Review and a New Design of the Chart of Nuclides
Yinfang LUO, Xinliang YAN, Meng WANG, Qian WANG, Xiaohong ZHOU
The chart of the nuclides is one of the fundamental tools in nuclear science and technology. In this paper, we present a new two-dimensional chart of the nuclides, which displays up-to-date ground state nuclear properties such as isotopic abundances of stable nuclei, decay modes, half-life of radioactive nuclei, atomic mass error, and other experimental information extracted from the latest atomic mass evaluation AME2020 and NUBASE2020 evaluation of nuclear physics properties. We review the current status and trends in the visualization of nuclear charts, taking the Karlsruher Nuklidkarte as an example. We discuss the brief history and future perspectives of isotope discovery and nuclear chart publication, followed by the design details of our new chart of the nuclides. Additionally, we recommend free and open-source nuclear chart plotting software/websites. Our newly designed chart of the nuclides will be available in printed versions, including a wall chart and an A4-size folded chart for desktop usage. We plan to update the printed charts synchronously with the AME and NUBASE publications. This will ensure that the charts serve as a regular medium for the concise presentation of the NUBASE database.
More>>
Correlation Between Neutron Star Observation and Equation of State of Nuclear Matter at Different Densities
Jing ZHANG, Dehua WEN
Neutron star matter is mainly composed of asymmetric dense nuclear matter. At present, there is still great uncertainty in the understanding of the high-density asymmetric nuclear matter through the terrestrial experiments, such as the heavy ion collisions. With the improvement of astronomical observation accuracy and the increase of observable measurements of neutron stars, it is possible to reverse constraint the state of high-density nuclear matter based on astronomical observation of neutron stars. Theoretically investigating the correlation between the observable measurements of neutron stars and the equation of states (EOSs) at different density sections will be helpful to the research of the reverse constraints. In this work, by employing the piecewise polytrope EOSs, the observable measurements of the radius(R), tidal deformability($\varLambda$ ), moment of inertia(I) of the neutron star $etc$ . are calculated and analyzed, and the correlations between these observations and each density segment of the EOSs are given. The results show that tidal deformability ($\varLambda$ ) and f-mode frequency ($\nu$ ) of a canonical neutron star ($M \!=\! 1.4\, M_{\odot}$ ) are mainly correlated with $0.5\rho_{\rm{sat}} \!\sim\! 1.5\rho_{ sat}$ , $2.5\rho_{\rm{sat}} \!\sim\! 3.5\rho_{\rm{sat}}$ and $3.5\rho_{\rm{sat}} \!\sim\! 4.5\rho_{\rm{sat}}$ segments of EOSs; the neutron star radius (R) are mainly correlated with $1.5\rho_{\rm{sat}} \!\sim\! 3.5\rho_{\rm{sat}}$ and the crust segments of EOSs; the moment of inertia (I) are mainly correlated with the density below $ 4.5\rho_{\rm{sat}}$ segments of EOSs.
More>>
Probing Clustering Configurations of 16O by the Yield Distribution in Heavy Ion Collisions at Fermi Energy
Chenchen GUO, Wanbing HE, Zhendong AN, Jun SU, Long ZHU, Lijuan WU
In recent years, the cluster structure in nuclei has attracted a lot of attention. The goal of this work is to investigate the yield distribution of heavy ion collisions at Fermi energy and evaluate the $\alpha$ cluster configurations in light nuclei. The 16O+16O reactions with four different initialization $\alpha$ configurations (long chain, kite, square, tetrahedron)are simulated based on the Extended Quantum Molecular Dynamics (EQMD) transport model. The nuclei with different structures are investigated by observation of the multiplicity distribution of yields in nuclear reactions. It is found that the yields of free protons and 4He were affected by different cluster configurations, which indicates that 4He/proton can be used as a characterization of cluster structure. In addition, the $\alpha$ cluster configuration information of 16O can be extracted from the outgoing $\theta$ and $\phi$ and the kinetic energy spectrum of of free protons and 4He.
More>>
An Overview and Prospect of Nuclear Battery
Xiaoyi LI, Jingbin LU, Renzhou ZHENG, Xu XU, Yu WANG, Yumin LIU, Rui HE, Lei LIANG
The nuclear battery has many advantages, including high energy density, stable performance, no manual intervention etc., which can be widely utilized in cases requiring long-term reliable power supply. Among them, the Radioisotope Thermoelectric Generators (RTG) is the earliest used and the most technically matured one, while betavoltaic battery is now commercialized. However, there are still some problems including self-absorption effect, low energy conversion efficiency and severe radiation damage which restrict the application of betavoltaic batteries. Additionally, for an actual nuclear battery, it should be noticed that the component and density of the source will be changed because the radiation source decays continually, which leads to the electrical performance decline. In this review, the major events in nuclear battery development are listed on a timeline, and the principles and applications of different types of nuclear batteries are also introduced. For betavoltaic battery, the existence of self-absorption effect is pointed out as an important scientific problem, and for batteries with 63Ni and TiT2 source, the time-related electrical properties are also obtained. This paper also pointed out that, fine and precise calculations are very crucial in the optimized designing processes for a particular structure of the practical nuclear battery. Finally, researching assumptions including combining the source and the energy converting material and the use of energy converting structures with heavier isotopes are presented, which are benefit to solve the self-absorption problem, rise the output power of the nuclear battery and reduce the influence of radiation damage.
More>>
Transport of Isospin Degree of Freedom in Heavy Ion Reactions and the Constraint of Symmetry Energy
Zhigang XIAO
Heavy ion reactions provide an effective tool to study the nuclear equation of state (EOS) in terristial laborartory. When the number of neutrons differs largely with the number of protons in a nuclear system or nuclei, the main contribution to the nuclear EOS comes from the symmetry energy term. The nuclear symmetry energy, reflecting the isovector sector of the nucleon-nucleon potential, is closely relevant to the structural properties of dense object and the merging process in stellar environments, as well as to the exotic properties of nuclei and the location of the board of nuclear chart. However, the density dependence of the nuclear symmetry energy is the most unknown ingredient in the properties of nuclear matter so far. Thus the investigation of nuclear symmetry energy in wide density range becomes the main frontiers in many world-level nuclear laboratories and astrophyics observatories. In this article, we review briefly the experimental progress in this field. Particularly the experimental studies on the transport of the isospin degree of freedom in heavy ion reactions and the constraint of nuclear symmetry energy based on the Heavy Ion Research Facity at Lanzhou (HIRFL) are introduced. It has been shown that the isospin drift process persists to the late stage of the reaction, indicating that the isospin transport time scale may depend on the physics process under investigation. Due to the long-time accumulation of isospin effects, the angular distribution of the isospin concentration of the light particles in a wide range of angle is a sensitive probe of nuclear symmetry energy. With ${S}\!=\!28.3\,\mathrm{M}\mathrm{e}\mathrm{V}$ fixed at saturation point, the slope of the symmetry energy depending on density is contrained in the range of $L\!=\!33\!\sim\!61\,\mathrm{M}\mathrm{e}\mathrm{V}$ at $ \mathrm{C}\mathrm{L}\!=\!95$ %. Using a Compact Spectrometer for Havy Ion Experiment (CSHINE) with ability to achieve isotopic particle identification and fission event reconstruction, the small angle correlation function of the isotope-resolved light charged particles can be measured to derive the time scale of isospin relaxation in heavy ion reactions at Fermi energies. In the last section of the article, the isovector orientation effect of the polarized deuteron beam scattering off heavy target is introduced, which offers a novel means to constrain the nuclear symmetry energy below saturation density.
More>>
MAGIC: Matter in Astrophysics, Gravitational Waves, and Ion Collisions
Motornenko Anton, Hanauske Matthias, Weih Lukas, Steinheimer Jan, Stöcker Horst
The gravitational waves emitted from a binary neutron star merger, as predicted from general relativistic magneto-hydrodynamics calculations, are sensitive to the appearance of quark matter and the stiffness of the equation of state of QCD matter present in the inner cores of the stars. These astrophysically created extremes of thermodynamics do match, to within 20%, the values of densities and temperatures which are found in relativistic heavy ion collisions, if though at quite different rapidity windows, impact parameters and bombarding energies of the heavy nuclear systems. In this article we combine the results obtained in general relativistic simulations of binary neutron star systems with ones from heavy ion collisions in the lab to pin down the EOS and the phase structure of dense matter. We discuss that the postmerger gravitational wave emission of the neutron star merger remnant might give, in the near future, insides about the properties of the hadron quark transition.
More>>
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Display Method:
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023065
Abstract:
In this work, we presented the test results for a prototype of plastic scintillation detectors for time-of-flight measurement, aiming to provide preliminary research for the future development of time-of-flight detectors for HIAFHFRS facility. Each timing detectors was composed of a fast scintillating plastic and four fast photomultiplier tubes coupled to its four sides. The time performance of the detectors was tested using pico-second pulsed laser, For two plastic scintillation detectors with different sizes, a pico-second pulsed laser was used to simulating the actual ionbeam situation by changing laser’s parameters including spot size, repetition rate, light intensity and hitting position. The data was processed utilizing CAEN-DT5742 digitizer and Mesytec-MCFD16+MTDC32 electronics. When the focused laser hit at the center of the plastic scintillators, the time-of-flight (ToF) resolution of two small-sized (7 cm×7cm)plastic scintillation detectors could reach 8 ps, whereas the ToF resolution of the small and large (26 cm×10 cm) detectors could achieve 12 ps. After varying the parameters of the laser, the corresponding ToF resolutions were found to be in the range of 10–16 ps and 19–46 ps, respectively. The ToF resolutions from the test meets the timing-resolution requirement of the HFRS beamline, thereby establishing a solid foundation for further optimizing the time-of-flight detectors.
In this work, we presented the test results for a prototype of plastic scintillation detectors for time-of-flight measurement, aiming to provide preliminary research for the future development of time-of-flight detectors for HIAFHFRS facility. Each timing detectors was composed of a fast scintillating plastic and four fast photomultiplier tubes coupled to its four sides. The time performance of the detectors was tested using pico-second pulsed laser, For two plastic scintillation detectors with different sizes, a pico-second pulsed laser was used to simulating the actual ionbeam situation by changing laser’s parameters including spot size, repetition rate, light intensity and hitting position. The data was processed utilizing CAEN-DT5742 digitizer and Mesytec-MCFD16+MTDC32 electronics. When the focused laser hit at the center of the plastic scintillators, the time-of-flight (ToF) resolution of two small-sized (7 cm×7cm)plastic scintillation detectors could reach 8 ps, whereas the ToF resolution of the small and large (26 cm×10 cm) detectors could achieve 12 ps. After varying the parameters of the laser, the corresponding ToF resolutions were found to be in the range of 10–16 ps and 19–46 ps, respectively. The ToF resolutions from the test meets the timing-resolution requirement of the HFRS beamline, thereby establishing a solid foundation for further optimizing the time-of-flight detectors.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC11
Abstract:
Based on the group-algebra theory, we illustrate how to build the quadrupole-quadrupole dynamics for the identical fermion and boson systems within the s, d single-particle orbits, by which the influence of identity principle on the many-body dynamical structures of nuclei is discussed. The results indicate that the dimension of low-spin states in the identical fermion system with a given number of particle is much larger than the corresponding situation in the identical boson system, which means that the former can involve a richer rotational structure than the latter under similar conditions. The present analysis provides an example for analyzing nuclear structural model using the SU(3) group-algebra theory.
