(EC+β⁺) Decay of ¹²⁹Ce

The nuclide ¹²⁹Ce was produced by a (¹⁶O, 4n) reaction on an enriched ¹¹⁷Sn target. Reaction products were transported to a shielded location by using a helium-jet tape transport system. An activity of 4.1 min in chemically separated cerium sample was identified as ¹²⁹Ce. Based on x-γ-t and γ-γ-t coincidence measurements, the (EC+β⁺) decay scheme of ¹²⁹Ce was proposed, and takes accounts of 50 observed γ-lines.