Current experimental techniques still face challenges in clarifying the structural and dynamic properties of helium(He)in liquid lithium(Li).A critical example of this technical hurdle is the formation of He bubbles,w...Current experimental techniques still face challenges in clarifying the structural and dynamic properties of helium(He)in liquid lithium(Li).A critical example of this technical hurdle is the formation of He bubbles,which significantly affects the transport of He within liquid Li—a vital aspect when considering liquid Li as a plasma-facing material in nuclear fusion reactors.We develop a machine-learning-based deep potential(DP)with ab initio accuracy for the Li-He system and perform molecular dynamics simulations at temperatures ranging from 470 K to 1270 K with a wide range of He concentrations.We observe that He atoms exhibit a tendency to aggregate and form clusters and bubbles in liquid Li.Notably,He clusters exhibit a significant increase in size at elevated temperatures and high concentrations of He,accompanied by the phase separation of Li and He atoms.We also observe an anomalous non-linear relationship between the diffusion coefficient of He and temperature,which is attributed to the larger cluster size at higher temperatures.Our study provides a deeper understanding of the behavior of He in liquid Li and further supports the potential application of liquid Li under extreme conditions.展开更多
Lead(Pb)is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses.Under shock-wave loading,its dynamic mechanical behavior comprises two key phenomena:pla...Lead(Pb)is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses.Under shock-wave loading,its dynamic mechanical behavior comprises two key phenomena:plastic deformation and shock-induced phase transitions.The underlying mechanisms of these processes are still poorly understood.Revealing these mechanisms remains challenging for experimental approaches.Non-equilibrium molecular dynamics(NEMD)simulations are an alternative theoretical tool for studying dynamic responses,as they capture atomic-scale mechanisms such as defect evolution and deformation pathways.However,due to the limited accuracy of empirical interatomic potentials,the reliability of previous NEMD studies has been questioned.Using our newly developed machine learning potential for Pb-Sn alloys,we revisited the microstructural evolution in response to shock loading under various shock orientations.The results reveal that shock loading along the[001]orientation of Pb exhibits a fast,reversible,and massive phase transition and stacking-fault evolution.The behavior of Pb differs from previous studies by the absence of twinning during plastic deformation.Loading along the[011]orientation leads to slow,irreversible plastic deformation,and a localized FCC-BCC phase transition in the Pitsch orientation relationship.This study provides crucial theoretical insights into the dynamic mechanical response of Pb,offering a theoretical input for understanding the microstructure-performance relationship under extreme conditions.展开更多
In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order hom...In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.展开更多
High-power laser pulses interacting with targets can generate intense electromagnetic pulses(EMPs),which can disrupt physical experimental diagnostics and even damage diagnostic equipment,posing a threat to the reliab...High-power laser pulses interacting with targets can generate intense electromagnetic pulses(EMPs),which can disrupt physical experimental diagnostics and even damage diagnostic equipment,posing a threat to the reliable operation of experiments.In this study,EMPs resulting from multi-petawatt laser irradiating nitrogen gas jets were systematically analyzed and investigated.The experimental results revealed that the EMP amplitude is positively correlated with the quantity and energy of the electrons captured and accelerated by the plasma channel.These factors are reflected by parameters such as laser energy and nitrogen gas jet pressure.Additionally,we propose several potential sources of EMPs produced by laser-irradiated gas jets and separately analyzed their spatiotemporal distributions.The findings provide insight into the mechanisms of EMP generation and introduce a new approach to achieve controllable EMPs by regulating the laser energy and gas jet pressure.展开更多
