Summary
The advantages that accelerator mass spectrometry (AMS) provide for radiocarbon analysis, notably smaller sample sizes and shorter measurement times, also apply to the analysis of 129I. In this paper, the requirements for a mass spectrometry system for measuring extremely low concentrations of rare atoms are discussed and these requirements are illustrated using the details of the AMS analysis of 129I. As an example of an application of this AMS technology, a series of 129I measurements, used to identify isolated events in which radioactivity has been atmospherically transported into the Arctic, is described. Such investigations could not be carried out without the small sample size capability of AMS analysis.