Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely s...Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely small atomic nuclei to explain the evolution of the universe.Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain unsolved.To achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models.Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar evolution.Given the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several decades.These are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive isotopes.However,direct measurement is still preferable,such as in the case of reactions involving light and stable nuclei.As an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent years.To overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution.Therefore,underground experiments have emerged as a new and promising direction of research.In addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot.In recent years,the CIAE team conducted a series of distinctive nuclear astrophysics studies,relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories,including the Beijing Radioactive Ion beam Facility,as well as other scientifc platforms at home and abroad.This research covered nuclear theories,numerical models,direct measurements,indirect measurements,and other novel approaches,achieving great interdisciplinary research results,with high-level academic publications and signifcant international impacts.This article reviews the above research and predicts future developments.展开更多
We have developed a computerized system for measuring field electron emission （FE） and field ionization （FI）, which has a three-electrode configuration with emitters biased up to 25 kV, and is programmed by the La...We have developed a computerized system for measuring field electron emission （FE） and field ionization （FI）, which has a three-electrode configuration with emitters biased up to 25 kV, and is programmed by the Labview software. The current-voltage curves of nano-tip tungsten and carbon nanotube （CNT） arrays were measured. The electron emission of CNTs proceeded with a turn-on field of 1.24 V/μm and a threshold field of 1.85 V/μm. Compared to the field emission, field ionization turned on at 3.5 V/μm. Raman spectroscopy and scanning electron microscopy （SEM） measurements showed degradation of the CNTs after FE/FI testing. The measurement of a W-tip revealed strong electron emission and instability behavior at a field strength higher than 7.0 V/μm.展开更多
The production mechanism of heavy neutronrich nuclei is investigated by using the multinucleon transfer reactions of ^(136;148)Xe+^(208)Pb and ^(238)U+^(208)Pb in the framework of a dinuclear system model. The evapora...The production mechanism of heavy neutronrich nuclei is investigated by using the multinucleon transfer reactions of ^(136;148)Xe+^(208)Pb and ^(238)U+^(208)Pb in the framework of a dinuclear system model. The evaporation residual cross sections of target-like fragments are studied with the reaction system ^(148)Xe+^(208)Pb at near barrier energies. The results show that the final isotopic production cross sections in the neutron-deficient side are very sensitive to incident energy while it is not sensitive in the neutron-rich side. Comparing the isotopic production cross sections for the reactions of ^(208)Pb bombarded with stable and radioactive projectiles, we find that neutron-rich radioactive beams can significantly increase the production cross sections of heavy neutron-rich nuclei.展开更多
The electronic structures of Ag-doped rutile and anatase Ti02 are studied by first-principles band calculations based on density functional theory with the full-potential linearized-augmented-plane-wave method. New oc...The electronic structures of Ag-doped rutile and anatase Ti02 are studied by first-principles band calculations based on density functional theory with the full-potential linearized-augmented-plane-wave method. New occupied bands are found between the band gaps of both Ag-doped rutile and anatase TiO2. The formation of these new bands can be explained mainly by their orbitals of Ag 4d states mixed with Ti 3d states and are supposed to contribute to their visible light absorption.展开更多
Nitrogen-doped TiO2 nanotubes(TNTs)were prepared by ion implantation and anodic oxidation.The prepared samples were applied in photocatalytic(PC)oxidation of methyl blue,rhodamine B,and bisphenol A under light irradia...Nitrogen-doped TiO2 nanotubes(TNTs)were prepared by ion implantation and anodic oxidation.The prepared samples were applied in photocatalytic(PC)oxidation of methyl blue,rhodamine B,and bisphenol A under light irradiation.To explore the influence of doped ions on the band and electronic structure of TiO2,computer simulations were performed using the VASP code implementing spin-polarized density functional theory(DFT).Both substitutional and interstitial nitrogen atoms were considered.The experimental and computational results propose that the electronic structure of TiO2 was modified because of the emergence of impurity states in the band gap by introducing nitrogen into the lattice,leading to the absorption of visible light.The synergy effects of tubular structures and doped nitrogen ions were responsible for highly efficient and stable PC activities induced by visible and ultraviolet(UV)light.展开更多
