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High-Performance 14C Gas-Proportional Counting System Applying Pulse-Shape Discrimination

Published online by Cambridge University Press:  18 July 2016

Osmo Äikää ,
Pertti Mäntynen  and
Tuovi Kankainen
Osmo Äikää
Affiliation:
Geological Survey of Finland, SF-02150 Espoo, Finland
Pertti Mäntynen
Affiliation:
Geological Survey of Finland, SF-02150 Espoo, Finland
Tuovi Kankainen
Affiliation:
Geological Survey of Finland, SF-02150 Espoo, Finland
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Abstract

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The new 14C dating system of the Geological Survey of Finland consists of three CO2 proportional counters of conventional size, a liquid scintillation anticoincidence guard, and a passive shield of about 90-year-old iron. The counting room is an air-conditioned Faraday cage constructed of concrete with aggregate of crystalline Precambrian limestone. We apply pulse-shape discrimination that greatly improves the precision of our 14C analyses - the reduction of background is over 70%, while the modern count rate is reduced only by 15 to 20%. The purity of the counting gas is monitored by recording the cosmic muon pulse-height spectrum. At present, the dating limit for a two-day measurement is 57 ka. We summarize here the most significant results and aspects of pulse-shape discrimination

Type
I. Sample Preparation and Measurement Techniques
Information
Radiocarbon , Volume 34 , Issue 3: Proceedings of the 14th International Radiocarbon Conference , 1992 , pp. 414 - 419
Copyright
Copyright © The American Journal of Science 

References

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