 ± 0.4) and (6.7 ± 0.3) kg−1 day−1, respectively. The production channels were studied and identified. By studying the difference in the production of 73Ge*(1/2−) between the reactor ON and OFF spectra, limiting sensitivities in the range of for the cross sections of neutrino-induced nuclear transitions were derived. The dominant backgrounds are due to β− decays of cosmic-ray-induced 73Ga. The prospects of enhancing the sensitivities at underground locations are discussed.