Determination of the characteristic limits (decision threshold, detection limit and limits of the coverage interval) for measurements of ionizing radiation - Fundamentals and application - Part 1: Elementary applications (ISO 11929-1:2019)

The ISO 11929 series specifies a procedure, in the field of ionizing radiation metrology, for the calculation of the "decision threshold", the "detection limit" and the "limits of the coverage interval" for a non-negative ionizing radiation measurand when counting measurements with preselection of time or counts are carried out. The measurand results from a gross count rate and a background count rate as well as from further quantities on the basis of a model of the evaluation. In particular, the measurand can be the net count rate as the difference of the gross count rate and the background count rate, or the net activity of a sample. It can also be influenced by calibration of the measuring system, by sample treatment and by other factors.
ISO 11929 has been divided into four parts covering elementary applications in this document, advanced applications on the basis of the ISO/IEC Guide 3-1 in ISO 11929-2, applications to unfolding methods in ISO 11929-3, and guidance to the application in ISO 11929-4.
This document covers basic applications of counting measurements frequently used in the field of ionizing radiation metrology. It is restricted to applications for which the uncertainties can be evaluated on the basis of the ISO/IEC Guide 98-3 (JCGM 2008). In Annex A, the special case of repeated counting measurements with random influences is covered, while measurements with linear analogous ratemeters are covered in Annex B.
ISO 11929-2 extends the former ISO 11929:2010 to the evaluation of measurement uncertainties according to the ISO/IEC Guide 98-3-1. ISO 11929-2 also presents some explanatory notes regarding general aspects of counting measurements and on Bayesian statistics in measurements.
ISO 11929-3 deals with the evaluation of measurements using unfolding methods and counting spectrometric multi-channel measurements if evaluated by unfolding methods, in particular, for alpha- and gamma‑spectrometric measurements. Further, it provides some advice on how to deal with correlations and covariances.
ISO 11929-4 gives guidance to the application of the ISO 11929 series, summarizes shortly the general procedure and then presents a wide range of numerical examples. Information on the statistical roots of ISO 11929 and on its current development may be found elsewhere[33][34].
The ISO 11929 series also applies analogously to other measurements of any kind especially if a similar model of the evaluation is involved. Further practical examples can be found, for example, in ISO 18589[1], ISO 9696[2], ISO 9697[3], ISO 9698[4], ISO 10703[5], ISO 7503[6], ISO 28218[7], and ISO 11665[8].
NOTE A code system, named UncertRadio, is available for calculations according to ISO 11929-1 to ISO 11929-3. UncertRadio[31][32] can be downloaded for free from https://www.thuenen.de/de/fi/arbeitsbereiche/meeresumwelt/leitstelle-umweltradioaktivitaet-in-fisch/uncertradio/. The download contains a setup installation file which copies all files and folders into a folder specified by the user. After installation one has to add information to the PATH of Windows as indicated by a pop‑up window during installation. English language can be chosen and extensive "help" information is available.

Bestimmung der charakteristischen Grenzen (Erkennungsgrenze, Nachweisgrenze und Grenzen des Überdeckungsintervalls) bei Messungen ionisierender Strahlung - Grundlagen und Anwendungen - Teil 1: Elementare Anwendungen (ISO 11929-1:2019)

