Copper-64 is a radioisotope of medical interest that could be used for positron emission tomography imaging and targeted radiotherapy of cancer. In this work,we investigated the possibility of producing the^(64)Cu iso...Copper-64 is a radioisotope of medical interest that could be used for positron emission tomography imaging and targeted radiotherapy of cancer. In this work,we investigated the possibility of producing the^(64)Cu isotope through a^(65)Cu(γ,n) reaction using high-intensity γ-beams produced at the Extreme Light InfrastructureNuclear Physics facility(ELI-NP). The specific activity for^(64)Cu was obtained as a function of target geometry, irradiation time, and electron beam energy, which translates into γ-beam energy. Optimized conditions for the generation of^(64)Cu isotopes at the ELI-NP were discussed. We estimated that an achievable saturation specific activity is of the order of 1–2 m Ci/g for thin targets(radius 1–2 mm,thickness 1 cm) and for a γ-beam flux of 10^(11) s ~1. Based on these results, the ELI-NP could provide great potential for the production of some innovative radioisotopes of medical interest in sufficient quantities suitable for nuclear medicine research.展开更多
The emergence of a new era reaching beyond current state-of-the-art ultrashort and ultraintense laser technology has been enabled by the approval of around V 850 million worth of structural funds in 2011–2012 by the ...The emergence of a new era reaching beyond current state-of-the-art ultrashort and ultraintense laser technology has been enabled by the approval of around V 850 million worth of structural funds in 2011–2012 by the European Commission for the installation of Extreme Light Infrastructure(ELI).The ELI project consists of three pillars being built in the Czech Republic,Hungary,and Romania.This challenging proposal is based on recent technical progress allowing ultraintense laser fields in which intensities will soon be reaching as high as I0∼1023Wcm−2.This tremendous technological advance has been brought about by the invention of chirped pulse amplification by Mourou and Strickland.Romania is hosting the ELI for Nuclear Physics(ELI-NP)pillar in M˘agurele near Bucharest.The new facility,currently under construction,is intended to serve the broad national,European,and international scientific community.Its mission covers scientific research at the frontier of knowledge involving two domains.The first is laser-driven experiments related to NP,strong-field quantum electrodynamics,and associated vacuum effects.The second research domain is based on the establishment of a Compton-backscattering-based,high-brilliance,and intenseγbeam with Eγ≲19.5 MeV,which represents a merger between laser and accelerator technology.This system will allow the investigation of the nuclear structure of selected isotopes and nuclear reactions of relevance,for example,to astrophysics with hitherto unprecedented resolution and accuracy.In addition to fundamental themes,a large number of applications with significant societal impact will be developed.The implementation of the project started in January 2013 and is spearheaded by the ELI-NP/Horia Hulubei National Institute for Physics and Nuclear Engineering(IFIN-HH).Experiments will begin in early 2020.展开更多
For simulating more accurately neutron or proton production from photonuclear reactions,a data-based photonuclear reaction simulation algorithm has been developed.Reliable photonuclear cross sections from evaluated or...For simulating more accurately neutron or proton production from photonuclear reactions,a data-based photonuclear reaction simulation algorithm has been developed.Reliable photonuclear cross sections from evaluated or experimental database are chosen as input data.For checking the validity of the use of the data-based photonuclear algorithm,benchmarking simulations are presented in detail.We calculate photonuclear cross sections or reaction yield for ~9Be,^(48)Ti,^(133)Cs,and ^(197)Au and compare them with experimental data in the region of incident photon energy below ~30 MeV.While Geant4 can hardly reproduce photonuclear experimental data,results obtained from the data-based photonuclear algorithm are found in good agreement with experimental measurements.Potential application in estimation of specific activity of radioisotopes is further discussed.We conclude that the developed data-based photonuclear algorithm is suitable for an accurate prediction of photoninduced neutron or proton productions.展开更多
With the much-anticipated multi-petawatt(PW)laser facilities that are coming online,neutron sources with extreme fluxes could soon be in reach.Such sources would rely on spallation by protons accelerated by the high-i...With the much-anticipated multi-petawatt(PW)laser facilities that are coming online,neutron sources with extreme fluxes could soon be in reach.Such sources would rely on spallation by protons accelerated by the high-intensity lasers.These high neutron fluxes would make possible not only direct measurements of neutron capture andβ-decay rates related to the r-process of nucleosynthesis of heavy elements,but also such nuclear measurements in a hot plasma environment,which would be beneficial for s-process investigations in astrophysically relevant conditions.This could,in turn,finally allow possible reconciliation of the observed element abundances in stars and those derived from simulations,which at present show large discrepancies.Here,we review a possible pathway to reach unprecedented neutron fluxes using multi-PW lasers,as well as strategies to perform measurements to investigate the r-and s-processes of nucleosynthesis of heavy elements in cold matter,as well as in a hot plasma environment.展开更多
