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Decision threshold associated with multiple measurements.Application to the synthesis of the environment monitoring results

Published online by Cambridge University Press:  21 March 2012

A. Vivier
Affiliation:
CEA, Institut national des sciences et techniques nucléaires, Centre de Saclay, 91191 Gif-sur-Yvette Cedex, France
G. Manificat
Affiliation:
IRSN, Direction de l’environnement et de l’intervention, Service d’étude et de surveillance de la radioactivité dans l’environnement, BP 40035, 78116 Le Vésinet Cedex, France
J-L. Picolo
Affiliation:
IRSN, Direction de l’environnement et de l’intervention, Service de traitement des échantillons et de métrologie pour l'environnement, BP 40035, 78116 Le Vésinet Cedex, France
S. Fleury
Affiliation:
IRSN, Direction de l’environnement et de l’intervention, Service de traitement des échantillons et de métrologie pour l'environnement, BP 40035, 78116 Le Vésinet Cedex, France
M. Mokili
Affiliation:
Laboratoire SUBATECH – UMR 6457, école des Mines de Nantes, IN2P3/CNRS, Université de Nantes, 4 rue Alfred Kastler, La Chantrerie, BP 20722, 44307 Nantes Cedex 03, France
X. Guo
Affiliation:
ORTEC-AMETEK Inc, 801 S. Illinois Ave., Oak Ridge, TN 37830, USA
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Abstract

When the sample activity is measured for various reasonsseveral times, then with each measurement can be associated an individualdecision threshold and limit of detection. Each measurement canbe analyzed through its own decision threshold. The whole measurementscan sometimes present contradictory results, some measurements beinglower than the decision threshold and other higher. The problemthen arises to build a decision threshold and a detection limittaking into account all the individual results, and to decide ifthe radioactivity is finally detected or not. It is interestingto note that it is possible sometimes that the decision thresholdtaking account all results makes it possible to decide that the radioactivityis present whereas the totality of the individual results are negativein terms of individual decision threshold. The purpose of this articleis to show how these thresholds and these coherent limits cumulatedcan be determined in way according to the experimental conditions.In a general way a rigorous method of cumulating makes it possibleto systematically decrease the decision threshold and limit of detectionin terms of activity. This approach has interesting applicationsin gamma spectrometry with multi-emitters, discharge or periodicalenvironmental measurements. On the basis of measurements realizedby the IRSN within the framework of the national monitoring of theenvironment, we will see the potential impact of these methods onthe final assessments.

Type
Research Article
Copyright
© EDP Sciences, 2012

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References

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