Development of an AMS method to study oceanic circulation characteristics using cosmogenic Ar-39

Initial experiments at the ATLAS facility [Nucl. Instr. and Meth. B 92 (1994) 241] resulted in a clear detection of cosmogenic Ar-39 signal at the natural level. The present paper summarizes the recent developments of Ar-39 AMS measurements at ATLAS: the use of an electron cyclotron resonance (ECR) positive ion source equipped with a special quartz liner to reduce K-39 background, the development of a gas handling system for small volume argon samples, the acceleration of Ar-39(8+) ions to 232 MeV, and the final separation of Ar-39 from K-39 in a gas-filled spectrograph. The first successful AXIS measurements of Ar-39 in ocean water samples from the Southern Atlantic ventilation experiment (SAVE) are reported. Published by Elsevier B.V.