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Study on the Energy Spectrum Response of a CdZnTe Detector
Yuandong Li,Liangquan Ge,Kun Sun,Shangqing Sun,Guoqiang Zeng,Chengjun Tan 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.9
In order to study the energy spectrum response of a CdZnTe detector, we firstly measured the temperature dependence and the bias dependence of the main characteristic parameters for both a quasi-hemispherical detector and a CAPtureTM plus detector. Secondly, we designed a low-noise readout circuit for the CdZnTe detector and measured the noise. Finally, we evaluated the energy spectrum response of the detector to different radioactive sources at different temperatures by connecting the detector to the readout circuit. The research showed that both detectors had low leakage current and junction capacitance, as well as good stability in temperature and bias; the quasi-hemispheric detector had a smaller leakage current and junction capacitance compared to the CAPtureTM plus detector; under zero input capacitor, the noise of the readout circuit was 612e, with the noise slope being 5.44e/pF; at room temperature(20 °C), the energy resolutions of the detector reached 3.84% and 1.36% for X-rays from 241Am (59.5 keV) and gamma-rays from 137Cs (662 keV), respectively; the signal-noise ratio of the output signal reached 31:1 with the rise time being 90 ns; at low temperature, the energy resolution reached 3.41% for the X-rays from 241Am (59.5 keV); the detector achieved an excellent spectrum response and was able to distinguish clearly the energy peaks of 152Eu and 226Ra.
Sun Shangqing,Ge Liangquan,Li Yuandong,Hu Chuanhao 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.12
The energy resolution of a LaBr3(Ce) scintillation counter can reach 2.7% (662 keV) at room temperature. As a radiation measuring device, it has remarkably good characteristics. However, the LaBr3(Ce) crystal has its own intrinsic radioactivity background, which mainly comes from 138La and from 227Ac and its daughters. 138La can emit β, γ and X-rays through β and γ decay; 227Ac and its daughters can emit α, β and γ-rays through α, β and γ decay. α, γ and X-ray energy are characteristic while β-ray energy is continuous. The energy of α, β and X-rays is mainly deposited in the crystal unless the α, β and X-rays at the edge of the crystal can escape from the crystal. Therefore, the α, β, γ and X-rays generated by the intrinsic radioactivity of the crystal are superimposed on the instrument spectrum, which makes the instrument spectrum more complicated and produces the coincidence summing effects of γ + X, γ + β and γ + α. In this research, the GEANT4.9.5 software package was used to simulate the spectra of α, β, γ and X-rays. On the basis of a combination of fitting decomposition and reconstruction, the simulation spectrum of the LaBr3(Ce) self-radioactive background was obtained accurately and was verified by using physical experiments.
Yi Gu,Heng Lu,Meng Wang,Liangquan Ge,Qingxian Zhang 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.5
This paper discusses an advanced spectral-ratio method that subtracts Compton scattering rays by using a Fast Fourier Transform rather than tripping ratios and establishes a new radon background estimation mathematical model. A ground model calibration technology and a non-radioactive calibration technology based on a multiple-step Monte Carlo simulation are proposed for determining the new calibration coefficients. Applying the new calibration coefficients by using the two calibration technologies, we can remove successfully from the U window. The relative standard deviation of the radon-corrected U window count between the two calibration technologies is less than 30% within the height of the airborne survey, and it is reduced as the height increases.
Xia Jigen,Song Baolin,Gu Yi,Li Zhiqiang,Xu Jie,Ge Liangquan,Zhang Qingxian,Zeng Guoqiang,Liu Qiushi,Yang Xiaofeng 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8
The influence of the atmospheric radon background on the airborne gamma spectrum can seriously affect researchers’ judgement of ground radiation information. However, due to load and endurance, unmanned aerial vehicle (UAV)-borne gamma-ray spectrometry is difficulty installing upward-looking detectors to monitor atmospheric radon background. In this paper, an advanced spectral-ratio method was used to correct the atmospheric radon background for a UAV-borne gamma-ray spectrometry in Inner Mongolia, China. By correcting atmospheric radon background, the ratio of the average count rate of U window in the anomalous radon zone (S5) to that in other survey zone decreased from 1.91 to 1.03, and the average uranium content in S5 decreased from 4.65 mg/kg to 3.37 mg/kg. The results show that the advanced spectral-ratio method efficiently eliminated the influence of the atmospheric radon background on the UAV-borne gamma-ray spectrometry to accurately obtain ground radiation information in uranium exploration. It can also be used for uranium tailings monitoring, and environmental radiation background surveys