DIN EN ISO 11929-4:2024-03

Measurement uncertainties and characteristic limits, namely characteristic limits such as the decision threshold, the detection limit and the limits of the coverage interval, as well as the best estimate and the standard uncertainty associated with it, are of particular importance in metrology in general and in radiation protection in particular. Quantifying the uncertainty associated with a measurement result provides a basis for the confidence that an individual can place in that measurement result. ISO 11929 deals with the characteristic limits for a non-negative measured variable in the measurement of ionizing radiation. However, it is applicable to a wide range of measurement procedures that goes far beyond the measurement of ionizing radiation. The ISO 11929 series of standards consists of four documents: - ISO 11929-1 (VDE 0493-9291) deals with elementary applications of counting measurements, such as those frequently encountered in the field of metrology of ionizing radiation; DIN EN ISO 11929-2 (VDE 0493-9292) extends DIN EN ISO 11929-1 (VDE 0493-9291) to the evaluation of measurements in which the measurement uncertainties are determined according to ISO/IEC Guide 98-3:2008/Supplement 1. The standard also contains explanations of general aspects of counting measurements and of the application of Bayesian statistics to measurements; - DIN EN ISO 11929-3 (VDE 0493-9293) deals with the evaluation of measurements using unfolding methods and counting spectrometric multi-channel measurements if evaluated by unfolding methods, in particular, alpha- and gamma-spectrometric measurements. Further, it provides some advice how to deal with correlations and covariances. DIN EN ISO 11929-4 (VDE 0493-9294) provides a brief description of the procedure with a total of thirteen numerical examples to illustrate how to apply the standards in the DIN EN ISO 11929 series. The standard differs from DIN ISO 11929-4 (VDE 0493-9294): 2021-06 as follows: a) the corrections marked with national footnotes in DIN ISO 11929-4 (VDE 0493-9294):2021-06 compared to ISO 11929-4:2020 have been incorporated into the 2022 edition of the ISO standard. The application examples covered in this document are: - the simple model of a counting measurement with small or moderate relative uncertainties, which is used in the vast majority of laboratory measurements, - an example of the measurement of alpha particles with few counting events, - a counting measurement with uncertain geometry, where the uncertainties of the calibration factor are large and, as a consequence, a dominant uncertainty in the numerator of the calibration factor occurs, - a counting measurement in the form of a wipe test, where the uncertainties are generally large and a dominant uncertainty in the denominator of the calibration factor occurs, - a measurement in which large uncertainties occur as a result of shielding of the background, as is the case, for example, with measurements using a portal monitor, - a release measurement of a bulk sample of concrete using a special measuring device, taking into account the natural radioactivity of the sample when subtracting the background, - the general model for gamma spectrometry of U-235 taking into account an interference of Ra-226, - a measurement of an ambient dose equivalent rate with a measurement set-up of unknown functionality and algorithms; that is, a so-called black box measurement, for which no information about the measurement procedure is available and only the read values of an indicator are available, - the case of counting measurements with random influences of sample treatment, - a counting measurement with known influence of the sample treatment procedure, - the case of an active personal dosimeter in which the standard uncertainty associated with the gross quantity is constant and thus allows the calculation of the standard uncertainty as a function of the true value of the measured quantity, - a measurement of the dose rate with a neutron local dosimeter, where the actual numbers of the gross and background measurements are unknown, - a simple example for calculating the calibration factor.