Based on the group-algebra theory, we illustrate how to build the quadrupole-quadrupole dynamics for the identical fermion and boson systems within the s, d single-particle orbits, by which the influence of identity principle on the many-body dynamical structures of nuclei is discussed. The results indicate that the dimension of low-spin states in the identical fermion system with a given number of particle is much larger than the corresponding situation in the identical boson system, which means that the former can involve a richer rotational structure than the latter under similar conditions. The present analysis provides an example for analyzing nuclear structural model using the SU(3) group-algebra theory.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC01
Abstract:
Reaction dynamics, especially the breakup mechanisms, induced by proton drip-line nuclei at energies around the Coulomb barrier, is one of the most popular topics in nuclear physics. In order to further investigate the reaction mechanisms of proton drip-line nuclei, we performed the complete-kinematics measurements of 8B+120Sn and 17F+58Ni at CRIB, University of Tokyo. This paper summarizes our research findings and unveils for the first time the fusion cross-section results in the 8B+120Sn measurement. Two detector arrays, i.e., the silicon telescope array of STARE and the ionization chamber array of MITA, were designed respectively for the measurements of 8B and 17F. Reaction products were completely identified with the help of these two arrays. For the 8B+120Sn system, the coincident measurement of the breakup fragments was achieved for the first time. The correlations between the breakup fragments reveal that the prompt breakup occurring on the outgoing trajectory dominates the breakup dynamics of 8B. For 17F+58Ni, the complete reaction channel information, such as quasi-elastic scattering, breakup and total fusion, was derived for the first time. An enhancement of the fusion cross section of 17F+58Ni was observed at the energy below the Coulomb barrier. Theoretical calculations indicate that this phenomenon is mainly due to the coupling to the continuum states. Moreover, different direct reaction dynamics were found in 8B and 17F systems, suggesting the influence of proton-halo structure on the reaction dynamics.
Reaction dynamics, especially the breakup mechanisms, induced by proton drip-line nuclei at energies around the Coulomb barrier, is one of the most popular topics in nuclear physics. In order to further investigate the reaction mechanisms of proton drip-line nuclei, we performed the complete-kinematics measurements of 8B+120Sn and 17F+58Ni at CRIB, University of Tokyo. This paper summarizes our research findings and unveils for the first time the fusion cross-section results in the 8B+120Sn measurement. Two detector arrays, i.e., the silicon telescope array of STARE and the ionization chamber array of MITA, were designed respectively for the measurements of 8B and 17F. Reaction products were completely identified with the help of these two arrays. For the 8B+120Sn system, the coincident measurement of the breakup fragments was achieved for the first time. The correlations between the breakup fragments reveal that the prompt breakup occurring on the outgoing trajectory dominates the breakup dynamics of 8B. For 17F+58Ni, the complete reaction channel information, such as quasi-elastic scattering, breakup and total fusion, was derived for the first time. An enhancement of the fusion cross section of 17F+58Ni was observed at the energy below the Coulomb barrier. Theoretical calculations indicate that this phenomenon is mainly due to the coupling to the continuum states. Moreover, different direct reaction dynamics were found in 8B and 17F systems, suggesting the influence of proton-halo structure on the reaction dynamics.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC05
Abstract:
In this work, the Gamow-like model for calculating the one-proton radioactivity half-life is improved by introducing the deformation of the nucleus. The calculations show that the deformed Gamow-like model can reproduce the experimental data better than the Gamow-like model. In addition, the reliability of the deformed Gamow-like model is confirmed by studying the linear relationship between the logarithmic form of the experimental half-life and the logarithmic form of the theoretical penetration probability. As an application, the one-proton radioactivity half-life of the deformed nucleus is predicted using the deformed Gamow-like model, and the predictions are able to comply well with the Geiger-Nuttall law. Finally, by studying the relationship between the orbital angular momentum and the calculated half-life, the reference values of the orbital angular momentum of 109I and 131Eu are given to obtain a more accurate theoretical half-life for one-proton radioactivity.
In this work, the Gamow-like model for calculating the one-proton radioactivity half-life is improved by introducing the deformation of the nucleus. The calculations show that the deformed Gamow-like model can reproduce the experimental data better than the Gamow-like model. In addition, the reliability of the deformed Gamow-like model is confirmed by studying the linear relationship between the logarithmic form of the experimental half-life and the logarithmic form of the theoretical penetration probability. As an application, the one-proton radioactivity half-life of the deformed nucleus is predicted using the deformed Gamow-like model, and the predictions are able to comply well with the Geiger-Nuttall law. Finally, by studying the relationship between the orbital angular momentum and the calculated half-life, the reference values of the orbital angular momentum of 109I and 131Eu are given to obtain a more accurate theoretical half-life for one-proton radioactivity.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC07
Abstract:
Relativistic Brueckner-Hartree-Fock(RBHF) theory is one of the most important ab initio methods in the relativistic framework, where the saturation properties of nuclear matter could be described satisfactorily with only considering two-body forces. By achieving the self-consistent solution of the RBHF equations for nuclear matter in the full Dirac space, the scalar and vector components of the single-particle potential have been determined uniquely, the uncertainties caused by the neglect of negative-energy states(NESs) have been avoided, and the long-standing problem over 40 years of not being able to uniquely determine the single-particle potential has been solved. The history of the RBHF theory is briefly reviewed, and the necessity of considering NESs is illustrated. The latest results of nuclear matter and neutron star matter by the RBHF theory in the full Dirac space are discussed, including the effective mass, the binding energy per particle of pure neutron matter, the pressure of symmetric nuclear matter and pure neutron matter, the particle fractions as well as the equation of state for neutron star matter, and the mass-radius relation as well as the tidal deformability of a neutron star. Possible applications of the RBHF theory in the full Dirac space are also discussed, including the calibration of the parameters in density functional theory, the microscopic description of nucleon-nucleus elastic scattering, and the research on the hadron-quark transition inside neutron stars.
Relativistic Brueckner-Hartree-Fock(RBHF) theory is one of the most important ab initio methods in the relativistic framework, where the saturation properties of nuclear matter could be described satisfactorily with only considering two-body forces. By achieving the self-consistent solution of the RBHF equations for nuclear matter in the full Dirac space, the scalar and vector components of the single-particle potential have been determined uniquely, the uncertainties caused by the neglect of negative-energy states(NESs) have been avoided, and the long-standing problem over 40 years of not being able to uniquely determine the single-particle potential has been solved. The history of the RBHF theory is briefly reviewed, and the necessity of considering NESs is illustrated. The latest results of nuclear matter and neutron star matter by the RBHF theory in the full Dirac space are discussed, including the effective mass, the binding energy per particle of pure neutron matter, the pressure of symmetric nuclear matter and pure neutron matter, the particle fractions as well as the equation of state for neutron star matter, and the mass-radius relation as well as the tidal deformability of a neutron star. Possible applications of the RBHF theory in the full Dirac space are also discussed, including the calibration of the parameters in density functional theory, the microscopic description of nucleon-nucleus elastic scattering, and the research on the hadron-quark transition inside neutron stars.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC17
Abstract:
In heavy ion collisions(HICs), the production of light particles plays an important role in extracting information about the equation of state(EoS) of nuclear matter. Based on the Ultra-relativistic Quantum Molecular Dynamics(UrQMD) model, the effect of the sequential decay on the collective flows and the nuclear stopping power of light particles in Au+Au collisions at intermediate energies were investigated, with the statistical decay model GEMINI++ is used to process the secondary decay of the primary fragments. It is found that due to the memory effect and the daughter nuclei produced by decay inherent part of the dynamic information of the parent nucleus, the experimental data can be better described by considering the sequential decay. And the influence of the sequential decay on the observables weakens with the increase of the collision energy. The results highlight that the sequential decay and the production of light particles in HICs have an obvious effect on the observables sensitive to the EoS, and these effects should be considered when adopting these observables to extract the information of the EoS.
In heavy ion collisions(HICs), the production of light particles plays an important role in extracting information about the equation of state(EoS) of nuclear matter. Based on the Ultra-relativistic Quantum Molecular Dynamics(UrQMD) model, the effect of the sequential decay on the collective flows and the nuclear stopping power of light particles in Au+Au collisions at intermediate energies were investigated, with the statistical decay model GEMINI++ is used to process the secondary decay of the primary fragments. It is found that due to the memory effect and the daughter nuclei produced by decay inherent part of the dynamic information of the parent nucleus, the experimental data can be better described by considering the sequential decay. And the influence of the sequential decay on the observables weakens with the increase of the collision energy. The results highlight that the sequential decay and the production of light particles in HICs have an obvious effect on the observables sensitive to the EoS, and these effects should be considered when adopting these observables to extract the information of the EoS.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC18
Abstract:
The nucleon-nucleon short-range correlation(NN-SRC) is one of the key issues in nuclear physics that cause high-momentum tails in the nucleon momentum distributions. In this paper, the nuclear spectral functions are constructed based on the axially deformed relativistic mean-field model, and the correction of the short-range correlation effect is introduced. Then, the inclusive scattering cross sections are calculated using the nuclear spectral function and the framework of the plane wave impulse approximation, including both the quasielastic and Δ resonance parts. In particular, in the Δ resonance region, the electromagnetic structure of the nucleon resonance state Δ(1232) is reconsidered, which effectively improves the theoretical calculations that can be in better agreement with experimental data. The paper further divides the inclusive scattering cross sections into the contributions of NN-SRC and mean-field. It is found that, the quasielastic peak and Δ resonance peak not only reflect the mean-field structure but also are sensitive to NN-SRC information. Finally, we propose a method for extracting the NN-SRC strength of nuclei from experimental cross-section data.
The nucleon-nucleon short-range correlation(NN-SRC) is one of the key issues in nuclear physics that cause high-momentum tails in the nucleon momentum distributions. In this paper, the nuclear spectral functions are constructed based on the axially deformed relativistic mean-field model, and the correction of the short-range correlation effect is introduced. Then, the inclusive scattering cross sections are calculated using the nuclear spectral function and the framework of the plane wave impulse approximation, including both the quasielastic and Δ resonance parts. In particular, in the Δ resonance region, the electromagnetic structure of the nucleon resonance state Δ(1232) is reconsidered, which effectively improves the theoretical calculations that can be in better agreement with experimental data. The paper further divides the inclusive scattering cross sections into the contributions of NN-SRC and mean-field. It is found that, the quasielastic peak and Δ resonance peak not only reflect the mean-field structure but also are sensitive to NN-SRC information. Finally, we propose a method for extracting the NN-SRC strength of nuclei from experimental cross-section data.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC04
Abstract:
The recent progresses on the wobbling motion are briefly introduced. So far 17 wobbling candidates have been reported in odd-A and even-even nuclei that spread over A≈100, 130, 160 and 190 mass regions. The two-quasiparticle configuration wobbling in 130Ba and the wobbling motion in a triaxial rotor are taken as examples in this paper to show the wobbling motion in even-even nuclei. For the 130Ba, the wobbling are investigated based on the combination of the covariant density functional theory (CDFT) and the particle rotor model (PRM). The CDFT provides crucial information on the configuration and deformation parameters of observed bands, serving as input for PRM calculations. The corresponding experimental energy spectra and electromagnetic transition probabilities are reproduced. An analysis of the angular momentum geometry reveals the enhanced stability of transverse wobbling of a two-quasiparticle configuration compared to a single-quasiparticle one. For the triaxial rotor, the time evolution of wobbling motion is explored through the solution of Euler equations. This investigation yields valuable insights into the evolution of orientation angles ($\phi $ and $\theta $ ) and angular momentum components. Notably, the study reveals that low-energy states of a triaxial rotor predominantly exhibit wobbling motion around the intermediate axis. Moreover, an increase in excitation energy corresponds to a prolonged period of intermediate axis wobbling motion. Conversely, a contrasting trend is observed in the case of long axis wobbling, where an increase in excitation energy leads to a decrease in the wobbling period.
