Purpose Fast neutrons and gamma-ray imaging detection is an effective way to detect and identify radioactive material in the field of nuclear security.A compact coded aperture imaging(CAI)camera was designed to be sen...Purpose Fast neutrons and gamma-ray imaging detection is an effective way to detect and identify radioactive material in the field of nuclear security.A compact coded aperture imaging(CAI)camera was designed to be sensitive to both gamma and neutron radiation based on plastic scintillators and multi-pixel photon counters(MPPC).Methods MPPCs coupling with the 13×13 pixelated plastic scintillators one-to-one were utilized to reduce the scale of the CAI system while maintaining good positional performance.The symmetric charge division(SCD)circuit was adopted to reduce the 169 signals output from the MPPC array to 26.Each waveform was collected and processed with four Domino Ring Sampler 4(DRS4)chips and two 16-channel analog-to-digital converter(ADC)modules.As the pulse shapes of fast neutrons would be broadened after elastic scattering multiple times in the scintillators,the Anger-Logic method was applied to eliminate multiple elastic scattering events so that good pulse shape discrimination(PSD)performance can be achieved.Results The imaging and detection ability of the camerawas evaluated using the 241Am-Be(5.9×10^(5) n/s)neutron source and 137Cs(370 MBq)gammasource.The camera can be used to detect fast neutrons(0.5–10 MeV)and gammarays(0.2–2.5MeV).Furthermore,it can implement efficient neutron/gamma PSD capabilities in the mixed-field environment.The figure of merit(FOM)of the camera calculated at 400keVee energy cut is 0.93.Conclusion A compact MPPC-based CAI camera was designed to detect and discriminate fast neutrons and gamma rays.Its good PSD performance was well suited to distinguish fast neutrons from gamma rays in a dual-particle environment.The portable design makes it promising for complex monitoring scenarios in nuclear security.展开更多
With the advancements in nuclear energy,methods that can accurately obtain the spatial information of radioactive sources have become essential for nuclear energy safety.Coded aperture imaging technology is widely use...With the advancements in nuclear energy,methods that can accurately obtain the spatial information of radioactive sources have become essential for nuclear energy safety.Coded aperture imaging technology is widely used because it provides two-dimensional distribution information of radioactive sources.The coded array is a major component of a coded aperture gamma camera,and it affects the key performance parameters of the camera.Currently,commonly used coded arrays such as uniformly redundant arrays(URAs)and modified uniformly redundant arrays(MURAs)have prime numbers of rows or columns and may lead to wastage of detector pixels.A 16×16 coded array was designed on the basis of an existing 16×16 multi-pixel position-sensitive cadmium zinc telluride detector.The digital signal-to-noise(SNR)ratio of the point spread function at the center of the array is 25.67.Furthermore,Monte Carlo camera models and experimental devices based on rank-13 MURA and rank-16 URA have been constructed.With the same angular resolution,the field size of view under rank-16 URA is 1.53 times that of under rank-13 MURA.Simulations(Am-241,Co-57,Ir-192,Cs-137)and experiments(Co-57)are conducted to compare the imaging performance between rank-16 URA and rank-13 MURA.The contrast-to-noise ratio of the reconstructed image of the rank-16 array is great and only slightly lower than that of rank-13 MURA.However,as the photon energy increases,the gap becomes almost negligible.展开更多
The encoding aperture snapshot spectral imaging system,based on the compressive sensing theory,can be regarded as an encoder,which can efficiently obtain compressed two-dimensional spectral data and then decode it int...The encoding aperture snapshot spectral imaging system,based on the compressive sensing theory,can be regarded as an encoder,which can efficiently obtain compressed two-dimensional spectral data and then decode it into three-dimensional spectral data through deep neural networks.However,training the deep neural net⁃works requires a large amount of clean data that is difficult to obtain.To address the problem of insufficient training data for deep neural networks,a self-supervised hyperspectral denoising neural network based on neighbor⁃hood sampling is proposed.This network is integrated into a deep plug-and-play framework to achieve self-supervised spectral reconstruction.The study also examines the impact of different noise degradation models on the fi⁃nal reconstruction quality.Experimental results demonstrate that the self-supervised learning method enhances the average peak signal-to-noise ratio by 1.18 dB and improves the structural similarity by 0.009 compared with the supervised learning method.Additionally,it achieves better visual reconstruction results.展开更多
