Applications of Accelerator Mass Spectrometry

Abstract

(1 .5 x 106 yr half-life), 26 Al (7.2 x 105 yr), and 36CI (3.0 x 105 yr), are now routinely observable using accelerator mass spectrom­ etry and are finding increasing use in earth and planetary sciences. Their use for radioactive dating, an idea that figured prominently in the papers reporting the first experiments, has been a small part of subsequent work, but their use as tracers has developed rapidly, with the result that this review covers areas unsuspected in 1977. The application to radiocarbon has proved arduous owing to the need to determine isotopic ratios to a precision of 1%, a restriction that has seldom hampered the method when applied to the other isotopes, which are generally measured to accuracies of 5 to 10%. The precision desired for radiocarbon, implying an age uncertainty of 83 yr, although trivial by the standards of low-energy mass spectrometry, has only recently been achieved for sustained periods of machine operation. The technique has been applied to research on the atmosphere, the cosmic-ray history found in Arctic ice, manganese nodules,