ISO 11929-1:2025

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 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 REF Annex_sec_A \r \h Annex A 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000C00000041006E006E00650078005F007300650063005F0041000000 , the special case of repeated counting measurements with random influences is covered, while measurements with linear analogous ratemeters are covered in REF Annex_sec_B \r \h Annex B 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000C00000041006E006E00650078005F007300650063005F0042000000 . ISO 11929-2 extends the former ISO 11929:2010 to the evaluation of measurement uncertainties according to the ISO/IEC Guide 98-3:2008/Suppl 1:2008. 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[ REF Reference_ref_40 \r \h 33 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000110000005200650066006500720065006E00630065005F007200650066005F00340030000000 ][ REF Reference_ref_41 \r \h 34 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000110000005200650066006500720065006E00630065005F007200650066005F00340031000000 ]. 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[ REF Reference_ref_8 \r \h 1 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000100000005200650066006500720065006E00630065005F007200650066005F0038000000 ], ISO 9696[ REF Reference_ref_9 \r \h 2 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000100000005200650066006500720065006E00630065005F007200650066005F0039000000 ], ISO 9697[ REF Reference_ref_10 \r \h 3 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000110000005200650066006500720065006E00630065005F007200650066005F00310030000000 ], ISO 9698[ REF Reference_ref_11 \r \h 4 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000110000005200650066006500720065006E00630065005F007200650066005F00310031000000 ], ISO 10703[ REF Reference_ref_12 \r \h 5 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000110000005200650066006500720065006E00630065005F007200650066005F00310032000000 ], ISO 7503[ REF Reference_ref_13 \r \h 6 08D0C9EA79