The nuclide Ce-129 was produced by a (O-16,4n) reaction with an enriched Sn
-117 target. With the aid of a helium-jet tape transport system, the reacti
on products were transported to a shielded location,where Ce samples were p
repared after chemical separation. The neighboring isotopes of Sn-117, Sn-1
16 and Sn-118,were also bombarded with O-16 beam. Different isotopes of Ce
were further separated by comparing the products in the above three reactio
ns. An activity with a half-life of 4.1 min in the chemically purified ceri
um samples was identified as Ce-129. Based on X-gamma -t and gamma-gamma -t
coincidence measurements, the EC/beta (+) decay scheme of Ce-129, includin
g 51 gamma lines, was proposed. Using the observed growth-decay curve of an
intense 278.6keV gamma line of La-129 decay, the beta feeding branch from
the ground state of Ce-129 directly to the ground state of La-129 was estim
ated to be (26 +/- 7) %. In addition, the gamma spectra gated by both La-K-
alpha-X ray and intense 68.2keV gamma ray of Ce-129 decay as well as the ti
me spectra of typical gamma rays were also presented here.