Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely s...Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely small atomic nuclei to explain the evolution of the universe.Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain unsolved.To achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models.Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar evolution.Given the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several decades.These are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive isotopes.However,direct measurement is still preferable,such as in the case of reactions involving light and stable nuclei.As an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent years.To overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution.Therefore,underground experiments have emerged as a new and promising direction of research.In addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot.In recent years,the CIAE team conducted a series of distinctive nuclear astrophysics studies,relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories,including the Beijing Radioactive Ion beam Facility,as well as other scientifc platforms at home and abroad.This research covered nuclear theories,numerical models,direct measurements,indirect measurements,and other novel approaches,achieving great interdisciplinary research results,with high-level academic publications and signifcant international impacts.This article reviews the above research and predicts future developments.展开更多
Life exists in the universe and therefore the astrophysical properties of the universe must be such that they allow the origin of life. We connect astrobiology and astrophysics via one astrobiological quantity—the pr...Life exists in the universe and therefore the astrophysical properties of the universe must be such that they allow the origin of life. We connect astrobiology and astrophysics via one astrobiological quantity—the probability of the origin of life. We show how this probability, if it is very low, will allow us to answer profound astrophysical questions such as the type of universe we live in, the fate of our universe, whether neutron stars, white and brown dwarfs evaporate and whether protons decay.展开更多
This paper reports on two nuclear astrophysics experiments performed in collabora- tion with Ruhr University. In a 12C＋2C fusion reaction, the 12C（12C, a）20e and 12C（12C, p）23Na reactions were studied in the ener...This paper reports on two nuclear astrophysics experiments performed in collabora- tion with Ruhr University. In a 12C＋2C fusion reaction, the 12C（12C, a）20e and 12C（12C, p）23Na reactions were studied in the energy range of E = 2.10 MeV to 4.75 MeV using -y-ray spectroscopy. The deduced astrophysical S（E）＊ factor exhibited a new, strong resonance at E -= 2.14 MeV, which lay at the high-energy tail of the Gamow peak. The resonance increased the reaction rate of the ^-channel by a factor of five near T = 8 ~ l0s K. The electron screening in d（d, p）t was stud- ied for a series of deuterated metal, insulator and semiconductor targets. Compared with the measurements performed with a gaseous D2 target, a large effect was observed in most metals, while a comparatively small effect was found in the insulators and semiconductors. Subsequently the temperature dependence of the electron screening in the d（d, p）t reaction was studied for the deuterated metals Pt and Co. Enhanced electron screening decreased with increasing tempera- ture. These data represent the first observations of the temperature dependence of a nuclear cross section.展开更多
An international bimonthly journal,founded in 2001 as a continuation of Acta Astrophysica Sinica(founded in 1981,ISSN 0253-2379).The Chinese Journal of Astronomy and Astrophysics (ISSN 1009-9271)is published for the C...An international bimonthly journal,founded in 2001 as a continuation of Acta Astrophysica Sinica(founded in 1981,ISSN 0253-2379).The Chinese Journal of Astronomy and Astrophysics (ISSN 1009-9271)is published for the Chinese Astronomical Society and the National Astronomical Observatories of Chinese Academy of Sciences by the Science Press in Beijing.展开更多
The coherence of the interaction of light with a collisionless gas (Einstein 1917) founds the theory of gas lasers. It is, for the understanding of universe, a simpler and more powerful tool than the big bang which re...The coherence of the interaction of light with a collisionless gas (Einstein 1917) founds the theory of gas lasers. It is, for the understanding of universe, a simpler and more powerful tool than the big bang which requires questionable supplements (dark matter, MOND, etc.). The Impulsive Stimulated Raman Scattering (ISRS) redshifts gradually light pulses which cross excited atomic hydrogen H*, so that the redshift is a measure of the column density of H*. Thus, the distance of the hot stars, surrounded by much H*, is exaggerated by the use of Hubble’s law. Local exaggerated distances create voids in the maps of galaxies which become spongy. The interpretation of spectra of quasars, the periodicity of galaxy redshifts introduce an experimental “Karlsson’s constant” exactly