Coded aperture imaging(CAI)is widely used as an energetic-particles telescope in high-energy astrophysics.A typical CAI system consists of a coded mask(CM),a position-sensitive detector,and reconstruction algorithms t...Coded aperture imaging(CAI)is widely used as an energetic-particles telescope in high-energy astrophysics.A typical CAI system consists of a coded mask(CM),a position-sensitive detector,and reconstruction algorithms that recover the source distributions from the measured projections.The imaging performance of CAI largely depends on the CM design,which governs the field-of-view(FOV),spatial resolution,sensitivity,and signalto-noise ratio(SNR).展开更多
Coded aperture imaging(CAI)is a technique to image three-dimensional scenes with special controlled abilities.In this review,we survey several recently proposed techniques to control the parameters of CAI by engineeri...Coded aperture imaging(CAI)is a technique to image three-dimensional scenes with special controlled abilities.In this review,we survey several recently proposed techniques to control the parameters of CAI by engineering the aperture of the system.The prime architectures of these indirect methods of imaging are reviewed.For each design,we mention the relevant application of the CAI recorders and summarize this overview with a general perspective on this research topic.展开更多
The grid-based energetic neutral atom imager(GENA)onboard the Queqiao-2 satellite is designed to capture high spatiotemporal resolution data of the Earth's ring current from a lunar orbit at a distance of 380000 k...The grid-based energetic neutral atom imager(GENA)onboard the Queqiao-2 satellite is designed to capture high spatiotemporal resolution data of the Earth's ring current from a lunar orbit at a distance of 380000 km.The instrument operates based on the time-of-flight(TOF)method and the grid-based encoding modulation principle.Key specifications of GENA include the following:detection of H atoms with an energy range of 4–200 keV,detection of O atoms with an energy range of 8–250 ke V,an energy resolution of better than 1 keV@10 keV,a field of view(FOV)of 19.72°×45.07°,an angular resolution of 0.43°,and a geometric factor of 19.2 cm^(2)sr.This paper presents some ground calibration results obtained during the testing of the proposed imager.GENA is expected to perform energetic neutral atom imaging of the Earth's magnetosphere and provide crucial data for studying particle injection from the magnetotail into the ring current region,as well as the generation and evolution of geomagnetic storms.展开更多
基金the MajorDeployment Projects of Chinese Academy of Sciences(Grant Number ZDRWCN-2018-1-01)the Research Equipment Development Project of Chinese Academy of Sciences(Grant Number YZ201415).
文摘Purpose Fast neutrons and gamma-ray imaging detection is an effective way to detect and identify radioactive material in the field of nuclear security.A compact coded aperture imaging(CAI)camera was designed to be sensitive to both gamma and neutron radiation based on plastic scintillators and multi-pixel photon counters(MPPC).Methods MPPCs coupling with the 13×13 pixelated plastic scintillators one-to-one were utilized to reduce the scale of the CAI system while maintaining good positional performance.The symmetric charge division(SCD)circuit was adopted to reduce the 169 signals output from the MPPC array to 26.Each waveform was collected and processed with four Domino Ring Sampler 4(DRS4)chips and two 16-channel analog-to-digital converter(ADC)modules.As the pulse shapes of fast neutrons would be broadened after elastic scattering multiple times in the scintillators,the Anger-Logic method was applied to eliminate multiple elastic scattering events so that good pulse shape discrimination(PSD)performance can be achieved.Results The imaging and detection ability of the camerawas evaluated using the 241Am-Be(5.9×10^(5) n/s)neutron source and 137Cs(370 MBq)gammasource.The camera can be used to detect fast neutrons(0.5–10 MeV)and gammarays(0.2–2.5MeV).Furthermore,it can implement efficient neutron/gamma PSD capabilities in the mixed-field environment.The figure of merit(FOM)of the camera calculated at 400keVee energy cut is 0.93.Conclusion A compact MPPC-based CAI camera was designed to detect and discriminate fast neutrons and gamma rays.Its good PSD performance was well suited to distinguish fast neutrons from gamma rays in a dual-particle environment.The portable design makes it promising for complex monitoring scenarios in nuclear security.
