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A gas ion source for continuous-flow AMS

Schneider, R. J. and Kim, S.-W and von Reden, K. F. and Hayes, J. M. and Wills, J. S. C and Griffin, V. S. and Sessions, A. L. and Sylva, S. (2004) A gas ion source for continuous-flow AMS. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 223 . pp. 149-154. ISSN 0168-583X.

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The first gas-fed ion source for radiocarbon AMS applications (without sputtering) has been operated at the Woods Hole NOSAMS Facility. A three-year, off-line test program resulted in positive carbon ion currents up to 1 mA and negative ion currents up to 80 µA. Recently, the compact, permanent-magnet microwave plasma ion source and magnesium vapor charge-exchange canal were coupled to the recombinator injector of the 2.5 MV Tandetron. When the ion source was operated on CO_2 at a flow rate of about 200 µ1 per minute, negative carbon ion beams up to 20 µA were obtained, at an energy of 35 keV. Radiocarbon measurements were performed on standard reference gases and the dynamic response to square-wave pulses of gas was determined. Time constants in the ion source are less than 1 s, which should allow analysis of chromatographic peaks of CO_2 with very little broadening. A combustion device has been constructed to generate CO_2 for direct injection into the source. Argon carrier gas is used to buffer the pressure at one atmosphere in the sample gas injector. A dedicated ion-beam injector, with higher angular acceptance and higher transmitted currents, is being constructed for the AMS system.

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Sessions, A. L.0000-0001-6120-2763
Additional Information:© 2004 Elsevier B.V. Gas samples were supplied by the Sample Preparation Laboratory at NOSAMS. We thank the University of Toronto, for loaning us the compact microwave plasma ion source, originally built at the Chalk River Laboratories of Atomic Energy of Canada Limited and also for the loan of a large ion implanter magnet, which was used as part of the test stand. We thank Diamond Semiconductor Group (Gloucester,MA) for the loan of a 40kV power supply. This work has been supported in part by a National Science Foundation Cooperative Agreement, OCE-9807266.
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Subject Keywords:Radiocarbon; Ion source; Accelerator mass spectrometry
Record Number:CaltechAUTHORS:20130612-105641499
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Official Citation:R.J Schneider, S.-W Kim, K.F von Reden, J.M Hayes, J.S.C Wills, V.S Griffin, A.L Sessions, S Sylva, A gas ion source for continuous-flow AMS, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volumes 223–224, August 2004, Pages 149-154
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38913
Deposited By: John Wade
Deposited On:13 Jun 2013 15:39
Last Modified:03 Oct 2019 05:02

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