Die Reihe ISO 11929 legt im Bereich der Metrologie ionisierender Strahlung ein Verfahren zur Berechnung der „Erkennungsgrenze“, der „Nachweisgrenze“ und der „Grenzen des Überdeckungsintervalls“ für eine nicht-negative Messgröße der ionisierenden Strahlung bei Messungen mit Zeit- und Impulsvorwahl fest. Das Mess-ergebnis ergibt sich aus den Ergebnissen von Messungen einer Bruttozählrate und einer Nulleffektzähl¬rate sowie weiteren Größen aufgrund eines Modells der Auswertung. Insbesondere kann die Messgröße die Net-tozählrate als Differenz der Bruttozählrate und der Nulleffektzählrate oder die Nettoaktivität einer Probe sein. Sie kann auch durch Kalibrierung der Messeinrichtung, Probenbehandlung und andere Faktoren beein¬flusst sein.
ISO 11929 ist in vier Teile aufgeteilt: elementare Anwendungen in ISO 11929-1, fortgeschrittene Anwendun-gen auf der Grundlage von ISO/IEC Guide 98-3-1 in ISO 11929-2, Anwendungen auf Entfaltungsmethoden in ISO 11929-3 und Anleitungen zur Anwendung in ISO 11929-4.
Dieses Dokument behandelt elementare Anwendungen zählender Messungen, wie sie häufig im Bereich der Metrologie ionisierender Strahlung auftreten werden. Es beschränkt sich auf Anwendungen, bei denen die Unsicherheiten auf der Grundlage des ISO/IEC Guide 98-3 (JCGM 2008) ermittelt werden können. In Anhang A wird der spezielle Fall wiederholter zählender Messungen mit zufälligen Einflüssen und in Anhang B werden Messungen mit linearen analogen Ratemetern behandelt.
ISO 11929-2 erweitert die frühere ISO 11929:2010 um die Auswertung von Messungen, bei denen die Mess-unsicherheiten nach ISO/IEC Guide 98-3-1 ermittelt werden. ISO 11929-2 enthält außerdem Erläuterungen zu allgemeinen Aspekten zählender Messungen und zur Anwendung der Bayes-Statistik auf Messungen.
ISO 11929-3 behandelt die Auswertung von Messungen mit Hilfe von Entfaltungsverfahren und zählende Vielkanalmessungen, falls sie mit Entfaltungsmethoden ausgewertet werden, insbesondere für alpha- und gamma-spektrometrische Messungen. Außerdem gibt ISO 11929-3 Anleitungen, wie mit Korrelationen und Kovarianzen zu verfahren ist.
ISO 11929-4 gibt nach einer kurzen Darstellung des Verfahrens mit einer Fülle von numerischen Beispielen Anleitungen zur Anwendung der Reihe ISO 11929. Informationen über die statistischen Grundlagen von ISO 11929 und ihrer aktuellen Entwicklung können an anderer Stelle gefunden werden [33], [34].
Sinngemäß gilt die Reihe ISO 11929 auch bei anderen Messungen gleich welcher Art, wenn das selbe Modell der Auswertung anzuwenden ist. Weitere praktische Beispiele können anderen ISO-Normen entnom-men werden, z. B. ISO 18589 [1], ISO 9696 [2], ISO 9697 [3], ISO 9698 [4], ISO 10703 [5], ISO 7503 [6], ISO 28218 [7], und ISO 11665 [8].
ANMERKUNG   Ein Programmpaket namens UncertRadio ist für Berechnungen nach ISO 11929-1 bis ISO 11929-3 ver¬fügbar. UncertRadio [31], [32] kann unter https://www.thuenen.de/de/fi/arbeitsbereiche/meeresumwelt/leitstelle-umwelt¬radio¬aktivität-in-fisch/uncertradio/ kostenfrei heruntergeladen werden. Der Download enthält eine Installationsdatei, die alle Dateien in einen vom Benutzer spezifizierten Ordner kopiert. Nach der Installation ist noch eine Information, die wäh¬rend der Installation durch ein Pop-up-Fenster angezeigt wird, zum „PFAD“ von Windows hinzuzufügen. Es kann deut¬sche oder englische Sprache gewählt werdenN2 und es ist eine ausführliche „Hilfe“-Information verfügbar.

Détermination des limites caractéristiques (seuil de décision, limite de détection et extrémités de l'intervalle élargi) pour mesurages de rayonnements ionisants - Principes fondamentaux et applications - Partie 1: Applications élémentaires (ISO 11929-1:2019)