Sodium borosilicate glasses are candidate materials for high-level radioactive waste vitrification;therefore, understanding the irradiation effects in model borosilicate glass is crucial. Effects of electronic energy ...Sodium borosilicate glasses are candidate materials for high-level radioactive waste vitrification;therefore, understanding the irradiation effects in model borosilicate glass is crucial. Effects of electronic energy deposition and nuclear energy deposition induced by the impact of heavy ions on the hardness and Young’s modulus of sodium borosilicate glass were investigated. The work concentrates on sodium borosilicate glasses, henceforth termed NBS1 (60.0% SiO2, 15.0% B2O3, and 25.0% Na2O in mol%). The NBS1 glasses were irradiated by P, Kr, and Xe ions with 0.3 MeV, 4 MeV, and 5 MeV, respectively. The hardness and Young’s modulus of ion-irradiated NBS1 glasses were measured by nanoindentation tests. The relationships between the evolution of the hardness, the change in the Young’s modulus of the NBS1 glasses, and the energy deposition were investigated. With the increase in the nuclear energy deposition, both the hardness and Young’s modulus of NBS1 glasses dropped exponentially and then saturated. Regardless of the ion species, the nuclear energy depositions required for the saturation of hardness and Young’s modulus were apparent at approximately 1.2 × 10^20 keV/cm^3 and 1.8 × 10^20 keV/cm^3, respectively. The dose dependency of the hardness and Young’s modulus of NBS1 glasses was consistent with previous studies by Peuget et al. Moreover, the electronic energy loss is less than 4 keV/nm, and the electronic energy deposition is less than 3.0 × 10^22 keV/cm^3 in this work. Therefore, the evolution of hardness and Young’s modulus could have been primarily induced by nuclear energy deposition.展开更多
Antimony ions were implanted into ZnMnO films grown on silicon （Si） by radio- frequency magnetron sputtering. The implanted samples were treated by rapid thermal annealing and investigated by X-ray photoelectron spe...Antimony ions were implanted into ZnMnO films grown on silicon （Si） by radio- frequency magnetron sputtering. The implanted samples were treated by rapid thermal annealing and investigated by X-ray photoelectron spectroscopy, X-ray diffraction and Raman scattering. In the wurtzite of ZnMnO, both manganese （Mn） and stibium （Sb） substituted the lattice position of zinc （Zn）. The ZnMnO films were characterized by Raman scattering at 522 cm-1, attributed to a local vibration of Mn. After implantation with Sb ions, two new peaks 681 cm^-1 and 823 cm^-1 were observed in the ZnMnO films, as a result of ion-induced damage to the lattice.展开更多
The electron energy spectrum is one of the most important characteristics of an electron beam that is extracted from a linear accelerator. The most direct way to determine an electron spectrum would be to use a magnet...The electron energy spectrum is one of the most important characteristics of an electron beam that is extracted from a linear accelerator. The most direct way to determine an electron spectrum would be to use a magnetic spectrometer and this method could also give results with high precision and effectiveness. In this article we describe our design of a new multi-layer absorption method, which is based on the depth-dose curves method that can be used in most irradiation accelerators, and adds the Monte Carlo simulation and iterative algorithm in order to reconstruct the electron energy spectrum. In this article the energy spectrum was measured using these two methods, and good results were acquired. These results could be crosschecked, which made the results more reliable.展开更多
Using the time dependent local density approximation, applied to valence electrons, coupled non-adiabatically to molecular dynamics of ions, the collision process between ethylene and fast charged projectiles is studi...Using the time dependent local density approximation, applied to valence electrons, coupled non-adiabatically to molecular dynamics of ions, the collision process between ethylene and fast charged projectiles is studied in the microscopic way. The impact of ionic motion on the ionization is explored to show the importance of treating electronic and ionic degrees of freedom simultaneously. The number of escaped electrons, ionization probabilities are obtained. Furthermore, it is found that the ionic extensions in different directions show the different patterns.展开更多
The fragmentation cross sections of reactions ^12C＋^2H, ^12C, ^14N, ^16O at beam energies from 50 to 100 MeV/nucleon are investigated using the isospin-dependent Boltzmann-Langevin equation model. It is found that fr...The fragmentation cross sections of reactions ^12C＋^2H, ^12C, ^14N, ^16O at beam energies from 50 to 100 MeV/nucleon are investigated using the isospin-dependent Boltzmann-Langevin equation model. It is found that fragment species increase approximately with the increasing target mass. The fragment species and some fragments production cross sections in reactions of ^12C＋^12C, ^14N, ^16O show an obvious variation at the beam energies from 50 to 80 MeV/nucleon. However the calculated fragment production cross sections do not change much when the incident energy increases from 80 to 100 MeV/nucleon.展开更多
A new method to measure the divergence of x-ray beams propagated out from several capillaries is introduced, This new method is based on Bragg＇s law and is proven efficiently by the experimental measurement with coll...A new method to measure the divergence of x-ray beams propagated out from several capillaries is introduced, This new method is based on Bragg＇s law and is proven efficiently by the experimental measurement with collimators and straight polycapillaries.展开更多