The multiscale computational method with asymptotic analysis and reduced-order homogenization(ROH)gives a practical numerical solution for engineering problems,especially composite materials.Under the ROH framework,a ...The multiscale computational method with asymptotic analysis and reduced-order homogenization(ROH)gives a practical numerical solution for engineering problems,especially composite materials.Under the ROH framework,a partition-based unitcell structure at the mesoscale is utilized to give a mechanical state at the macro-scale quadrature point with pre-evaluated influence functions.In the past,the“1-phase,1-partition”rule was usually adopted in numerical analysis,where one constituent phase at the mesoscale formed one partition.The numerical cost then is significantly reduced by introducing an assumption that the mechanical responses are the same all the time at the same constituent,while it also introduces numerical inaccuracy.This study proposes a new partitioning method for fibrous unitcells under a reduced-order homogenization methodology.In this method,the fiber phase remains 1 partition,but the matrix phase is divided into 2 partitions,which refers to the“12”partitioning scheme.Analytical elastic influence+functions are derived by introducing the elastic strain energy equivalence(Hill-Mandel condition).This research also obtains the analytical eigenstrain influence functions by alleviating the so-called“inclusion-locking”phenomenon.In addition,a numerical approach to minimize the error of strain energy density is introduced to determine the partitioning of the matrix phase.Several numerical examples are presented to compare the differences among direct numerical simulation(DNS),“11”,and“12”partitioning schemes.The numerical simulations show improved++numerical accuracy by the“12”partitioning scheme.展开更多
Terahertz(THz)radiation is rapidly emerging as a powerful tool with diverse applications,including high-speed imaging,laser-driven particle acceleration,and ultra-high frequency(UHF)communications.However,generating m...Terahertz(THz)radiation is rapidly emerging as a powerful tool with diverse applications,including high-speed imaging,laser-driven particle acceleration,and ultra-high frequency(UHF)communications.However,generating multipulse THz radiation with controllable time intervals remains a significant challenge.This study presents an approach to overcome this hurdle by exploiting the interaction between an electron beam and plasma.Using numerical simulations and theoretical analysis,we investigated the behavior of an electron beam within a plasma and its interaction with the longitudinal sheath field.This interaction resulted in the generation of multiple distinct THz pulses.We demonstrated that the plasma length adjustment allows for precise tuning of the interval between THz pulses.Moreover,the radiation intensity could be controlled by the electron beam energy and the electron bunch duration.The proposed scheme can generate multipulse THz radiation in a flexible and precise manner,paving the way for advancements in applications requiring high temporal resolution.展开更多
Terahertz(THz) radiation, spanning the frequency range 100 GHz to 10 THz, offers diverse applications in spectroscopy, materials characterization, medical diagnostics and environmental monitoring. Despite its potentia...Terahertz(THz) radiation, spanning the frequency range 100 GHz to 10 THz, offers diverse applications in spectroscopy, materials characterization, medical diagnostics and environmental monitoring. Despite its potential, the generation of high-intensity, tunable THz radiation remains a significant challenge. In this work, we explore a novel approach to the efficient generation of THz radiation based on laser–plasma interactions, utilizing the principles of photon deceleration.When a relativistic CO_(2) laser passes through a pre-ionized plasma, the laser induces a nonlinear wakefield, creating a strong refractive index gradient. This gradient, combined with the lower-density region of the wakefield, slows down the laser, facilitating the accumulation of THz radiation. The resulting THz pulse exhibits extreme collimation, high energy efficiency and tunability. Our work shows that this method can achieve up to 10% conversion efficiency with optimal plasma density near the critical density. This technique presents a promising solution for overcoming current limitations in THz source development and offers potential for diverse applications.展开更多
By adopting stochastic density functional theory(SDFT)and mixed stochastic-deterministic density functional theory(MDFT)methods,we perform first-principles calculations to predict the shock Hugoniot curves of boron(pr...By adopting stochastic density functional theory(SDFT)and mixed stochastic-deterministic density functional theory(MDFT)methods,we perform first-principles calculations to predict the shock Hugoniot curves of boron(pressure P=7.9×10^(3)-1.6×10^(6) GPa and temperature T=25-2800 eV),silicon(P=2.6×10^(3)-7.9×10^(5) GPa and T=21.5-1393 eV),and aluminum(P=5.2×10^(3)-9.0×10^(5) GPa and T=25-1393 eV)over wide ranges of pressure and temperature.In particular,we systematically investigate the impact of different cutoff radii in norm-conserving pseudopotentials on the calculated properties at elevated temperatures,such as pressure,ionization energy,and equation of state.By comparing the SDFT and MDFT results with those of other first-principles methods,such as extended first-principles molecular dynamics and path integral Monte Carlo methods,we find that the SDFT and MDFT methods show satisfactory precision,which advances our understanding of first-principles methods when applied to studies of matter at extremely high pressures and temperatures.展开更多