The interaction of micro-bubbles with ultra-intense laser pulses has been shown to generate ultra-high proton densities and correspondingly high electric fields.Weinvestigate the possibility of using such a combinatio...The interaction of micro-bubbles with ultra-intense laser pulses has been shown to generate ultra-high proton densities and correspondingly high electric fields.Weinvestigate the possibility of using such a combination to study the fundamental physical phenomenon of vacuum polarization.With current or near-future laser systems,measurement of vacuum polarization via the bending of gamma rays that pass near imploded microbubbles may be possible.Since it is independent of photon energy to within the leading-order solution of the Heisenberg–Euler Lagrangian and the geometric optics approximation,the corresponding index of refraction can dominate the indices of refraction due to other effects at sufficiently high photon energies.We consider the possibility of its application to a transient gamma-ray lens.展开更多
Laser Wakefield plasma acceleration of electrons to energies above 10 GeV, may be possible in the new high power Laser beam facilities. The design of an Electron Spectrometer with an electro-magnet with adjustable mag...Laser Wakefield plasma acceleration of electrons to energies above 10 GeV, may be possible in the new high power Laser beam facilities. The design of an Electron Spectrometer with an electro-magnet with adjustable magnetic field is proposed for the characterization of electron energy spectrum with a precision better than 10% for the entire energy range from 0.5 GeV to 38 GeV. The expected precision in the measurement of the electron energy is calculated as a function of the magnetic field, of the electron energy and of the magnet length. To outline the advantages offered by a pulsed electromagnet with high magnetic fields, the mass and the electric power lost in the coils of a 4 m long electromagnet with continuous current and Iron yoke are calculated.展开更多
Laser irradiation of solid targets can drive short and high-charge relativistic electron bunches over micron-scale acceleration gradients.However,for a long time,this technique was not considered a viable means of ele...Laser irradiation of solid targets can drive short and high-charge relativistic electron bunches over micron-scale acceleration gradients.However,for a long time,this technique was not considered a viable means of electron acceleration due to the large intrinsic divergence(∼50°half-angle)of the electrons.Recently,a reduction in this divergence to 10°–20°half-angle has been obtained,using plasma-based magnetic fields or very high contrast laser pulses to extract the electrons into the vacuum.Here we show that we can further improve the electron beam collimation,down to∼1.5°half-angle,of a high-charge(6 nC)beam,and in a highly reproducible manner,while using standard stand-alone 100 TW-class laser pulses.This is obtained by embedding the laser-target interaction in an external,large-scale(cm),homogeneous,extremely stable,and high-strength(20 T)magnetic field that is independent of the laser.With upcoming multi-PW,high repetition-rate lasers,this technique opens the door to achieving even higher charges(>100 nC).展开更多
Recent achievements in laboratory astrophysics experiments with high-power lasers have allowed progress in our understanding of the early stages of star formation.In particular,we have recently demonstrated the possib...Recent achievements in laboratory astrophysics experiments with high-power lasers have allowed progress in our understanding of the early stages of star formation.In particular,we have recently demonstrated the possibility of simulating in the laboratory the process of the accretion of matter on young stars[G.Revet et al.,Sci.Adv.3,e1700982(2017)].The present paper focuses on x-ray spectroscopy methods that allow us to investigate the complex plasma hydrodynamics involved in such experiments.We demonstrate that we can infer the formation of a plasma shell,surrounding the accretion column at the location of impact with the stellar surface,and thus resolve the present discrepancies between mass accretion rates derived from x-ray and optical-radiation astronomical observations originating from the same object.In our experiments,the accretion column ismodeled by having a collimated narrow(1 mm diameter)plasma stream first propagate along the lines of a large-scale external magnetic field and then impact onto an obstacle,mimicking the high-density region of the stellar chromosphere.A combined approach using steady-state and quasi-stationarymodels was successfully applied tomeasure the parameters of the plasma all along its propagation,at the impact site,and in the structure surrounding the impact region.The formation of a hot plasma shell,surrounding the denser and colder core,formed by the incoming stream of matter is observed near the obstacle using x-ray spatially resolved spectroscopy.展开更多
We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and ho...We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and homogeneity of targets to be driven by optical laser pulse.By developing X-ray imaging,based on the use of an LiF crystal detector,we were able to measure the distribution of energy inside a hard X-ray beam with unprecedented high spatial resolution(~1 mm)and across a field of view larger than some millimetres.This diagnostic can be used in situ,provides a very high dynamic range,has an extremely limited cost,and is relatively easy to be implemented in pump-probe experiments.The proposed methods were successfully applied in pump-probe experiments at the SPring-8 Angstrom Compact free electron LAser(SACLA)XFEL facility and its potential was demonstrated for current and future High Energy Density Science experiments.展开更多