La série ISO 11929 spécifie une procédure applicable, dans le domaine de la métrologie des rayonnements ionisants, pour le calcul du «seuil de décision», de la «limite de détection» et des «limites de l'intervalle élargi» pour un mesurande de rayonnement ionisant non négatif, lorsque des mesurages par comptage sont effectués avec une présélection du temps ou du nombre d'impulsions. Le mesurande résulte d'un taux de comptage brut et d'un taux de comptage du bruit de fond ainsi que de grandeurs supplémentaires reposant sur un modèle d'évaluation. En particulier, le mesurande peut être le taux de comptage net défini comme la différence du taux de comptage brut et du taux de comptage du bruit de fond, ou l'activité nette d'un échantillon. Il peut également être influencé par l'étalonnage du système de mesure, par le traitement de l'échantillon et par d'autres facteurs.
L'ISO 11929 a été scindée en quatre parties couvrant les applications élémentaires dans le présent document, les applications avancées reposant sur le Guide ISO/IEC 3-1 dans l'ISO 11929-2, les applications aux méthodes de déconvolution dans l'ISO 11929-3, et les recommandations d'application dans l'ISO 11929-4.
Le présent document couvre les applications de base des mesurages par comptage souvent utilisés dans le domaine de la métrologie des rayonnements ionisants. Il se limite aux applications pour lesquelles il est possible d'évaluer les incertitudes sur la base du Guide ISO/IEC 98-3 (JCGM 2008). L'Annexe A traite du cas particulier des mesurages répétés par comptage avec des influences aléatoires, alors que l'Annexe B couvre les mesurages avec des ictomètres analogiques linéaires.
L'ISO 11929-2 étend l'ancienne ISO 11929:2010 à l'évaluation des incertitudes de mesure conformément au Guide ISO/IEC 98-3-1. L'ISO 11929-2 contient également plusieurs notes explicatives concernant les aspects généraux des mesurages par comptage et les statistiques bayésiennes dans les mesurages.
L'ISO 11929-3 traite de l'évaluation des mesurages en utilisant des méthodes de déconvolution ainsi que de l'évaluation des mesurages multicanaux spectrométriques par comptage en cas d'évaluation par des méthodes de déconvolution, en particulier pour les mesurages spectrométriques alpha et gamma. Elle fournit en outre des conseils pour le traitement avec des corrélations et des covariances.
L'ISO 11929-4 fournit des recommandations pour l'application de la série ISO 11929, résume les grandes lignes de la procédure générale et présente ensuite un large éventail d'exemples numériques. Des informations relatives à l'origine des statistiques de l'ISO 11929 et à son stade de développement actuel peuvent être trouvées dans les Références [33][34].
La série ISO 11929 s'applique également de manière analogue à d'autres mesurages de tout type, notamment si un modèle d'évaluation similaire est concerné. Des exemples pratiques complémentaires peuvent être trouvés, par exemple, dans l'ISO 18589[1], l'ISO 9696[2], l'ISO 9697[3], l'ISO 9698[4], l'ISO 10703[5], l'ISO 7503[6], l'ISO 28218[7] et l'ISO 11665[8].
NOTE Un logiciel, baptisé UncertRadio, est disponible pour les calculs conformes aux ISO 11929-1 à ISO 11929-3. UncertRadio[31][32] peut être téléchargé gratuitement à l'adresse: https://www.thuenen.de/de/fi/arbeitsbereiche/meeresumwelt/leitstelle-umweltradioaktivitaet-in-fisch/uncertradio/. Le logiciel disponible en téléchargement contient un fichier d'installation qui copie tous les fichiers et dossiers

Ugotavljanje karakterističnih mej (odločitveni prag, zaznavanje meje in omejitev intervala pokritja) pri meritvah ionizirnega sevanja - Osnove in uporaba - 1. del: Osnovne aplikacije (ISO 11929-1:2019)

General Information

Status
Published
Public Enquiry End Date
16-Dec-2020
Publication Date
21-Feb-2021
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
18-Feb-2021
Due Date
25-Apr-2021
Completion Date
22-Feb-2021

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SLOVENSKI STANDARD
SIST EN ISO 11929-1:2021
01-april-2021
Ugotavljanje karakterističnih mej (odločitveni prag, zaznavanje meje in omejitev

intervala pokritja) pri meritvah ionizirnega sevanja - Osnove in uporaba - 1. del:

Osnovne aplikacije (ISO 11929-1:2019)

Determination of the characteristic limits (decision threshold, detection limit and limits of

the coverage interval) for measurements of ionizing radiation - Fundamentals and
application - Part 1: Elementary applications (ISO 11929-1:2019)
Bestimmung der charakteristischen Grenzen (Erkennungsgrenze, Nachweisgrenze und
Grenzen des Überdeckungsintervalls) bei Messungen ionisierender Strahlung -
Grundlagen und Anwendungen - Teil 1: Elementare Anwendungen (ISO 11929-1:2019)

