General analytical methods of high-purity germanium gamma spectrometer
1 Scope
This standard specifies a general method for the analysis of gamma radionuclides in samples using a high-purity germanium (HPGe) gamma spectrometer.
This standard is applicable to the measurement and analysis of gamma radionuclides with gamma-ray energy greater than 40 keV and characteristic spectral lines that can be resolved in the laboratory.
2 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
2.1
intrinsic detection efficiency
parameters used to express the performance of the detector itself; it is equal to the ratio of the number of recorded pulses to the number of gamma photons emitted from persons to the sensitive volume of the detector
2.2
relative detection efficiency
ratio of the total absorption peak area of 60Co source 1332.5 keV gamma-ray measured by HPGe detector and the standard cylindrical NaI (T1) scintillating crystal (φ × h: 7.62 cm × 7.62 cm) detector when the distance from the source to the front surface of the probe is 25 cm
2.3
total absorption detection efficiency for nuclide
ratio of the net count in the detected total absorption peak to the total decay of the nuclide in the radiation source in the same time interval for the given measurement conditions and the characteristic gamma radiation with the energy Eγ emitted by the nuclide
2.4
total absorption detection efficiency for gamma-ray
ratio of the net count in the detected total absorption peak to the total number of gamma-rays of this energy emitted by the radiation source in the same time interval for a given measurement condition and gamma-ray energy
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2.5
background
count of other factors, such as cosmic rays, radioactive contamination, electromagnetic disturbance in the energy range of the studied spectrum in the absence of the measured radiation source (sample).
2.6
full width at half maximum; FWHM
full width (the distance between the abscissa of two points) at half of the peak (maximum value) on the distribution curve composed of only one peak, that is, the half width
2.7
energy resolution
ability of detectors to distinguish incident gamma-rays with different but very similar energies; energy resolution is related to the incident gamma-ray energy; for a monoenergetic gamma-ray with a specified energy, it is often expressed by the full width at half height of the total absorption peak of that energy
2.8
Foreword i
1 Scope
2 Terms and definitions
3 Basic requirements for configuration and main components of spectrometers
4 Calibration source and system calibration
5 Measurement of sample
6 Calculation
7 Report
Annex A (Information) Monoenergetic and polyenergetic nuclides for energy calibration
Annex B (Normative) Preparation of calibration source for gamma spectrometer
Annex C (Normative) LLD of gamma spectrum measurement
