Isotopic Analysis: Cerium-141 and Cerium-144

Cerium-141 and cerium-144 are determined in the presence of each other by performing a suitable cerium chemical separation and then measuring the radiation from each nuclide. Cerium-144 is determined by counting the 3.0-Mev Pr¹⁴⁴ beta ray; cerium-141 is determined by integrating beneath the 145-kev gamma-ray peak observed with a sodium iodide gamma-ray spectrometer. In the later case correction for contributions from cerium-144 must be made. The gamma/beta branchings for the 145-kev gamma ray in cerium-141 and the 134-kev gamma ray in cerium-144 were determined.