The recent progresses on the wobbling motion are briefly introduced. So far 17 wobbling candidates have been reported in odd-A and even-even nuclei that spread over A≈100, 130, 160 and 190 mass regions. The two-quasiparticle configuration wobbling in 130Ba and the wobbling motion in a triaxial rotor are taken as examples in this paper to show the wobbling motion in even-even nuclei. For the 130Ba, the wobbling are investigated based on the combination of the covariant density functional theory (CDFT) and the particle rotor model (PRM). The CDFT provides crucial information on the configuration and deformation parameters of observed bands, serving as input for PRM calculations. The corresponding experimental energy spectra and electromagnetic transition probabilities are reproduced. An analysis of the angular momentum geometry reveals the enhanced stability of transverse wobbling of a two-quasiparticle configuration compared to a single-quasiparticle one. For the triaxial rotor, the time evolution of wobbling motion is explored through the solution of Euler equations. This investigation yields valuable insights into the evolution of orientation angles (
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC24
Abstract:
Based on the self-consistent RBUU transport theory, the isospin-dependent in-medium$ {\rm{N}} \Delta \rightarrow {\rm{N}} \Delta$ cross section is investigated. It is found that the isospin effect has a relatively obvious influence on the effective mass of baryons and the total $ {\rm{N}} \Delta $ elastic cross section in different density regions. With the increase of baryon density, the effective mass splitting between different isospin states of baryons increases gradually. Under the joint effect of density-dependent baryon effective mass splitting, coupling constant, as well as Born terms such as $\sigma-\delta$ , $\sigma-\rho$ , $\omega-\delta$ , $\omega-\rho$ , the elastic cross-sections of sub-channels with different isospin states exhibit different density-dependent behaviors. The total cross-section has an obvious reduction effect of medium in the low-energy region, and the medium effect is weakened in the high-energy region.
Based on the self-consistent RBUU transport theory, the isospin-dependent in-medium
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC20
Abstract:
Nuclear mass plays an important role in both nuclear physics and astrophysics. While the theoretical accuracy of masses has reached quite astonishing accuracy, their extrapolations have been conflicting, especially in neutron-rich regions. This paper reviews the main results of the extrapolations of nuclear mass models in recent years. By using a rigorous multi-objective optimization on mass models, we take the mass differences α decay energy and the Garvey-Kelson relations as multiple physical constraints to reduce the degree of overfitting phenomenon, resulting that the predictive power of models was improved in some degree. In addition, we use the improved mass data for the rapid neutron capture processes in nuclear astrophysics, further validating the reliability of the extrapolations.
Nuclear mass plays an important role in both nuclear physics and astrophysics. While the theoretical accuracy of masses has reached quite astonishing accuracy, their extrapolations have been conflicting, especially in neutron-rich regions. This paper reviews the main results of the extrapolations of nuclear mass models in recent years. By using a rigorous multi-objective optimization on mass models, we take the mass differences α decay energy and the Garvey-Kelson relations as multiple physical constraints to reduce the degree of overfitting phenomenon, resulting that the predictive power of models was improved in some degree. In addition, we use the improved mass data for the rapid neutron capture processes in nuclear astrophysics, further validating the reliability of the extrapolations.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC03
Abstract:
The diamond-like carbon(DLC) stripper foils with ~5 μg/cm2 in thickness were produced by using the composite technology of the filtered cathodic vacuum arc(FCVA)- alternating current carbon arc(ACCA)-relaxation technique. The uniformity of the DLC foils were measured by the XP2U balance. The results show that the maximum inhomongeneity of DLC foils in the range of Φ100 mm is 8.82%. The microstructure of the DLC foils were measured by the scanning electron microscopy(SEM), Raman spectroscopy and X-ray photoelectron spectroscopy(XPS). The SEM images show that the DLC foils are smooth, and contain hardly droplets through the double 90° filters. The Raman spectrum indicates that the DLC foils are amorphous carbon films. The X-ray photoelectron spectrum indicates the sp3 bonds of the DLC foils exceed 70%. The irradiation lifetimes of the DLC stripper foils were tested with the heavy ion beams at the Beijing HI-13 Tandem Accelerator. The results indicate that the lifetime of the DLC stripper foils after relaxation is ~3 times of the DLC stripper foils before relaxation. The lifetime of DLC stripper foil is respectively 4 and 13 times of the carbon stripper foil for the 197Au− and 63Cu− ion beams(~9 MV, ~1 μA). The lifetime of DLC stripper foil is 2.6~10.0 times of the carbon stripper foil for the 107Ag−、70Ge−、48Ti−、28Si− and 127I− ion beams. The heavier ions and the stronger beam current, the longer lifetime of DLC stripper foil compared with that of carbon stripper foil. The lifetime of the DLC stripper foils is related to the substrate bias voltage, and increases at first and then decreases with the increasing of the substrate bias voltage. The lifetime reaches the peak value when the substrate bias voltage is −400 V.
The diamond-like carbon(DLC) stripper foils with ~5 μg/cm2 in thickness were produced by using the composite technology of the filtered cathodic vacuum arc(FCVA)- alternating current carbon arc(ACCA)-relaxation technique. The uniformity of the DLC foils were measured by the XP2U balance. The results show that the maximum inhomongeneity of DLC foils in the range of Φ100 mm is 8.82%. The microstructure of the DLC foils were measured by the scanning electron microscopy(SEM), Raman spectroscopy and X-ray photoelectron spectroscopy(XPS). The SEM images show that the DLC foils are smooth, and contain hardly droplets through the double 90° filters. The Raman spectrum indicates that the DLC foils are amorphous carbon films. The X-ray photoelectron spectrum indicates the sp3 bonds of the DLC foils exceed 70%. The irradiation lifetimes of the DLC stripper foils were tested with the heavy ion beams at the Beijing HI-13 Tandem Accelerator. The results indicate that the lifetime of the DLC stripper foils after relaxation is ~3 times of the DLC stripper foils before relaxation. The lifetime of DLC stripper foil is respectively 4 and 13 times of the carbon stripper foil for the 197Au− and 63Cu− ion beams(~9 MV, ~1 μA). The lifetime of DLC stripper foil is 2.6~10.0 times of the carbon stripper foil for the 107Ag−、70Ge−、48Ti−、28Si− and 127I− ion beams. The heavier ions and the stronger beam current, the longer lifetime of DLC stripper foil compared with that of carbon stripper foil. The lifetime of the DLC stripper foils is related to the substrate bias voltage, and increases at first and then decreases with the increasing of the substrate bias voltage. The lifetime reaches the peak value when the substrate bias voltage is −400 V.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC12
Abstract:
High-spin level structure of 95Nb has been investigated using the multi-detector array of the conjoint gamma array in China via the 82Se(18O, p4n)95Nb. Based on γ-γ coincidence relationships, the level scheme of 95Nb has been modified and extended with 25 new γ rays and 15 new levels. The new level structure of 95Nb has been compared with the shell model calculations. It is suggested that the proton core excitation(f5/2→g9/2) across$Z = 38 $ sub-shell should be taken into account in order to adequately describe the high-spin level structure in 95Nb above spin of 39/2.
High-spin level structure of 95Nb has been investigated using the multi-detector array of the conjoint gamma array in China via the 82Se(18O, p4n)95Nb. Based on γ-γ coincidence relationships, the level scheme of 95Nb has been modified and extended with 25 new γ rays and 15 new levels. The new level structure of 95Nb has been compared with the shell model calculations. It is suggested that the proton core excitation(f5/2→g9/2) across
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC23
Abstract:
The Lanzhou Heavy Ion Accelerator Cooling Storage Ring(HIRFL-CSR) is an ideal device for studying the decay of highly charged and short-lived isomers. In the lifetime measurement experiment of the short-lived highly charged ion$^{94m}{\rm{Ru}}^{44+}$ , we directly observed the decay of $^{94}{\rm{Ru}}$ from 8+ isomer to the ground state, and identified 49 decay events in the observation time window of (20 μs, 180 μs). In order to identify more decay events, a new method based on amplitude of frequency spectrum was studied in this paper. Based on the simulation results, this new method can effectively identify decay events within (15 μs, 185 μs). By applying the new identification method to the experimental data processing, 54 decay events were identified within (15 μs, 185 μs). Based on these 54 decay events, the lifetime of $^{94m}{\rm{Ru}}^{44+}$ in the laboratory frame was calculated to be 194(121) μs. The new lifetime result is within the error range of the previous result 218(148) μs.
The Lanzhou Heavy Ion Accelerator Cooling Storage Ring(HIRFL-CSR) is an ideal device for studying the decay of highly charged and short-lived isomers. In the lifetime measurement experiment of the short-lived highly charged ion
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC14
Abstract:
There must be electromagnetic fields created during high-energy heavy-ion collisions. Although the electromagnetic field may become weak with the evolution of the quark-gluon plasma (QGP), compared to the energy scales of the strong interaction, they are potentially important to some electromagnetic probes. In this work, we propose the coupled effect of the weak magnetic field and the longitudinal dynamics of the background medium for the first time. We demonstrate that the induced photon spectrum can be highly azimuthally anisotropic when the quark-gluon plasma is in the presence of a weak external magnetic field. On the other hand, the weak magnetic photon emission from quark-gluon plasma only leads to a small correction to the photon production rate. After hydrodynamic evolution with a tilted fireball configuration, the experimentally measured direct photon elliptic flow is well reproduced. Meanwhile, the used time-averaged magnetic field in the hydrodynamic stage is found no larger than a few percent of the pion mass square.
There must be electromagnetic fields created during high-energy heavy-ion collisions. Although the electromagnetic field may become weak with the evolution of the quark-gluon plasma (QGP), compared to the energy scales of the strong interaction, they are potentially important to some electromagnetic probes. In this work, we propose the coupled effect of the weak magnetic field and the longitudinal dynamics of the background medium for the first time. We demonstrate that the induced photon spectrum can be highly azimuthally anisotropic when the quark-gluon plasma is in the presence of a weak external magnetic field. On the other hand, the weak magnetic photon emission from quark-gluon plasma only leads to a small correction to the photon production rate. After hydrodynamic evolution with a tilted fireball configuration, the experimentally measured direct photon elliptic flow is well reproduced. Meanwhile, the used time-averaged magnetic field in the hydrodynamic stage is found no larger than a few percent of the pion mass square.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC19
Abstract:
The number of constituent quark(NCQ) scaling of elliptic flow in heavy-ion collisions is one of the important signals of parton anisotropic degrees of freedom. In this work, we systematically study the$\upsilon_{2}^{}$ of light flavor hadrons as well as its NCQ scaling in p−Pb collisions at 5.02 TeV, with a multiphase transport(AMPT) model. Based on the advanced flow extraction method, the AMPT model calculations provide a good description of the measured transverse momentum($p_{\mathrm{T}}^{}$ )-differential $\upsilon_{2}^{}$ of mesons but exhibit a slight deviation of the baryon $\upsilon_{2}^{}$ . We find that the NCQ scaling is mainly driven by the combination of parton cascade and quark recombination, and also affected by the nonflow contribution and hardronic rescattering. This study provides new insights into understanding the origin of collective-like behaviors in small collision system.
