DIN IEC 61452:2023-02: Nuclear instrumentation - Measurement of activity or emission rate of gamma-ray emitting radionuclides - Calibration and use of germanium-based spectrometers (IEC 61452:2021)

This document establishes procedures for the calibration and use of high-purity germanium spectrometers for measuring the energies and emission rates of photons in the energy range from 45 keV to about 3000 keV and for calculating the activity of radionuclides based on these measurements. The purpose of this document is to provide a basis for the routine calibration and use of germanium (HPGe) semiconductor detectors for measuring the emission rates and thereby the activity measurement of radionuclides in a sample. It is intended for use by persons who understand the principles of HPGe gamma spectrometry and are responsible for establishing correct procedures for the calibration and use of such detectors. The performance tests described ensure that the spectrometer operates within acceptable limits. These tests are used to determine the limits of the algorithms for peak searching and fitting to individual peaks and multipletts. Furthermore, procedures for measurement and correction for spiking are proposed. A test for determining the approximate magnitude of true coincidence summation is described, techniques for checking spectral analysis results for errors that may arise from true coincidence summation of cascade gamma quanta in the detector are recommended. Recommendations are given for the construction of data libraries for radionuclide identification, decay corrections, conversion of gamma emission rates to decay rates and Monte Carlo simulations. The measurement of X-ray emission rates is not included here because other fitting functions are required for X-ray lines. Also not included is the measurement of emission rates from lines of annihilation radiation or single or double escape lines that result from partial energy deposition in pair formation: Escape lines might require different matching functions than comparable total absorption lines. Furthermore, annihilation radiation and single escape lines have a different, larger width than gamma ray lines of comparable energy. Discussion of acceptable methods for measuring detection limits related to specific radionuclides is also outside the scope of this document.