Xu, S., Dougans, A., Freeman, S. P.H.T. , Maden, C. and Loger, R. (2007) A gas ion source for radiocarbon measurement at SUERC. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 259(1), pp. 76-82. (doi: 10.1016/j.nimb.2007.01.311)
Full text not currently available from Enlighten.
Abstract
Development of radiocarbon AMS measurement of CO2 samples using the 39-cathode NEC MC-SNICS gas/solid hybrid ion source in the SUERC AMS system is in progress. Stable and reproducible C− currents up to 12 μA can be achieved for an optimal CO2 gas flow rate of 1.5 ± 0.5 μl min−1, resulting in typical efficiency of 8% from CO2 to C− and that of 5% from CO2 to C4+. The precision is limited by the lifetime of the gas cathode, but measurements with modern materials have shown that a precision of better than 0.5% and 1% on >200 μg C and 10–200 μg C respectively is obtainable on a routine basis. The normalized 14C values for TIRI intercomparison sample A (Barley mash) agree well with the consensus value within the margin of uncertainty. The background comes from the gas cathode and probably cross contamination, which is estimated to be ca. 1 pMC. Large-sized samples (usually >200 μg C) can readily be run as pure CO2 while samples as small as 40 μg C can be measured at an optimal flow rate using helium carrier gas. Even smaller samples (>5 μg C) have been analysed at a reduced current. At present, source poisoning effects at helium flow rates above 130 μl min−1 limit the further reduction in measurable sample size. A manifold redesign is expected to address this problem. PACS 27.20.+n; 29.25.Ni; 82.80.Ms
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Dougans, Mr Andrew and Xu, Dr Sheng and Freeman, Professor Stewart |
| Authors: | Xu, S., Dougans, A., Freeman, S. P.H.T., Maden, C., and Loger, R. |
| College/School: | College of Science and Engineering > Scottish Universities Environmental Research Centre |
| Journal Name: | Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms |
| Publisher: | Elsevier |
| ISSN: | 0168-583X |
| ISSN (Online): | 1872-9584 |
| Published Online: | 12 March 2007 |
University Staff: Request a correction | Enlighten Editors: Update this record
Deposit and Record Details
Deposit and Record Details