Plutonium(Pu)is an anthropogenic radionuclide which mainly derived from atmospheric nuclear tests in the environment.In this study,the Pu isotopes(^(239)Pu and^(240)Pu)in aerosol samples collected during the sandstorm...Plutonium(Pu)is an anthropogenic radionuclide which mainly derived from atmospheric nuclear tests in the environment.In this study,the Pu isotopes(^(239)Pu and^(240)Pu)in aerosol samples collected during the sandstorm and non-sandstorm period were measured by accelerator mass spectrometry(AMS)and the behavior of Pu was studied.The activity concentrations of ^(239)Pu and ^(240)Pu in the aerosol samples of Beijing were ranged from 0.62 nB q/m^(3)to 99.6 n Bq/m^(3)for ^(239)Pu and 3.51 nBq/m^(3)to 60.23 n Bq/m^(3)for ^(240)Pu,respectively.^(239)Pu and ^(240)Pu concentrations exhibited a remarkable seasonal variation trend,with the higher results showed in spring,and the relatively lower concentrations in winter.The observed higher concentration of^(239)Pu and^(240)Pu detected in sandstorm samples further indicated Pu was closely related to the occurrence of sandstorms.The global fallout characteristics of^(240)Pu/^(239)Pu atom ratios(average0.20,ranging from 0.16 to 0.27)in aerosol samples indicating that global fallout was the major source of Pu in the atmosphere.Using aluminum(Al)as an indicator of soil resuspension,significant positive correlation between^(239)Pu and Al(r^(2)=0.934),240Pu and Al(^(r)2=0.525)revealed that soil resuspension was a primary source of atmospheric Pu in Beijing.These results implied that the combination of^(239)Pu,^(240)Pu and Al could be used as the potential tracer of sandstorm.展开更多
In the field of nuclear radiation detection, sodium iodide (NaI(Tl)) and lanthanum bromide (LaBr<sub>3</sub>) are the primary scintillation crystals used for energy spectrum detectors. Furthermore, energy ...In the field of nuclear radiation detection, sodium iodide (NaI(Tl)) and lanthanum bromide (LaBr<sub>3</sub>) are the primary scintillation crystals used for energy spectrum detectors. Furthermore, energy spectrum detectors based on gadolinium gallium aluminum garnet (Ce:GAGG) scintillation crystals are minor. In this work, a 1-inch Ce:GAGG and Silicon Photomultipliers (SiPMs) are employed to construct a detector, and the coupled medium was silicone oil. An optimal SiPMs quantity scheme for the energy resolution was determined by varying the number of SiPMs coupled to Ce:GAGG and studying the effect of the different number of SiPMs on the energy resolution of the detector. Energy-resolution contrast experiments between Ce:GAGG and NaI(Tl) were performed using this scheme. The experimental results demonstrate that increasing the number of SiPMs enhances the energy resolution of the detector significantly. Notably, the energy resolution of the Ce:GAGG detector is comparable to that of the NaI(Tl) detector. Additionally, both detectors exhibit an energy linearity exceeding 99.9%. .展开更多
Purpose Position-sensitive detectors play a crucial role in gamma-ray imaging systems.To enhance the detector’s inherent spatial resolution,one promising technique involves the phoswich design,which combines pixelate...Purpose Position-sensitive detectors play a crucial role in gamma-ray imaging systems.To enhance the detector’s inherent spatial resolution,one promising technique involves the phoswich design,which combines pixelated scintillators with different decay times.Method In a previous study,we constructed a phoswich detector comprising a side-by-side GAGG-F/GAGG-T scintillator array coupled to an 8×8 SiPM array.Traditionally,all pulses are distinguished using a parameter with a global cut value.However,due to the non-uniformity of the array,pulse shapes vary with the interaction position of the gamma-ray.In this paper,we propose a novel procedure for crystal discrimination.Initially,the crystal flood map with all events is roughly segmented.Subsequently,the crystal discrimination values of each zone are histogrammed to generate the cut value for each zone.Following this,flood maps of GAGG-F and GAGG-T are generated using these cut values.Finally,flood maps of GAGG-F and GAGG-T are segmented,respectively.Results The novel procedure is compared with the traditional procedure,with results demonstrating that the novel procedure improves pulse discrimination.Conclusion In conclusion,the crystal discrimination for position-sensitive gamma-ray detectors can be enhanced by incorporating interaction position information.展开更多
