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IEC 61452
Edition 2.0 2021-06
INTERNATIONAL
STANDARD
colour
inside
Nuclear instrumentation – Measurement of activity or emission rate of gamma-
ray emitting radionuclides – Calibration and use of germanium-based
spectrometers
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IEC 61452
Edition 2.0 2021-06
INTERNATIONAL
STANDARD
colour
inside
Nuclear instrumentation – Measurement of activity or emission rate of gamma-
ray emitting radionuclides – Calibration and use of germanium-based
spectrometers
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.240 ISBN 978-2-8322-9813-8
– 2 – IEC 61452:2021 © IEC 2021
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms, definitions and symbols. 10
3.1 Terms and definitions . 10
3.2 Symbols . 15
4 Installation of instrumentation . 16
5 Peak analysis and calibration procedures . 16
5.1 Energy calibration . 16
5.2 Energy resolution calibration . 17
5.3 Peak-finding algorithm . 17
5.4 Peak position and area measurement . 17
5.5 Efficiency calibration measurement . 18
5.5.1 General . 18
5.5.2 Standardization coefficient for specific radionuclides . 18
5.5.3 Detector efficiency as a function of energy . 18
5.5.4 Efficiency function . 19
6 Gamma-ray measurements with HPGe spectrometers . 21
6.1 Measurement of gamma-ray energies . 21
6.2 Measurement of gamma-ray emission rates and radionuclide activities . 21
6.2.1 General . 21
6.2.2 Subtraction of interference peaks in the background . 22
6.2.3 Radioactive decay . 23
6.2.4 Pulse pile-up (random summing) . 25
6.2.5 True coincidence (cascade) summing . 26
6.2.6 Efficiency transfer corrections . 26
7 Performance tests of the spectrometry system . 29
7.1 General . 29
7.2 Multichannel-analyser and digital signal processing clocks . 29
7.3 DC offset and pole-zero settings . 29
7.4 Energy calibration . 29
7.5 Spectrometer efficiency and energy resolution . 29
7.6 Pulse pile-up (random summing) . 30
8 Performance tests of the analysis software . 31
8.1 General . 31
8.2 Test of automatic peak-finding algorithm . 31
8.3 Test of independence of peak-area from the gross peak-height to continuum-
height ratio. 33
8.4 Test of the doublet-peak finding and fitting algorithms . 34
9 Verification of the entire analysis process . 37
9.1 Assessment of the magnitude of true coincidence summing . 37
9.2 Deviations in the relative full-energy-peak efficiency . 40
9.3 Accuracy of the full-energy-peak efficiency . 41
10 Radionuclide identification . 41
10.1 General . 41
10.2 Identification through multipeak analysis and correction for interference from
other radionuclides . 42
10.3 Detection limits . 42
11 Uncertainties and uncertainty propagation . 42
12 Mathematical efficiency and correction factors modelling . 45
12.1 General . 45
12.2 Mathematical full energy peak efficiency calculations . 46
12.2.1 General . 46
12.2.2 Construction of the detector model . 46
12.2.3 Creation of sample geometries . 47
12.2.4 Validation of the detector and sample container . 47
12.2.5 Estimation of uncertainties for Monte Carlo codes for full energy peak
efficiencies . 47
12.3 Estimation of uncertainties from geometry variations . 48
12.4 Efficiency transfer . 49
12.5 True coincidence summing corrections . 49
Annex A (informative) Procedures for characterization of a HPGe gamma-ray
spectrometer . 51
A.1 General . 51
A.2 Adjustment of the pole-zero cancellation and direct current level . 51
A.2.1 Rationale for systems using analog electronics . 51
A.2.2 Adjustment of the pole-zero cancellation . 51
A.2.3 Adjustment of the direct current (DC) level . 51
A.3 Adjustment of the lower-level discriminator (LLD), ADC zero and initial
energy scale . 53
A.3.1 Rationale . 53
A.3.2 Adjustment of the lower-level discriminator . 53
A.3.3 Adjustment of the ADC zero and initial energy scale . 53
A.4 Check of the multichannel analyser (MCA) real-time clock . 54
A.4.1 Rationale . 54
A.4.2 Instructions . 54
A.5 Digital electronics . 55
A.6 Measurement of energy resolution and peak-to-Compton ratio . 55
A.6.1 Rationale . 55
A.6.2 Measurement of the energy resolution at 122 keV and 1 332 keV . 56
A.6.3 Measurement of the peak-to-Compton ratio for Co . 57
A.7 Correction for losses due to counting rate . 57
A.7.1 Rationale . 57
A.7.2 Empirical or source method . 58
A.7.3 Live-time extension method (see [18]) . 60
A.7.4 Pulser method (see [10], [14] and [17] to [22]) . 61
A.7.5 Virtual pulser and add "N" counts method . 65
A.8 Measurement of the full-energy peak efficiency curve . 65
A.8.1 Rationale . 65
A.8.2 Measurement of standardization coefficients for specific radionuclides . 65
A.8.3 Measurement of the detector efficiency versus energy for large sample-
to-detector distances . 66
A.8.4 Measurement of the detector efficiency versus energy for small sample-
to-detector distances . 69
A.9 Preparation of reference sources from standard solutions . 70
– 4 – IEC 61452:2021 © IEC 2021
A.9.1 Rationale . 70
A.9.2 Preparation of standard sources . 70
A.9.3 Preparation of soil sources . 71
A.9.4 Preparation of filter sources . 72
Annex B (informative) Measurement of peak posit
...