AMS of solid natural materials

Accelerator mass spectrometry has been applied, in a very few laboratories, to the in-situ analysis of trace elements in solids such as metals, semiconductors and minerals. The latter have largely been electrically-conducting phases with minimum grain size 0.5 mm, including graphite, sulphides and oxides, native Cu and Ni-Fe alloys. The emphasis has been mostly on precious metals analysis, with practical detection limits ranging from 0.005 to 50 ppb (parts per billion by weight) using Cs+ sputter sources of negative ions [1]. Broader applications to natural materials will be found only by extending this capability to include common rock-forming minerals, generally silicates, preferably with an option for spatial resolution down to 30-50 mu m. Versatile strategies include using negative primary ion beams (or other forms of ion sources, for bulk sampling) to generate positive ions which may then be neutralized prior to injection into the accelerator. The presentation will include aspects of ion source design, neutral injection AMS, and associated applications [2].