The number of constituent quark(NCQ) scaling of elliptic flow in heavy-ion collisions is one of the important signals of parton anisotropic degrees of freedom. In this work, we systematically study the
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC16
Abstract:
The investigation of the equation of state(EoS) of nuclear matter, especially at high baryon densities is one of the hot topics in the frontier of nuclear physics. The impact of the EoS at 2~5 times saturation density$\rho_{0}$ on the two-particle correlation is discussed with the ultra-relativistic quantum molecular dynamics(UrQMD) model. Focusing on the two π Hanbury-Brown-Twiss(HBT) correlations, by adopting different EoSs, the effects of potential interaction and phase transition on the HBT correlation and the spatiotemporal properties of the emission source of π are investigated. The results show that below $\sim5 \rho_{0}$ , the HBT radius and parameters are sensitive to the stiffness of the EoS. By comparing with the experiment data, first-order phase transition with a significant softening of the equation of state below 4 times nuclear saturation density can be excluded using HBT data, and the available data on the HBT radii in the investigated energy region favor a relatively stiff EoS at low densities, which then turns into a soft EoS at high densities. These results highlight that the pion's HBT radius and parameters are sensitive to the stiffness of the equation of state, and can be used to constrain and understand the equation of state in the high baryon density region.
The investigation of the equation of state(EoS) of nuclear matter, especially at high baryon densities is one of the hot topics in the frontier of nuclear physics. The impact of the EoS at 2~5 times saturation density
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC09
Abstract:
$ C_I $ \begin{document}$ {{M}}_\odot $\end{document} \begin{document}$ 70 \leqslant \varLambda_{1.4} \leqslant 580 $\end{document} $ C_I $
Research performed during the past decade revealed an important role of symmetry energy in the equation of state of quark matter. By introducing an isospin-dependent term into the quark mass scaling, the stability window of quark matter was studied in the equivparticle model. The results show that a sufficiently strong isospin dependence
can significantly widen the absolute stable region of strange quark matter, yielding results that simultaneously satisfy the constraints of the astrophysical observations of PSR J1614-2230 with (1.928 ± 0.017)
and tidal deformability
measured in the event GW170817. Contrary to the case of strange quark matter, the stable region of u-d quark matter narrows with isospin dependence
, leading to inconsistency with astrophysical observations. Finally, we found that the symmetry energy of strange quark matter is much larger than that of u-d quark matter, and one-gluon exchange interaction between quarks causes the symmetry energy of strange quark matter to become softer.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC08
Abstract:
Schottky diodes are fabricated using 100 µm thick 4H-SiC epitaxial wafers with Ohmic and Schottky contacts, and packaged as SiC detectors to meet the requirements of high temperature and radiation environments. The current-voltage (I-V) curves are measured in the range of 25 to 150 ºC. The experimental results show that the leakage current changes very little when the temperature is less than or equal to 105 ºC. The change rate of leakage current is 0.33%/ºC, when the reverse bias is −500 V and the temperature rises from 25 to 105 ºC. The SiC detector is irradiated by 60Co source in Peking University. The I-V characteristics of the SiC detector are compared before and after the irradiation experiment with total dose of 1 Mrad. The experimental data indicates that the leakage current has almost no significant change.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC22
Abstract:
The space charge effect is the core problem of high intensity proton accelerator, especially at injection and initial acceleration stages. Using the phase space painting with optimized process, will effectively reduce the influence of space charge effect on injection and acceleration efficiency, and emittance increase. Transverse phase space painting methods can be divided into correlated painting and anti-correlated painting. In this paper, firstly, the transverse phase space paintings for the high intensity proton synchrotron are discussed in detail, including different painting methods and different implementation methods. Secondly, based on the injection system of the China Spallation Neutron Source (CSNS), the beam injection process and anti-correlated painting design scheme are studied in detail. The reasons for the reduction of the actual vertical painting range and the influence of edge focusing effects of the bump magnets on the painting and beam dynamics are deeply explored. In addition, the method to perform the correlated painting based on the mechanical structure of the anti-correlated painting scheme and its key role in realizing the CSNS design goal are briefly introduced. Finally, according to the requirement of switching between different painting methods online in future accelerators, a new injection scheme that can realize correlated and anti-correlated painting simultaneously has been proposed. The new painting injection scheme has been demonstrated, simulated and optimized in detail.
The space charge effect is the core problem of high intensity proton accelerator, especially at injection and initial acceleration stages. Using the phase space painting with optimized process, will effectively reduce the influence of space charge effect on injection and acceleration efficiency, and emittance increase. Transverse phase space painting methods can be divided into correlated painting and anti-correlated painting. In this paper, firstly, the transverse phase space paintings for the high intensity proton synchrotron are discussed in detail, including different painting methods and different implementation methods. Secondly, based on the injection system of the China Spallation Neutron Source (CSNS), the beam injection process and anti-correlated painting design scheme are studied in detail. The reasons for the reduction of the actual vertical painting range and the influence of edge focusing effects of the bump magnets on the painting and beam dynamics are deeply explored. In addition, the method to perform the correlated painting based on the mechanical structure of the anti-correlated painting scheme and its key role in realizing the CSNS design goal are briefly introduced. Finally, according to the requirement of switching between different painting methods online in future accelerators, a new injection scheme that can realize correlated and anti-correlated painting simultaneously has been proposed. The new painting injection scheme has been demonstrated, simulated and optimized in detail.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC72
Abstract:
This study establishes a novel high-resolution fast magnetic resonance imaging(MRI) method that incorporates Beam Eye View(BEV) and Beam Path View(BPV) fusion information. Three liver metastasis patients undergoing MRI guided radiotherapy(MRgRT) were selected. A total of 31 200 frames of MRI images were acquired from each patient using two motion patterns: restricted abdominal motion using an abdominal compression belt(RAM group) and free breathing(FB group). Tumor tracking was performed using nearby vessels with clear boundaries, and the radial vector motion amplitude difference(∆R95) within the 95% confidence interval was calculated. The differences in ΔR95 between the RAM and FB groups in all fractions on the BEV/BPV plane were as follows: for Patient 1, they were all less than 0.58 mm; for Patient 2, they were greater than 2.57 mm; for Patient 3, they were 0.71 mm and 1.05 mm, respectively. The results indicate that the abdominal compression technique can effectively reduce tumor motion magnitude, and the tumor motion magnitude ΔR95 variation is highly individual-specific. This method can serve as an imaging basis for the tumor margin reduction in MRgRT.
This study establishes a novel high-resolution fast magnetic resonance imaging(MRI) method that incorporates Beam Eye View(BEV) and Beam Path View(BPV) fusion information. Three liver metastasis patients undergoing MRI guided radiotherapy(MRgRT) were selected. A total of 31 200 frames of MRI images were acquired from each patient using two motion patterns: restricted abdominal motion using an abdominal compression belt(RAM group) and free breathing(FB group). Tumor tracking was performed using nearby vessels with clear boundaries, and the radial vector motion amplitude difference(∆R95) within the 95% confidence interval was calculated. The differences in ΔR95 between the RAM and FB groups in all fractions on the BEV/BPV plane were as follows: for Patient 1, they were all less than 0.58 mm; for Patient 2, they were greater than 2.57 mm; for Patient 3, they were 0.71 mm and 1.05 mm, respectively. The results indicate that the abdominal compression technique can effectively reduce tumor motion magnitude, and the tumor motion magnitude ΔR95 variation is highly individual-specific. This method can serve as an imaging basis for the tumor margin reduction in MRgRT.
, Update time: ,
doi: 10.11804/NuclPhysRev.41.2023CNPC06
Abstract:
Multi-Wire gaseous detectors have been widely used in the fields of nuclear physics and nuclear technology since they have the advantages of radiation hardness, fast response, large sensitive area, low cost and convenient fabrication. First, the electric field calculation theories for multi-wire gaseous detectors were introduced, and then the electric field calculations and the structure design for the drift region and avalanche region of a multi-wire gaseous detector had been carried out with ANSYS and GARFIELD. Next, the designed detector had been simulated in the case of cosmic ray irradiation with GEANT4, and the output results of current pulses, voltage pulses, the integrated charge for each event and the overall statistic results of the integrated charge were obtained. Furthermore, the multi-wire gaseous detector had been built and was used to measure the cosmic rays. The experiment results agree well with the previous simulation results. The simulation methods and the related experiment technologies in this study can be used to do design optimizations and experiment evaluations for gaseous detectors.
Display Method:
2023, 40(4): 493-501.
doi: 10.11804/NuclPhysRev.40.2023025
Abstract:
Based on the three-flavor Polyakov-looped Nambu−Jona-Lasinio(pNJL) model, we have studied the structure of the three-dimensional QCD phase diagram with respect to the temperature, the baryon chemical potential, and the isospin chemical potential, by investigating the interplay among the chiral quark condensate, the pion condensate, and the Polyakov loop. While the pNJL model leads to qualitatively similar structure of the normal quark phase, the pion superfluid phase, and the Sarma phase as well as their phase boundaries, when compared to the NJL model, the inclusion of the Polyakov loop enlarges considerably the areas of the pion superfluid phase and the Sarma phase, and leads to critical end points at higher temperatures. With the contribution of the gluon dynamics effectively included, the present study is expected to give a more reliable prediction of the three-dimensional QCD phase diagram compared to that in the NJL model.
Based on the three-flavor Polyakov-looped Nambu−Jona-Lasinio(pNJL) model, we have studied the structure of the three-dimensional QCD phase diagram with respect to the temperature, the baryon chemical potential, and the isospin chemical potential, by investigating the interplay among the chiral quark condensate, the pion condensate, and the Polyakov loop. While the pNJL model leads to qualitatively similar structure of the normal quark phase, the pion superfluid phase, and the Sarma phase as well as their phase boundaries, when compared to the NJL model, the inclusion of the Polyakov loop enlarges considerably the areas of the pion superfluid phase and the Sarma phase, and leads to critical end points at higher temperatures. With the contribution of the gluon dynamics effectively included, the present study is expected to give a more reliable prediction of the three-dimensional QCD phase diagram compared to that in the NJL model.
2023, 40(4): 502-510.
doi: 10.11804/NuclPhysRev.40.2023013
Abstract:
In this paper, we investigate the impact of pairing correlations on the fission barriers of Th, Pa, U, Np, Pu, Am, Cm, Bk, and Cf isotopes using an exactly solvable pairing model. Our results show that the pairing correlation plays a crucial role in determining the fission barrier height. Specifically, we find that the role of neutron and proton pairing in fission barrier heights is not universal across all isotopes, and the exact nature of the interaction depends on the specific isotopes being studied. Our calculated barrier heights are consistent with experimental data, and we propose using the odd-even mass difference(ground-state properties) and barrier height(excited-state properties) as experimentally observable quantities to determine the pairing interaction strengths in the fission process.
In this paper, we investigate the impact of pairing correlations on the fission barriers of Th, Pa, U, Np, Pu, Am, Cm, Bk, and Cf isotopes using an exactly solvable pairing model. Our results show that the pairing correlation plays a crucial role in determining the fission barrier height. Specifically, we find that the role of neutron and proton pairing in fission barrier heights is not universal across all isotopes, and the exact nature of the interaction depends on the specific isotopes being studied. Our calculated barrier heights are consistent with experimental data, and we propose using the odd-even mass difference(ground-state properties) and barrier height(excited-state properties) as experimentally observable quantities to determine the pairing interaction strengths in the fission process.
