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Enhanced beam currents with co-precipitated niobium as a matrix for AMS measurements of 10Be
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. (Jonfysik)
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
2010 (English)In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, Vol. 268, no 7-8, 795-798 p.Article in journal (Refereed) Published
Abstract [en]

When dealing with small amounts of 10Be, it is challenging to achieve the good performance in the ion source that is needed to enable a reliable AMS measurement. We have co-precipitated beryllium with dissolved NbCl5, using a range of mixing ratios, to establish an optimal and practical procedure. 9Be16O beam currents for co-precipitated samples of 9Be-Nb are often higher, but show a slower rise than for samples either co-precipitated or mixed with silver. However, while the Ag sample currents soon deteriorate, Nb sample currents stay high for an extended time, leading to higher measuring performance and better statistics. Although co-precipitated Be-Nb mixtures do not reach such high beam currents as BeO mechanically mixed with Nb powder, we prefer co-precipitation as it provides enough material for handling and an additional mixing step is avoided. We recommend use of NbCl5 as an alternative to AgNO3 on account of the much lower boron association of niobium compared to silver. No critical limit in the matrix:Be mixing ratio was observed, but we note a steady decline of maximum currents reached with increasing mixing ratio.

Place, publisher, year, edition, pages
2010. Vol. 268, no 7-8, 795-798 p.
Keyword [en]
AMS, Beryllium-10, Niobium, Beam currents, Co-precipitation
National Category
Geology Subatomic Physics Engineering and Technology
Research subject
Ion Physics; Earth Science with specialization in Quaternary Geology
URN: urn:nbn:se:uu:diva-103023DOI: 10.1016/j.nimb.2009.10.033ISI: 000277462300029OAI: oai:DiVA.org:uu-103023DiVA: diva2:217222
Available from: 2009-05-13 Created: 2009-05-13 Last updated: 2014-12-11Bibliographically approved
In thesis
1. Influence of solar activity and environment on 10Be in recent natural archives
Open this publication in new window or tab >>Influence of solar activity and environment on 10Be in recent natural archives
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Understanding the link between the Sun and climate is vital in the current incidence of global climate change, and 10Be in natural archives constitutes an excellent tracer for this purpose. As cosmic rays enter the atmosphere, cosmogenic isotopes like 10Be and 14C are formed. Variations in solar activity modulate the amount of incoming cosmic rays, and thereby cosmogenic isotope production. Atmospherically produced 10Be enters natural archives such as sediments and glaciers by wet and dry deposition within about a year of production. 10Be from natural archives therefore provides information on past solar activity, and because these archives also contain climate information, solar activity and climate can be linked.

One remaining question is to what degree 10Be in natural archives reflects production, and to what extent the local and regional environment overprints the production signal. To explore this, 10Be was measured at annual resolution over the last 600 years in a Greenland ice core. Measurement potentials for these samples benefited from the development of a new laboratory method of co-precipitating 10Be with niobium. To diversify geographic location and archive media type, a pioneer study of measuring 10Be with annual resolution in varved lake sediments from Finland was conducted, with samples from the entire 20th century.

Pathways of 10Be into lake sediments are more complex than into glacial ice, inferring that contemporary atmospheric conditions may not be recorded. Here, it is shown for the first time that tracing the 11-year solar cycle through lake sediment 10Be variations is possible. Results also show that on an annual basis, 10Be deposition in ice and sediment archives is affected by local environmental conditions. On a slightly longer timescale, however, diverse 10Be records exhibit similar trends and a negative correlation with solar activity. Cyclic variability of 10Be deposition persisted throughout past grand solar minima, when little or no sunspot activity was recorded. 10Be levels indicate that although solar activity has been high during the 20th century, levels are not unprecedented in the investigated 600 years. Aerosol 10Be/7Be values indicate possible influence of stratosphere-troposphere exchange on isotope abundance and the production signal.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 64 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 654
cosmogenic isotopes, beryllium, ice cores, varved lake sediments, accelerator mass spectrometry, co-precipitation
National Category
urn:nbn:se:uu:diva-103031 (URN)978-91-554-7549-9 (ISBN)
Public defence
2009-06-11, Hambergsalen, Villavägen 16, Uppsala, 10:00 (English)
Available from: 2009-05-19 Created: 2009-05-13 Last updated: 2009-05-28Bibliographically approved

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Possnert, Göran
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