Détermination des limites caractéristiques (seuil de décision, limite de détection et

extrémités de l'intervalle élargi) pour mesurages de rayonnements ionisants - Principes

fondamentaux et applications - Partie 1: Applications élémentaires (ISO 11929-1:2019)

Ta slovenski standard je istoveten z: EN ISO 11929-1:2021
ICS:
17.240 Merjenje sevanja Radiation measurements
SIST EN ISO 11929-1:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 11929-1:2021
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SIST EN ISO 11929-1:2021
EN ISO 11929-1
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2021
EUROPÄISCHE NORM
ICS 17.240
English Version
Determination of the characteristic limits (decision
threshold, detection limit and limits of the coverage
interval) for measurements of ionizing radiation -
Fundamentals and application - Part 1: Elementary
applications (ISO 11929-1:2019)

Détermination des limites caractéristiques (seuil de Bestimmung der charakteristischen Grenzen

décision, limite de détection et extrémités de (Erkennungsgrenze, Nachweisgrenze und Grenzen des

l'intervalle élargi) pour mesurages de rayonnements Überdeckungsintervalls) bei Messungen ionisierender

ionisants - Principes fondamentaux et applications - Strahlung - Grundlagen und Anwendungen - Teil 1:

Partie 1: Applications élémentaires (ISO 11929- Elementare Anwendungen (ISO 11929-1:2019)

1:2019)
This European Standard was approved by CEN on 18 January 2021.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11929-1:2021 E

worldwide for CEN national Members.
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SIST EN ISO 11929-1:2021
EN ISO 11929-1:2021 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 11929-1:2021
EN ISO 11929-1:2021 (E)
European foreword

The text of ISO 11929-1:2019 has been prepared by Technical Committee ISO/TC 85 "Nuclear energy,

nuclear technologies, and radiological protection” of the International Organization for Standardization

(ISO) and has been taken over as EN ISO 11929-1:2021 by Technical Committee CEN/TC 430 “Nuclear

energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by August 2021, and conflicting national standards shall

be withdrawn at the latest by August 2021.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 11929-1:2019 has been approved by CEN as EN ISO 11929-1:2021 without any

modification.
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SIST EN ISO 11929-1:2021
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SIST EN ISO 11929-1:2021
INTERNATIONAL ISO
STANDARD 11929-1
Second edition
2019-02
Determination of the characteristic
limits (decision threshold, detection
limit and limits of the coverage
interval) for measurements of ionizing
radiation — Fundamentals and
application —
Part 1:
Elementary applications
Détermination des limites caractéristiques (seuil de décision, limite
de détection et extrémités de l'intervalle élargi) pour mesurages de
rayonnements ionisants — Principes fondamentaux et applications —
Partie 1: Applications élémentaires
Reference number
ISO 11929-1:2019(E)
ISO 2019
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SIST EN ISO 11929-1:2021
ISO 11929-1:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
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Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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SIST EN ISO 11929-1:2021
ISO 11929-1:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 2

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Quantities and symbols ................................................................................................................................................................................. 6

5 Summary of procedures for evaluating a measurement and calculating the

characteristic limits .......................................................................................................................................................................................... 8

5.1 General aspects ....................................................................................................................................................................................... 8

5.2 Modelling the measurement ....................................................................................................................................................... 9

5.3 General considerations about the applicability of the ISO/IEC Guide 98-3 ....................................... 9

5.4 Evaluating the input quantities, standard uncertainties and covariances, and the

primary result and its associated standard uncertainty ..................................................................................10

5.5 Evaluating the standard uncertainty as a function of an assumed true value of the

measurand ...............................................................................................................................................................................................10

5.6 Calculating the decision threshold and decisions to be made ....................................................................11

5.7 Calculating the detection limit and assessment of the measurement procedure ......................12

5.8 Calculating a coverage interval for the measurand ..............................................................................................12

5.9 Calculating the best estimate of the measurand and its associated standard uncertainty 13

5.10 Reporting the results ......................................................................................................................................................................14

6 Fundamentals and evaluation of the measurement .....................................................................................................16

6.1 General aspects concerning the measurand ...............................................................................................................16

6.2 Model of evaluation ..........................................................................................................................................................................16

