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Examination of Background Contamination Levels for Gas Counting and AMS Target Preparation in Trondheim

Published online by Cambridge University Press:  18 July 2016

Steinar Gulliksen
Affiliation:
Radiological Dating Laboratory, The Norwegian Institute of Technology, N-7034 Trondheim Norway
Mette S. Thomsen
Affiliation:
Radiological Dating Laboratory, The Norwegian Institute of Technology, N-7034 Trondheim Norway
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Abstract

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The Radiological Dating Laboratory in Trondheim relatively often dates samples with ages >30 ka BP. Contaminated background materials are known to affect the accuracy of very old dates. We have found, by measurements of different materials, that such contamination is small when using our conventional gas proportional counting (GPC) system. We have also studied contamination levels of our target preparation for 14C accelerator mass spectrometry (AMS) dating in Uppsala. A significant lower background is obtained for Icelandic double spar than for marbles, probably due to a crystal structure of the double spar that is more insensitive to contaminating processes. The background for combusted samples is at the same level as for samples of double spar, indicating that additional 14C contamination due to combustion is negligible. Dates obtained on interstadial samples (T >30 ka bp) by both GPC and AMS agree well.

Type
I. Sample Preparation and Measurement Techniques
Copyright
Copyright © The American Journal of Science 

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