Collisionless shocks are ubiquitous in the Universe and are held responsible for the production of nonthermal particles and high-energy radiation.In the absence of particle collisions in the system,theory shows that t...Collisionless shocks are ubiquitous in the Universe and are held responsible for the production of nonthermal particles and high-energy radiation.In the absence of particle collisions in the system,theory shows that the interaction of an expanding plasma with a pre-existing electromagnetic structure(as in our case)is able to induce energy dissipation and allow shock formation.Shock formation can alternatively take place when two plasmas interact,through microscopic instabilities inducing electromagnetic fields that are able in turn to mediate energy dissipation and shock formation.Using our platform in which we couple a rapidly expanding plasma induced by high-power lasers(JLF/Titan at LLNL and LULI2000)with high-strength magnetic fields,we have investigated the generation of a magnetized collisionless shock and the associated particle energization.We have characterized the shock as being collisionless and supercritical.We report here on measurements of the plasma density and temperature,the electromagnetic field structures,and the particle energization in the experiments,under various conditions of ambient plasma and magnetic field.We have also modeled the formation of the shocks using macroscopic hydrodynamic simulations and the associated particle acceleration using kinetic particle-in-cell simulations.As a companion paper to Yao et al.[Nat.Phys.17,1177–1182(2021)],here we show additional results of the experiments and simulations,providing more information to allow their reproduction and to demonstrate the robustness of our interpretation of the proton energization mechanism as being shock surfing acceleration.展开更多
The spatial distribution of beams with orbital angular momentum in the far field is known to be extremely sensitive to angular aberrations,such as astigmatism,coma and trefoil.This poses a challenge for conventional b...The spatial distribution of beams with orbital angular momentum in the far field is known to be extremely sensitive to angular aberrations,such as astigmatism,coma and trefoil.This poses a challenge for conventional beam optimization strategies when a homogeneous ring intensity is required for an application.We developed a novel approach for estimating the Zernike coefficients of low-order angular aberrations in the near field based solely on the analysis of the ring deformations in the far field.A fast,iterative reconstruction of the focal ring recreates the deformations and provides insight into the wavefront deformations in the near field without relying on conventional phase retrieval approaches.The output of our algorithm can be used to optimize the focal ring,as demonstrated experimentally at the 100 TW beamline at the Extreme Light Infrastructure-Nuclear Physics facility.展开更多
Mass is a fundamental property and an important fingerprint of atomic nucleus.It provides an extremely useful test ground for nuclear models and is crucial to understand energy generation in stars as well as the heavy...Mass is a fundamental property and an important fingerprint of atomic nucleus.It provides an extremely useful test ground for nuclear models and is crucial to understand energy generation in stars as well as the heavy elements synthesized in stellar explosions.Nuclear physicists have been attempting at developing a precise,reliable,and predictive nuclear model that is suitable for the whole nuclear chart,while this still remains a great challenge even in recent days.Here we employ the Fourier spectral analysis to examine the deviations of nuclear mass predictions to the experimental data and to present a novel way for accurate nuclear mass predictions.In this analysis,we map the mass deviations from the space of nucleon number to its conjugate space of frequency,and are able to pin down the main contributions to the model deficiencies.By using the radial basis function approach we can further isolate and quantify the sources.Taking a pedagogical mass model as an example,we examine explicitly the correlation between nuclear effective interactions and the distributions of mass deviations in the frequency domain.The method presented in this work,therefore,opens up a new way for improving the nuclear mass predictions towards a hundred kilo-electron-volt accuracy,which is argued to be the chaos-related limit for the nuclear mass predictions.展开更多
After the introduction of the ionization-injection scheme in laser wake field acceleration and of related high-quality electron beam generation methods,such as two-color and resonant multi-pulse ionization injection(R...After the introduction of the ionization-injection scheme in laser wake field acceleration and of related high-quality electron beam generation methods,such as two-color and resonant multi-pulse ionization injection(Re MPI),the theory of thermal emittance has been used to predict the beam normalized emittance obtainable with those schemes.We recast and extend such a theory,including both higher order terms in the polynomial laser field expansion and non-polynomial corrections due to the onset of saturation effects on a single cycle.Also,a very accurate model for predicting the cycle-averaged distribution of the extracted electrons,including saturation and multi-process events,is proposed and tested.We show that our theory is very accurate for the selected processes of Kr^(8+→10+) and Ar^(8+→10+),resulting in a maximum error below 1%,even in a deep-saturation regime.The accurate prediction of the beam phase-space can be implemented,for example,in laser-envelope or hybrid particle-in-cell(PIC)/fiuid codes,to correctly mimic the cycle-averaged momentum distribution without the need for resolving the intra-cycle dynamics.We introduce further spatial averaging,obtaining expressions for the whole-beam emittance fitting with simulations in a saturated regime,too.Finally,a PIC simulation for a laser wakefield acceleration injector in the Re MPI configuration is discussed.展开更多