Molecular dynamics simulations are performed to investigate the polymorphism and flexibility of DNA in water,ethylene glycol(EG)and ethanol(EA)solutions.DNA in EG resembles the structure of DNA in water exhibiting B-D...Molecular dynamics simulations are performed to investigate the polymorphism and flexibility of DNA in water,ethylene glycol(EG)and ethanol(EA)solutions.DNA in EG resembles the structure of DNA in water exhibiting B-DNA.In contrast,the DNA is an A-DNA state in the EA.We demonstrate that one important cause of these A$\leftrightarrow$B state changes is the competition between hydration and direct cation coupling to the phosphate groups on DNA backbones.To DNA structural polymorphism,it is caused by competition between hydration and cation coupling to the base pairs on grooves.Unlike flexible DNA in water and EA,DNA is immobilized around the canonical structure in EG solution,eliminating the potential biological effects of less common non-canonical DNA sub-states.展开更多
Both tetrahydrofuran （THF） and 2-methyltetrahydrofuran （MTHF） are studied systematically at desired temperatures using molecular dynamics simulations. The results show that the calculated densities are well consis...Both tetrahydrofuran （THF） and 2-methyltetrahydrofuran （MTHF） are studied systematically at desired temperatures using molecular dynamics simulations. The results show that the calculated densities are well consistent with experiment. Their glass transition temperatures are obtained： 115 K - 130 K for THF and 131 K - 142 K for MTHF. The calculated results from the dipolar orientational time correlation functions indicate that the ＂long time＂ behavior is often associated with a glass transition. From the radial and spatial distributions, we also find that the methyl has a direct impact on the structural symmetry of molecules, which leads to the differences of physical properties between THF and MTHF.展开更多
Based on the GEANT4 toolkit, we study the transportation of nucleons and nuclei in tissue-like media. The fragmentation of projectile nuclei and secondary interactions of produced nuclear fragments are considered. Liv...Based on the GEANT4 toolkit, we study the transportation of nucleons and nuclei in tissue-like media. The fragmentation of projectile nuclei and secondary interactions of produced nuclear fragments are considered. Livermore data is used to calculate electromagnetic interaction of primary and secondary charged particles. We validate the models using experimental data of 200 MeV/u and 400 MeV/u carbon ions, interacting with tissue equivalent materials of water. The model can well describe the depth-dose distributions in water and the doses measured for secondary fragments of certain charge and certain mass number. The secondary beam fragments produced by 200 MeV/u and 400 MeV/u ^12C^6＋ ions in water are investigated using the model. When the primary nuclei are in water, several neutron production mechanisms are involved. The light charged particles （p, d, t, ^3He and ^4He） and fast neutrons contribute to the dose tail behind the Bragg peak. The ^11C fragments which may be the most suitable nuclei for monitoring the energy deposition in carbon-ion therapy are also discussed.展开更多
The exotic structures of the ground state of the mirror nuclei ^17Ne and ^17N are investigated by means of the asymptotic normalization coefficient （ANC） method to explore the role of the Coulomb interaction, The pr...The exotic structures of the ground state of the mirror nuclei ^17Ne and ^17N are investigated by means of the asymptotic normalization coefficient （ANC） method to explore the role of the Coulomb interaction, The probebilities of a valence nucleon outside the binding-potential are P = 56.69±2.98/7.46% for ^17Ne and P = 45.51±2.32/5.81% for ^17N. The rms radii are （r^2）^1/2 = 5.06±0.11/0.30 fm and （r^2）^1/2=4.24±0.06/0.16 fm, respectively. The results obtained are nearly independent of the potential parameters. According to the halo occurrence conditions, it is suggested that ^17Ne is a two-proton halo and ^17N is a two-neutron skin. Moreover, two effects of the Coulomb interact-ion on the exotic structure are analysed. From the present results, the exotic structure of the nucleus in the proton-rich side is more obvious than that of its mirror nucleus because of the Coulomb interaction.展开更多
An efficient quantum cryptography network protocol is proposed with d-dimensional polarized photons, without resorting to entanglement and quantum memory. A server on the network, say Alice, provides the service for p...An efficient quantum cryptography network protocol is proposed with d-dimensional polarized photons, without resorting to entanglement and quantum memory. A server on the network, say Alice, provides the service for preparing and measuring single photons whose initial state are ｜0〉. The users code the information on the single photons with some unitary operations. To prevent the untrustworthy server Alice from eavesdropping the quantum lines, a nonorthogonal-coding technique is used in the process that the quantum signal is transmitted between the users. This protocol does not require the servers and the users to store the quantum states and almost all of the single photons can be used for carrying the information, which makes it more convenient for application than others with present technology. We also discuss the case with a faint laser pulse.展开更多
