New results for single stage low energy carbon AMS

A new configuration of the NEC single stage, low energy carbon AMS system (U.S. Patent 6,815,666 B2) has been built and tested. The injector includes two 40-sample ion sources, electrostatic and magnetic analysis, and fast sequential injection. The gas stripper, analyzing magnet, electrostatic analyzer, and detector are on an open air 250 kV deck. Both C-12 and C-13 currents are measured on the deck after the stripper, and an SSB detector is used for C-14 counting. Injected C-12 and mass 13 (C-13 and (CH)-C-12) currents are also measured. Automated controls follow a user-specified run list for unattended operation. Initial test results show precision for C-14/C-12 ratios of better than 5 per mil, and backgrounds for unprocessed graphite of less than 0.005 x modern. We will report final results for precision, background, and throughput and discuss related design features. (c) 2005 Elsevier B.V. All rights reserved.