In this paper,a radially polarised cosh-Gaussian laser beam(CGLB)is used to study the electron acceleration produced in vacuum.A highly energetic electron beam can be achieved by a CGLB,even with comparatively low-pow...In this paper,a radially polarised cosh-Gaussian laser beam(CGLB)is used to study the electron acceleration produced in vacuum.A highly energetic electron beam can be achieved by a CGLB,even with comparatively low-powered lasers.The properties of a CGLB cause it to focus earlier,over a shorter duration than a Gaussian laser beam,which makes it suitable for obtaining high energies over small durations.It is found that the energy gained by the electrons strongly depends upon the decentering parameter of the laser profile.It is also observed that for a fixed value of energy gain,if the decentering parameter is increased,then the intensity of the laser field decreases.The dependence of the energy gained by electrons on the laser intensity and the laserspot size is also studied.展开更多
The rich phenomena of deformations in neutron-deficient krypton isotopes, such as shape evolution with neutron number and shape coexistence, have attracted the interest of nuclear physicists for decades. It is interes...The rich phenomena of deformations in neutron-deficient krypton isotopes, such as shape evolution with neutron number and shape coexistence, have attracted the interest of nuclear physicists for decades. It is interesting to study such shape phenomena using a novel way, e.g. by thermally exciting the nucleus. In this work, we develop the finite temperature covariant density functional theory for axially deformed nuclei with the treatment of pairing correlations by the BCS approach, and apply this approach for the study of shape evolution in 72,74Kr with increasing temperature. For 72Kr, with temperature increasing, the nucleus firstly experiences a relatively quick weakening in oblate deformation at temperature T-0.9 MeV, and then changes from oblate to spherical at T-2.1 MeV. For 74Kr, its global minimum is at quadrupole deformation β2--0.14 and abruptly changes to spherical at T-1.7 MeV. The proton pairing transition occurs at critical temperature 0.6 MeV following the rule Tc =0.6△p (0), where △p(0) is the proton pairing gap at zero temperature. The signatures of the above pairing transition and shape changes can be found in the specific heat curve. The single-particle level evolutions with temperature are presented.展开更多
A new generation of high power laser facilities will provide laser pulses with extremely high powers of 10 petawatt(PW)and even 100 PW, capable of reaching intensities of 1023 W/cm^2 in the laser focus. These ultra-hi...A new generation of high power laser facilities will provide laser pulses with extremely high powers of 10 petawatt(PW)and even 100 PW, capable of reaching intensities of 1023 W/cm^2 in the laser focus. These ultra-high intensities are nevertheless lower than the Schwinger intensity IS= 2.3×1029 W/cm^2 at which the theory of quantum electrodynamics(QED) predicts that a large part of the energy of the laser photons will be transformed to hard Gamma-ray photons and even to matter, via electron–positron pair production. To enable the investigation of this physics at the intensities achievable with the next generation of high power laser facilities, an approach involving the interaction of two colliding PW laser pulses is being adopted. Theoretical simulations predict strong QED effects with colliding laser pulses of 10 PW focused to intensities 10^(22) W/cm^2.展开更多
基金supported by Extreme Light Infrastructure-Nuclear Physics(ELI-NP)-Phase Ia project co-financed by the European Union through the European Regional Development Fund+1 种基金the National Natural Science Foundation of China(No.11405083)the Young Talent Project of the University of South China
文摘Copper-64 is a radioisotope of medical interest that could be used for positron emission tomography imaging and targeted radiotherapy of cancer. In this work,we investigated the possibility of producing the^(64)Cu isotope through a^(65)Cu(γ,n) reaction using high-intensity γ-beams produced at the Extreme Light InfrastructureNuclear Physics facility(ELI-NP). The specific activity for^(64)Cu was obtained as a function of target geometry, irradiation time, and electron beam energy, which translates into γ-beam energy. Optimized conditions for the generation of^(64)Cu isotopes at the ELI-NP were discussed. We estimated that an achievable saturation specific activity is of the order of 1–2 m Ci/g for thin targets(radius 1–2 mm,thickness 1 cm) and for a γ-beam flux of 10^(11) s ~1. Based on these results, the ELI-NP could provide great potential for the production of some innovative radioisotopes of medical interest in sufficient quantities suitable for nuclear medicine research.
基金The contribution of the entire ELI-NP team and collaborators to the project implementation is gratefully acknowledged,especially the help of A.Imreh in creating the complex 3D figures.The work has been supported by Extreme Light Infrastructure Nuclear Physics Phase II,a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund and the Competitiveness Operational Programme(No.1/07.07.2016,COP,ID 1334).