2023, 40(4): 511-518.
doi: 10.11804/NuclPhysRev.40.2023059
Abstract:
The nuclear ground state properties of the superheavy nucleus 296Og, such as the potential energy surface, single-particle energy spectrum, two-neutron separation energy and α-decay energy, are studied with the volume, surface and mixed pairings based on the SLy4 interaction in the framework of the deformed Skyrme-Hartree-Fock-Bogoliubov(SHFB) theory. It is found that 1) The ground state shape of 296Og is nearly spherical with the volume and mixed pairings. However, the shape coexistence of 296Og is predicted with the surface pairing. 2) The super-deformed states are predicted by all of the three kinds of pairings. The binding energy, potential well depth and excitation energy of the super-deformed states are influenced by the pairings. At the same time, the surface pairing effect on the properties of the super-deformed states is the most evident. 3) The pairings have certain influence on the shell structure, two-neutron separation energy, α-decay energy and α-decay half-life of 296Og and the impact from the surface pairing is the strongest. Moreover, the order of magnitude of α-decay half-life is varied occasionally owing to the change of the α-decay energy caused by the pairings.
The nuclear ground state properties of the superheavy nucleus 296Og, such as the potential energy surface, single-particle energy spectrum, two-neutron separation energy and α-decay energy, are studied with the volume, surface and mixed pairings based on the SLy4 interaction in the framework of the deformed Skyrme-Hartree-Fock-Bogoliubov(SHFB) theory. It is found that 1) The ground state shape of 296Og is nearly spherical with the volume and mixed pairings. However, the shape coexistence of 296Og is predicted with the surface pairing. 2) The super-deformed states are predicted by all of the three kinds of pairings. The binding energy, potential well depth and excitation energy of the super-deformed states are influenced by the pairings. At the same time, the surface pairing effect on the properties of the super-deformed states is the most evident. 3) The pairings have certain influence on the shell structure, two-neutron separation energy, α-decay energy and α-decay half-life of 296Og and the impact from the surface pairing is the strongest. Moreover, the order of magnitude of α-decay half-life is varied occasionally owing to the change of the α-decay energy caused by the pairings.
2023, 40(4): 519-526.
doi: 10.11804/NuclPhysRev.40.2022110
Abstract:
In the investigations of the level structure of$A \approx 90$ nuclei, whose numbers of protons and neutrons are close to the $Z = 40$ semimagic number and $N = 50$ magic number, have become a hot spot in nuclear physics. The aim of this work is to further probe the characteristics of single-particle excitation, core breaking, high-$j$ intruder states and isomeric states in the $A\approx 90$ mass region based on the existing experimental results. Investigations show that the low energy levels of the odd-$A$ nuclei originate from their neighboring even-even nuclei coupled to a valence nucleon. The systematics of the $2_{1}^{+}$ excitation energies and the values of ${\rm{E}}_{4_{1}^{+}}$ /${\rm{E}}_{2_{1}^{+}}$ indicate that the $N = 56$ subshell closure may appear at $Z = 40$ (41) and disappear for $Z > 42$ nuclei. Furthermore, in this mass region, the strong ${\rm{E}}2$ transitions at low or medium spins are interpreted as the recoupling of the pure protons in ($f_{5/2}^{}$ , $p_{3/2}^{}$ , $p_{1/2}^{}$ , $g_{9/2}^{}$ ) orbits, and the strong $M1$ transitions are explicated by moving proton from the ($f_{5/2}^{}$ , $p_{3/2}^{}$ , $p_{1/2}^{}$ ) orbits to the $g_{9/2}^{}$ orbit, coupling to a neutron excitation from the $g_{9/2}^{}$ orbit across $N = 50$ closed shell into the $d_{5/2}^{}$ orbit. The isomeric states in odd-$A$ nuclei with $N = 50 $ (51) can be interpreted as a spin-aligned configuration in which a single neutron or proton couples with a fully aligned proton pair in the $\pi g_{9/2}^{}$ orbit.
In the investigations of the level structure of
2023, 40(4): 527-533.
doi: 10.11804/NuclPhysRev.40.2022101
Abstract:
In order to understand more comprehensively the dynamical mechanism of the multifragmentation taking place in heavy ion collision at intermediate energies, in the present paper, with help of the factorial moment method, we analyze the concrete behaviors of intermittent chaos and fractal in the distributions of the fragments in the reaction final states and the primary fragments formed during the fragmentation process, by simulating some collisions within the framework of the isospin dependent quantum molecular dynamics model. Our results show that 1) the fluctuations of the distribution of these fragments multiplicity are multi-fractal rather than mono-fractal, and 2) the intermittent exponent reaches its maximum at the stage of the multi-fragmentation taking place during the collisions. The universality of these features is verified by studying the similar colliding systems with the same analysis method. These new features we have revealed here not only help us to deepen our understanding of the dynamic mechanism of the multifragmentation, but also enrich our knowledge of nonlinear dynamics.
In order to understand more comprehensively the dynamical mechanism of the multifragmentation taking place in heavy ion collision at intermediate energies, in the present paper, with help of the factorial moment method, we analyze the concrete behaviors of intermittent chaos and fractal in the distributions of the fragments in the reaction final states and the primary fragments formed during the fragmentation process, by simulating some collisions within the framework of the isospin dependent quantum molecular dynamics model. Our results show that 1) the fluctuations of the distribution of these fragments multiplicity are multi-fractal rather than mono-fractal, and 2) the intermittent exponent reaches its maximum at the stage of the multi-fragmentation taking place during the collisions. The universality of these features is verified by studying the similar colliding systems with the same analysis method. These new features we have revealed here not only help us to deepen our understanding of the dynamic mechanism of the multifragmentation, but also enrich our knowledge of nonlinear dynamics.
2023, 40(4): 534-540.
doi: 10.11804/NuclPhysRev.40.2022025
Abstract:
Based on KONUS dynamics, the beam dynamic design of a compact IH-DTL with built-in permanent magnet quadrupole lens was completed. The DTL consists 37 acceleration cells and two sets of permanent magnet quadrupole lenses, enabling the acceleration of C6+ ion beam of 20 emA from 0.5 MeV/u to 4.0 MeV/u. Throughout the design process, significant focus was placed on optimizing the voltage of the acceleration gap, the parameters of the quadrupole magnet, the phase setting of the beam injection, and the energy and phase setting of the 0-degree reference particle to control the transverse and longitudinal emittance growth of the high-current ion beam in the low-energy range. Consequently, transverse normalized RMS acceptance of the IH-DTL reaches 0.37 πmm · mrad, and the transmission efficiency exceeds 95%.
Based on KONUS dynamics, the beam dynamic design of a compact IH-DTL with built-in permanent magnet quadrupole lens was completed. The DTL consists 37 acceleration cells and two sets of permanent magnet quadrupole lenses, enabling the acceleration of C6+ ion beam of 20 emA from 0.5 MeV/u to 4.0 MeV/u. Throughout the design process, significant focus was placed on optimizing the voltage of the acceleration gap, the parameters of the quadrupole magnet, the phase setting of the beam injection, and the energy and phase setting of the 0-degree reference particle to control the transverse and longitudinal emittance growth of the high-current ion beam in the low-energy range. Consequently, transverse normalized RMS acceptance of the IH-DTL reaches 0.37 πmm · mrad, and the transmission efficiency exceeds 95%.
2023, 40(4): 541-546.
doi: 10.11804/NuclPhysRev.40.2022086
Abstract:
Copper-based niobium thin film cavity is one kind of superconducting radio frequency(SRF) cavities developed from bulk niobium cavity. This new type of cavity has similar SRF properties to the pure niobium cavities but is more economical, mechanically stable, and thermally stable, making it promising for industrial SRF applications. However, the inevitable surface defects of niobium film on the surface of Nb/Cu cavities induce extra power dissipation, and require post-treatment before cavity operation. Near-surface annealing of SRF cavity by nanosecond high-intensity pulsed laser is an emerging surface treatment technology for SRF cavity. Using high power and short pulsed laser with peak power flux exceeding 100 MW/cm2 to locally recrystallize the surface can reduce the surface roughness, increase the grain size and eliminates some surface defects, so as to obtain better surface RF properties. At present, the type of laser selected in this direction is mainly the solid-state laser with high peak power, which has a very low average power, not practical for the actual superconducting cavity with an m2 inner wall surface area. To solve this issue, a whole-cavity laser processing system based on a kW-level power nanosecond pulse fiber laser has been established by the Surface Treatment Research Team of the Institute of Modern Physics. In this study, finite element simulation was conducted with the parameters of the system to investigate the temperature distribution on the surface and inside the material under near-actual working conditions. Combined with the material properties, the laser surface treatment effect of pure niobium material was simulated. This study preliminarily confirms the feasibility of using nanosecond pulse laser for complete annealing of the inner wall of superconducting cavities, and provides an effective method for achieving better RF superconducting performance.
Copper-based niobium thin film cavity is one kind of superconducting radio frequency(SRF) cavities developed from bulk niobium cavity. This new type of cavity has similar SRF properties to the pure niobium cavities but is more economical, mechanically stable, and thermally stable, making it promising for industrial SRF applications. However, the inevitable surface defects of niobium film on the surface of Nb/Cu cavities induce extra power dissipation, and require post-treatment before cavity operation. Near-surface annealing of SRF cavity by nanosecond high-intensity pulsed laser is an emerging surface treatment technology for SRF cavity. Using high power and short pulsed laser with peak power flux exceeding 100 MW/cm2 to locally recrystallize the surface can reduce the surface roughness, increase the grain size and eliminates some surface defects, so as to obtain better surface RF properties. At present, the type of laser selected in this direction is mainly the solid-state laser with high peak power, which has a very low average power, not practical for the actual superconducting cavity with an m2 inner wall surface area. To solve this issue, a whole-cavity laser processing system based on a kW-level power nanosecond pulse fiber laser has been established by the Surface Treatment Research Team of the Institute of Modern Physics. In this study, finite element simulation was conducted with the parameters of the system to investigate the temperature distribution on the surface and inside the material under near-actual working conditions. Combined with the material properties, the laser surface treatment effect of pure niobium material was simulated. This study preliminarily confirms the feasibility of using nanosecond pulse laser for complete annealing of the inner wall of superconducting cavities, and provides an effective method for achieving better RF superconducting performance.
2023, 40(4): 547-554.
doi: 10.11804/NuclPhysRev.40.2022100
Abstract:
The booster ring(BRing) of High Intensity heavy-ion Accelerator Facility(HIAF) is characterized by high intensity and high energy. Failures of key equipment such as magnets and RF system will lead to significant beam losses and damage to the accelerator. A beam dynamics simulation code BTracker is developed to study beam losses under equipment failures and beam dynamics during beam dumping for the HIAF machine protrection. With this code, beam loss distribution under power failure of dipole and quadrupole magnets is simulated, and the results are benchmarked with MAD-X code. In addition, BTracker provides user-friendliness, interface flexibility and high performance to meet the requirements of machine protection simulation for HIAF-BRing.
The booster ring(BRing) of High Intensity heavy-ion Accelerator Facility(HIAF) is characterized by high intensity and high energy. Failures of key equipment such as magnets and RF system will lead to significant beam losses and damage to the accelerator. A beam dynamics simulation code BTracker is developed to study beam losses under equipment failures and beam dynamics during beam dumping for the HIAF machine protrection. With this code, beam loss distribution under power failure of dipole and quadrupole magnets is simulated, and the results are benchmarked with MAD-X code. In addition, BTracker provides user-friendliness, interface flexibility and high performance to meet the requirements of machine protection simulation for HIAF-BRing.
