Purpose Coded aperture imaging was a widely used imaging method for radiation sources.However,the traditional gamma camera based on two-dimensional projection information for coded aperture imaging ignored the influen...Purpose Coded aperture imaging was a widely used imaging method for radiation sources.However,the traditional gamma camera based on two-dimensional projection information for coded aperture imaging ignored the influence of the interaction depth of particles and detectors on the projection information,which reduced the imaging quality of the camera to some extent.Therefore,a method of correcting the coded gamma camera based on the interaction depth of particles and detectors is proposed to improve the location accuracy of detectors.Methods The camera developed in this work uses a 7×7 YSO crystal array coupled with two 7×7 Si-PM arrays.The crystal is evenly divided into 11 parts in the depth direction,with a voxel size of 3×3×3 mm3.The coded mask is a 13×13 array,which is a mosaic of two cycles of 7×7 modified uniformly redundant array mask.The depth resolution of the detector is obtained via the subsurface laser engraving dual-end readout method.After obtaining the three-dimensional position information of the interaction point the projection information obtained by the detector is layered,and the image is reconstructed.According to the spatial position information of the detector and the coded mask,the corresponding field of view of each layer of the detector is calculated,and the reconstructed image of each layer is amplified and superimposed according to the ratio of the field of view to obtain the reconstructed image combined with the depth information.Results and conclusion According to Monte Carlo simulation and radiation source imaging experiment results,this method can effectively improve the positioning ability of the detector.For the experimental scenario mentioned in the paper,the location accuracy can be improved by up to 1.54°.展开更多
The exploration of high-performance dielectric ceramics with dielectric constants lower than 10 is of great significance for the next generation of wireless communication.In this study,we reported the Yb_(2)Si_(2)O_(7...The exploration of high-performance dielectric ceramics with dielectric constants lower than 10 is of great significance for the next generation of wireless communication.In this study,we reported the Yb_(2)Si_(2)O_(7)(YSO)dielectric ceramics synthesized using a facile solid-state reaction technique.X-ray diffraction(XRD)and transmission electron microscopy(TEM)characterization confirmed that YSO ceramics had a monoclinic structure.At a sintering temperature of 1500℃,the sintered sample reached a maximum relative density of 96%and demonstrated the best dielectric properties:dielectric constant(ε_(r))=7.57,Q×f=78,645 GHz(Q is quality factor,and f is the resonant frequency of 13.5 GHz),andtemperature coefficient of the resonant frequency(τ_(f))=−13.5 ppm/℃.Moreover,Raman analysis revealed that the Si–O bond dominated the lattice vibration,and the full width at half maximum(FWHM)of the strong peak at 922 cm^(−1)was inversely proportional to the Q×f value.According to the Phillips–van Vechten–Levine(P–V–L)theory,the values of Q×f andτ_(f)are affected primarily by the Si–O bond,whileε_(r)is influenced mainly by the Yb–O bond.YSO ceramics demonstrated excellent dielectric properties in the terahertz band(ε_(r)=8.13,Q×f=112,758 GHz),making them promising candidates for future applications in the terahertz band.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos.12005234 and 12105307.
文摘Purpose Coded aperture imaging was a widely used imaging method for radiation sources.However,the traditional gamma camera based on two-dimensional projection information for coded aperture imaging ignored the influence of the interaction depth of particles and detectors on the projection information,which reduced the imaging quality of the camera to some extent.Therefore,a method of correcting the coded gamma camera based on the interaction depth of particles and detectors is proposed to improve the location accuracy of detectors.Methods The camera developed in this work uses a 7×7 YSO crystal array coupled with two 7×7 Si-PM arrays.The crystal is evenly divided into 11 parts in the depth direction,with a voxel size of 3×3×3 mm3.The coded mask is a 13×13 array,which is a mosaic of two cycles of 7×7 modified uniformly redundant array mask.The depth resolution of the detector is obtained via the subsurface laser engraving dual-end readout method.After obtaining the three-dimensional position information of the interaction point the projection information obtained by the detector is layered,and the image is reconstructed.According to the spatial position information of the detector and the coded mask,the corresponding field of view of each layer of the detector is calculated,and the reconstructed image of each layer is amplified and superimposed according to the ratio of the field of view to obtain the reconstructed image combined with the depth information.Results and conclusion According to Monte Carlo simulation and radiation source imaging experiment results,this method can effectively improve the positioning ability of the detector.For the experimental scenario mentioned in the paper,the location accuracy can be improved by up to 1.54°.
基金support from the National Natural Science Foundation of China(Nos.52102123 and 62171080)the Graduate Scientific Research Innovation Project of Shaoyang University,China(No.CX2023SY065).
文摘The exploration of high-performance dielectric ceramics with dielectric constants lower than 10 is of great significance for the next generation of wireless communication.In this study,we reported the Yb_(2)Si_(2)O_(7)(YSO)dielectric ceramics synthesized using a facile solid-state reaction technique.X-ray diffraction(XRD)and transmission electron microscopy(TEM)characterization confirmed that YSO ceramics had a monoclinic structure.At a sintering temperature of 1500℃,the sintered sample reached a maximum relative density of 96%and demonstrated the best dielectric properties:dielectric constant(ε_(r))=7.57,Q×f=78,645 GHz(Q is quality factor,and f is the resonant frequency of 13.5 GHz),andtemperature coefficient of the resonant frequency(τ_(f))=−13.5 ppm/℃.Moreover,Raman analysis revealed that the Si–O bond dominated the lattice vibration,and the full width at half maximum(FWHM)of the strong peak at 922 cm^(−1)was inversely proportional to the Q×f value.According to the Phillips–van Vechten–Levine(P–V–L)theory,the values of Q×f andτ_(f)are affected primarily by the Si–O bond,whileε_(r)is influenced mainly by the Yb–O bond.YSO ceramics demonstrated excellent dielectric properties in the terahertz band(ε_(r)=8.13,Q×f=112,758 GHz),making them promising candidates for future applications in the terahertz band.
