High accuracy isotope ratio measurements of nuclear materials by thermal ionization mass spectrometry (CAT#: STEM-ST-0189-LJX)

Introduction

Isotopic measurements of uranium are performed on a broad range of samples, including bulk fuel or weapons materials with considerable quantities of actinides, environmental soils, biota, and water, and individual particles with picograms or less of analyte. The variation of the uranium isotopic composition between different samples as well as the dynamic range of the isotope ratios is large compared to most other elements. The variety of sample compositions and especially the dynamic range of the ratios place considerable demands on the mass spectrometer, in particular, the need for high abundance sensitivity and ionization efficiency, low background and noise, and high linearity and efficiency of detectors.
For certain types of analyses, such as the certification of isotopic reference materials or the age determination of geological samples, state-of-the-art technology presently favors thermal ionization mass spectrometry (TIMS).