2023, 40(4): 555-559.
doi: 10.11804/NuclPhysRev.40.2023023
Abstract:
High Purity Germanium(HPGe) detectors have been widely used in γ spectroscopy. The add-back performance of Clover type HPGe detector is studied based on Monte Carlo simulation. We have simulated the energy spectrum from a single crystal and the Compton scattering probability of γ ray between different crystals. Good agreements have been achieved between the simulated results and experimental data. Afterwards the add-back performance is further studied in terms of γ ray multiplicity and the distance between γ source and the detector. The studies revealed that the higher multiplicity ($M = 6 $ ) affects slightly on the add-back factor at 25 cm distance, mainly in the low energy region. With the distance decreases, the add-back factor changes dramatically. Typically, in the situation of 5 cm distance and $M = 6 $ , the add-back analysis is not recommended.
High Purity Germanium(HPGe) detectors have been widely used in γ spectroscopy. The add-back performance of Clover type HPGe detector is studied based on Monte Carlo simulation. We have simulated the energy spectrum from a single crystal and the Compton scattering probability of γ ray between different crystals. Good agreements have been achieved between the simulated results and experimental data. Afterwards the add-back performance is further studied in terms of γ ray multiplicity and the distance between γ source and the detector. The studies revealed that the higher multiplicity (
2023, 40(4): 560-565.
doi: 10.11804/NuclPhysRev.40.2023110
Abstract:
A new compact accelerator mass spectrometer(AMS) facility, used for 14C, 129I, 239Pu, etc. measurement, has been successfully established by China Institute of Atomic Energy(CIAE) recently. As 129I is a commonly used nuclide for environmental tracing, the performance of 129I measurement is crucial for the applications of the facility. After systematic research, 129I measurement technologies of the compact AMS has been established. The measurement sensitivity and the measurement accuracy of 129I/127I reached to 1.5×10-14 and 0.81%, respectively. The measurement results show that the compact AMS has reached the international advanced level and can lay the solid foundation for the application of 129I in fields like nuclear environmental monitoring and marine pollution tracing.
A new compact accelerator mass spectrometer(AMS) facility, used for 14C, 129I, 239Pu, etc. measurement, has been successfully established by China Institute of Atomic Energy(CIAE) recently. As 129I is a commonly used nuclide for environmental tracing, the performance of 129I measurement is crucial for the applications of the facility. After systematic research, 129I measurement technologies of the compact AMS has been established. The measurement sensitivity and the measurement accuracy of 129I/127I reached to 1.5×10-14 and 0.81%, respectively. The measurement results show that the compact AMS has reached the international advanced level and can lay the solid foundation for the application of 129I in fields like nuclear environmental monitoring and marine pollution tracing.
2023, 40(4): 566-571.
doi: 10.11804/NuclPhysRev.40.2022128
Abstract:
A design scheme of fluorescence detector was proposed for rapidly acquiring the Bragg peak position of carbon ion beam in scintillator material. Based on the characteristic of scintillator emitting fluorescence under the irradiation of carbon ion beam, CMOS camera is applied to acquire the image of fluorescent intensity distribution on the side of a thin scintillator, and then the Bragg peak position of carbon ion beam in the scintillator material is quickly obtained by analyzing the fluorescent image. According to the scheme, a fluorescence detector was developed and then used for experimental measurement under the irradiation of carbon-ion uniform fields and pencil beams with different energies. The experimental results showed that the Bragg peak position of the carbon ion beams could be clearly observed from the fluorescent image obtained by the detector. Moreover, the method of Monte Carlo simulation was used to calculate the depth dose distribution of carbon ion beams under the experimental conditions mentioned above. It was found that there was a penetration depth difference between the measured and calculated Bragg peak positions of carbon ion beam in the scintillator material by the fluorescence detector and the Monte Carlo simulation due to the difference between their settings, but the differences under the various irradiation conditions were nearly the same. Therefore, the experimental measurements and Monte Carlo simulations verified that the fluorescence detector scheme could be used for quickly acquiring the Bragg peak position of carbon ion beam in the scintillator material definitely, which provides a substantial basis for establishing a fast fluorescence detector-based quality assurance measurement method in carbon ion radiotherapy.
A design scheme of fluorescence detector was proposed for rapidly acquiring the Bragg peak position of carbon ion beam in scintillator material. Based on the characteristic of scintillator emitting fluorescence under the irradiation of carbon ion beam, CMOS camera is applied to acquire the image of fluorescent intensity distribution on the side of a thin scintillator, and then the Bragg peak position of carbon ion beam in the scintillator material is quickly obtained by analyzing the fluorescent image. According to the scheme, a fluorescence detector was developed and then used for experimental measurement under the irradiation of carbon-ion uniform fields and pencil beams with different energies. The experimental results showed that the Bragg peak position of the carbon ion beams could be clearly observed from the fluorescent image obtained by the detector. Moreover, the method of Monte Carlo simulation was used to calculate the depth dose distribution of carbon ion beams under the experimental conditions mentioned above. It was found that there was a penetration depth difference between the measured and calculated Bragg peak positions of carbon ion beam in the scintillator material by the fluorescence detector and the Monte Carlo simulation due to the difference between their settings, but the differences under the various irradiation conditions were nearly the same. Therefore, the experimental measurements and Monte Carlo simulations verified that the fluorescence detector scheme could be used for quickly acquiring the Bragg peak position of carbon ion beam in the scintillator material definitely, which provides a substantial basis for establishing a fast fluorescence detector-based quality assurance measurement method in carbon ion radiotherapy.
2023, 40(4): 572-578.
doi: 10.11804/NuclPhysRev.40.2022118
Abstract:
In order to solve the problems of low efficiency and high error in traditional radiation shielding design, an intelligent optimization method for reactor shielding design based on the coupling of the fully connected neural network (FCNN) and the third generation non dominated sorting genetic algorithm (NSGA-III) was proposed. Taking a molten salt reactor as an example, the reactor shielding optimization model is established and Monte Carlo software is used to calculate a large number of samples. FCNN is used to machine learn the calculation data, and the multi-dimensional nonlinear mapping relationship between input layer parameters and output layer parameters is established. The neural network prediction results are used as the basis for calculating the fitness function. Based on NSGA-III, multi-objective optimization is carried out to obtain the Pareto optimal solution for multi-objective optimization of radiation shielding design. The results show that the FCNN coupled NSGA-III method performs well in solving multi-objective optimization problems and can be applied to reactor shielding design.
In order to solve the problems of low efficiency and high error in traditional radiation shielding design, an intelligent optimization method for reactor shielding design based on the coupling of the fully connected neural network (FCNN) and the third generation non dominated sorting genetic algorithm (NSGA-III) was proposed. Taking a molten salt reactor as an example, the reactor shielding optimization model is established and Monte Carlo software is used to calculate a large number of samples. FCNN is used to machine learn the calculation data, and the multi-dimensional nonlinear mapping relationship between input layer parameters and output layer parameters is established. The neural network prediction results are used as the basis for calculating the fitness function. Based on NSGA-III, multi-objective optimization is carried out to obtain the Pareto optimal solution for multi-objective optimization of radiation shielding design. The results show that the FCNN coupled NSGA-III method performs well in solving multi-objective optimization problems and can be applied to reactor shielding design.
2023, 40(4): 579-588.
doi: 10.11804/NuclPhysRev.40.2022102
Abstract:
Time-Interleaved Analog-to-Digital Conversion(TIADC) is one of the most important techniques in the design of high-speed waveform digitization systems, it can multiple the sampling rate of a sampling system. However, there are mismatch errors between different sampling channels, which will make the dynamic performance of a TIADC system significantly lower than that of a single ADC. Therefore, mismatch errors should be corrected in TIADC system design. To evaluate the quality of the system design and promote the next optimization design, it is necessary to conduct scientific performance test and evaluation on the TIADC system. In this work, aiming at the test and evaluation, the performance indexes and test methods of TIADC system are introduced in detail, a series of performance tests of the system are completed, and mismatch errors are corrected based on perfect reconstruction algorithm. The test results show that the system can achieve an equivalent 5 Gsps sampling rate and can realize mismatch error correction in a wide band based on the proposed mismatch error correction method. After correction, the dynamic performance of the TIADC system is significantly enhanced compared with that without correction. For example, the Effective Number of Bits(ENOB) of the proposed system reaches 9.2 bits at 247 MHz, 8.9 bits at 857 MHz, which is equivalent to the performance index of a single ADC.
Time-Interleaved Analog-to-Digital Conversion(TIADC) is one of the most important techniques in the design of high-speed waveform digitization systems, it can multiple the sampling rate of a sampling system. However, there are mismatch errors between different sampling channels, which will make the dynamic performance of a TIADC system significantly lower than that of a single ADC. Therefore, mismatch errors should be corrected in TIADC system design. To evaluate the quality of the system design and promote the next optimization design, it is necessary to conduct scientific performance test and evaluation on the TIADC system. In this work, aiming at the test and evaluation, the performance indexes and test methods of TIADC system are introduced in detail, a series of performance tests of the system are completed, and mismatch errors are corrected based on perfect reconstruction algorithm. The test results show that the system can achieve an equivalent 5 Gsps sampling rate and can realize mismatch error correction in a wide band based on the proposed mismatch error correction method. After correction, the dynamic performance of the TIADC system is significantly enhanced compared with that without correction. For example, the Effective Number of Bits(ENOB) of the proposed system reaches 9.2 bits at 247 MHz, 8.9 bits at 857 MHz, which is equivalent to the performance index of a single ADC.
2023, 40(4): 589-598.
doi: 10.11804/NuclPhysRev.40.2023017
Abstract:
High purity germanium detectors are widely employed for gamma ray measurements in nuclear spectroscopy experiments at the moment. The application of high voltage during operation necessitates stringent monitoring and control conditions. Traditional manual observation-based monitoring methods prove inefficient and slow in response, often resulting in varying degrees of detector damage. To address this issue, real-time temperature changes in the high purity germanium detector are converted into resistance value measurements using Pt100 sensors. Subsequently, a high-voltage module controller is designed and implemented to establish a protection system for the high purity germanium detector's high voltage supply. The hardware and logic of the controller are meticulously designed, while noise reduction algorithms are studied to enhance performance. Finally, circuit tests validate that the developed system automatically cuts off the high voltage when the detector temperature exceeds an upper threshold and restores it when the temperature falls below a lower threshold. This system effectively meets real-time protection requirements for high-voltage applications with respect to high purity germanium detectors.
High purity germanium detectors are widely employed for gamma ray measurements in nuclear spectroscopy experiments at the moment. The application of high voltage during operation necessitates stringent monitoring and control conditions. Traditional manual observation-based monitoring methods prove inefficient and slow in response, often resulting in varying degrees of detector damage. To address this issue, real-time temperature changes in the high purity germanium detector are converted into resistance value measurements using Pt100 sensors. Subsequently, a high-voltage module controller is designed and implemented to establish a protection system for the high purity germanium detector's high voltage supply. The hardware and logic of the controller are meticulously designed, while noise reduction algorithms are studied to enhance performance. Finally, circuit tests validate that the developed system automatically cuts off the high voltage when the detector temperature exceeds an upper threshold and restores it when the temperature falls below a lower threshold. This system effectively meets real-time protection requirements for high-voltage applications with respect to high purity germanium detectors.
2023, 40(4): 599-606.
doi: 10.11804/NuclPhysRev.40.2023002
Abstract:
For the low power and digital readout requirements of plastic scintillation detector(PSD), a multi-channel 10 bit 20 MSPS Pipeline Analog-to-Digital Converter(ADC) chip is developed. In order to evaluate the performance of the ADC chip, a systematic test is needed. In the work of this paper, a test system is developed, which included the hardware design of the circuits, the design of the FPGA firmware and the analysis programme. The ADC chip was systematically tested and analysed according to IEEE standards.The test results indicate that, when the input signal frequency is in baseband range, the performance of the ADC chip meets the design requirements, and the Effective Number of Bit(ENOB) is close to 8.0 bit. The Integral nonlinearity(INL) is 0.75 LSB, and the differential nonlinearity(DNL) is 1.09 LSB, which provides strong support for future optimization design and parameter improvement of the ADC chips.