computed by ISRS. The need for dark matter comes from the exaggeration of the distance, therefore the size of galaxies. Without dark matter, celestial mechanics provides a reliable distance of spiral galaxies. Coherence also introduces superradiance and mode competition that explain that only the limbs of Stromgren spheres are visible as circles maybe punctuated by an even number of dots: Too numerous, the figures assigned to gravitational lenses can be such limbs. The coincidence of the ignition of the rings of SNR1987A with the extinction of the star is due to a multiphoton coherent scattering of star light, which amplifies the superradiant emission of the rings. A blueshift of microwaves crossing H* resulting, between 10 and 15 AU, of the expansion of solar wind, explains the “anomalous acceleration” of Pioneer probes. All is obtained without any change in theories of standard spectroscopy.展开更多
The nuclear astrophysics experiments terminal of RIBLL1 (Radioactive Ion Beam Line in Lanzhou) is composed of two slide rails and a four-knife precision slit structure. Both of them are placed in a terminal chamber as...The nuclear astrophysics experiments terminal of RIBLL1 (Radioactive Ion Beam Line in Lanzhou) is composed of two slide rails and a four-knife precision slit structure. Both of them are placed in a terminal chamber as shown in Fig. 1. During experiments, PPAC and experiment target are placed on two slide rails respectively. The width of four-knife slit is required to be adjusted during experiments. Also, in order to get results of different positions in chamber space, the position of PPAC and target must be able to be adjusted precisely in real time.展开更多
以及Research in Astronomy and Astrophysics的发展历程的统计分析为例,解析如何实现中国科技期刊国际化。对其高被引论文做学科分布及学术特征分析,对于刊物各栏目的影响做比较分析,对于天文和天体物理的研究领域和方向做统计分析,总...以及Research in Astronomy and Astrophysics的发展历程的统计分析为例,解析如何实现中国科技期刊国际化。对其高被引论文做学科分布及学术特征分析,对于刊物各栏目的影响做比较分析,对于天文和天体物理的研究领域和方向做统计分析,总结该刊办刊的经验教训,提出期刊国际化的发展建议。展开更多
【目的】探索实现我国科技期刊国际化的途径,提供一些国际化办刊思路。【方法】以Research in Astronomy and Astrophysics(RAA)走向国际化的努力为例,重点介绍RAA建设国际化编委队伍、争取国际优秀稿源、实现国际化审稿,并在出版发行...【目的】探索实现我国科技期刊国际化的途径,提供一些国际化办刊思路。【方法】以Research in Astronomy and Astrophysics(RAA)走向国际化的努力为例,重点介绍RAA建设国际化编委队伍、争取国际优秀稿源、实现国际化审稿,并在出版发行方面开展国际化合作等方面采取的一系列措施。【结论】RAA通过全方位的国际化努力,进一步扩大了期刊的宣传力,加强了期刊的影响力,从而提高了期刊的影响因子。展开更多
We present a theoretical model for detecting axions from neutron stars in a QCD phase of quark matter. The axions would be produced from a quark-antiquark pair uu¯or dd¯, in loop(s) involving gluons. The chi...We present a theoretical model for detecting axions from neutron stars in a QCD phase of quark matter. The axions would be produced from a quark-antiquark pair uu¯or dd¯, in loop(s) involving gluons. The chiral anomaly of QCD and the spontaneously broken symmetry are invoked to explain the non-conservation of the axion current. From the coupling form factors, the axion emissivities ϵacan be derived, from which fluxes can be determined. We predict a photon flux, which may be detectable by Fermi LAT, and limits on the QCD mass ma. In this model, axions decay to gamma rays in a 2-photon vertex. We may determine the expected fluxes from the theoretical emissivity. The sensitivity curve from the Fermi Large Area Telescope (Fermi LAT) would allow axion mass constraints for neutron stars as low as ma≤10−14eV 95% C.L. Axions could thus be detectable in gamma rays for neutron stars as distant as 100 kpc. A signal from LIGO GWS 170817 could be placed from the NS-NS merger, which gives an upper limit of ma≤10−10eV.展开更多
We report the observation of Zeeman splitting in multiple spectral lines emitted by a laser-produced,magnetized plasma(1–3×10^(18)cm^(-3),1–15 eV)in the context of a laboratory astrophysics experiment under a c...We report the observation of Zeeman splitting in multiple spectral lines emitted by a laser-produced,magnetized plasma(1–3×10^(18)cm^(-3),1–15 eV)in the context of a laboratory astrophysics experiment under a controlled magneticfield up to 20T.Nitrogen lines(NII)in the visible range were used to diagnose the magneticfield and plasma conditions.This was performed by coupling our data with(563–574 nm)the Stark–Zeeman line-shape code PPPB.The excellent agreement between experiment and simulations paves the way for a non-intrusive experimental platform to get time-resolved measurements of the local magneticfield in laboratory plasmas.展开更多
The ^(25)Mg(p,γ)^(26)Al reaction plays an important role in the study of cosmic 1.809 MeV γ-ray as a signature of ongoing nucleosynthesis in the Galaxy.At astrophysical temperature around 0.1 GK,the ^(25)Mg(p,γ)^(2...The ^(25)Mg(p,γ)^(26)Al reaction plays an important role in the study of cosmic 1.809 MeV γ-ray as a signature of ongoing nucleosynthesis in the Galaxy.At astrophysical temperature around 0.1 GK,the ^(25)Mg(p,γ)^(26)Al reaction rates are dominated by the 92 keV resonance capture process.We report a precise measurement of the 92 keV ^(25)Mg(p,γ)^(26)Al resonance in the day-one experiment at Jinping Underground Nuclear Astrophysics experiment(JUNA)facility in the China Jinping Underground Laboratory(CJPL).The resonance strength and ground state feeding factor are determined to be 3.8±0.3×10^(-10) eV and 0:660:04,respectively.The results are in agreement with those reported in the previous direct underground measurement within uncertainty,but with significantly reduced uncertainties.Consequently,we recommend new ^(25)Mg(p,γ)^(26)Al reaction rates which are by a factor of 2.4 larger than those adopted in REACLIB database at the temperature around 0.1 GK.The new results indicate higher production rates of ^(26g)Al and the cosmic 1.809 MeV γ-ray.The implication of the new rates for the understanding of other astrophysical situations is also discussed.展开更多
