In situ microanalysis for trace element and isotopic data by AMS

An AMS system incorporating a microbeam Cs source has been developed at the CSIRO HIAF laboratory in Sydney. The system, known as AMS for Ultra Sensit ive TRAce element and Isotopic Studies (AUSTRALIS), is designed to perform in situ microanalysis for geochronology and geochemistry applications in mi neral exploration research. The source produces a 30 mu m Cs beam routinely , to be developed further to achieve 1 mu m resolution. The sample chamber features a microscope for direct viewing at high magnification for precise selection of analytical points. The high energy system features a novel iso tope switching method, and is capable of analysing all elements in the peri odic table at terminal voltages up to 2.5 MV. The development of AUSTRALIS commenced in 1994; the first Pb isotope measurements were carried out in mi d 1997. Current development of applications includes analysis of stable iso topes such as S-34. Isotopic ratio precision better than a permil has been obtained for Pb isotopes, made possible by a fast (< 1 ms) isotope switchin g system that circumvents source instabilities. In general the trace elemen t detection limit is expected to be better than 1 ppm for most elements. Th e instrument presents a powerful new tool for trace element and isotopic da ta acquisition. (C) 1999 Elsevier Science B.V. All rights reserved.