6.2.1 General model .................................................................................................................................................................16

6.2.2 Model in ionizing radiation counting measurements ...................................................................17

6.3 Evaluation of the primary measurement result ......................................................................................................18

6.4 Standard uncertainty associated with the primary measurement result .........................................18

7 Standard uncertainty as a function of an assumed value of the measurand ......................................19

8 Decision threshold, detection limit and assessments ................................................................................................21

8.1 Specifications.........................................................................................................................................................................................21

8.2 Decision threshold ............................................................................................................................................................................21

8.3 Detection limit ......................................................................................................................................................................................21

8.4 Assessments ...........................................................................................................................................................................................22

9 Limits of the coverage interval ............................................................................................................................................................23

9.1 General aspects ....................................................................................................................................................................................23

9.2 The probabilistically symmetric coverage interval ..............................................................................................23

9.3 The shortest coverage interval ...............................................................................................................................................24

10 The best estimate and its associated standard uncertainty .................................................................................24

11 Documentation ....................................................................................................................................................................................................25

Annex A (normative) Repeated counting measurements with random influences .........................................26

Annex B (normative) Measurements with ratemeters ...................................................................................................................31

Annex C (informative) Calculation of the detection limit by iteration ...........................................................................33

Annex D (informative) Calculations with a generalized net count rate ........................................................................35

Annex E (informative) Distribution function of the standardized normal distribution ..............................38

Bibliography .............................................................................................................................................................................................................................40

© ISO 2019 – All rights reserved iii
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SIST EN ISO 11929-1:2021
ISO 11929-1:2019(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso

.org/iso/foreword .html.

This document was prepared by This document was prepared by ISO/TC 85, Nuclear energy, nuclear

technologies, and radiological protection, Subcommittee SC 2, Radiological protection.

This second edition of ISO 11929-1 together with ISO 11929-2 and ISO 11929-3, cancels and replaces

ISO 11929:2010, which has been technically revised. The main change is specifically with reference

to the type of statistical treatment of the data and extended with respect to the methodology of

uncertainty assessment from ISO/IEC Guide 98-3:2009, to the ISO/IEC Guide 98-3-1:2008.

A list of all the parts in the ISO 11929 series can be found on the ISO website.
iv © ISO 2019 – All rights reserved
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SIST EN ISO 11929-1:2021
ISO 11929-1:2019(E)
Introduction

Measurement uncertainties and characteristic values, such as the decision threshold, the detection limit

and limits of the coverage interval for measurements, as well as the best estimate and its associated

standard measurement uncertainty, are of importance in metrology in general and for radiological

protection in particular. The quantification of the uncertainty associated with a measurement result

provides a basis for the trust an individual can have in a measurement result. Conformity with

regulatory limits, constraints or reference values can only be demonstrated by taking into account and

quantifying all sources of uncertainty. Characteristic limits provide, at the end, the basis for deciding if

uncertainties have to be taken into account.

This standard provides characteristic values of a non-negative measurand of ionizing radiation. It is

also applicable for a wide range of measuring methods extending beyond measurements of ionizing

radiation.

The limits to be provided according to ISO 11929 series for specified probabilities of wrong decisions

allow detection possibilities to be assessed for a measurand and for the physical effect quantified by

this measurand as follows:

— the “decision threshold” allows a decision to be made on whether or not the physical effect quantified

by the measurand is present;

— the “detection limit” indicates the smallest true quantity value of the measurand that can still be

detected with the applied measurement procedure; this gives a decision on whether or not the

measurement procedure satisfies the requirements and is therefore suitable for the intended

measurement purpose;

— the “limits of the coverage interval” enclose, in the case of the physical effect recognized as present,

a coverage interval containing the true quantity value of the measurand with a specified probability.

Hereinafter, the limits mentioned are jointly called the “characteristic limits”.

NOTE According to ISO/IEC Guide 99:2007 updated by JCGM 200:2012 the term “coverage interval” is used

here instead of “confidence interval” in order to distinguish the wording of Bayesian terminology from that of

conventional statistics.

All the characteristic values are based on Bayesian statistics and on the ISO/IEC 98-3 as well as on

the ISO/IEC Guide 98-3-1 and ISO/IEC 98-3-2. As explained in detail in ISO 11929-2, the characteristic

values are mathematically defined by means of moments and quantiles of probability distributions of

the possible measurand values.