Controlling terahertz(THz)polarization with high stability and tunability is essential for achieving further progress in ultrafast spectroscopy,structured-light manipulation,and quantum information processing.Here,we ...Controlling terahertz(THz)polarization with high stability and tunability is essential for achieving further progress in ultrafast spectroscopy,structured-light manipulation,and quantum information processing.Here,we propose a magnetized plasma platform for dynamic THz polarization control by exploiting the intrinsic birefringence between extraordinary and ordinary modes.We identify a strong-magnetization,zero-group-velocity-mismatch regime where the two modes share matched group velocities while retaining finite phase birefringence,enabling robust,phase-stable spin angular momentum control.By tuning the plasma length and magnetic field,we realize programmable phase retardation and demonstrate universal single-qubit gates through parameterized unitary operations.Full-wave particle-in-cell simulations validate high-fidelity polarization transformations across the Poincarésphere and demonstrate the potential for generating structured vector beams under spatially varying magnetic fields.The platform offers ultrafast response,resilience to extreme THz intensities,and in situ tunability,positioning magnetized plasmas as a versatile and damage-resilient medium for next-generation THz polarization control and structured-wave applications.展开更多
The illicit trafficking of special nuclear materials(SNMs)poses a grave threat to global security and necessitates the development of effective nuclear material identification methods.This study investigated a method ...The illicit trafficking of special nuclear materials(SNMs)poses a grave threat to global security and necessitates the development of effective nuclear material identification methods.This study investigated a method to isotopically identify the SNMs,including^(233,235,238)U,^(239-242)Pu,and^(232)Th,based on the detection of delayedγ-rays from photofission fragments.The delayedγ-ray spectra resulting from the photofission of SNMs irradiated by a 14 MeVγbeam with a total of 10~9 were simulated using Geant4.Three high-yield fission fragments,namely^(138)Cs,^(89)Rb,and^(94)Y,were selected as candidate fragments for SNM identification.The yield ratios of these three fragments were calculated,and the results from the different SNMs were compared.The yield ratio of^(138)Cs/^(89)Rb was used to identify most SNMs,including^(233,235,238)U,^(242)Pu,and^(232)Th,with a confidence level above 95%.To identify^(239-241)Pu with the same confidence,a higher total number of 10^(11)γbeams is required.However,although the^(94)Y/^(89)Rb ratio is suitable for elementally identifying SNMs,isotopic identification is difficult.In addition,the count rate of the delayedγabove 3 MeV can be used to rapidly detect the presence of nuclear materials.展开更多
Correction to:Nuclear Science and Techniques(2025)36:100 https://doi.org/10.1007/s41365-025-01692-6 In this article,Fig.9 appeared incorrectly and have now been corrected in the original publication.For completeness a...Correction to:Nuclear Science and Techniques(2025)36:100 https://doi.org/10.1007/s41365-025-01692-6 In this article,Fig.9 appeared incorrectly and have now been corrected in the original publication.For completeness and transparency,both correct and incorrect versions are displayed below.展开更多
3D printing or additive manufacturing (AM) has revolutionized the way of manufacturing by designing complex structures in a customized feature which cannot be realized by traditional processing methods. Incoming mater...3D printing or additive manufacturing (AM) has revolutionized the way of manufacturing by designing complex structures in a customized feature which cannot be realized by traditional processing methods. Incoming materials are trying to adopt 3D printing techniques which directly fabricate sophisticated entities with multifunctionality like mechanical, electrical, thermal and magnetic properties etc. For the realization of advanced materials, 3D printing techniques are emerging from single material to composite materials manufacturing by simply introducing the nano- and micro-reinforcements with the matrix. In this review, we provide an outline of 3D printing graphene-based composites according to various AM techniques including fused deposition modeling (FDM), direct ink writing (DIW), stereolithography (SLA) and selective laser sintering (SLS). First a brief introduction of various AM techniques is given to get a basic understanding of the principles of 3D printing, and then the fabrication process, structural characteristics and applications of different 3D printing techniques for graphene-based composites are summarized. In addition, some effective simulation and characterization methods are also included. We hope that this review would clarify the potential of AM techniques for composite materials and can open new prospects for designing of novel materials.展开更多
