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Performance of the Packard Tri-Carb® 2770TR/SL Liquid Scintillation Analyzer for 14C Dating

Published online by Cambridge University Press:  18 July 2016

C. J. Passo ,
Robert Anderson ,
David Roberts  and
G. T. Cook
C. J. Passo
Affiliation:
Packard Instrument Company, 800 Research Parkway, Meriden, Connecticut 06450 USA
Robert Anderson
Affiliation:
Scottish Universities Research & Reactor Centre, Scottish Enterprise Technology Park, East Kilbride, G75 0QF, Scotland
David Roberts
Affiliation:
Packard Instrument Company, 800 Research Parkway, Meriden, Connecticut 06450 USA
G. T. Cook
Affiliation:
Scottish Universities Research & Reactor Centre, Scottish Enterprise Technology Park, East Kilbride, G75 0QF, Scotland
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Abstract

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We present results that demonstrate the potential of the Packard Tri-Carb® Model 2770TR/SL for radiocarbon dating. For 2 g of sample benzene, a stable background count rate of 0.307 cpm and a stable counting efficiency of 64.78% were determined using a 13–75 keV counting window. Changes to the mathematical routines for t-SIE (quench indicating parameter) calculation and a reduction in the activity of the external standard have enabled stability of the t-SIE to be achieved, and combined with the use of a suitable balance point counting window; all of these factors give the stability of performance required for 14C dating. Calculations based on the above parameters indicate that the limit of detection for 2 g samples, counted for 5000 min, is >48,900 yr bp. The great advantage of this system is that these data were acquired using inexpensive standard 7-mL low potassium borosilicate glass vials. Vial holders manufactured from BGO reduced the background to 0.15 cpm with a minimum effect on efficiency (64.46% for 13–75 keV). A similar calculation of the limit of detection gave >51,700 bp. The use of the BGO vial holders in other instruments employing time-resolved liquid scintillation counting (TR-LSC) (Models 2250CA and 2260XL) also brought about significant improvements in detection limits.

Type
Part 1: Methods
Information
Radiocarbon , Volume 40 , Issue 1: 16th International Radiocarbon Conference 16-20,1997 Groningen , 1997 , pp. 193 - 200
Copyright
Copyright © The American Journal of Science 

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