文摘The emergence of a new era reaching beyond current state-of-the-art ultrashort and ultraintense laser technology has been enabled by the approval of around V 850 million worth of structural funds in 2011–2012 by the European Commission for the installation of Extreme Light Infrastructure(ELI).The ELI project consists of three pillars being built in the Czech Republic,Hungary,and Romania.This challenging proposal is based on recent technical progress allowing ultraintense laser fields in which intensities will soon be reaching as high as I0∼1023Wcm−2.This tremendous technological advance has been brought about by the invention of chirped pulse amplification by Mourou and Strickland.Romania is hosting the ELI for Nuclear Physics(ELI-NP)pillar in M˘agurele near Bucharest.The new facility,currently under construction,is intended to serve the broad national,European,and international scientific community.Its mission covers scientific research at the frontier of knowledge involving two domains.The first is laser-driven experiments related to NP,strong-field quantum electrodynamics,and associated vacuum effects.The second research domain is based on the establishment of a Compton-backscattering-based,high-brilliance,and intenseγbeam with Eγ≲19.5 MeV,which represents a merger between laser and accelerator technology.This system will allow the investigation of the nuclear structure of selected isotopes and nuclear reactions of relevance,for example,to astrophysics with hitherto unprecedented resolution and accuracy.In addition to fundamental themes,a large number of applications with significant societal impact will be developed.The implementation of the project started in January 2013 and is spearheaded by the ELI-NP/Horia Hulubei National Institute for Physics and Nuclear Engineering(IFIN-HH).Experiments will begin in early 2020.
基金supported by the National Natural Science Foundation of China(Nos.11405083 and 11675075)the Young Talent Project of the University of South Chinathe Extreme Light Infrastructure-Nuclear Physics(ELI-NP)-Phase I,a project co-financed by the European Union through the European Regional Development Fund
文摘For simulating more accurately neutron or proton production from photonuclear reactions,a data-based photonuclear reaction simulation algorithm has been developed.Reliable photonuclear cross sections from evaluated or experimental database are chosen as input data.For checking the validity of the use of the data-based photonuclear algorithm,benchmarking simulations are presented in detail.We calculate photonuclear cross sections or reaction yield for ~9Be,^(48)Ti,^(133)Cs,and ^(197)Au and compare them with experimental data in the region of incident photon energy below ~30 MeV.While Geant4 can hardly reproduce photonuclear experimental data,results obtained from the data-based photonuclear algorithm are found in good agreement with experimental measurements.Potential application in estimation of specific activity of radioisotopes is further discussed.We conclude that the developed data-based photonuclear algorithm is suitable for an accurate prediction of photoninduced neutron or proton productions.
基金We acknowledge fruitful discussions with H.P´epin(INRS),V.M´eot,L.Gremillet,X.Davoine(CEA),S.Orlando(INAF),C.Guerrero(Universidad de Sevilla),and Y.Caristan(Universit´e Paris-Saclay).This project received funding from the European Research Council(ERC)under the European Union’s Horizon 2020 Research and Innovation Programme(Grant Agreement No.787539),and was partly conducted within the LABEX Plas@Par project and supported by Grant Nos.11-IDEX-0004-02 and an ANR-17-CE30-0026 PiNNaCLE grant from Agence Nationale de la Recherche(France).I.P.acknowledges the support of ISF Grant No.1135/15.The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase I,a project cofinanced by the Romanian Government and the European Union through the European Regional Development Fund.
文摘With the much-anticipated multi-petawatt(PW)laser facilities that are coming online,neutron sources with extreme fluxes could soon be in reach.Such sources would rely on spallation by protons accelerated by the high-intensity lasers.These high neutron fluxes would make possible not only direct measurements of neutron capture andβ-decay rates related to the r-process of nucleosynthesis of heavy elements,but also such nuclear measurements in a hot plasma environment,which would be beneficial for s-process investigations in astrophysically relevant conditions.This could,in turn,finally allow possible reconciliation of the observed element abundances in stars and those derived from simulations,which at present show large discrepancies.Here,we review a possible pathway to reach unprecedented neutron fluxes using multi-PW lasers,as well as strategies to perform measurements to investigate the r-and s-processes of nucleosynthesis of heavy elements in cold matter,as well as in a hot plasma environment.
文摘The interaction of micro-bubbles with ultra-intense laser pulses has been shown to generate ultra-high proton densities and correspondingly high electric fields.Weinvestigate the possibility of using such a combination to study the fundamental physical phenomenon of vacuum polarization.With current or near-future laser systems,measurement of vacuum polarization via the bending of gamma rays that pass near imploded microbubbles may be possible.Since it is independent of photon energy to within the leading-order solution of the Heisenberg–Euler Lagrangian and the geometric optics approximation,the corresponding index of refraction can dominate the indices of refraction due to other effects at sufficiently high photon energies.We consider the possibility of its application to a transient gamma-ray lens.
文摘Laser Wakefield plasma acceleration of electrons to energies above 10 GeV, may be possible in the new high power Laser beam facilities. The design of an Electron Spectrometer with an electro-magnet with adjustable magnetic field is proposed for the characterization of electron energy spectrum with a precision better than 10% for the entire energy range from 0.5 GeV to 38 GeV. The expected precision in the measurement of the electron energy is calculated as a function of the magnetic field, of the electron energy and of the magnet length. To outline the advantages offered by a pulsed electromagnet with high magnetic fields, the mass and the electric power lost in the coils of a 4 m long electromagnet with continuous current and Iron yoke are calculated.