基金supported by the financial supports from the National Natural Science Foundation of China(Nos.U1932103,U1832212,11875266)Key Deployment Projects of Chinese Academy of Sciences(No.ZDRW-CN-2018–1)Beijing Natural Science Foundation(No.7191008)。
文摘Plutonium(Pu)is an anthropogenic radionuclide which mainly derived from atmospheric nuclear tests in the environment.In this study,the Pu isotopes(^(239)Pu and^(240)Pu)in aerosol samples collected during the sandstorm and non-sandstorm period were measured by accelerator mass spectrometry(AMS)and the behavior of Pu was studied.The activity concentrations of ^(239)Pu and ^(240)Pu in the aerosol samples of Beijing were ranged from 0.62 nB q/m^(3)to 99.6 n Bq/m^(3)for ^(239)Pu and 3.51 nBq/m^(3)to 60.23 n Bq/m^(3)for ^(240)Pu,respectively.^(239)Pu and ^(240)Pu concentrations exhibited a remarkable seasonal variation trend,with the higher results showed in spring,and the relatively lower concentrations in winter.The observed higher concentration of^(239)Pu and^(240)Pu detected in sandstorm samples further indicated Pu was closely related to the occurrence of sandstorms.The global fallout characteristics of^(240)Pu/^(239)Pu atom ratios(average0.20,ranging from 0.16 to 0.27)in aerosol samples indicating that global fallout was the major source of Pu in the atmosphere.Using aluminum(Al)as an indicator of soil resuspension,significant positive correlation between^(239)Pu and Al(r^(2)=0.934),240Pu and Al(^(r)2=0.525)revealed that soil resuspension was a primary source of atmospheric Pu in Beijing.These results implied that the combination of^(239)Pu,^(240)Pu and Al could be used as the potential tracer of sandstorm.
文摘In the field of nuclear radiation detection, sodium iodide (NaI(Tl)) and lanthanum bromide (LaBr<sub>3</sub>) are the primary scintillation crystals used for energy spectrum detectors. Furthermore, energy spectrum detectors based on gadolinium gallium aluminum garnet (Ce:GAGG) scintillation crystals are minor. In this work, a 1-inch Ce:GAGG and Silicon Photomultipliers (SiPMs) are employed to construct a detector, and the coupled medium was silicone oil. An optimal SiPMs quantity scheme for the energy resolution was determined by varying the number of SiPMs coupled to Ce:GAGG and studying the effect of the different number of SiPMs on the energy resolution of the detector. Energy-resolution contrast experiments between Ce:GAGG and NaI(Tl) were performed using this scheme. The experimental results demonstrate that increasing the number of SiPMs enhances the energy resolution of the detector significantly. Notably, the energy resolution of the Ce:GAGG detector is comparable to that of the NaI(Tl) detector. Additionally, both detectors exhibit an energy linearity exceeding 99.9%. .
基金supported in part by National Key R&D Program of China(No.2022YFC2402001)the National Natural Science Foundation of China(No.12375337).
文摘Purpose Position-sensitive detectors play a crucial role in gamma-ray imaging systems.To enhance the detector’s inherent spatial resolution,one promising technique involves the phoswich design,which combines pixelated scintillators with different decay times.Method In a previous study,we constructed a phoswich detector comprising a side-by-side GAGG-F/GAGG-T scintillator array coupled to an 8×8 SiPM array.Traditionally,all pulses are distinguished using a parameter with a global cut value.However,due to the non-uniformity of the array,pulse shapes vary with the interaction position of the gamma-ray.In this paper,we propose a novel procedure for crystal discrimination.Initially,the crystal flood map with all events is roughly segmented.Subsequently,the crystal discrimination values of each zone are histogrammed to generate the cut value for each zone.Following this,flood maps of GAGG-F and GAGG-T are generated using these cut values.Finally,flood maps of GAGG-F and GAGG-T are segmented,respectively.Results The novel procedure is compared with the traditional procedure,with results demonstrating that the novel procedure improves pulse discrimination.Conclusion In conclusion,the crystal discrimination for position-sensitive gamma-ray detectors can be enhanced by incorporating interaction position information.
