Improving a gas ion source for C-14 AMS

Fahrni, Simon; Wacker, L.; Synal, H. A.; Szidat, Sönke (2013). Improving a gas ion source for C-14 AMS. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 294, pp. 320-327. Elsevier 10.1016/j.nimb.2012.03.037

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For more than 4 years, gaseous samples of 1-50 mu g carbon have been routinely measured with the gas ion source of the small AMS (Accelerator Mass Spectrometer) facility MICADAS (Mini CArbon DAting System) at ETH Zurich. The applied measurement technique offers a simple and fast way of C-14 measurements without the need of sample graphitization. A major drawback of gaseous C-14 measurements, however, is the relatively low negative ion current, which results in longer measurement times and lower precision compared to graphitized samples. In December 2009, a new, improved Cs sputter ion source was installed at MICADAS and we began to optimize conditions for the measurement of gaseous samples. C-12(-) currents from the new ion source were improved from initially 3 to 12-15 mu A for routine measurements and the negative ion yield was increased by a factor of 2, reaching 8 on average during routine operation. Moreover, the new measurement settings enable a doubled CO2 flow, thus substantially reducing measurement times. The achieved performance allows closing the sample size gap between gaseous and solid samples and makes the gas ion source a promising tool for dating with a measurement precision of 5 parts per thousand on samples as small as 50 mu g carbon. (C) 2012 Elsevier B.V. All rights reserved.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Fahrni, Simon and Szidat, Sönke

Subjects:

500 Science > 540 Chemistry

ISSN:

0168-583X

Publisher:

Elsevier

Language:

English

Submitter:

Brigitte Oggier

Date Deposited:

31 Mar 2014 17:38

Last Modified:

14 Mar 2016 12:47

Publisher DOI:

10.1016/j.nimb.2012.03.037

Uncontrolled Keywords:

Radiocarbon, 14C, Accelerator mass spectrometry, AMS, MICADAS, Gas ion source, Small samples

BORIS DOI:

10.7892/boris.47130

URI:

https://boris.unibe.ch/id/eprint/47130

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