基金supported by Grant Nos.11-IDEX-0004-02 and ANR-17-CE30-0026-Pinnacle from Agence Nationale de la Recherchethe European Union’s Horizon 2020 research and innovation program under Grant Agreement No.654148 Laserlab-Europe+3 种基金the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Grant Agreement No.787539)This work was supported by the Ministry of Education and Science of the Russian Federation under Contract No.14.Z50.31.0007The work of JIHT RAS team was done under financial support of the Russian Science Foundation(Grant No.17-72-20272)The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase I,a project co-financed by the Romanian Government and European Union through the European Regional Development Fund.
文摘Laser irradiation of solid targets can drive short and high-charge relativistic electron bunches over micron-scale acceleration gradients.However,for a long time,this technique was not considered a viable means of electron acceleration due to the large intrinsic divergence(∼50°half-angle)of the electrons.Recently,a reduction in this divergence to 10°–20°half-angle has been obtained,using plasma-based magnetic fields or very high contrast laser pulses to extract the electrons into the vacuum.Here we show that we can further improve the electron beam collimation,down to∼1.5°half-angle,of a high-charge(6 nC)beam,and in a highly reproducible manner,while using standard stand-alone 100 TW-class laser pulses.This is obtained by embedding the laser-target interaction in an external,large-scale(cm),homogeneous,extremely stable,and high-strength(20 T)magnetic field that is independent of the laser.With upcoming multi-PW,high repetition-rate lasers,this technique opens the door to achieving even higher charges(>100 nC).
基金X-ray data measurement,modeling and analysis were made by the JIHT RAS team with financial support from the Russian Science Foundation(Project No.17-72-20272)The authors thank the entire staff of the ELFIE laser facility at LULI for their support during the experimental preparation and execution.This work was supported by ANR Blanc Grant No.12-BS09-025-01 SILAMPA and has received funding from the European Union’s Horizon 2020 research and innovation program through the European Research Council(ERC,Grant Agreement No.787539)Some work was done within the LABEX Plas@Par project,which is supported by Grant No.11-IDEX-0004-02 from Agence Nationale de la Recherche.The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase I,a project co-financed by the Romanian Government and European Union through the European Regional Development Fund.This work was performed under the auspices of the U.S.Department of Energy by Lawrence Livermore National Laboratory under Contract No.DE-AC52-07NA27344.
文摘Recent achievements in laboratory astrophysics experiments with high-power lasers have allowed progress in our understanding of the early stages of star formation.In particular,we have recently demonstrated the possibility of simulating in the laboratory the process of the accretion of matter on young stars[G.Revet et al.,Sci.Adv.3,e1700982(2017)].The present paper focuses on x-ray spectroscopy methods that allow us to investigate the complex plasma hydrodynamics involved in such experiments.We demonstrate that we can infer the formation of a plasma shell,surrounding the accretion column at the location of impact with the stellar surface,and thus resolve the present discrepancies between mass accretion rates derived from x-ray and optical-radiation astronomical observations originating from the same object.In our experiments,the accretion column ismodeled by having a collimated narrow(1 mm diameter)plasma stream first propagate along the lines of a large-scale external magnetic field and then impact onto an obstacle,mimicking the high-density region of the stellar chromosphere.A combined approach using steady-state and quasi-stationarymodels was successfully applied tomeasure the parameters of the plasma all along its propagation,at the impact site,and in the structure surrounding the impact region.The formation of a hot plasma shell,surrounding the denser and colder core,formed by the incoming stream of matter is observed near the obstacle using x-ray spatially resolved spectroscopy.
基金The XFEL experiments were performed at the BL3 of SACLA with the approval of the Japan Synchrotron Radiation Research Institute(JASRI)(Proposals Nos.2014A8045,and 2014B8068)This research was partially supported by grants from Grants-in-Aid for Scientific Research(Kakenhi Grant Nos.15H02153 and 17K05729)+1 种基金the Core-to-Core Program on International Alliance for Material Science in Extreme States with High Power Laser of the Japan Society for the Promotion of Science(JSPS),from the X-ray Free Electron Laser Priority Strategy Program of the MEXT,contract 12005014,and within the state assignment of FASO of Russia(theme N01201357846)The part of work was supported by the Agence Nationale de la Recherche in the frame of the ANR project TurboHEDP(ANR-15-CE30-0011).
文摘We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and homogeneity of targets to be driven by optical laser pulse.By developing X-ray imaging,based on the use of an LiF crystal detector,we were able to measure the distribution of energy inside a hard X-ray beam with unprecedented high spatial resolution(~1 mm)and across a field of view larger than some millimetres.This diagnostic can be used in situ,provides a very high dynamic range,has an extremely limited cost,and is relatively easy to be implemented in pump-probe experiments.The proposed methods were successfully applied in pump-probe experiments at the SPring-8 Angstrom Compact free electron LAser(SACLA)XFEL facility and its potential was demonstrated for current and future High Energy Density Science experiments.