A new approach to target development for laboratory astrophysics experiments at high-power laser facilities is presented.With the dawn of high-power lasers,laboratory astrophysics has emerged as a field,bringing insig...A new approach to target development for laboratory astrophysics experiments at high-power laser facilities is presented.With the dawn of high-power lasers,laboratory astrophysics has emerged as a field,bringing insight into physical processes in astrophysical objects,such as the formation of stars.An important factor for success in these experiments is targetry.To date,targets have mainly relied on expensive and challenging microfabrication methods.The design presented incorporates replaceable machined parts that assemble into a structure that defines the experimental geometry.This can make targets cheaper and faster to manufacture,while maintaining robustness and reproducibility.The platform is intended for experiments on plasma flows,but it is flexible and may be adapted to the constraints of other experimental setups.Examples of targets used in experimental campaigns are shown,including a design for insertion in a high magnetic field coil.Experimental results are included,demonstrating the performance of the targets.展开更多
In 2018 the journal High Power Laser Science and Engineering produced a Special Issue on Laboratory Astrophysics.The scope of the special issue was to span the latest research and reviews on the following topics relat...In 2018 the journal High Power Laser Science and Engineering produced a Special Issue on Laboratory Astrophysics.The scope of the special issue was to span the latest research and reviews on the following topics related to laboratory astrophysics and related phenomena.The topics invited for inclusion were:·collisionless shocks;·planetary formation dynamics and planetary interiors;·warm dense matter;·hydrodynamic and magnetohydrodynamic instabilities;·magnetic reconnection;·relativistic plasmas;·magnetic turbulence and magnetic amplification;·nuclear astrophysics;·radiative transfer and radiation hydrodynamics;·target design;·laser-based HED facilities.although this was not meant as an exhaustive list.As is usual with a special issue of this type vip Editors were invited to lead in sourcing articles.展开更多
In this paper, the recent studies of laboratory astrophysics with strong magnetic fields in China have been reviewed.On the Shenguang-II laser facility of the National Laboratory on High-Power Lasers and Physics, a la...In this paper, the recent studies of laboratory astrophysics with strong magnetic fields in China have been reviewed.On the Shenguang-II laser facility of the National Laboratory on High-Power Lasers and Physics, a laser-driven strong magnetic field up to 200 T has been achieved. The experiment was performed to model the interaction of solar wind with dayside magnetosphere. Also the low beta plasma magnetic reconnection(MR) has been studied. Theoretically, the model has been developed to deal with the atomic structures and processes in strong magnetic field. Also the study of shock wave generation in the magnetized counter-streaming plasmas is introduced.展开更多
The paper includes discussions on the important role of neutron and alpha configurations in proton-rich nuclei in nuclear astrophysics in terms of nucleosynthesis under extremely high-temperature hydrogenburning condi...The paper includes discussions on the important role of neutron and alpha configurations in proton-rich nuclei in nuclear astrophysics in terms of nucleosynthesis under extremely high-temperature hydrogenburning conditions. The νp-process, which is supposed to take place at the very early epoch of type II supernovae, has considerable neutrons and alphas together with protons. The alpha-induced reactions on proton-rich unstable nuclei in the light mass regions is expected to play a crucial role, but very few of them were investigated well yet because of the experimental difficulties. Specifically, I report our recent experimental effort for the breakout process from the pp-chain region,~7Be(α, γ)^(11)C(α,p)^(14)N under the νp-process. The neutron-induced reactions on proton-rich nuclei, which is even more a challenging subject, were investigated previously for very few nuclei. One possible experimental method is the Trojan Horse Method(THM). We successfully have applied THM to the ^(18)F(n,α)^(14)N reaction study with an unstable beam of ^(18)F.展开更多
