The quasi-monochromatic,continuously energy-tunable,and high-brightness gamma rays that are produced by an inverse Compton scattering(ICS)light source provide an ideal probe for gamma-ray imaging.However,owing to the ...The quasi-monochromatic,continuously energy-tunable,and high-brightness gamma rays that are produced by an inverse Compton scattering(ICS)light source provide an ideal probe for gamma-ray imaging.However,owing to the influence of the intrinsic energy-angle correlation spectrum of this type of light source,monochromatic computed tomography(CT),especially in the gamma-ray energy region,can only be realized in a low-efficiency manner,similar to first-generation CT.A dual-energy scan scheme with a large imaging field of view(FOV)was developed in this study to improve the imaging efficiency.The effectiveness of this scheme was demonstrated based on the beam parameters of a typical ICS light source using Monte Carlo simulations.By leveraging the principle of basis material decomposition,the influence of the energyangle correlation spectrum on CT reconstruction was corrected,and a monochromatic CT image of the imaging object was accurately reconstructed.Furthermore,the electron density and effective atomic number of the imaging object could be obtained simultaneously.展开更多
Nanoscale metal-based tunneling junction(MTJ)devices were fabricated using the electromigration method,and their electrical properties were studied after exposure toγ-andβ-radiation.Irradiation caused the set thresh...Nanoscale metal-based tunneling junction(MTJ)devices were fabricated using the electromigration method,and their electrical properties were studied after exposure toγ-andβ-radiation.Irradiation caused the set threshold voltage(V_(set))of the MTJ devices to increase,leading to a transition from a low-resistance state(LRS)to a high-resistance state(HRS).This shift in V_(set)was due to atom displacement from high-energy electrons excited byγ-andβ-radiation.Unlike semiconductor devices,MTJ devices showed resilience to permanent damage and could be restored in-situ through multiple I-V(I is the drain current;V is the drain voltage)sweeps with appropriate configurations.This ability to recover suggests that MTJ devices have promising potential under irradiation.The reparability of irradiated MTJ devices is closely related to nothing-on-insulator(NOI)their structure,providing insights for other NOI and metal-based micro-nanoscale devices.展开更多
We employed Monte Carlo simulations via Geant4 to model the interactions of^(60)Co gamma rays(1.25 MeV),electrons(0.1-10 MeV),and protons(0.5-10 MeV)with Ta_(2)O_(5)optical coatings.By analyzing secondary electron gen...We employed Monte Carlo simulations via Geant4 to model the interactions of^(60)Co gamma rays(1.25 MeV),electrons(0.1-10 MeV),and protons(0.5-10 MeV)with Ta_(2)O_(5)optical coatings.By analyzing secondary electron generation and energy deposition,we found that 1.0 MeV electrons and protons produce 67.5 and 67 secondary electrons per particle,respectively,compared to 116 from 1.25 MeV gamma rays in thick targets.Boltzmann-function fitting revealed depth-dependent ionization equivalence:0.582 gamma photons match the secondary electron yield of a 1.0 MeV electron,and 0.577 gamma photons match a 1.0 MeV proton.These results establish a framework to convert ground-based gamma-ray test data to space environment scenarios,accounting for critical differences in penetration depth-protons deposit energy within 10μm(coating layers),while gamma rays penetrate>100 mm into substrates.This provides a theoretical basis for evaluating radiation effects using existing^(60)Co facilities,enabling reliable predictions of optical component durability in complex space environments.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12375157,12027902,and 11905011)。
文摘The quasi-monochromatic,continuously energy-tunable,and high-brightness gamma rays that are produced by an inverse Compton scattering(ICS)light source provide an ideal probe for gamma-ray imaging.However,owing to the influence of the intrinsic energy-angle correlation spectrum of this type of light source,monochromatic computed tomography(CT),especially in the gamma-ray energy region,can only be realized in a low-efficiency manner,similar to first-generation CT.A dual-energy scan scheme with a large imaging field of view(FOV)was developed in this study to improve the imaging efficiency.The effectiveness of this scheme was demonstrated based on the beam parameters of a typical ICS light source using Monte Carlo simulations.By leveraging the principle of basis material decomposition,the influence of the energyangle correlation spectrum on CT reconstruction was corrected,and a monochromatic CT image of the imaging object was accurately reconstructed.Furthermore,the electron density and effective atomic number of the imaging object could be obtained simultaneously.
基金supported by the National Natural Science Foundation of China(Nos.T2293703,T2293700)the Instrumental Analysis Fund of Peking University,China(No.KF-2305-07).
文摘Nanoscale metal-based tunneling junction(MTJ)devices were fabricated using the electromigration method,and their electrical properties were studied after exposure toγ-andβ-radiation.Irradiation caused the set threshold voltage(V_(set))of the MTJ devices to increase,leading to a transition from a low-resistance state(LRS)to a high-resistance state(HRS).This shift in V_(set)was due to atom displacement from high-energy electrons excited byγ-andβ-radiation.Unlike semiconductor devices,MTJ devices showed resilience to permanent damage and could be restored in-situ through multiple I-V(I is the drain current;V is the drain voltage)sweeps with appropriate configurations.This ability to recover suggests that MTJ devices have promising potential under irradiation.The reparability of irradiated MTJ devices is closely related to nothing-on-insulator(NOI)their structure,providing insights for other NOI and metal-based micro-nanoscale devices.
基金Funded by the Zibo Key Research and Development Project(No.2020XCCG0106)the Zibo Key Research and Development Project(No.2021SNPT0004)the Opening Project of Glass-based Functional Material Technology Innovation Center(No.GFMTIC2025C01)。
文摘We employed Monte Carlo simulations via Geant4 to model the interactions of^(60)Co gamma rays(1.25 MeV),electrons(0.1-10 MeV),and protons(0.5-10 MeV)with Ta_(2)O_(5)optical coatings.By analyzing secondary electron generation and energy deposition,we found that 1.0 MeV electrons and protons produce 67.5 and 67 secondary electrons per particle,respectively,compared to 116 from 1.25 MeV gamma rays in thick targets.Boltzmann-function fitting revealed depth-dependent ionization equivalence:0.582 gamma photons match the secondary electron yield of a 1.0 MeV electron,and 0.577 gamma photons match a 1.0 MeV proton.These results establish a framework to convert ground-based gamma-ray test data to space environment scenarios,accounting for critical differences in penetration depth-protons deposit energy within 10μm(coating layers),while gamma rays penetrate>100 mm into substrates.This provides a theoretical basis for evaluating radiation effects using existing^(60)Co facilities,enabling reliable predictions of optical component durability in complex space environments.
