The standardization of samarium-153.

Samarium-153 has been standardized by 4 pi beta liquid-scintillation counting, with an uncertainty of 0.4%. The probability per decay for the 103.2-keV gamma ray was measured, using two germanium detectors, to be 0.298 +/- 0.004. The half life, based on liquid-scintillation measurements over 6.4 half lives and pressurized-ionization-chamber measurements over four half lives, was found to be 46.27 +/- 0.02 h. The uncertainties given are one estimated standard deviation (of the mean when applicable) for random and non-random components.