A Long-Lived Activity in Neutron-Irradiated Niobium

An activity has been found in samples of niobium metal irradiated for long periods in the Chalk River reactor. Extensive chemical tests showed that the activity is niobium. The activity is most likely the long-lived ground state of ${\mathrm{Nb}}^{94}$. If so, its half-life is estimated as (2.2±0.5)×${10}^4$ years from its yield. It has a 0.50±0.05-Mev beta and three gammas, 0.70±0.01 Mev (92 percent), 0.87±0.01 Mev (92 percent), and 1.57±0.02 Mev (8 percent). The capture cross section of ${\mathrm{Nb}}^{94}$ is 15±4 barns.