The gravitational wave background(GWB) produced by extreme-mass-ratio inspirals(EMRIs) serves as a powerful tool for probing the astrophysical and dynamical processes in galactic centers. EMRI systems are a primary ta...The gravitational wave background(GWB) produced by extreme-mass-ratio inspirals(EMRIs) serves as a powerful tool for probing the astrophysical and dynamical processes in galactic centers. EMRI systems are a primary target for the space-based detector laser interferometer space antenna due to their long-lived signals and high signal-to-noise ratios. This study explores the statistical properties of the GWB from EMRI, focusing on the calculation methods for the GWB, the astrophysical distribution of EMRI sources, and the influence of key parameters, including the spin of supermassive black holes(SMBHs) and the masses of compact objects(COs). By analyzing these factors, we determine the distribution range of the characteristic strain of the GWB from EMRIs. We find that the final eccentricity distributions appear to have negligible effect on the intensity of the GWB due to rapid circularization before they become detectable and the spin of the SMBH enhances the gravitational wave characteristic strain by approximately 1% compared to cases without spin effects. The masses of COs can also significantly affect the characteristic strain of the GWB from EMRIs, with black hole as CO producing a gravitational wave signal intensity that is approximately one order of magnitude higher compared to cases where neutron star or white dwarf are the COs.展开更多
This paper describes the design and fabrication of a range of ‘gas cell' microtargets produced by the Target Fabrication Group in the Central Laser Facility(CLF) for academic access experiments on the Orion laser...This paper describes the design and fabrication of a range of ‘gas cell' microtargets produced by the Target Fabrication Group in the Central Laser Facility(CLF) for academic access experiments on the Orion laser facility at the Atomic Weapons Establishment(AWE). The experiments were carried out by an academic consortium led by Imperial College London. The underlying target methodology was an evolution of a range of targets used for experiments on radiative shocks and involved the fabrication of a precision machined cell containing a number of apertures for interaction foils or diagnostic windows. The interior of the cell was gas-filled before laser irradiation. This paper details the assembly processes, thin film requirements and micro-machining processes needed to produce the targets. Also described is the implementation of a gas-fill system to produce targets that are filled to a pressure of 0.1–1 bar. The paper discusses the challenges that are posed by such a target.展开更多
The Shanghai Laser Electron Gamma Source(SLEGS, located in BL03SSID) beamline at the Shanghai Synchrotron Radiation Facility(SSRF) is a Laser Compton Scattering(LCS) gamma source used for the investigation of nuclear ...The Shanghai Laser Electron Gamma Source(SLEGS, located in BL03SSID) beamline at the Shanghai Synchrotron Radiation Facility(SSRF) is a Laser Compton Scattering(LCS) gamma source used for the investigation of nuclear structure, which is in extensive demand in fields such as nuclear astrophysics, nuclear cluster structure, polarization physics, and nuclear energy. The beamline is based on the inverse Compton scattering of 10640 nm photons on 3.5 GeV electrons and a gamma source with variable energy by changing the scattering angle from 20° to 160°. γ rays of 0.25-21.1 MeV can be extracted by the scheme consisting of the interaction chamber, coarse collimator, fine collimator, and attenuator. The maximum photon flux for 180° is approximately 10~7 photons/s at the target at 21.7 MeV, with a 3-mm-diameter beam. The beamline was equipped with four types of spectrometers for experiments in( γ,γ'),( γ,n),( γ,p), and( γ,α). At present, Nuclear Resonance Fluorescence(NRF) spectrometry, Flat-Efficiency neutron Detector(FED) spectrometry, neutron Time-Of-Flight(TOF) spectrometry, and Light-Charged Particle(LCP) spectrometry methods have been developed.展开更多
The ^(12)C+^(12)C fusion is one of the most important reactions in modern nuclear astrophysics.The trend and magnitude of the reaction rate within the Gamow window strongly influence various astrophysical processes.Ho...The ^(12)C+^(12)C fusion is one of the most important reactions in modern nuclear astrophysics.The trend and magnitude of the reaction rate within the Gamow window strongly influence various astrophysical processes.However,direct measurement of this reaction is extremely difficult,which makes it necessary to develop indirect methods.In this study,the ^(23)Na+p reaction system was used to study the compound nucleus ^(24)Mg.We employed a thick-target inverse kinematics method combined with theγ-charged-particle coincidence technique to measure the proton andα exit channels of ^(24)Mg.Technical details of the ^(23)Na+p thick-target inverse kinematics experiment and analysis are presented herein.展开更多
基金National Natural Science Foundation of China(Nos.12435010)National Key R&D Program of China(No.2022YFA1602301)。