基金Project supported by the Excellence Research Group Program for Multiscale Problems in Nonlinear Mechanics of the National Natural Science Foundation of China(Grant No.12588201)the National Key R&D Program of China(Grant No.2025YFB3003603)+1 种基金the National Natural Science Foundation of China(Grant No.12135002)the Fundamental Research Funds for the Central Universities,Peking University,the Beijing Natural Science Foundation(Grant No.QY23030)。
文摘Current experimental techniques still face challenges in clarifying the structural and dynamic properties of helium(He)in liquid lithium(Li).A critical example of this technical hurdle is the formation of He bubbles,which significantly affects the transport of He within liquid Li—a vital aspect when considering liquid Li as a plasma-facing material in nuclear fusion reactors.We develop a machine-learning-based deep potential(DP)with ab initio accuracy for the Li-He system and perform molecular dynamics simulations at temperatures ranging from 470 K to 1270 K with a wide range of He concentrations.We observe that He atoms exhibit a tendency to aggregate and form clusters and bubbles in liquid Li.Notably,He clusters exhibit a significant increase in size at elevated temperatures and high concentrations of He,accompanied by the phase separation of Li and He atoms.We also observe an anomalous non-linear relationship between the diffusion coefficient of He and temperature,which is attributed to the larger cluster size at higher temperatures.Our study provides a deeper understanding of the behavior of He in liquid Li and further supports the potential application of liquid Li under extreme conditions.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1004300)the National Natural Science Foundation of China(Grant No.12404004)。
文摘Lead(Pb)is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses.Under shock-wave loading,its dynamic mechanical behavior comprises two key phenomena:plastic deformation and shock-induced phase transitions.The underlying mechanisms of these processes are still poorly understood.Revealing these mechanisms remains challenging for experimental approaches.Non-equilibrium molecular dynamics(NEMD)simulations are an alternative theoretical tool for studying dynamic responses,as they capture atomic-scale mechanisms such as defect evolution and deformation pathways.However,due to the limited accuracy of empirical interatomic potentials,the reliability of previous NEMD studies has been questioned.Using our newly developed machine learning potential for Pb-Sn alloys,we revisited the microstructural evolution in response to shock loading under various shock orientations.The results reveal that shock loading along the[001]orientation of Pb exhibits a fast,reversible,and massive phase transition and stacking-fault evolution.The behavior of Pb differs from previous studies by the absence of twinning during plastic deformation.Loading along the[011]orientation leads to slow,irreversible plastic deformation,and a localized FCC-BCC phase transition in the Pitsch orientation relationship.This study provides crucial theoretical insights into the dynamic mechanical response of Pb,offering a theoretical input for understanding the microstructure-performance relationship under extreme conditions.
基金support by the National Key R&D Program of China(Grant No.2023YFA1008901)the National Natural Science Foundation of China(Grant Nos.11988102,12172009)is gratefully acknowledged.
文摘In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.
基金supported by the National Grand Instrument Project(No.2019YFF01014404)the Natural Science Foundation of China(Nos.12122501,61631001,11921006,U2241281,and 11975037)the Foundation of Science and Technology on Plasma Physics Laboratory(No.6142A04220108)。
文摘High-power laser pulses interacting with targets can generate intense electromagnetic pulses(EMPs),which can disrupt physical experimental diagnostics and even damage diagnostic equipment,posing a threat to the reliable operation of experiments.In this study,EMPs resulting from multi-petawatt laser irradiating nitrogen gas jets were systematically analyzed and investigated.The experimental results revealed that the EMP amplitude is positively correlated with the quantity and energy of the electrons captured and accelerated by the plasma channel.These factors are reflected by parameters such as laser energy and nitrogen gas jet pressure.Additionally,we propose several potential sources of EMPs produced by laser-irradiated gas jets and separately analyzed their spatiotemporal distributions.The findings provide insight into the mechanisms of EMP generation and introduce a new approach to achieve controllable EMPs by regulating the laser energy and gas jet pressure.
基金funded by the National Key R&D Program of China(Grant No.2023YFA1008901)the National Natural Science Foundation of China(Grant Nos.11988102,12172009)“The Fundamental Research Funds for the Central Universities,Peking University”.