Since measurement uncertainty plays an important part in ISO 11929, the evaluation of measurements

and the treatment of measurement uncertainties are carried out by means of the general procedures

according to the ISO/IEC Guide 98-3 and to the ISO/IEC Guide 98-3-1; see also References [13] to [17].

This enables the strict separation of the evaluation of the measurements, on the one hand, and the

provision and calculation of the characteristic values, on the other hand. The ISO 11929 series makes use

of a theory of uncertainty in measurement [18] to [20] based on Bayesian statistics (e.g. see References

[21] to [26]) in order to take into account those uncertainties that cannot be derived from repeated or

counting measurements. The latter uncertainties cannot be handled by frequentist statistics.

Because of developments in metrology concerning measurement uncertainty laid down in the ISO/

IEC Guide 98-3, ISO 11929:2010 was drawn up on the basis of the ISO/IEC Guide 98-3, but using

Bayesian statistics and the Bayesian theory of measurement uncertainty. This theory provides a

Bayesian foundation for the ISO/IEC Guide 98-3. Moreover, ISO 11929:2010 was based on the definitions

[13] [14] [15]

of the characteristic values , the standard proposal , and the explanatory article . It unified

and replaced all earlier parts of ISO 11929 and was applicable not only to a large variety of particular

measurements of ionizing radiation but also, in analogy, to other measurement procedures.

In 2008 the ISO/IEC Guide 98-3-1 has been published, dealing comprehensively with a more general

treatment of measurement uncertainty using the Monte Carlo method in complex measurement

© ISO 2019 – All rights reserved v
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SIST EN ISO 11929-1:2021
ISO 11929-1:2019(E)
[16]

evaluations. This provided an incentive for writing a corresponding Monte Carlo supplement to

ISO 11929:2010 and to revise ISO 11929:2010. The revised ISO 11929 is also essentially founded on

Bayesian statistics and can serve as a bridge between ISO 11929:2010 and the ISO/IEC Guide 98-3-

1. Moreover, more general definitions of the characteristic values (ISO 11929-2) and the Monte Carlo

computation of the characteristic values make it possible to go a step beyond the present state of

standardization laid down in ISO 11929:2010 since probability distributions rather than uncertainties

can be propagated. It is thus more comprehensive and extending the range of applications.

The revised ISO 11929, moreover, is more explicit on the calculation of the characteristic values. It

corrects also a problem in ISO 11929:2010 regarding uncertain quantities and influences, which do not

behave randomly in measurements repeated several times. Reference [17] gives a survey on the basis

of the revision. Furthermore, in ISO 11929-3, it gives detailed advice how to calculate characteristic

values in the case of multivariate measurements using unfolding methods. For such measurements, the

ISO/IEC Guide 3-2 provides the basis of the uncertainty evaluation.

Formulas are provided for the calculation of the characteristic values of an ionizing radiation measurand

via the “standard measurement uncertainty” of the measurand (hereinafter the “standard uncertainty”)

derived according to the ISO/IEC Guide 98-3 as well as via probability density functions (PDFs) of

the measurand derived in accordance with the ISO/IEC Guide 98-3-1. The standard uncertainties or

probability density functions take into account the uncertainties of the actual measurement as well

as those of sample treatment, calibration of the measuring system and other influences. The latter

uncertainties are assumed to be known from previous investigations.
vi © ISO 2019 – All rights reserved
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SIST EN ISO 11929-1:2021
INTERNATIONAL STANDARD ISO 11929-1:2019(E)
Determination of the characteristic limits (decision
threshold, detection limit and limits of the coverage
interval) for measurements of ionizing radiation —
Fundamentals and application —
Part 1:
Elementary applications
1 Scope

The ISO 11929 series specifies a procedure, in the field of ionizing radiation metrology, for the

calculation of the “decision threshold”, the “detection limit” and the “limits of the coverage interval” for

a non-negative ionizing radiation measurand when counting measurements with preselection of time

or counts are carried out. The measurand results from a gross count rate and a background count rate

as well as from further quantities on the basis of a model of the evaluation. In particular, the measurand

can be the net count rate as the difference of the gross count rate and the background count rate, or

the net activity of a sample. It can also be influenced by calibration of the measuring system, by sample

treatment and by other factors.