文摘Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely small atomic nuclei to explain the evolution of the universe.Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain unsolved.To achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models.Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar evolution.Given the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several decades.These are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive isotopes.However,direct measurement is still preferable,such as in the case of reactions involving light and stable nuclei.As an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent years.To overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution.Therefore,underground experiments have emerged as a new and promising direction of research.In addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot.In recent years,the CIAE team conducted a series of distinctive nuclear astrophysics studies,relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories,including the Beijing Radioactive Ion beam Facility,as well as other scientifc platforms at home and abroad.This research covered nuclear theories,numerical models,direct measurements,indirect measurements,and other novel approaches,achieving great interdisciplinary research results,with high-level academic publications and signifcant international impacts.This article reviews the above research and predicts future developments.
文摘Life exists in the universe and therefore the astrophysical properties of the universe must be such that they allow the origin of life. We connect astrobiology and astrophysics via one astrobiological quantity—the probability of the origin of life. We show how this probability, if it is very low, will allow us to answer profound astrophysical questions such as the type of universe we live in, the fate of our universe, whether neutron stars, white and brown dwarfs evaporate and whether protons decay.
基金supported by the National Basic Research Program of China (Nos. 2003CB716704, 2007CB815003)
文摘This paper reports on two nuclear astrophysics experiments performed in collabora- tion with Ruhr University. In a 12C＋2C fusion reaction, the 12C（12C, a）20e and 12C（12C, p）23Na reactions were studied in the energy range of E = 2.10 MeV to 4.75 MeV using -y-ray spectroscopy. The deduced astrophysical S（E）＊ factor exhibited a new, strong resonance at E -= 2.14 MeV, which lay at the high-energy tail of the Gamow peak. The resonance increased the reaction rate of the ^-channel by a factor of five near T = 8 ~ l0s K. The electron screening in d（d, p）t was stud- ied for a series of deuterated metal, insulator and semiconductor targets. Compared with the measurements performed with a gaseous D2 target, a large effect was observed in most metals, while a comparatively small effect was found in the insulators and semiconductors. Subsequently the temperature dependence of the electron screening in the d（d, p）t reaction was studied for the deuterated metals Pt and Co. Enhanced electron screening decreased with increasing tempera- ture. These data represent the first observations of the temperature dependence of a nuclear cross section.
文摘An international bimonthly journal,founded in 2001 as a continuation of Acta Astrophysica Sinica(founded in 1981,ISSN 0253-2379).The Chinese Journal of Astronomy and Astrophysics (ISSN 1009-9271)is published for the Chinese Astronomical Society and the National Astronomical Observatories of Chinese Academy of Sciences by the Science Press in Beijing.
文摘The coherence of the interaction of light with a collisionless gas (Einstein 1917) founds the theory of gas lasers. It is, for the understanding of universe, a simpler and more powerful tool than the big bang which requires questionable supplements (dark matter, MOND, etc.). The Impulsive Stimulated Raman Scattering (ISRS) redshifts gradually light pulses which cross excited atomic hydrogen H*, so that the redshift is a measure of the column density of H*. Thus, the distance of the hot stars, surrounded by much H*, is exaggerated by the use of Hubble’s law. Local exaggerated distances create voids in the maps of galaxies which become spongy. The interpretation of spectra of quasars, the periodicity of galaxy redshifts introduce an experimental “Karlsson’s constant” exactly computed by ISRS. The need for dark matter comes from the exaggeration of the distance, therefore the size of galaxies. Without dark matter, celestial mechanics provides a reliable distance of spiral galaxies. Coherence also introduces superradiance and mode competition that explain that only the limbs of Stromgren spheres are visible as circles maybe punctuated by an even number of dots: Too numerous, the figures assigned to gravitational lenses can be such limbs. The coincidence of the ignition of the rings of SNR1987A with the extinction of the star is due to a multiphoton coherent scattering of star light, which amplifies the superradiant emission of the rings. A blueshift of microwaves crossing H* resulting, between 10 and 15 AU, of the expansion of solar wind, explains the “anomalous acceleration” of Pioneer probes. All is obtained without any change in theories of standard spectroscopy.