For the low power and digital readout requirements of plastic scintillation detector(PSD), a multi-channel 10 bit 20 MSPS Pipeline Analog-to-Digital Converter(ADC) chip is developed. In order to evaluate the performance of the ADC chip, a systematic test is needed. In the work of this paper, a test system is developed, which included the hardware design of the circuits, the design of the FPGA firmware and the analysis programme. The ADC chip was systematically tested and analysed according to IEEE standards.The test results indicate that, when the input signal frequency is in baseband range, the performance of the ADC chip meets the design requirements, and the Effective Number of Bit(ENOB) is close to 8.0 bit. The Integral nonlinearity(INL) is 0.75 LSB, and the differential nonlinearity(DNL) is 1.09 LSB, which provides strong support for future optimization design and parameter improvement of the ADC chips.
2023, 40(4): 607-618.
doi: 10.11804/NuclPhysRev.40.2022120
Abstract:
To explore the effects of high-energy heavy ion beams irradiation on the physiological and growth characteristics of Scutellaria baicalensis Georgi seedlings, different doses of carbon ion beam with total energy of 967 MeV were selected to irradiate seedlings to measure the survival rate, seedling height, number of leaves, number of branches, biomass, root-shoot ratio, antioxidant enzyme activity, photosynthetic characteristics and content of secondary metabolites. The results showed that the semi-lethal dose of seedlings was 32.82 Gy. The seedling height, number of leaves, number of branches, and biomass of Scutellaria baicalensis increased under 5 and 10 Gy, but decreased under 30 Gy compared with the control group. The activities of superoxide dismutase (SOD) and peroxidase (POD) in all treatment groups increased to reduce the damage of reactive oxygen species caused by irradiation. The content of chlorophyll in leaves decreased with the dose within 6 weeks after irradiation; the content of total chlorophyll, net photosynthetic rate and stomatal conductance of leaves increased under 5 and 10 Gy in 9 weeks after irradiation. In addition, the accumulation of total flavonoids and baicalein in the root were promoted under 10 Gy. These results indicated that 10 Gy heavy ion beams not only stimulated the growth, but also increased the content of medicinal ingredients in Scutellaria baicalensis. The study explored the contemporary biological effects of heavy ion beams radiation on Scutellaria baicalensis Georgi, which provides a basis for the follow-up research on irradiation stimulation effects and radiation breeding of Scutellaria baicalensis Georgi.
To explore the effects of high-energy heavy ion beams irradiation on the physiological and growth characteristics of Scutellaria baicalensis Georgi seedlings, different doses of carbon ion beam with total energy of 967 MeV were selected to irradiate seedlings to measure the survival rate, seedling height, number of leaves, number of branches, biomass, root-shoot ratio, antioxidant enzyme activity, photosynthetic characteristics and content of secondary metabolites. The results showed that the semi-lethal dose of seedlings was 32.82 Gy. The seedling height, number of leaves, number of branches, and biomass of Scutellaria baicalensis increased under 5 and 10 Gy, but decreased under 30 Gy compared with the control group. The activities of superoxide dismutase (SOD) and peroxidase (POD) in all treatment groups increased to reduce the damage of reactive oxygen species caused by irradiation. The content of chlorophyll in leaves decreased with the dose within 6 weeks after irradiation; the content of total chlorophyll, net photosynthetic rate and stomatal conductance of leaves increased under 5 and 10 Gy in 9 weeks after irradiation. In addition, the accumulation of total flavonoids and baicalein in the root were promoted under 10 Gy. These results indicated that 10 Gy heavy ion beams not only stimulated the growth, but also increased the content of medicinal ingredients in Scutellaria baicalensis. The study explored the contemporary biological effects of heavy ion beams radiation on Scutellaria baicalensis Georgi, which provides a basis for the follow-up research on irradiation stimulation effects and radiation breeding of Scutellaria baicalensis Georgi.
2023, 40(4): 619-627.
doi: 10.11804/NuclPhysRev.40.2022127
Abstract:
The influence of different data processing methods on the fitting values of linear square(LQ) model parameters and the calculated values of biological dose distribution used in treatment planning were investigated in the cell cloning survival experiment. Four sets of LET-α and LET-β data were obtained based on the LQ model fitted to the data from the clonogenic survival experiments of carbon ion irradiated cells from T98G cells, according to whether the standard deviation of the cell survival rate was taken into account, and the plating efficiency was taken into account in two different ways, respectively, and three of them were selected to build the basedata of three datasets of the matRad treatment planning system for the treatment planning study. When only the 0 Gy plating efficiency was considered, whether the fitting considered the standard deviation of survival rate had little influence on the α value when the LET was low, but had a greater influence on the β value; With the LET getting larger, it had a greater impact on the α value and a lesser impact on the β value. When considering the standard deviation of survival rate, the deviations of fitting results in 2 different ways to consider the plating efficiency were small. Except for 200 keV/μm, the relative deviation of α values between the two groups did not exceed ±10%. Planset2 always overestimated Dmax, Dmin and D95 compared to Planset1. The results illustrate that whether the standard deviation of survival rate were considered or not had a greater influence on the fitted α, β coefficients than considering the plating efficiency in 2 different ways. The relative deviation range of biological dose distribution’s calculation values among different datasets in the treatment planning system was smaller than the relative deviation range of α and β values of each group obtained by fitting the experimental data.
The influence of different data processing methods on the fitting values of linear square(LQ) model parameters and the calculated values of biological dose distribution used in treatment planning were investigated in the cell cloning survival experiment. Four sets of LET-α and LET-β data were obtained based on the LQ model fitted to the data from the clonogenic survival experiments of carbon ion irradiated cells from T98G cells, according to whether the standard deviation of the cell survival rate was taken into account, and the plating efficiency was taken into account in two different ways, respectively, and three of them were selected to build the basedata of three datasets of the matRad treatment planning system for the treatment planning study. When only the 0 Gy plating efficiency was considered, whether the fitting considered the standard deviation of survival rate had little influence on the α value when the LET was low, but had a greater influence on the β value; With the LET getting larger, it had a greater impact on the α value and a lesser impact on the β value. When considering the standard deviation of survival rate, the deviations of fitting results in 2 different ways to consider the plating efficiency were small. Except for 200 keV/μm, the relative deviation of α values between the two groups did not exceed ±10%. Planset2 always overestimated Dmax, Dmin and D95 compared to Planset1. The results illustrate that whether the standard deviation of survival rate were considered or not had a greater influence on the fitted α, β coefficients than considering the plating efficiency in 2 different ways. The relative deviation range of biological dose distribution’s calculation values among different datasets in the treatment planning system was smaller than the relative deviation range of α and β values of each group obtained by fitting the experimental data.
2023, 40(4): 628-635.
doi: 10.11804/NuclPhysRev.40.2022121
Abstract:
The Fully Depleted Silicon on Insulator(FDSOI) process is considered an ideal semiconductor technology for producing highly reliable aerospace electronic devices. Therefore, a comprehensive understanding of the single event effects mechanism in FDSOI devices is of theoretical significance for radiation-hardened design. This paper focuses on 22 nm FDSOI SRAM test devices and investigates the impact patterns and physical mechanisms of different heavy ions and electrical parameters on the sensitivity of Single Event Upset(SEU) in the devices. Experimental results indicate that in regions with high Linear Energy Transfer(LET) values, the proportion of Multi-Cell Upset(MCU) can reach 20%. Additionally, the core voltage has a relatively minor impact on the type proportion and occurrence probability of SEU. The incidence angle of heavy ions significantly increases the SEU cross-section of the devices, with a 130% difference observed when heavy ions are incident along parallel and perpendicular directions to the substrate well region. Therefore, when modeling Single Event Effect in FDSOI devices and designing for radiation hardening, it is imperative to consider the influence of non-direct diffusion charge sharing mechanisms and substrate potential distortion-triggered parasitic current mechanisms on the transient ionization charge collection process.
The Fully Depleted Silicon on Insulator(FDSOI) process is considered an ideal semiconductor technology for producing highly reliable aerospace electronic devices. Therefore, a comprehensive understanding of the single event effects mechanism in FDSOI devices is of theoretical significance for radiation-hardened design. This paper focuses on 22 nm FDSOI SRAM test devices and investigates the impact patterns and physical mechanisms of different heavy ions and electrical parameters on the sensitivity of Single Event Upset(SEU) in the devices. Experimental results indicate that in regions with high Linear Energy Transfer(LET) values, the proportion of Multi-Cell Upset(MCU) can reach 20%. Additionally, the core voltage has a relatively minor impact on the type proportion and occurrence probability of SEU. The incidence angle of heavy ions significantly increases the SEU cross-section of the devices, with a 130% difference observed when heavy ions are incident along parallel and perpendicular directions to the substrate well region. Therefore, when modeling Single Event Effect in FDSOI devices and designing for radiation hardening, it is imperative to consider the influence of non-direct diffusion charge sharing mechanisms and substrate potential distortion-triggered parasitic current mechanisms on the transient ionization charge collection process.
2023, 40(4): 636-642.
doi: 10.11804/NuclPhysRev.40.2023037
Abstract:
Using 129Xe20+ ions with kinetic energy of 100~500 keV and 1.2~6.0 MeV respectively incident on the Ta target, the spectral lines of transition radiation are measured between complex electronic configurations of excited atoms or ions during the interaction of incident ions at different velocities with the Ta surface. The ultraviolet spectral lines of the deexcitation radiation from multiple high Rydberg states to low energy state 5p5(2P°3/2)6s of Xe atoms are measured as the kinetic energy of Xe20+ranges from 100 to 500 keV, the principal quantum number of valence electrons of Rydberg states is$n = 15 $ , 13, 11, and 8, respectively. The results show that as the incident ion velocity increases, the single particle fluorescence yield of the the high Rydberg states spectral line of Xe atoms decreases. During this collision process, the single particle fluorescence yield increases of the spectral lines of the excited target atoms and ions with the increase of the incident ion velocity. When the ion kinetic energy increases to 1.2~6.0 MeV, the single particle yield of the Ta characteristic X-rays (Mα1, Mα2) increases with the velocity of the incident ions. When the kinetic energy of the incident ion is 6 MeV, the L X-ray spectra are measured of the Xe atom during the collision between Xe20+and the target atom.
Using 129Xe20+ ions with kinetic energy of 100~500 keV and 1.2~6.0 MeV respectively incident on the Ta target, the spectral lines of transition radiation are measured between complex electronic configurations of excited atoms or ions during the interaction of incident ions at different velocities with the Ta surface. The ultraviolet spectral lines of the deexcitation radiation from multiple high Rydberg states to low energy state 5p5(2P°3/2)6s of Xe atoms are measured as the kinetic energy of Xe20+ranges from 100 to 500 keV, the principal quantum number of valence electrons of Rydberg states is
2023, 40(4): 643-650.
doi: 10.11804/NuclPhysRev.40.2022115
Abstract:
The calculation of thermal neutron cross section for thermal neutron scattering materials in the field of nuclear engineering is based on the first principle. This study utilizes Al and Bi metals as examples for the determination of thermal neutron cross sections. The frozen phonon method and density functional perturbation method are applied to calculate the thermal neutron cross sections for Al and Bi, respectively. Phonon dispersion relation and phonon density of state are computed using VASP and PHONONY. Subsequently, coherent scattering for Bi is incorporated into LEAPR using NJOY to generate the thermal neutron scattering cross-section libraries for Al and Bi. The results reveal that, in the case of Al, the thermal neutron scattering cross section obtained using the density functional perturbation theory is in better agreement with ENDF8.0 compared to the frozen phonon method. Conversely, for Bi, the density functional perturbation method eliminates the imaginary frequency phenomenon observed in the frozen phonon method, resulting in thermal neutron scattering results that align well with experimental data. The paper proposes a more fundamental and predictable method for generating thermal neutron cross-sections by exploring the internal characteristic mechanism of the material, thus laying a theoretical foundation for studying the thermal mechanisms of new reactor nuclear materials..