A general scheme for controlled teleportation of an arbitrary multi-qudit state with d-dimensional Greenberger- Horne--Zeilinger （GHZ） states is proposed. For an arbitrary m-qudit state, the sender Alice performs m ...A general scheme for controlled teleportation of an arbitrary multi-qudit state with d-dimensional Greenberger- Horne--Zeilinger （GHZ） states is proposed. For an arbitrary m-qudit state, the sender Alice performs m generalized Bell-state projective measurements on her 2m qudits and the controllers need only take some single-particle measurements. The receiver Charlie can reconstruct the unknown m-qudit state by performing some single-qudit unitary operations on her particles if she cooperates with all the controllers. As the quantum channel is a sequence of maximally entangled GHZ states, the intrinsic efticiency for qudits in this scheme approaches 100% in principle.展开更多
An improved isospin dependent Boltzmann Langevin model,in which the inelastic channels and momentum dependent interactions are incorporated,is used to investigate the high-density behavior of nuclear symmetry energy.B...An improved isospin dependent Boltzmann Langevin model,in which the inelastic channels and momentum dependent interactions are incorporated,is used to investigate the high-density behavior of nuclear symmetry energy.By taking several forms of nuclear symmetry energy,we calculate the time evolutions of neutron over proton ratio,π multiplicity and π-/π+ ratio,and the kinetic energy and transverse momentum spectra of π-/π+ ratio in the heavy ion collisions at 400A MeV.It is found that the neutron over proton ratio and π-/π+ ratio are very sensitive to the nuclear symmetry energy,and the π-is more sensitive to the nuclear symmetry energy than the π+.A supersoft symmetry energy results in a larger π-/π+ ratio.展开更多
The neutron flow model predicts that neutrons start to flow freely between the approaching nuclei ^58Fe and ^208 pb at s=3fm, a length in which the effective surfaces of these nuclei are 3 fm apart. As a result of neu...The neutron flow model predicts that neutrons start to flow freely between the approaching nuclei ^58Fe and ^208 pb at s=3fm, a length in which the effective surfaces of these nuclei are 3 fm apart. As a result of neutron flow, the N/Z value rapidly reaches an equilibrium distribution. Meanwhile the system, originally in the fusion valley, is injected into the asymmetric fission valley. The dynamic process of the composite nucleus in the asymmetric fission valley is treated with a two-parameter Smoluchowski equation. It is shown that the probability to overcome the asymmetric fission barrier and to achieve compound nucleus configuration, hence the fusion cross section is obviously suppressed due to the effect of isospin equilibrium.展开更多
Silver indium cadmium(Ag–In–Cd) control rod is widely used in pressurized water reactor nuclear power plants,and it is continuously consumed in a high neutron flux environment. The mass ratio of ^(107)Ag in the Ag...Silver indium cadmium(Ag–In–Cd) control rod is widely used in pressurized water reactor nuclear power plants,and it is continuously consumed in a high neutron flux environment. The mass ratio of ^(107)Ag in the Ag–In–Cd control rod is 41.44%. To accurately calculate the consumption value of the control rod, a reliable neutron reaction cross section of the ^(107)Ag is required. Meanwhile,^(107)Ag is also an important weak r nucleus. Thus, the cross sections for neutron induced interactions with ^(107)Ag are very important both in nuclear energy and nuclear astrophysics. The(n, γ) cross section of ^(107)Ag has been measured in the energy range of 1–60 eV using a back streaming white neutron beam line at China spallation neutron source. The resonance parameters are extracted by an R-matrix code. All the cross section of ^(107)Ag and resonance parameters are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00010.展开更多
基金National Natural Science Foundation of China(Nos.12435010)National Key R&D Program of China(No.2022YFA1602301)。
文摘Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely small atomic nuclei to explain the evolution of the universe.Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain unsolved.To achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models.Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar evolution.Given the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several decades.These are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive isotopes.However,direct measurement is still preferable,such as in the case of reactions involving light and stable nuclei.As an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent years.To overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution.Therefore,underground experiments have emerged as a new and promising direction of research.In addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot.In recent years,the CIAE team conducted a series of distinctive nuclear astrophysics studies,relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories,including the Beijing Radioactive Ion beam Facility,as well as other scientifc platforms at home and abroad.This research covered nuclear theories,numerical models,direct measurements,indirect measurements,and other novel approaches,achieving great interdisciplinary research results,with high-level academic publications and signifcant international impacts.This article reviews the above research and predicts future developments.
