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JiaTong Li,WenBao Jia,DaQian Hei,Zeen Yao,Can Cheng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.6
In this research, for improving the measurement performance of Prompt Gamma-ray Neutron ActivationAnalysis (PGNAA) set-up, a new optimization method for set-up design was proposed and investigated. At first, the calculation method for Signal-to-Noise Ratio (SNR) was proposed. Since the SNR could becalculated and quantified accurately, the SNR was chosen as the evaluation parameter in the newoptimization method. For discussing the feasibility of the SNR optimization method, two kinds of PGNAAset-ups were designed in the MCNP code, based on the SNR optimization method and the previous signaloptimization method, respectively. Meanwhile, the single element spectra analysis method was proposed, and the analysis effect of single element spectra as well as element sensitivity were used forcomparing the measurement performance. Since the simulation results showed the better measurementperformance of set-up designed by SNR optimization method, the experimental set-ups were built forthe further testing, finally demonstrating the feasibility of the SNR optimization method for PGNAA setup design
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Zhao Dong,Jia Wenbao,Hei Daqian,Cheng Can,Cheng Wei,Liang Xuwen,Li Ji 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.5
Time-encoded imagers (TEI) are important class of instruments to search for potential radioactive sources to prevent illicit transportation and trafficking of nuclear materials and other radioactive sources. The energy of the radiation cannot be known in advance due to the type and shielding of source is unknown in practice. However, the response function of the time-encoded imagers is related to the energy of neutrons or gamma-rays. An improved image reconstruction method based on MLEM was proposed to correct for the energy induced response difference. In this method, the count vector versus time was first smoothed. Then, the preset response function was adaptively corrected according to the measured counts. Finally, the smoothed count vector and corrected response were used in MLEM to reconstruct the source distribution. A one-dimensional dual-particle time-encode imager was developed and used to verify the improved method through imaging an AmeBe neutron source. The improvement of this method was demonstrated by the image reconstruction results. For gamma-ray and neutron images, the angular resolution improved by 17.2% and 7.0%; the contrast-to-noise ratio improved by 58.7% and 14.9%; the signal-to-noise ratio improved by 36.3% and 11.7%, respectively.
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A design of transmission-type multi-target X-ray tube based on electric field modulation
Zhao, Lei,Jia, Wenbao,Jin, Limin,Shan, Qing,Cheng, Can,Zhu, Hongkui,Hei, Daqian Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.9
Multi-target X-ray tube is a new type X-ray source, and can be applied in many fields such as sensitive X-ray fluorescence analysis and medical imaging. In this work, we report an electric field modulation multi-target X-ray tube, which contains four targets (Cr, Ni, Au, Mo) coated on a Beryllium (Be) window. A four-valve electric field deflector was developed to deflect the electron beam to bombard the corresponding targets. Particle dynamics analysis software was employed to simulate the particle tracking of electron beam. The results show that the 30 keV electron beam could get a 6.7 mm displacement on the target plane by 10<sup>5</sup> V/m electric field. The focus areas are about 2 mm × 5 mm and 4 mm × 2.5 mm after deflection in two directions. Thermal behavior calculated by ANSYS shows that the designed target assembly could withstand a 10 W continuous power. The optimum target thicknesses and emission spectra were obtained by Geant4 when the thickness of Be window was 300 mm and the electron beam incident angle was 0.141 rad. The results indicate that this multi-target X-ray tube could provide different X-ray sources effectively.
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