基金supported by funding from the European Research Council(ERC)under the European Unions Horizon 2020 research and innovation program(Grant Agreement No.787539)The computational resources of this work were supported by the National Sciences and Engineering Research Council of Canada(NSERC)and Compute Canada(Job Grant No.pve-323-ac)+4 种基金Part of the experimental system is covered by a patent(No.1000183285,2013,INPI-France)The FLASH software used was developed,in part,by the DOE NNSA ASC-and the DOE Office of Science ASCR-supported Flash Center for Computational Science at the University of ChicagoWe thank J.L.Dubois for providing us EOS and opacities.The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase II,a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund,and by the Project No.ELIRO-2020-23 funded by IFA(Romania)IHT RAS team members are supported by the Ministry of Science and Higher Education of the Russian Federation(State Assignment No.075-00460-21-00)The study reported here was funded by the Russian Foundation for Basic Research,Project No.19-32-60008.
文摘Collisionless shocks are ubiquitous in the Universe and are held responsible for the production of nonthermal particles and high-energy radiation.In the absence of particle collisions in the system,theory shows that the interaction of an expanding plasma with a pre-existing electromagnetic structure(as in our case)is able to induce energy dissipation and allow shock formation.Shock formation can alternatively take place when two plasmas interact,through microscopic instabilities inducing electromagnetic fields that are able in turn to mediate energy dissipation and shock formation.Using our platform in which we couple a rapidly expanding plasma induced by high-power lasers(JLF/Titan at LLNL and LULI2000)with high-strength magnetic fields,we have investigated the generation of a magnetized collisionless shock and the associated particle energization.We have characterized the shock as being collisionless and supercritical.We report here on measurements of the plasma density and temperature,the electromagnetic field structures,and the particle energization in the experiments,under various conditions of ambient plasma and magnetic field.We have also modeled the formation of the shocks using macroscopic hydrodynamic simulations and the associated particle acceleration using kinetic particle-in-cell simulations.As a companion paper to Yao et al.[Nat.Phys.17,1177–1182(2021)],here we show additional results of the experiments and simulations,providing more information to allow their reproduction and to demonstrate the robustness of our interpretation of the proton energization mechanism as being shock surfing acceleration.
基金funded through IOSIN,Nucleu PN-IFIN-HH 23-26 Code PN 2321Extreme Light Infrastructure-Nuclear Physics(ELI-NP)Phase II+2 种基金a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund and the Competitiveness Operational Programme(1/07.07.2016,COP,ID 1334)through IFA project ELI-RO 03/2020 Pulse-Mereadreceived funding from the European Union’s HORIZON-INFRA-2022-TECH-01 call under grant agreement number 101095207
文摘The spatial distribution of beams with orbital angular momentum in the far field is known to be extremely sensitive to angular aberrations,such as astigmatism,coma and trefoil.This poses a challenge for conventional beam optimization strategies when a homogeneous ring intensity is required for an application.We developed a novel approach for estimating the Zernike coefficients of low-order angular aberrations in the near field based solely on the analysis of the ring deformations in the far field.A fast,iterative reconstruction of the focal ring recreates the deformations and provides insight into the wavefront deformations in the near field without relying on conventional phase retrieval approaches.The output of our algorithm can be used to optimize the focal ring,as demonstrated experimentally at the 100 TW beamline at the Extreme Light Infrastructure-Nuclear Physics facility.
基金supported by the National Program on Key Basic Research Project of China(2013CB834400)the National Natural Science Foundation of China(11205004,11305161,11335002,11475014,11575002,and 11411130147)+2 种基金the Natural Science Foundation of Anhui Province(1708085QA10)the RIKEN iTHES ProjectiTHEMS Program
文摘Mass is a fundamental property and an important fingerprint of atomic nucleus.It provides an extremely useful test ground for nuclear models and is crucial to understand energy generation in stars as well as the heavy elements synthesized in stellar explosions.Nuclear physicists have been attempting at developing a precise,reliable,and predictive nuclear model that is suitable for the whole nuclear chart,while this still remains a great challenge even in recent days.Here we employ the Fourier spectral analysis to examine the deviations of nuclear mass predictions to the experimental data and to present a novel way for accurate nuclear mass predictions.In this analysis,we map the mass deviations from the space of nucleon number to its conjugate space of frequency,and are able to pin down the main contributions to the model deficiencies.By using the radial basis function approach we can further isolate and quantify the sources.Taking a pedagogical mass model as an example,we examine explicitly the correlation between nuclear effective interactions and the distributions of mass deviations in the frequency domain.The method presented in this work,therefore,opens up a new way for improving the nuclear mass predictions towards a hundred kilo-electron-volt accuracy,which is argued to be the chaos-related limit for the nuclear mass predictions.
