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Balanced Window Method in 14C Liquid Scintillation Counting

Published online by Cambridge University Press:  18 July 2016

P Theodórsson ,
S Ingvarsdottir  and
G I Gudjonsson
P Theodórsson*
Affiliation:
Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland.
S Ingvarsdottir
Affiliation:
Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland.
G I Gudjonsson
Affiliation:
Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland.
*
Corresponding author. Email: pth@raunvis.hi.is.
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Abstract

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The authors present a detailed theoretical and experimental study of the liquid scintillation balanced counting method, widely used in radiocarbon dating, using a simple, laboratory-made system. A fixed counting window becomes a balanced window when the high voltage is set where the 14C count rate rises to a maximum. Using a measured 14C pulse height spectrum, we have calculated the lower and upper limits for 11 balanced windows of varying width and their respective counting efficiencies. Furthermore, we have studied: (1) theoretically and experimentally, the counting efficiency for up to a ±15% shift in pulse height from the balanced setting, (2) the change in pulse height due to temperature variations, (3) the long-time stability of the system, and (4) a method that allows a quick determination of the balance voltage for individual samples, using the Compton spectrum of 133Ba. The standard deviation for thirty 24-hr measuring periods for a 14C standard (190 Bq) was within the expected statistical standard error (0.03%).

Type
Notes & Comments
Information
Radiocarbon , Volume 45 , Issue 1 , 2003 , pp. 113 - 122
Copyright
Copyright © The Arizona Board of Regents on behalf of the University of Arizona 

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