文摘The multiscale computational method with asymptotic analysis and reduced-order homogenization(ROH)gives a practical numerical solution for engineering problems,especially composite materials.Under the ROH framework,a partition-based unitcell structure at the mesoscale is utilized to give a mechanical state at the macro-scale quadrature point with pre-evaluated influence functions.In the past,the“1-phase,1-partition”rule was usually adopted in numerical analysis,where one constituent phase at the mesoscale formed one partition.The numerical cost then is significantly reduced by introducing an assumption that the mechanical responses are the same all the time at the same constituent,while it also introduces numerical inaccuracy.This study proposes a new partitioning method for fibrous unitcells under a reduced-order homogenization methodology.In this method,the fiber phase remains 1 partition,but the matrix phase is divided into 2 partitions,which refers to the“12”partitioning scheme.Analytical elastic influence+functions are derived by introducing the elastic strain energy equivalence(Hill-Mandel condition).This research also obtains the analytical eigenstrain influence functions by alleviating the so-called“inclusion-locking”phenomenon.In addition,a numerical approach to minimize the error of strain energy density is introduced to determine the partitioning of the matrix phase.Several numerical examples are presented to compare the differences among direct numerical simulation(DNS),“11”,and“12”partitioning schemes.The numerical simulations show improved++numerical accuracy by the“12”partitioning scheme.
基金supported by the National Natural Science Foundation of China(Grant No.12175058)the National Science Fund of Hunan Province for Distinguished Young Scholars(Grant No.2024JJ2009)。
文摘Terahertz(THz)radiation is rapidly emerging as a powerful tool with diverse applications,including high-speed imaging,laser-driven particle acceleration,and ultra-high frequency(UHF)communications.However,generating multipulse THz radiation with controllable time intervals remains a significant challenge.This study presents an approach to overcome this hurdle by exploiting the interaction between an electron beam and plasma.Using numerical simulations and theoretical analysis,we investigated the behavior of an electron beam within a plasma and its interaction with the longitudinal sheath field.This interaction resulted in the generation of multiple distinct THz pulses.We demonstrated that the plasma length adjustment allows for precise tuning of the interval between THz pulses.Moreover,the radiation intensity could be controlled by the electron beam energy and the electron bunch duration.The proposed scheme can generate multipulse THz radiation in a flexible and precise manner,paving the way for advancements in applications requiring high temporal resolution.
基金Project supported by the China Postdoctoral Science Foundation (Grant No. 2024T170021)the Beijing Municipal Science & Technology Commission, Administrative Commission of Zhongguancun Science Park (Grant No. Z231100006023003)+2 种基金the National Natural Science Foundation of China (Grant Nos. 12175058, 12205007, and 11921006)the National Science Fund of Hunan Province for Distinguished Young Scholars (Grant No. 2024JJ2009)The computing was supported by the High-performance Computing Platform of Peking University。
文摘Terahertz(THz) radiation, spanning the frequency range 100 GHz to 10 THz, offers diverse applications in spectroscopy, materials characterization, medical diagnostics and environmental monitoring. Despite its potential, the generation of high-intensity, tunable THz radiation remains a significant challenge. In this work, we explore a novel approach to the efficient generation of THz radiation based on laser–plasma interactions, utilizing the principles of photon deceleration.When a relativistic CO_(2) laser passes through a pre-ionized plasma, the laser induces a nonlinear wakefield, creating a strong refractive index gradient. This gradient, combined with the lower-density region of the wakefield, slows down the laser, facilitating the accumulation of THz radiation. The resulting THz pulse exhibits extreme collimation, high energy efficiency and tunability. Our work shows that this method can achieve up to 10% conversion efficiency with optimal plasma density near the critical density. This technique presents a promising solution for overcoming current limitations in THz source development and offers potential for diverse applications.
基金supported by the National Key R&D Program of China under Grant No.2025YFB3003603the National Natural Science Foundation of China under Grant Nos.12135002 and 12105209.