文摘The nuclear astrophysics experiments terminal of RIBLL1 (Radioactive Ion Beam Line in Lanzhou) is composed of two slide rails and a four-knife precision slit structure. Both of them are placed in a terminal chamber as shown in Fig. 1. During experiments, PPAC and experiment target are placed on two slide rails respectively. The width of four-knife slit is required to be adjusted during experiments. Also, in order to get results of different positions in chamber space, the position of PPAC and target must be able to be adjusted precisely in real time.
文摘以及Research in Astronomy and Astrophysics的发展历程的统计分析为例,解析如何实现中国科技期刊国际化。对其高被引论文做学科分布及学术特征分析,对于刊物各栏目的影响做比较分析,对于天文和天体物理的研究领域和方向做统计分析,总结该刊办刊的经验教训,提出期刊国际化的发展建议。
文摘【目的】探索实现我国科技期刊国际化的途径,提供一些国际化办刊思路。【方法】以Research in Astronomy and Astrophysics(RAA)走向国际化的努力为例,重点介绍RAA建设国际化编委队伍、争取国际优秀稿源、实现国际化审稿,并在出版发行方面开展国际化合作等方面采取的一系列措施。【结论】RAA通过全方位的国际化努力,进一步扩大了期刊的宣传力,加强了期刊的影响力,从而提高了期刊的影响因子。
文摘We present a theoretical model for detecting axions from neutron stars in a QCD phase of quark matter. The axions would be produced from a quark-antiquark pair uu¯or dd¯, in loop(s) involving gluons. The chiral anomaly of QCD and the spontaneously broken symmetry are invoked to explain the non-conservation of the axion current. From the coupling form factors, the axion emissivities ϵacan be derived, from which fluxes can be determined. We predict a photon flux, which may be detectable by Fermi LAT, and limits on the QCD mass ma. In this model, axions decay to gamma rays in a 2-photon vertex. We may determine the expected fluxes from the theoretical emissivity. The sensitivity curve from the Fermi Large Area Telescope (Fermi LAT) would allow axion mass constraints for neutron stars as low as ma≤10−14eV 95% C.L. Axions could thus be detectable in gamma rays for neutron stars as distant as 100 kpc. A signal from LIGO GWS 170817 could be placed from the NS-NS merger, which gives an upper limit of ma≤10−10eV.
基金supported by grants managed by l’Agence Nationale de la Recherche under the Investissements d’Avenir programs Grant Nos. ANR-18-EURE-0014, ANR-10-LABX-0039-PALM, and ANR-22-CE30-0044supported by grants from Japan Society for the Promotion of Science (JSPS) KAKENHI (Grant No. 23K20038)+2 种基金JSPS Core-to-Core program (Grant No. JPJSCCA20230003)carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No. 101052200-EUROfusion)operated within the framework of the Enabling Research Project No. AWP24-ENR-IFE.02.CEA-01 “Magnetized ICF”
文摘We report the observation of Zeeman splitting in multiple spectral lines emitted by a laser-produced,magnetized plasma(1–3×10^(18)cm^(-3),1–15 eV)in the context of a laboratory astrophysics experiment under a controlled magneticfield up to 20T.Nitrogen lines(NII)in the visible range were used to diagnose the magneticfield and plasma conditions.This was performed by coupling our data with(563–574 nm)the Stark–Zeeman line-shape code PPPB.The excellent agreement between experiment and simulations paves the way for a non-intrusive experimental platform to get time-resolved measurements of the local magneticfield in laboratory plasmas.
