Distortions caused by the neutron spectrum and scattered neutrons are major problems in fast neutron radiography and should be considered for improving the image quality. This paper puts emphasis on the removal of the...Distortions caused by the neutron spectrum and scattered neutrons are major problems in fast neutron radiography and should be considered for improving the image quality. This paper puts emphasis on the removal of these image distortions and deviations for fast neutron radiography performed at the NECTAR facility of the research reactor FRM-II in Technische Universit/it Mfinchen （TUM）, Germany. The NECTAR energy spectrum is analyzed and established to modify the influence caused by the neutron spectrum, and the Point Scattered Function （PSeF） simulated by the Monte-Carlo program MCNPX is used to evaluate scattering effects from the object and improve image quality. Good analysis results prove the sound effects of the above two corrections.展开更多
Fast neutron tomography has been established as an inspection and detection tool at the NECTAR facility at the FRM-II reactor.Scattered neutrons from the object become a major disturbance and bring in artifacts and de...Fast neutron tomography has been established as an inspection and detection tool at the NECTAR facility at the FRM-II reactor.Scattered neutrons from the object become a major disturbance and bring in artifacts and deviations in reconstruction results,especially for hydrogenous material object.In this article,an iterative scattering correction method for fast neutron tomography was proposed.In each loop of iteration the scattering component of the projections will be simulated by Monte-Carlo program MCNPX based on the previous reconstruction result and then it will be subtracted from original projections.The differences between scattering components at different perspectives were quantitatively evaluated and an average scattering component image was used for all projections finally.Smooth and uniform slices with more clear edges were obtained and the new reconstructed attenuation coefficients are quite close to the real one compared to the results without scattering correction,in which case the relative error of the reconstructed attenuation coefficients is about 10%–30%.展开更多
基金Supported by National Natural Science Foundation of China(11079001)
文摘Distortions caused by the neutron spectrum and scattered neutrons are major problems in fast neutron radiography and should be considered for improving the image quality. This paper puts emphasis on the removal of these image distortions and deviations for fast neutron radiography performed at the NECTAR facility of the research reactor FRM-II in Technische Universit/it Mfinchen （TUM）, Germany. The NECTAR energy spectrum is analyzed and established to modify the influence caused by the neutron spectrum, and the Point Scattered Function （PSeF） simulated by the Monte-Carlo program MCNPX is used to evaluate scattering effects from the object and improve image quality. Good analysis results prove the sound effects of the above two corrections.
基金supported by the Academic Exchange Fund of Peking University Graduate Schoolthe National Basic Research Program of China(Grant No.2010CB833106)
文摘Fast neutron tomography has been established as an inspection and detection tool at the NECTAR facility at the FRM-II reactor.Scattered neutrons from the object become a major disturbance and bring in artifacts and deviations in reconstruction results,especially for hydrogenous material object.In this article,an iterative scattering correction method for fast neutron tomography was proposed.In each loop of iteration the scattering component of the projections will be simulated by Monte-Carlo program MCNPX based on the previous reconstruction result and then it will be subtracted from original projections.The differences between scattering components at different perspectives were quantitatively evaluated and an average scattering component image was used for all projections finally.Smooth and uniform slices with more clear edges were obtained and the new reconstructed attenuation coefficients are quite close to the real one compared to the results without scattering correction,in which case the relative error of the reconstructed attenuation coefficients is about 10%–30%.