基金supported by National Natural Science Foundation(No.11075121)the International Science and Technology Cooperation Program(No.2010DFA02010)Three Gorges University of China(KJ2009B011)
文摘We have developed a computerized system for measuring field electron emission （FE） and field ionization （FI）, which has a three-electrode configuration with emitters biased up to 25 kV, and is programmed by the Labview software. The current-voltage curves of nano-tip tungsten and carbon nanotube （CNT） arrays were measured. The electron emission of CNTs proceeded with a turn-on field of 1.24 V/μm and a threshold field of 1.85 V/μm. Compared to the field emission, field ionization turned on at 3.5 V/μm. Raman spectroscopy and scanning electron microscopy （SEM） measurements showed degradation of the CNTs after FE/FI testing. The measurement of a W-tip revealed strong electron emission and instability behavior at a field strength higher than 7.0 V/μm.
基金supported by the National Natural Science Foundation of China under Grants Nos.11635003,11025524 and 11161130520the National Basic Research Program of China under Grant No.2010CB832903+1 种基金the European Commission’s 7th Framework Programme(Fp7-PEOPLE-2010-IRSES)under Grant Agreement Project No.269131the Project funded by China Postdoctoral Science Foundation(Grant No.2016M600956)
文摘The production mechanism of heavy neutronrich nuclei is investigated by using the multinucleon transfer reactions of ^(136;148)Xe+^(208)Pb and ^(238)U+^(208)Pb in the framework of a dinuclear system model. The evaporation residual cross sections of target-like fragments are studied with the reaction system ^(148)Xe+^(208)Pb at near barrier energies. The results show that the final isotopic production cross sections in the neutron-deficient side are very sensitive to incident energy while it is not sensitive in the neutron-rich side. Comparing the isotopic production cross sections for the reactions of ^(208)Pb bombarded with stable and radioactive projectiles, we find that neutron-rich radioactive beams can significantly increase the production cross sections of heavy neutron-rich nuclei.
基金Supported by THE Tianjin Municipal Universities Science and Technology Development Foundation under Grant No 20070508, and the Tianjin Municipal Natural Science Foundation under Grant No 07JCYBJC14900.
文摘The electronic structures of Ag-doped rutile and anatase Ti02 are studied by first-principles band calculations based on density functional theory with the full-potential linearized-augmented-plane-wave method. New occupied bands are found between the band gaps of both Ag-doped rutile and anatase TiO2. The formation of these new bands can be explained mainly by their orbitals of Ag 4d states mixed with Ti 3d states and are supposed to contribute to their visible light absorption.
基金Project supported by the National Natural Science Foundation for Joint Fund Key Project of China(Grant No.U1865206)the National Science and Technology Major Project of China(Grant No.2017-Ⅶ-0012-0107)+1 种基金the National Defense Science and Technology Key Laboratory Fund of China(Grant No.614220207011802)the Key Area Research and Development Program of Guangdong Province,China(Grant No.2019B090909002)。
文摘Nitrogen-doped TiO2 nanotubes(TNTs)were prepared by ion implantation and anodic oxidation.The prepared samples were applied in photocatalytic(PC)oxidation of methyl blue,rhodamine B,and bisphenol A under light irradiation.To explore the influence of doped ions on the band and electronic structure of TiO2,computer simulations were performed using the VASP code implementing spin-polarized density functional theory(DFT).Both substitutional and interstitial nitrogen atoms were considered.The experimental and computational results propose that the electronic structure of TiO2 was modified because of the emergence of impurity states in the band gap by introducing nitrogen into the lattice,leading to the absorption of visible light.The synergy effects of tubular structures and doped nitrogen ions were responsible for highly efficient and stable PC activities induced by visible and ultraviolet(UV)light.