基金supported by the National Natural Science Foundation of China(No.11675078)the Primary Research and Development Plan of Jiangsu Province(No.BE2017729)the Foundation of Graduate Innovation Center in NUAA(No.kfjj20190614)。
文摘With the advancements in nuclear energy,methods that can accurately obtain the spatial information of radioactive sources have become essential for nuclear energy safety.Coded aperture imaging technology is widely used because it provides two-dimensional distribution information of radioactive sources.The coded array is a major component of a coded aperture gamma camera,and it affects the key performance parameters of the camera.Currently,commonly used coded arrays such as uniformly redundant arrays(URAs)and modified uniformly redundant arrays(MURAs)have prime numbers of rows or columns and may lead to wastage of detector pixels.A 16×16 coded array was designed on the basis of an existing 16×16 multi-pixel position-sensitive cadmium zinc telluride detector.The digital signal-to-noise(SNR)ratio of the point spread function at the center of the array is 25.67.Furthermore,Monte Carlo camera models and experimental devices based on rank-13 MURA and rank-16 URA have been constructed.With the same angular resolution,the field size of view under rank-16 URA is 1.53 times that of under rank-13 MURA.Simulations(Am-241,Co-57,Ir-192,Cs-137)and experiments(Co-57)are conducted to compare the imaging performance between rank-16 URA and rank-13 MURA.The contrast-to-noise ratio of the reconstructed image of the rank-16 array is great and only slightly lower than that of rank-13 MURA.However,as the photon energy increases,the gap becomes almost negligible.
基金Supported by the Zhejiang Provincial"Jianbing"and"Lingyan"R&D Programs(2023C03012,2024C01126)。
文摘The encoding aperture snapshot spectral imaging system,based on the compressive sensing theory,can be regarded as an encoder,which can efficiently obtain compressed two-dimensional spectral data and then decode it into three-dimensional spectral data through deep neural networks.However,training the deep neural net⁃works requires a large amount of clean data that is difficult to obtain.To address the problem of insufficient training data for deep neural networks,a self-supervised hyperspectral denoising neural network based on neighbor⁃hood sampling is proposed.This network is integrated into a deep plug-and-play framework to achieve self-supervised spectral reconstruction.The study also examines the impact of different noise degradation models on the fi⁃nal reconstruction quality.Experimental results demonstrate that the self-supervised learning method enhances the average peak signal-to-noise ratio by 1.18 dB and improves the structural similarity by 0.009 compared with the supervised learning method.Additionally,it achieves better visual reconstruction results.
文摘Coded aperture imaging(CAI)is widely used as an energetic-particles telescope in high-energy astrophysics.A typical CAI system consists of a coded mask(CM),a position-sensitive detector,and reconstruction algorithms that recover the source distributions from the measured projections.The imaging performance of CAI largely depends on the CM design,which governs the field-of-view(FOV),spatial resolution,sensitivity,and signalto-noise ratio(SNR).
基金Australian Research Council(LP190100505).European Union's Horizon 2020 research and innovation programme under grant agreement No.857627(CIPHR).
文摘Coded aperture imaging(CAI)is a technique to image three-dimensional scenes with special controlled abilities.In this review,we survey several recently proposed techniques to control the parameters of CAI by engineering the aperture of the system.The prime architectures of these indirect methods of imaging are reviewed.For each design,we mention the relevant application of the CAI recorders and summarize this overview with a general perspective on this research topic.
基金supported by the National Natural Science Foundation of China(Grant Nos.42322408,42188108,42441809)the Climbing Program of National Space Science Center,Chinese Academy of Sciences(Grant Nos.E4PD3005,E4PD40015S)。
文摘The grid-based energetic neutral atom imager(GENA)onboard the Queqiao-2 satellite is designed to capture high spatiotemporal resolution data of the Earth's ring current from a lunar orbit at a distance of 380000 km.The instrument operates based on the time-of-flight(TOF)method and the grid-based encoding modulation principle.Key specifications of GENA include the following:detection of H atoms with an energy range of 4–200 keV,detection of O atoms with an energy range of 8–250 ke V,an energy resolution of better than 1 keV@10 keV,a field of view(FOV)of 19.72°×45.07°,an angular resolution of 0.43°,and a geometric factor of 19.2 cm^(2)sr.This paper presents some ground calibration results obtained during the testing of the proposed imager.GENA is expected to perform energetic neutral atom imaging of the Earth's magnetosphere and provide crucial data for studying particle injection from the magnetotail into the ring current region,as well as the generation and evolution of geomagnetic storms.
