Accelerator Mass Spectrometry and its Applications

Abstract

In this overview, the technique of accelerator mass spectrometry (AMS) and its applications are described. AMS is a highly sensitive method of counting atoms. It is used to detect very low concentrations of natural isotopic abundances (typically in the range between 10 −12 and 10 −16 ) of both radionuclides and stable nuclides. The main advantages of AMS compared to conventional radiometric methods are the use of smaller samples (milligram and even submilligram size) and shorter measuring times (<1 h). The equipment used for AMS is almost exclusively based on the tandem accelerator, although some of the newest systems are based on a slightly different principle. The most widely used isotope studied with AMS is 14 C. Besides radiocarbon dating, this isotope is used in climate studies, biomedicine applications, and many other fields. Worldwide, more than 100 000 14 C samples are measured per year. Other isotopes studied include 10 Be, 26 Al, 36 Cl, 41 Ca, 59 Ni, 129 I, U, and Pu. Although these measurements are important, the number of samples of these other isotopes measured each year is estimated to be <10% of the number of 14 C samples.