文摘By adopting stochastic density functional theory(SDFT)and mixed stochastic-deterministic density functional theory(MDFT)methods,we perform first-principles calculations to predict the shock Hugoniot curves of boron(pressure P=7.9×10^(3)-1.6×10^(6) GPa and temperature T=25-2800 eV),silicon(P=2.6×10^(3)-7.9×10^(5) GPa and T=21.5-1393 eV),and aluminum(P=5.2×10^(3)-9.0×10^(5) GPa and T=25-1393 eV)over wide ranges of pressure and temperature.In particular,we systematically investigate the impact of different cutoff radii in norm-conserving pseudopotentials on the calculated properties at elevated temperatures,such as pressure,ionization energy,and equation of state.By comparing the SDFT and MDFT results with those of other first-principles methods,such as extended first-principles molecular dynamics and path integral Monte Carlo methods,we find that the SDFT and MDFT methods show satisfactory precision,which advances our understanding of first-principles methods when applied to studies of matter at extremely high pressures and temperatures.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12175058 and 11921006)the National Grand Instrument Project (No. 2019YFF01014402)the Beijing Distinguished Young Scientist Program and National Grand Instrument Project No. SQ2019YFF01014400
文摘Controlling terahertz(THz)polarization with high stability and tunability is essential for achieving further progress in ultrafast spectroscopy,structured-light manipulation,and quantum information processing.Here,we propose a magnetized plasma platform for dynamic THz polarization control by exploiting the intrinsic birefringence between extraordinary and ordinary modes.We identify a strong-magnetization,zero-group-velocity-mismatch regime where the two modes share matched group velocities while retaining finite phase birefringence,enabling robust,phase-stable spin angular momentum control.By tuning the plasma length and magnetic field,we realize programmable phase retardation and demonstrate universal single-qubit gates through parameterized unitary operations.Full-wave particle-in-cell simulations validate high-fidelity polarization transformations across the Poincarésphere and demonstrate the potential for generating structured vector beams under spatially varying magnetic fields.The platform offers ultrafast response,resilience to extreme THz intensities,and in situ tunability,positioning magnetized plasmas as a versatile and damage-resilient medium for next-generation THz polarization control and structured-wave applications.
基金supported by the National Key Research and Development Program(No.2022YFA1603300)the National Natural Science Foundation of China(Nos.U2230133,12305266,11921006,12405282)National Grand Instrument Project(No.2019YFF01014400)。
文摘The illicit trafficking of special nuclear materials(SNMs)poses a grave threat to global security and necessitates the development of effective nuclear material identification methods.This study investigated a method to isotopically identify the SNMs,including^(233,235,238)U,^(239-242)Pu,and^(232)Th,based on the detection of delayedγ-rays from photofission fragments.The delayedγ-ray spectra resulting from the photofission of SNMs irradiated by a 14 MeVγbeam with a total of 10~9 were simulated using Geant4.Three high-yield fission fragments,namely^(138)Cs,^(89)Rb,and^(94)Y,were selected as candidate fragments for SNM identification.The yield ratios of these three fragments were calculated,and the results from the different SNMs were compared.The yield ratio of^(138)Cs/^(89)Rb was used to identify most SNMs,including^(233,235,238)U,^(242)Pu,and^(232)Th,with a confidence level above 95%.To identify^(239-241)Pu with the same confidence,a higher total number of 10^(11)γbeams is required.However,although the^(94)Y/^(89)Rb ratio is suitable for elementally identifying SNMs,isotopic identification is difficult.In addition,the count rate of the delayedγabove 3 MeV can be used to rapidly detect the presence of nuclear materials.
文摘Correction to:Nuclear Science and Techniques(2025)36:100 https://doi.org/10.1007/s41365-025-01692-6 In this article,Fig.9 appeared incorrectly and have now been corrected in the original publication.For completeness and transparency,both correct and incorrect versions are displayed below.
基金supported by NSFC (Grant No.11672002)NSAF (Grant No. U1730103)
文摘3D printing or additive manufacturing (AM) has revolutionized the way of manufacturing by designing complex structures in a customized feature which cannot be realized by traditional processing methods. Incoming materials are trying to adopt 3D printing techniques which directly fabricate sophisticated entities with multifunctionality like mechanical, electrical, thermal and magnetic properties etc. For the realization of advanced materials, 3D printing techniques are emerging from single material to composite materials manufacturing by simply introducing the nano- and micro-reinforcements with the matrix. In this review, we provide an outline of 3D printing graphene-based composites according to various AM techniques including fused deposition modeling (FDM), direct ink writing (DIW), stereolithography (SLA) and selective laser sintering (SLS). First a brief introduction of various AM techniques is given to get a basic understanding of the principles of 3D printing, and then the fabrication process, structural characteristics and applications of different 3D printing techniques for graphene-based composites are summarized. In addition, some effective simulation and characterization methods are also included. We hope that this review would clarify the potential of AM techniques for composite materials and can open new prospects for designing of novel materials.