基金supported by the National Natural Science Foundation of China(1149056312125509U18672111196114100311775133and 12175152)the Continuous Basic Scientific Research Project No.WDJC-2019-13+1 种基金the Equipment Research and Development Project of Chinese Academy of Sciences(28Y531040)research fund of CNNC。
文摘The ^(25)Mg(p,γ)^(26)Al reaction plays an important role in the study of cosmic 1.809 MeV γ-ray as a signature of ongoing nucleosynthesis in the Galaxy.At astrophysical temperature around 0.1 GK,the ^(25)Mg(p,γ)^(26)Al reaction rates are dominated by the 92 keV resonance capture process.We report a precise measurement of the 92 keV ^(25)Mg(p,γ)^(26)Al resonance in the day-one experiment at Jinping Underground Nuclear Astrophysics experiment(JUNA)facility in the China Jinping Underground Laboratory(CJPL).The resonance strength and ground state feeding factor are determined to be 3.8±0.3×10^(-10) eV and 0:660:04,respectively.The results are in agreement with those reported in the previous direct underground measurement within uncertainty,but with significantly reduced uncertainties.Consequently,we recommend new ^(25)Mg(p,γ)^(26)Al reaction rates which are by a factor of 2.4 larger than those adopted in REACLIB database at the temperature around 0.1 GK.The new results indicate higher production rates of ^(26g)Al and the cosmic 1.809 MeV γ-ray.The implication of the new rates for the understanding of other astrophysical situations is also discussed.
基金Additional funding was provided by the Student Grant Competition of CTU(No.SGS22/180/OHK4/3T/14)the Ministry of Education,Youth&Sports of the Czech Republic(No.LM2018114)+1 种基金the Horizon 2020 project Laserlab-Europe V(No.871124)This work was funded by the Helmholtz Association(No.VHNG-1338).
文摘A new approach to target development for laboratory astrophysics experiments at high-power laser facilities is presented.With the dawn of high-power lasers,laboratory astrophysics has emerged as a field,bringing insight into physical processes in astrophysical objects,such as the formation of stars.An important factor for success in these experiments is targetry.To date,targets have mainly relied on expensive and challenging microfabrication methods.The design presented incorporates replaceable machined parts that assemble into a structure that defines the experimental geometry.This can make targets cheaper and faster to manufacture,while maintaining robustness and reproducibility.The platform is intended for experiments on plasma flows,but it is flexible and may be adapted to the constraints of other experimental setups.Examples of targets used in experimental campaigns are shown,including a design for insertion in a high magnetic field coil.Experimental results are included,demonstrating the performance of the targets.
文摘In 2018 the journal High Power Laser Science and Engineering produced a Special Issue on Laboratory Astrophysics.The scope of the special issue was to span the latest research and reviews on the following topics related to laboratory astrophysics and related phenomena.The topics invited for inclusion were:·collisionless shocks;·planetary formation dynamics and planetary interiors;·warm dense matter;·hydrodynamic and magnetohydrodynamic instabilities;·magnetic reconnection;·relativistic plasmas;·magnetic turbulence and magnetic amplification;·nuclear astrophysics;·radiative transfer and radiation hydrodynamics;·target design;·laser-based HED facilities.although this was not meant as an exhaustive list.As is usual with a special issue of this type vip Editors were invited to lead in sourcing articles.
基金supported by National Basic Research Program of China (973 Program) under grant No.2013CBA01503the National Natural Science Foundation of China under grant No.11573040, 11503041 and 11135012supported by the Science Challenge Program
文摘In this paper, the recent studies of laboratory astrophysics with strong magnetic fields in China have been reviewed.On the Shenguang-II laser facility of the National Laboratory on High-Power Lasers and Physics, a laser-driven strong magnetic field up to 200 T has been achieved. The experiment was performed to model the interaction of solar wind with dayside magnetosphere. Also the low beta plasma magnetic reconnection(MR) has been studied. Theoretically, the model has been developed to deal with the atomic structures and processes in strong magnetic field. Also the study of shock wave generation in the magnetized counter-streaming plasmas is introduced.
基金Japan Society for the Promotion of Science(JSPS)Research(KAKENHI)(26287058)
文摘The paper includes discussions on the important role of neutron and alpha configurations in proton-rich nuclei in nuclear astrophysics in terms of nucleosynthesis under extremely high-temperature hydrogenburning conditions. The νp-process, which is supposed to take place at the very early epoch of type II supernovae, has considerable neutrons and alphas together with protons. The alpha-induced reactions on proton-rich unstable nuclei in the light mass regions is expected to play a crucial role, but very few of them were investigated well yet because of the experimental difficulties. Specifically, I report our recent experimental effort for the breakout process from the pp-chain region,~7Be(α, γ)^(11)C(α,p)^(14)N under the νp-process. The neutron-induced reactions on proton-rich nuclei, which is even more a challenging subject, were investigated previously for very few nuclei. One possible experimental method is the Trojan Horse Method(THM). We successfully have applied THM to the ^(18)F(n,α)^(14)N reaction study with an unstable beam of ^(18)F.
