IEC 61452:2021
(Main)Nuclear instrumentation - Measurement of activity or emission rate of gamma-ray emitting radionuclides - Calibration and use of germanium-based spectrometers
Nuclear instrumentation - Measurement of activity or emission rate of gamma-ray emitting radionuclides - Calibration and use of germanium-based spectrometers
IEC 61452:2021 establishes methods for the calibration and use of high purity germanium spectrometers for the measurement of photon energies and emission rates over the energy range from 45 keV to approximately 3 000 keV and the calculation of radionuclide activities from these measurements. Minimum requirements for automated peak finding are stated. This document establishes methods for measuring the full-energy peak efficiency with calibrated sources.
The object of this document is to provide a basis for the routine calibration and use of germanium (HPGe) semiconductor detectors for the measurement of gamma-ray emission rates and thereby the activities of the radionuclides in a sample. It is intended for use by persons who have an understanding of the principles of HPGe gamma-ray spectrometry and are responsible for the development of correct procedures for the calibration and use of such detectors. This document is primarily intended for routine analytical measurements. Related documents are IEC 60973 and ISO 20042.
This second edition cancels and replaces the first edition published in 1995. This edition includes the following significant technical changes with respect to the previous edition:
a. title modified;
b. additional information on digital electronics;
c. information on Monte Carlo simulations;
d. reference to detection limits calculations.
General Information
Standards Content (Sample)
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
...
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