基金supported by the National Natural Science Foundations of China(Nos.11505085 and 11505086)the Fundamental Research Funds for the Central Universities(No.lzujbky-2018-72)DSTI Foundation of Gansu(No.2018ZX-07)
文摘Sodium borosilicate glasses are candidate materials for high-level radioactive waste vitrification;therefore, understanding the irradiation effects in model borosilicate glass is crucial. Effects of electronic energy deposition and nuclear energy deposition induced by the impact of heavy ions on the hardness and Young’s modulus of sodium borosilicate glass were investigated. The work concentrates on sodium borosilicate glasses, henceforth termed NBS1 (60.0% SiO2, 15.0% B2O3, and 25.0% Na2O in mol%). The NBS1 glasses were irradiated by P, Kr, and Xe ions with 0.3 MeV, 4 MeV, and 5 MeV, respectively. The hardness and Young’s modulus of ion-irradiated NBS1 glasses were measured by nanoindentation tests. The relationships between the evolution of the hardness, the change in the Young’s modulus of the NBS1 glasses, and the energy deposition were investigated. With the increase in the nuclear energy deposition, both the hardness and Young’s modulus of NBS1 glasses dropped exponentially and then saturated. Regardless of the ion species, the nuclear energy depositions required for the saturation of hardness and Young’s modulus were apparent at approximately 1.2 × 10^20 keV/cm^3 and 1.8 × 10^20 keV/cm^3, respectively. The dose dependency of the hardness and Young’s modulus of NBS1 glasses was consistent with previous studies by Peuget et al. Moreover, the electronic energy loss is less than 4 keV/nm, and the electronic energy deposition is less than 3.0 × 10^22 keV/cm^3 in this work. Therefore, the evolution of hardness and Young’s modulus could have been primarily induced by nuclear energy deposition.
基金supported by National Natural Science Foundation of China(Nos. 10675095, 10875090)
文摘Antimony ions were implanted into ZnMnO films grown on silicon （Si） by radio- frequency magnetron sputtering. The implanted samples were treated by rapid thermal annealing and investigated by X-ray photoelectron spectroscopy, X-ray diffraction and Raman scattering. In the wurtzite of ZnMnO, both manganese （Mn） and stibium （Sb） substituted the lattice position of zinc （Zn）. The ZnMnO films were characterized by Raman scattering at 522 cm-1, attributed to a local vibration of Mn. After implantation with Sb ions, two new peaks 681 cm^-1 and 823 cm^-1 were observed in the ZnMnO films, as a result of ion-induced damage to the lattice.
文摘The electron energy spectrum is one of the most important characteristics of an electron beam that is extracted from a linear accelerator. The most direct way to determine an electron spectrum would be to use a magnetic spectrometer and this method could also give results with high precision and effectiveness. In this article we describe our design of a new multi-layer absorption method, which is based on the depth-dose curves method that can be used in most irradiation accelerators, and adds the Monte Carlo simulation and iterative algorithm in order to reconstruct the electron energy spectrum. In this article the energy spectrum was measured using these two methods, and good results were acquired. These results could be crosschecked, which made the results more reliable.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10575012 and 10435020, the National Basic Research Program of China under Grant No 2010CB832903, the Doctoral Station Foundation of Ministry of Education of China under Grant No 200800270017.
文摘Using the time dependent local density approximation, applied to valence electrons, coupled non-adiabatically to molecular dynamics of ions, the collision process between ethylene and fast charged projectiles is studied in the microscopic way. The impact of ionic motion on the ionization is explored to show the importance of treating electronic and ionic degrees of freedom simultaneously. The number of escaped electrons, ionization probabilities are obtained. Furthermore, it is found that the ionic extensions in different directions show the different patterns.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10575012 and 10435020, the Beijing Education Committee under Grant No XK100270454, and the Science Foundation of Beijing Normal University.