基金the financial contribution from the CNR funded Italian Research Network ELI-Italy (D.M. No. 631 08.08.2016)from the EU Horizon 2020 Research and Innovation Program under Grant Agreement No. 653782 Eu PRAXIA。
文摘After the introduction of the ionization-injection scheme in laser wake field acceleration and of related high-quality electron beam generation methods,such as two-color and resonant multi-pulse ionization injection(Re MPI),the theory of thermal emittance has been used to predict the beam normalized emittance obtainable with those schemes.We recast and extend such a theory,including both higher order terms in the polynomial laser field expansion and non-polynomial corrections due to the onset of saturation effects on a single cycle.Also,a very accurate model for predicting the cycle-averaged distribution of the extracted electrons,including saturation and multi-process events,is proposed and tested.We show that our theory is very accurate for the selected processes of Kr^(8+→10+) and Ar^(8+→10+),resulting in a maximum error below 1%,even in a deep-saturation regime.The accurate prediction of the beam phase-space can be implemented,for example,in laser-envelope or hybrid particle-in-cell(PIC)/fiuid codes,to correctly mimic the cycle-averaged momentum distribution without the need for resolving the intra-cycle dynamics.We introduce further spatial averaging,obtaining expressions for the whole-beam emittance fitting with simulations in a saturated regime,too.Finally,a PIC simulation for a laser wakefield acceleration injector in the Re MPI configuration is discussed.
文摘In this paper,a radially polarised cosh-Gaussian laser beam(CGLB)is used to study the electron acceleration produced in vacuum.A highly energetic electron beam can be achieved by a CGLB,even with comparatively low-powered lasers.The properties of a CGLB cause it to focus earlier,over a shorter duration than a Gaussian laser beam,which makes it suitable for obtaining high energies over small durations.It is found that the energy gained by the electrons strongly depends upon the decentering parameter of the laser profile.It is also observed that for a fixed value of energy gain,if the decentering parameter is increased,then the intensity of the laser field decreases.The dependence of the energy gained by electrons on the laser intensity and the laserspot size is also studied.
基金Supported by National Natural Science Foundation of China(11105042,11305161,11505157)Open Fund of Key Laboratory of Time and Frequency Primary Standards,CASSupport from Henan Administration of Foreign Experts Affairs
文摘The rich phenomena of deformations in neutron-deficient krypton isotopes, such as shape evolution with neutron number and shape coexistence, have attracted the interest of nuclear physicists for decades. It is interesting to study such shape phenomena using a novel way, e.g. by thermally exciting the nucleus. In this work, we develop the finite temperature covariant density functional theory for axially deformed nuclei with the treatment of pairing correlations by the BCS approach, and apply this approach for the study of shape evolution in 72,74Kr with increasing temperature. For 72Kr, with temperature increasing, the nucleus firstly experiences a relatively quick weakening in oblate deformation at temperature T-0.9 MeV, and then changes from oblate to spherical at T-2.1 MeV. For 74Kr, its global minimum is at quadrupole deformation β2--0.14 and abruptly changes to spherical at T-1.7 MeV. The proton pairing transition occurs at critical temperature 0.6 MeV following the rule Tc =0.6△p (0), where △p(0) is the proton pairing gap at zero temperature. The signatures of the above pairing transition and shape changes can be found in the specific heat curve. The single-particle level evolutions with temperature are presented.
基金support from the National Key Research and Development Program of China(No.2016YFA0300803)support from the Project of Shanghai HIgh repetition rate XFEL aNd Extreme light facility(SHINE)+13 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB16)support from the EPSRC,UK(Nos.EP/L013975 and EP/N022696/1)support from Extreme Light Infrastructure Nuclear Physics(ELI-NP) Phase IIa project co-financed by the Romanian Government and the European Union through the European Regional Development Fundsupport from EPSRC(No.EP/M018091/1)support from EPSRC(No.EP/M018555/1)STFC(Nos.ST/J002062/1 and ST/P002021/1)Horizon2020 funding from the European Research Council(ERC)(No.682399)support from the National Natural Science Foundation of China(Nos.11622547,11875319,11875091,11474360,and 11175255)the National Key Research and Development Program of China(No.2018YFA0404802)the Science Challenge Program(No.TZ2016005)the Hunan Province Science and Technology Program of China(No.2017RS3042)supported by the National Natural Science Foundation of China(Nos.11347028,11405083,and 11675075)UK Engineering and Physics Sciences Research Council(Nos.EP/G054940/1,EP/G055165/1,and EP/G056803/1)
文摘A new generation of high power laser facilities will provide laser pulses with extremely high powers of 10 petawatt(PW)and even 100 PW, capable of reaching intensities of 1023 W/cm^2 in the laser focus. These ultra-high intensities are nevertheless lower than the Schwinger intensity IS= 2.3×1029 W/cm^2 at which the theory of quantum electrodynamics(QED) predicts that a large part of the energy of the laser photons will be transformed to hard Gamma-ray photons and even to matter, via electron–positron pair production. To enable the investigation of this physics at the intensities achievable with the next generation of high power laser facilities, an approach involving the interaction of two colliding PW laser pulses is being adopted. Theoretical simulations predict strong QED effects with colliding laser pulses of 10 PW focused to intensities 10^(22) W/cm^2.