ISO 11929 has been divided into four parts covering elementary applications in this document, advanced

applications on the basis of the ISO/IEC Guide 3-1 in ISO 11929-2, applications to unfolding methods in

ISO 11929-3, and guidance to the application in ISO 11929-4.

This document covers basic applications of counting measurements frequently used in the field

of ionizing radiation metrology. It is restricted to applications for which the uncertainties can be

evaluated on the basis of the ISO/IEC Guide 98-3 (JCGM 2008). In Annex A, the special case of repeated

counting measurements with random influences is covered, while measurements with linear analogous

ratemeters are covered in Annex B.

ISO 11929-2 extends the former ISO 11929:2010 to the evaluation of measurement uncertainties

according to the ISO/IEC Guide 98-3-1. ISO 11929-2 also presents some explanatory notes regarding

general aspects of counting measurements and on Bayesian statistics in measurements.

ISO 11929-3 deals with the evaluation of measurements using unfolding methods and counting

spectrometric multi-channel measurements if evaluated by unfolding methods, in particular, for

alpha- and gamma-spectrometric measurements. Further, it provides some advice on how to deal with

correlations and covariances.

ISO 11929-4 gives guidance to the application of the ISO 11929 series, summarizes shortly the general

procedure and then presents a wide range of numerical examples. Information on the statistical roots

[33][34]
of ISO 11929 and on its current development may be found elsewhere .

The ISO 11929 series also applies analogously to other measurements of any kind especially if a

similar model of the evaluation is involved. Further practical examples can be found, for example,

[1] [2] [3] [4] [5] [6] [7]

in ISO 18589 , ISO 9696 , ISO 9697 , ISO 9698 , ISO 10703 , ISO 7503 , ISO 28218 , and

[8]
ISO 11665 .

NOTE A code system, named UncertRadio, is available for calculations according to ISO 11929-1

[31][32]

to ISO 11929-3. UncertRadio can be downloaded for free from https: //www .thuenen

.de/de/fi/arbeitsbereiche/meeresumwelt/leitstelle -umweltradioaktivitaet -in -fisch/uncertradio/. The

download contains a setup installation file which copies all files and folders into a folder specified by the user.

After installation one has to add information to the PATH of Windows as indicated by a pop-up window during

installation. English language can be chosen and extensive “help” information is available.

© ISO 2019 – All rights reserved 1
---------------------- Page: 13 ----------------------
SIST EN ISO 11929-1:2021
ISO 11929-1:2019(E)
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 3534-1, Statistics — Vocabulary and symbols — Part 1: General statistical terms and terms used in

probability
ISO 80000-1, Quantities and units — Part 1: General
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 1: Guide to the expression of uncertainty in

measurement, JCGM 100:2008.

ISO/IEC Guide 98-3-1, Evaluation of measurement data — Supplement 1 to the “Guide to the expression of

uncertainty in measurement” — a Propagation of distributions using a Monte Carlo method, JCGM 101:2008

ISO/IEC Guide 98-3-2, Evaluation of measurement data — Supplement 2 to the “Guide to the expression of

uncertainty in measurement” — Models with any number of output quantities, JCGM 102:2011

ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated

terms (VIM), JCGM 200:2012
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 80000-1, ISO 80000-10,

ISO/IEC Guide 98-3, ISO/IEC Guide 98-3-1, ISO/IEC 98-3-2, ISO/IEC Guide 99 and ISO 3534-1 and the

following apply.
3.1
quantity value
value of a quantity
value
number and reference together expressing magnitude of a quantity
[SOURCE: JCGM 200:2012, 1.19]
3.2
measurement

process of experimentally obtaining one or more quantity values that can reasonably be attributed to a

quantity
[SOURCE: JCGM 200:2012, 2.1]
3.3
measurand
quantity intended to be measured
[SOURCE: JCGM 200:2012, 2.3]
3.4
coverage interval

interval containing the set of true quantity values of a measurand with a stated probability, based on

the information available
[SOURCE: JCGM 200:2012, 2.36]

Note 1 to entry: A coverage interval does not need to be centred on the chosen measured quantity value (see

JCGM
...

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