文摘The fragmentation cross sections of reactions ^12C＋^2H, ^12C, ^14N, ^16O at beam energies from 50 to 100 MeV/nucleon are investigated using the isospin-dependent Boltzmann-Langevin equation model. It is found that fragment species increase approximately with the increasing target mass. The fragment species and some fragments production cross sections in reactions of ^12C＋^12C, ^14N, ^16O show an obvious variation at the beam energies from 50 to 80 MeV/nucleon. However the calculated fragment production cross sections do not change much when the incident energy increases from 80 to 100 MeV/nucleon.
文摘A new method to measure the divergence of x-ray beams propagated out from several capillaries is introduced, This new method is based on Bragg＇s law and is proven efficiently by the experimental measurement with collimators and straight polycapillaries.
基金Supported by the National Natural Science Foundation of China(Grants Nos.11635003,11025524 and 11161130520)the National Basic Research Program of China(Grant No.2010CB832903)the European Commission's 7th Framework Programme(Fp7-PEOPLE-2010-IRSES)(Grant No.269131).
文摘Molecular dynamics simulations are performed to investigate the polymorphism and flexibility of DNA in water,ethylene glycol(EG)and ethanol(EA)solutions.DNA in EG resembles the structure of DNA in water exhibiting B-DNA.In contrast,the DNA is an A-DNA state in the EA.We demonstrate that one important cause of these A$\leftrightarrow$B state changes is the competition between hydration and direct cation coupling to the phosphate groups on DNA backbones.To DNA structural polymorphism,it is caused by competition between hydration and cation coupling to the base pairs on grooves.Unlike flexible DNA in water and EA,DNA is immobilized around the canonical structure in EG solution,eliminating the potential biological effects of less common non-canonical DNA sub-states.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11025524 and 11161130520)the National Basic Research Program of China (Grant No. 2010CB832903)
文摘Both tetrahydrofuran （THF） and 2-methyltetrahydrofuran （MTHF） are studied systematically at desired temperatures using molecular dynamics simulations. The results show that the calculated densities are well consistent with experiment. Their glass transition temperatures are obtained： 115 K - 130 K for THF and 131 K - 142 K for MTHF. The calculated results from the dipolar orientational time correlation functions indicate that the ＂long time＂ behavior is often associated with a glass transition. From the radial and spatial distributions, we also find that the methyl has a direct impact on the structural symmetry of molecules, which leads to the differences of physical properties between THF and MTHF.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10575012 and 10435020, and the Specialized Research Fund for the Doctoral Programme of Higher Education of China under Grant No 200800270017, and the Beijing Education Committee under Grant No XK100270454.
文摘Based on the GEANT4 toolkit, we study the transportation of nucleons and nuclei in tissue-like media. The fragmentation of projectile nuclei and secondary interactions of produced nuclear fragments are considered. Livermore data is used to calculate electromagnetic interaction of primary and secondary charged particles. We validate the models using experimental data of 200 MeV/u and 400 MeV/u carbon ions, interacting with tissue equivalent materials of water. The model can well describe the depth-dose distributions in water and the doses measured for secondary fragments of certain charge and certain mass number. The secondary beam fragments produced by 200 MeV/u and 400 MeV/u ^12C^6＋ ions in water are investigated using the model. When the primary nuclei are in water, several neutron production mechanisms are involved. The light charged particles （p, d, t, ^3He and ^4He） and fast neutrons contribute to the dose tail behind the Bragg peak. The ^11C fragments which may be the most suitable nuclei for monitoring the energy deposition in carbon-ion therapy are also discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10254002, A0325401, 10075077, 10105016, and 10275092, and Major State Basic Research Development Programme of China under Grant No G200007400.
文摘The exotic structures of the ground state of the mirror nuclei ^17Ne and ^17N are investigated by means of the asymptotic normalization coefficient （ANC） method to explore the role of the Coulomb interaction, The probebilities of a valence nucleon outside the binding-potential are P = 56.69±2.98/7.46% for ^17Ne and P = 45.51±2.32/5.81% for ^17N. The rms radii are （r^2）^1/2 = 5.06±0.11/0.30 fm and （r^2）^1/2=4.24±0.06/0.16 fm, respectively. The results obtained are nearly independent of the potential parameters. According to the halo occurrence conditions, it is suggested that ^17Ne is a two-proton halo and ^17N is a two-neutron skin. Moreover, two effects of the Coulomb interact-ion on the exotic structure are analysed. From the present results, the exotic structure of the nucleus in the proton-rich side is more obvious than that of its mirror nucleus because of the Coulomb interaction.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10604008, 10435020, 10254002 and A0325401, and the Beijing Education Committee under Grant No XK100270454.
