Comparative study of Fe-C bead and graphite target performance with the National Ocean Science AMS (NOSAMS) facility recombinator ion source

Abstract

An accelerator mass spectrometry (AMS) experiment was designed to investigate 14C target performance for two target types over a range of isotopic concentrations and sample sizes, with a special focus on the ability to measure 14C in environmental samples having only microgram amounts of carbon. The findings were positive, showing that precision, accuracy, and stability were adequate to determine 14C to 1% or better in samples containing as little as 25 μg carbon. Satisfactory Poisson uncertainty and target stability were demonstrated down to a level of 7 μg carbon, but experimental data showed that accurate measurements at that level require detailed knowledge of blank variability and mass dependence of the modern carbon calibration factor.