Excess carbon‐14 abundances in uranium ores: Possible evidence for emission from uranium‐series isotopes

Significant levels of ¹⁴C have been detected in uranium‐bearing minerals using the tandem accelerator mass spectrometer at the University of Arizona. The amount of ¹⁴C detected in a given mineral is proportional to the concentration of uranium in that mineral. The average value of ¹⁴C atoms/uranium atom is (2.2±0.5)×10⁻¹⁵ (2σ). These data are consistent with the assumption of direct ¹⁴C emission from one or more nuclei in the ²³⁸U decay chain with a branching ratio of 1.0 to 2.0×10⁻⁹, relative to alpha decay. The uncertainty results from the possible production of ¹⁴C from ¹¹B(α,p)¹⁴C.