ISO 11929-3:2019
Determination of the characteristic limits (decision threshold, detection limit and limits of the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 3: Applications to unfolding methods
Determination of the characteristic limits (decision threshold, detection limit and limits of the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 3: Applications to unfolding methods
- Статус документа:
- Отменён
- Формат:
- Электронный (PDF)
- Количество страниц:
- 39
- Дата публикации:
- 13 февраля 2019 г.
- Издание:
- ISO IS 11929 edition 2 version 1
- ICS:
- 17.240
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 ISO 11929-1, advanced applications on the basis of the ISO/IEC Guide 98-3-1 in ISO 11929-2, applications to unfolding methods in this document, and guidance to the application in ISO 11929-4. ISO 11929-1 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 of ISO 11929-1:2019, the special case of repeated counting measurements with random influences is covered, while measurements with linear analogous ratemeters, are covered in Annex B of ISO 11929-1:2019. 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. This document 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. ISO 11929 Standard 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[7], ISO 9696[2], ISO 9697[3], ISO 9698[4], ISO 10703[5], ISO 7503[1], ISO 28218[8], and ISO 11665[6]. NOTE A code system, named UncertRadio, is available for calculations according to ISO 11929- 1 to ISO 11929-3. UncertRadio[35][36] can be downloaded for free from https://www.thuenen.de/en/fi/fields-of-activity/marine-environment/coordination-centre-of-radioactivity/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.
Abstract
Overview
ISO 11929-3:2019 is Part 3 of the ISO 11929 series that defines procedures to determine characteristic limits - the decision threshold, detection limit and limits of the coverage interval - for measurements of ionizing radiation when evaluated by unfolding methods. Built on the ISO/IEC Guide 98-3 and its Monte Carlo supplement (Guide 98-3-1), the standard adopts Bayesian-based uncertainty treatment and is applicable to multichannel spectrometric data, in particular alpha- and gamma‑spectrometric measurements and other measurements that use similar evaluation models.
Key Topics
- Unfolding methods: Guidance on modelling unfolding as a sub-model within the overall measurement evaluation and on the stepwise unfolding procedure.
- Characteristic limits: Definitions and calculation approaches for the decision threshold, detection limit and coverage interval for non‑negative measurands.
- Measurement uncertainty: Evaluation following ISO/IEC Guide 98-3 and Guide 98-3-1, including propagation of uncertainties via Monte Carlo techniques and Bayesian statistics.
- Count data treatment: Adaptations for Poisson-distributed counts and preselection by time or counts.
- Correlations and covariances: Advice on handling multivariate correlations arising in spectrum unfolding and multi‑channel measurements.
- Documentation and reporting: Requirements for documenting models, input quantities and uncertainty assessments.
- Tools: Reference to the UncertRadio code for calculations compatible with ISO 11929-1 to -3.
Applications
ISO 11929-3 is used where reliable detection capability and uncertainty characterization are essential:
- Radiological protection and environmental monitoring (low‑level radioactivity surveys)
- Nuclear industry and laboratories performing alpha/gamma spectrometry and multi‑channel analyses
- Calibration and metrology institutes that evaluate complex instrument response via unfolding
- Research groups working on spectrometric deconvolution, detector response correction, or multivariate measurement models
Users benefit from standardized procedures to decide whether a physical effect is present (decision threshold), quantify minimal detectable values (detection limit), and provide probabilistic coverage intervals for reported measurands.
Related Standards
- ISO 11929-1: Basic counting applications and special cases (repeated counts, ratemeters)
- ISO 11929-2: Advanced uncertainty treatment and Monte Carlo methods (Guide 98-3-1)
- ISO 11929-4: Guidance, summary and numerical examples for the ISO 11929 series
- ISO/IEC Guide 98-3 and Guide 98-3-1: Uncertainty of measurement and Monte Carlo methods
Keywords: ISO 11929-3, decision threshold, detection limit, coverage interval, unfolding methods, ionizing radiation, measurement uncertainty, Bayesian, Monte Carlo, alpha spectrometry, gamma spectrometry, UncertRadio.
Технические детали
- Технический комитет
- ISO/TC 85/SC 2 - Radiological protection
- SKU
- ISO 11929-3:2019
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