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  • 1 Operated by Battelle Memorial Institute Richland Physical Sciences Department Pacific Northwest Laboratory 99352 Washington (USA)
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A rare earth group separation scheme followed by normal Ge(Li), low energy photon detector (LEPD), and Ge(Li)−NaI(Tl) coincidence-noncoincidence spectrometry significantly enhances the detection sensitivity of individual rare earth elements (REE) at or below the ppb level. Based on the selected γ-ray energies, normal Ge(Li) counting is favored for140La,170Tb and169Yb; LEPD is favored for low γ-ray energies of147Nd,153Sm,166Ho and169Yb; and noncoincidence counting is favored for141Ce,143Ce,142Pr,153Sm,171Er and175Yb. The detection of radionuclides152mEu,159Gd and177Lu is equally sensitive by normal Ge(Li) and noncoincidence counting;152Eu is equally sensitive by LEPD and normal Ge(Li); and153Gd and170Tm is equally favored by all the counting modes. Overall, noncoincidence counting is favored for most of the REE. Precise measurements of the REE were made in geological and biological standards.