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

The Ge-73*(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 (nu) over bar (e) flux was 6.4 x 10(12) cm(-2) s(-1). The measured average and equilibrium production rates of Ge-73*(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 similar to 10(-42) to 10(-43) cm(2) for the cross sections of neutrino-induced nuclear transitions were derived. The dominant backgrounds are due to beta(-) decays of cosmic-ray-induced Ga-73. The prospects of enhancing the sensitivities at underground locations are discussed.