文摘An efficient quantum cryptography network protocol is proposed with d-dimensional polarized photons, without resorting to entanglement and quantum memory. A server on the network, say Alice, provides the service for preparing and measuring single photons whose initial state are ｜0〉. The users code the information on the single photons with some unitary operations. To prevent the untrustworthy server Alice from eavesdropping the quantum lines, a nonorthogonal-coding technique is used in the process that the quantum signal is transmitted between the users. This protocol does not require the servers and the users to store the quantum states and almost all of the single photons can be used for carrying the information, which makes it more convenient for application than others with present technology. We also discuss the case with a faint laser pulse.
基金＊ Supported by the National Natural Science Foundation of China under Grant Nos 10604008 and 10435020, and Beijing Education Committee under Grant No XK100270454.
文摘A general scheme for controlled teleportation of an arbitrary multi-qudit state with d-dimensional Greenberger- Horne--Zeilinger （GHZ） states is proposed. For an arbitrary m-qudit state, the sender Alice performs m generalized Bell-state projective measurements on her 2m qudits and the controllers need only take some single-particle measurements. The receiver Charlie can reconstruct the unknown m-qudit state by performing some single-qudit unitary operations on her particles if she cooperates with all the controllers. As the quantum channel is a sequence of maximally entangled GHZ states, the intrinsic efticiency for qudits in this scheme approaches 100% in principle.
基金Supported by National Natural Science Foundation of China(NSFC) projects (Nos.11025524 and 11161130520)National Basic Research Program of China(No.2010CB832903)
文摘An improved isospin dependent Boltzmann Langevin model,in which the inelastic channels and momentum dependent interactions are incorporated,is used to investigate the high-density behavior of nuclear symmetry energy.By taking several forms of nuclear symmetry energy,we calculate the time evolutions of neutron over proton ratio,π multiplicity and π-/π+ ratio,and the kinetic energy and transverse momentum spectra of π-/π+ ratio in the heavy ion collisions at 400A MeV.It is found that the neutron over proton ratio and π-/π+ ratio are very sensitive to the nuclear symmetry energy,and the π-is more sensitive to the nuclear symmetry energy than the π+.A supersoft symmetry energy results in a larger π-/π+ ratio.
基金Supported by the National Natural Science Foundation of China under Grants Nos 10235020 and 10235030, and the Major State Basic Research Development Programme under Grant No G200007400.
文摘The neutron flow model predicts that neutrons start to flow freely between the approaching nuclei ^58Fe and ^208 pb at s=3fm, a length in which the effective surfaces of these nuclei are 3 fm apart. As a result of neutron flow, the N/Z value rapidly reaches an equilibrium distribution. Meanwhile the system, originally in the fusion valley, is injected into the asymmetric fission valley. The dynamic process of the composite nucleus in the asymmetric fission valley is treated with a two-parameter Smoluchowski equation. It is shown that the probability to overcome the asymmetric fission barrier and to achieve compound nucleus configuration, hence the fusion cross section is obviously suppressed due to the effect of isospin equilibrium.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11875311, 11905274, 1705156, U2032146, 11865010, 11765015, and 1160509)the Natural Science Foundation of Inner Mongolia, China (Grant Nos. 2019JQ01 and 2018MS01009)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB34030000)。
文摘Silver indium cadmium(Ag–In–Cd) control rod is widely used in pressurized water reactor nuclear power plants,and it is continuously consumed in a high neutron flux environment. The mass ratio of ^(107)Ag in the Ag–In–Cd control rod is 41.44%. To accurately calculate the consumption value of the control rod, a reliable neutron reaction cross section of the ^(107)Ag is required. Meanwhile,^(107)Ag is also an important weak r nucleus. Thus, the cross sections for neutron induced interactions with ^(107)Ag are very important both in nuclear energy and nuclear astrophysics. The(n, γ) cross section of ^(107)Ag has been measured in the energy range of 1–60 eV using a back streaming white neutron beam line at China spallation neutron source. The resonance parameters are extracted by an R-matrix code. All the cross section of ^(107)Ag and resonance parameters are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00010.