基金supported by the National Key R&D Program of China (Grant No. 2020YFC2201400)。
文摘The gravitational wave background(GWB) produced by extreme-mass-ratio inspirals(EMRIs) serves as a powerful tool for probing the astrophysical and dynamical processes in galactic centers. EMRI systems are a primary target for the space-based detector laser interferometer space antenna due to their long-lived signals and high signal-to-noise ratios. This study explores the statistical properties of the GWB from EMRI, focusing on the calculation methods for the GWB, the astrophysical distribution of EMRI sources, and the influence of key parameters, including the spin of supermassive black holes(SMBHs) and the masses of compact objects(COs). By analyzing these factors, we determine the distribution range of the characteristic strain of the GWB from EMRIs. We find that the final eccentricity distributions appear to have negligible effect on the intensity of the GWB due to rapid circularization before they become detectable and the spin of the SMBH enhances the gravitational wave characteristic strain by approximately 1% compared to cases without spin effects. The masses of COs can also significantly affect the characteristic strain of the GWB from EMRIs, with black hole as CO producing a gravitational wave signal intensity that is approximately one order of magnitude higher compared to cases where neutron star or white dwarf are the COs.
文摘This paper describes the design and fabrication of a range of ‘gas cell' microtargets produced by the Target Fabrication Group in the Central Laser Facility(CLF) for academic access experiments on the Orion laser facility at the Atomic Weapons Establishment(AWE). The experiments were carried out by an academic consortium led by Imperial College London. The underlying target methodology was an evolution of a range of targets used for experiments on radiative shocks and involved the fabrication of a precision machined cell containing a number of apertures for interaction foils or diagnostic windows. The interior of the cell was gas-filled before laser irradiation. This paper details the assembly processes, thin film requirements and micro-machining processes needed to produce the targets. Also described is the implementation of a gas-fill system to produce targets that are filled to a pressure of 0.1–1 bar. The paper discusses the challenges that are posed by such a target.
文摘The Shanghai Laser Electron Gamma Source(SLEGS, located in BL03SSID) beamline at the Shanghai Synchrotron Radiation Facility(SSRF) is a Laser Compton Scattering(LCS) gamma source used for the investigation of nuclear structure, which is in extensive demand in fields such as nuclear astrophysics, nuclear cluster structure, polarization physics, and nuclear energy. The beamline is based on the inverse Compton scattering of 10640 nm photons on 3.5 GeV electrons and a gamma source with variable energy by changing the scattering angle from 20° to 160°. γ rays of 0.25-21.1 MeV can be extracted by the scheme consisting of the interaction chamber, coarse collimator, fine collimator, and attenuator. The maximum photon flux for 180° is approximately 10~7 photons/s at the target at 21.7 MeV, with a 3-mm-diameter beam. The beamline was equipped with four types of spectrometers for experiments in( γ,γ'),( γ,n),( γ,p), and( γ,α). At present, Nuclear Resonance Fluorescence(NRF) spectrometry, Flat-Efficiency neutron Detector(FED) spectrometry, neutron Time-Of-Flight(TOF) spectrometry, and Light-Charged Particle(LCP) spectrometry methods have been developed.
基金supported by the National Key Research and Development Project (No. 2022YFA1602301)the National Natural Science Foundation of China (Nos. U2267205, 12275361, 12125509, 12222514, 11961141003, and 12005304)+2 种基金the CAST Young Talent Support Planthe CNNC Science Fund for Talented Young Scholarsthe Continuous-Support Basic Scientific Research Project
文摘The ^(12)C+^(12)C fusion is one of the most important reactions in modern nuclear astrophysics.The trend and magnitude of the reaction rate within the Gamow window strongly influence various astrophysical processes.However,direct measurement of this reaction is extremely difficult,which makes it necessary to develop indirect methods.In this study,the ^(23)Na+p reaction system was used to study the compound nucleus ^(24)Mg.We employed a thick-target inverse kinematics method combined with theγ-charged-particle coincidence technique to measure the proton andα exit channels of ^(24)Mg.Technical details of the ^(23)Na+p thick-target inverse kinematics experiment and analysis are presented herein.
