DETERMINATION OF THE ISOTOPIC COMPOSITIONS OF SAMARIUM AND GADOLINIUM BY THERMAL IONIZATION MASS SPECTROMETRY

摘要

Because of the large neutron capture cross sections for Sm-149, Gd-155 and Gd-157, accurate and sensitive isotopic analyses of samarium and gadolinium can be used to investigate natural neutron irradiation exposure. in this paper, chemical separation procedures and mass spectrometric methods for the precise determination of samarium and gadolinium isotopic compositions are described. Isotopic ratios other than Sm-144/Sm-152, Gd-152/Gd-160, and Gd-154/Gd-160 for both samarium and gadolinium commercial reagents, artificially neutron-irradiated reagents, and geological reference reeks are quantified within 0.001% precision at the 95% confidence level. The present method can detect effects caused by time-integrated neutron flux of 1.3 x 10(14) neutrons/cm(2) in the environmental samples.