An external-beam charged-particle (alpha) activation system for direct trace element analysis in liquids

An external-beam system based on charged-particle activation analysis for determination of trace elements in liquids has been developed at the Variable Energy Cyclotron Centre, Calcutta. The system developed is direct, instrumental, non-destructive, simple and suitable for both aqueous and non-aqueous samples. This paper gives the construction details of the system and its standardization for quantitative estimation of transition metals. Medium-energy alpha particles were used. As part of the standardization process the beam energy, beam current, observed interferences, minimum detection limits, system linearity, reproducibility and precision are discussed. We have mainly used aqueous and crude oil samples during this work. A novel method for calibrating the target position with respect to the beam is reported. (author)