The calculation of thermal neutron cross section for thermal neutron scattering materials in the field of nuclear engineering is based on the first principle. This study utilizes Al and Bi metals as examples for the determination of thermal neutron cross sections. The frozen phonon method and density functional perturbation method are applied to calculate the thermal neutron cross sections for Al and Bi, respectively. Phonon dispersion relation and phonon density of state are computed using VASP and PHONONY. Subsequently, coherent scattering for Bi is incorporated into LEAPR using NJOY to generate the thermal neutron scattering cross-section libraries for Al and Bi. The results reveal that, in the case of Al, the thermal neutron scattering cross section obtained using the density functional perturbation theory is in better agreement with ENDF8.0 compared to the frozen phonon method. Conversely, for Bi, the density functional perturbation method eliminates the imaginary frequency phenomenon observed in the frozen phonon method, resulting in thermal neutron scattering results that align well with experimental data. The paper proposes a more fundamental and predictable method for generating thermal neutron cross-sections by exploring the internal characteristic mechanism of the material, thus laying a theoretical foundation for studying the thermal mechanisms of new reactor nuclear materials..
2023, 40(4): 651-659.
doi: 10.11804/NuclPhysRev.40.2022091
Abstract:
Through the thermal coupling between ADS liquid lead bismuth target and lead based subcritical reactor, this paper studies the effect of whether a thermal barrier layer is added between the target and the reactor, the thermal conductivity and thickness of the layer, and when a gas thermal barrier layer is added, gas pressure on the heat flow between target and reactor. The study found that adding a thermal barrier layer can reduce the heat flow after coupling. Adding a gas layer can significantly reduce the heat flow, and allow the flow velocity of lead-bismuth in both target and reactor and the temperature difference between target and reactor to fluctuate over a wider range. The heat flow is proportional to the thermal conductivity of the thermal barrier layer and inversely proportional to the thickness of the layer. The thickness of the gas layer can be selected between 0.06 m and 0.08 m. The pressure of the gas thermal barrier is in the range of 0.1 to 10 Pa, and the heat flow varies significantly with the pressure. Therefore, the pressure of the gas thermal barrier layer can be selected to be about 0.1 Pa.
Through the thermal coupling between ADS liquid lead bismuth target and lead based subcritical reactor, this paper studies the effect of whether a thermal barrier layer is added between the target and the reactor, the thermal conductivity and thickness of the layer, and when a gas thermal barrier layer is added, gas pressure on the heat flow between target and reactor. The study found that adding a thermal barrier layer can reduce the heat flow after coupling. Adding a gas layer can significantly reduce the heat flow, and allow the flow velocity of lead-bismuth in both target and reactor and the temperature difference between target and reactor to fluctuate over a wider range. The heat flow is proportional to the thermal conductivity of the thermal barrier layer and inversely proportional to the thickness of the layer. The thickness of the gas layer can be selected between 0.06 m and 0.08 m. The pressure of the gas thermal barrier is in the range of 0.1 to 10 Pa, and the heat flow varies significantly with the pressure. Therefore, the pressure of the gas thermal barrier layer can be selected to be about 0.1 Pa.
2023, 40(4): 660-667.
doi: 10.11804/NuclPhysRev.40.2022125
Abstract:
As one of the fourth-generation advanced nuclear energy systems, Lead-Bismuth Eutectic(LBE) cooled reactor has excellent neutron economy and inherent safety. To improve its compactness and safety, the main coolant system of LBE-cooled reactor tends to adopt the integrated pool structure design concept, but this design concept also introduces complex thermal hydraulic problems. To solve the above issues, the multi-physics coupling transient safety analysis code for LBE-cooled reactor MPC_LBE was developed, but this code uses a constant temperature simplified model which are not able to simulate the heat exchange process between the first and second circuits, and the accident transient simulation is rather conservative which deviating from the actual condition. To solve this problem, the numerical simulation method of the heat exchanger module for LBE-cooled reactor was carried out in this paper. A one-dimensional numerical calculation models were employed for the primary side, pipe wall and secondary side of heat exchanger, and the numerical heat transfer model was constructed. Finally, the heat exchanger module was coupled with the MPC_LBE code by external explicit means. For the heat exchanger numerical calculation module, steady-state verification and time step sensitivity analysis were performed separately, and the results show that the time step sensitivity of the explicit coupling strategy is large, while the time step setting of the implicit coupling strategy has almost no effect on the simulation results. For the new MPC_LBE program coupled with the numerical calculation module of the heat exchanger, the steady-state simulation application of the natural cycle lead-bismuth reactor was carried out.
As one of the fourth-generation advanced nuclear energy systems, Lead-Bismuth Eutectic(LBE) cooled reactor has excellent neutron economy and inherent safety. To improve its compactness and safety, the main coolant system of LBE-cooled reactor tends to adopt the integrated pool structure design concept, but this design concept also introduces complex thermal hydraulic problems. To solve the above issues, the multi-physics coupling transient safety analysis code for LBE-cooled reactor MPC_LBE was developed, but this code uses a constant temperature simplified model which are not able to simulate the heat exchange process between the first and second circuits, and the accident transient simulation is rather conservative which deviating from the actual condition. To solve this problem, the numerical simulation method of the heat exchanger module for LBE-cooled reactor was carried out in this paper. A one-dimensional numerical calculation models were employed for the primary side, pipe wall and secondary side of heat exchanger, and the numerical heat transfer model was constructed. Finally, the heat exchanger module was coupled with the MPC_LBE code by external explicit means. For the heat exchanger numerical calculation module, steady-state verification and time step sensitivity analysis were performed separately, and the results show that the time step sensitivity of the explicit coupling strategy is large, while the time step setting of the implicit coupling strategy has almost no effect on the simulation results. For the new MPC_LBE program coupled with the numerical calculation module of the heat exchanger, the steady-state simulation application of the natural cycle lead-bismuth reactor was carried out.
2023, 40(4): 668-675.
doi: 10.11804/NuclPhysRev.40.2022129
Abstract:
The offshore nuclear energy platform, characterized by low operating costs, reliable energy supply, and environmental friendliness, can provide stable and reliable energy for the development of offshore oil and gas resources and the livelihood support of personnel. The offshore fixed lead-cooled reactor platform, addressing the demand for stable energy supply in China's maritime regions, aims to propose a conceptual design for a reactor with an electrical power output of 20 MW, a service life of 40 years, and no need for replacement of materials throughout its entire lifespan. This paper uses the CAR-3600 benchmark and validates the applicability of the burnup module of the open-source Monte Carlo program OpenMC in a lead-cooled fast reactor. A comparison of the calculation results for the offshore fixed lead-cooled reactor core between the OpenMC and MCNP programs is conducted, analyzing the differences in results obtained using different nuclear databases in the OpenMC program and exploring possible reasons for these differences. The research results indicate that the burnup module of the OpenMC program is applicable in fast reactors. The calculation results of OpenMC and MCNP programs are close, and a comparative validation of the design scheme for the offshore fixed lead-cooled reactor is carried out using different simulation software. The simulation also reveals that due to differences in capture cross-sections of 235U and 238U, the reactivity fluctuations obtained from the ENDF/B-VIII.0 library and the JEFF-3.3 library are larger than the design target of$ 1\; \$$ , requiring further optimization of the scheme to reduce burnup reactivity fluctuations.
The offshore nuclear energy platform, characterized by low operating costs, reliable energy supply, and environmental friendliness, can provide stable and reliable energy for the development of offshore oil and gas resources and the livelihood support of personnel. The offshore fixed lead-cooled reactor platform, addressing the demand for stable energy supply in China's maritime regions, aims to propose a conceptual design for a reactor with an electrical power output of 20 MW, a service life of 40 years, and no need for replacement of materials throughout its entire lifespan. This paper uses the CAR-3600 benchmark and validates the applicability of the burnup module of the open-source Monte Carlo program OpenMC in a lead-cooled fast reactor. A comparison of the calculation results for the offshore fixed lead-cooled reactor core between the OpenMC and MCNP programs is conducted, analyzing the differences in results obtained using different nuclear databases in the OpenMC program and exploring possible reasons for these differences. The research results indicate that the burnup module of the OpenMC program is applicable in fast reactors. The calculation results of OpenMC and MCNP programs are close, and a comparative validation of the design scheme for the offshore fixed lead-cooled reactor is carried out using different simulation software. The simulation also reveals that due to differences in capture cross-sections of 235U and 238U, the reactivity fluctuations obtained from the ENDF/B-VIII.0 library and the JEFF-3.3 library are larger than the design target of
2023, 40(4): 676-683.
doi: 10.11804/NuclPhysRev.40.2022126
Abstract:
In the unresolved energy region, due to the dense distribution of resonance peaks, the precise resonance parameter data cannot be obtained due to the resolution limitation of the nuclear measuring instrument. For this energy region, the Evaluation Nuclear Data Files only provides the average values and distribution functions of the resonance parameters. In order to consider the resonance self-shielding effect in the unresolved resonance energy region, it is necessary to calculate the effective self-shielding cross-section based on these parameters with probability distribution properties. For the treatment of resonance self-shielding effect in the unresolved resonance energy region, a probability table module PUnresXS and an effective self-shielding cross-section calculation module UnresXS were developed in the advanced nuclear cross-section processing program AXSP based on the "Ladder Sampling" and integral statistics principle method. The algorithms in the probability table calculation module were also improved. By comparing with the reference solution obtained from NJOY2016 calculations, the PUnresXS and UnresXS modules were independently validated. The results showed that the efficiency of the probability table module was improved by more than 60%, the keff and neutron spectrum were in good agreement with the reference solution. The developed resonance self-shielding cross-section calculation module exhibited similar accuracy to NJOY2016, demonstrating the correctness of these two modules developed in the AXSP program.
In the unresolved energy region, due to the dense distribution of resonance peaks, the precise resonance parameter data cannot be obtained due to the resolution limitation of the nuclear measuring instrument. For this energy region, the Evaluation Nuclear Data Files only provides the average values and distribution functions of the resonance parameters. In order to consider the resonance self-shielding effect in the unresolved resonance energy region, it is necessary to calculate the effective self-shielding cross-section based on these parameters with probability distribution properties. For the treatment of resonance self-shielding effect in the unresolved resonance energy region, a probability table module PUnresXS and an effective self-shielding cross-section calculation module UnresXS were developed in the advanced nuclear cross-section processing program AXSP based on the "Ladder Sampling" and integral statistics principle method. The algorithms in the probability table calculation module were also improved. By comparing with the reference solution obtained from NJOY2016 calculations, the PUnresXS and UnresXS modules were independently validated. The results showed that the efficiency of the probability table module was improved by more than 60%, the keff and neutron spectrum were in good agreement with the reference solution. The developed resonance self-shielding cross-section calculation module exhibited similar accuracy to NJOY2016, demonstrating the correctness of these two modules developed in the AXSP program.
甘公网安备 62010202000723号