UNE-EN ISO 11929-2:2025

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 GUM Supplement 1 in this document, applications to unfolding methods in

ISO 11929-3, 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 ISO 11929-1: , Annex A, the special case of repeated counting

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

are covered in ISO 11929-1: , Annex B.

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 ISO 11929, 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[30][31].

ISO 11929 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 119291 to ISO 11929-3.

UncertRadio[27][28] can be downloaded for free from https:// www .thuenen .de/ en/ institutes/ fisheries -ecology/ 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. Another tool is the package metRology [32] which is available

for programming in R. It contains the two R functions uncert and uncertMC which perform the GUM conform

uncertainty propagation, either analytically or by the Monte Carlo method, respectively. Covariances/correlations of

input quantities are included. Applying these two functions within iterations for decision threshold and the detection

limit calculations simplifies the programming effort significantly. It is also possible to implement this document in a

spreadsheet containing a Monte Carlo add-in or into other commercial mathematics software.