Australis: Progress Report

The first stage of the development of AUSTRALIS, a microbeam AMS system at the HIGF laboratory at North Ryde, Sydney has been completed. The system is designed to enable in-situ microanalysis of geological samples for ultra-traces and for isotopic data for minerals exploration research. The negative ions for analysis are produced by sputtering with a microbeam of Cs+from a modified General Ionex model 834 HICONEX ion source. The source features a novel intermediate or 'screen' electrode to correct for the effect of the secondary ion extraction field on the trajectory of the primary beam,in order to bring the primary beam to the geometric centre. The high energy analysis system of AUSTRALIS features a pair of deflector systems to permit fast switching of isotopes without altering the magnet setting. The paper describes the initial tests' results showing good agreement with the design parameters. 5 refs., 4 figs