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Th Stohlker - One of the best experts on this subject based on the ideXlab platform.

  • the magnetic toroidal sector as a broad band electron positron Pair spectrometer i lepton trajectories
    Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2019
    Co-Authors: S Hagmann, P M Hillenbrand, Yu A Litvinov, U Spillmann, Th Stohlker
    Abstract:

    Abstract We report an analysis of electron-optical properties of a toroidal magnetic sector spectrometer and examine parameters for its implementation in a relativistic heavy-ion storage ring like HESR. For studies of free-free Pair production in heavy- ion atom collisions this spectrometer exhibits very high efficiencies for coincident e + -e − Pair spectroscopy over a wide range of momenta of emitted lepton Pairs. The high coincidence efficiency of the spectrometer is the key for stringent tests of theoretical predictions for the coincident positron- and electron emission characteristics and for the phase space correlation of lepton vector momenta in free-free Pair production.

  • electron positron Pair production in slow collisions of heavy nuclei beyond the monopole approximation
    Physical Review A, 2018
    Co-Authors: I A Maltsev, V M Shabaev, Y S Kozhedub, G Plunien, Th Stohlker, R V Popov, X Y
    Abstract:

    Electron-Positron Pair production in low-energy collisions of heavy nuclei is considered beyond the monopole approximation. The calculation method is based on the numerical solving of the time-dependent Dirac equation with the full two-center potential. Bound-free and free-free Pair-production probabilities as well as the energy spectra of the emitted positrons are calculated for the collisions of bare uranium nuclei. The calculations are performed for collision energy near the Coulomb barrier for different values of the impact parameter. The obtained results are compared with the corresponding values calculated in the monopole approximation.

  • Pair production in low energy collisions of uranium nuclei beyond the monopole approximation
    Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2017
    Co-Authors: I A Maltsev, V M Shabaev, I I Tupitsyn, Y S Kozhedub, G Plunien, Th Stohlker
    Abstract:

    Abstract A method for calculation of Electron-Positron Pair production in low-energy heavy-ion collisions beyond the monopole approximation is presented. The method is based on the numerical solving of the time-dependent Dirac equation with the full two-center potential. The one-electron wave functions are expanded in the finite basis set constructed on the two-dimensional spatial grid. Employing the developed approach the probabilities of bound-free Pair production are calculated for collisions of bare uranium nuclei at the energy near the Coulomb barrier. The obtained results are compared with the corresponding values calculated in the monopole approximation.

  • electron positron Pair creation in low energy collisions of heavy bare nuclei
    Physical Review A, 2015
    Co-Authors: I A Maltsev, V M Shabaev, I I Tupitsyn, Y S Kozhedub, G Plunien, A I Bondarev, Th Stohlker
    Abstract:

    A new method for calculations of Electron-Positron Pair-creation probabilities in low-energy heavy-ion collisions is developed. The approach is based on the propagation of all one-electron states via the numerical solving of the time-dependent Dirac equation in the monopole approximation. The electron wave functions are represented as finite sums of basis functions constructed from B-splines using the dual-kinetic-balance technique. The calculations of the created particle numbers and the positron energy spectra are performed for the collisions of bare nuclei at the energies near the Coulomb barrier with the Rutherford trajectory and for different values of the nuclear charge and the impact parameter. To examine the role of the spontaneous Pair creation the collisions with a modified velocity and with a time delay are also considered. The obtained results are compared with the previous calculations and the possibility of observation of the spontaneous Pair creation is discussed.

E. N. Nerush - One of the best experts on this subject based on the ideXlab platform.

  • production and dynamics of positrons in ultrahigh intensity laser foil interactions
    Physics of Plasmas, 2016
    Co-Authors: Yu I Kostyukov, E. N. Nerush
    Abstract:

    The Electron-Positron Pair production accompanying interaction of a circularly polarized laser pulse with a foil is studied for laser intensities higher than 1024 W cm−2. The laser energy penetrates into the foil due to the effect of the relativistic hole-boring. It is demonstrated that the Electron-Positron plasma is produced as a result of quantum-electrodynamical cascading in the field of the incident and reflected laser light in front of the foil. The incident and reflected laser light make up the circularly polarized standing wave in the reference frame of the hole-boring front and the Pair density peaks near the nodes and anti-nodes of the wave. A model based on the particle dynamics with radiation reaction effect near the magnetic nodes is developed. The model predictions are verified by three dimensional particle-in-cell Monte Carlo simulations.

  • production and dynamics of positrons in ultrahigh intensity laser foil interactions
    arXiv: Plasma Physics, 2016
    Co-Authors: Yu I Kostyukov, E. N. Nerush
    Abstract:

    The Electron-Positron Pair production accompanying interaction of a circularly polarized laser pulse with a foil is studied for laser intensities higher than $10^{24}$W cm$^{-2}$. The laser energy penetrates into the foil due to the effect of the relativistic hole-boring. It is demonstrated that the Electron-Positron plasma is produced as a result of quantum-electrodynamical cascading in the field of the incident and reflected laser light in front of the foil. The incident and reflected laser light makes up the circularly polarized standing wave in the reference frame of the hole-boring front and the Pair density peaks near the nodes and antinodes of the wave. A model based on the particle dynamics with radiation reaction effect near the magnetic nodes is developed. The model predictions are verified by 3D PIC-MC simulations.

  • Laser field absorption in self-generated Electron-Positron Pair plasma.
    Physical Review Letters, 2011
    Co-Authors: E. N. Nerush, I. Yu. Kostyukov, Alexander Fedotov, N. B. Narozhny, N. V. Elkina, Hartmut Ruhl
    Abstract:

    Recently, much attention has been attracted to the problem of limitations on the attainable intensity of high power lasers [A. M. Fedotov et al., Phys. Rev. Lett. 105, 080402 (2010)]. The laser energy can be absorbed by Electron-Positron Pair plasma produced from a seed by a strong laser field via the development of the electromagnetic cascades. The numerical model for a self-consistent study of Electron-Positron Pair plasma dynamics is developed. Strong absorption of the laser energy in self-generated overdense Electron-Positron Pair plasma is demonstrated. It is shown that the absorption becomes important for a not extremely high laser intensity I{approx}10{sup 24} W/cm{sup 2} achievable in the near future.

  • laser field absorption in self generated electron positron Pair plasma
    Physical Review Letters, 2011
    Co-Authors: E. N. Nerush, N. B. Narozhny, N. V. Elkina, A M Fedotov, Yu I Kostyukov, Hartmut Ruhl
    Abstract:

    Recently, much attention has been attracted to the problem of limitations on the attainable intensity of high power lasers [A. M. Fedotov et al., Phys. Rev. Lett. 105, 080402 (2010)]. The laser energy can be absorbed by Electron-Positron Pair plasma produced from a seed by a strong laser field via the development of the electromagnetic cascades. The numerical model for a self-consistent study of Electron-Positron Pair plasma dynamics is developed. Strong absorption of the laser energy in self-generated overdense Electron-Positron Pair plasma is demonstrated. It is shown that the absorption becomes important for a not extremely high laser intensity $I\ensuremath{\sim}{10}^{24}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$ achievable in the near future.

Christoph H. Keitel - One of the best experts on this subject based on the ideXlab platform.

  • photon polarization effects in polarized electron positron Pair production in a strong laser field
    Matter and Radiation at Extremes, 2022
    Co-Authors: Yanan Dai, Karen Zaven Hatsagortsyan, Christoph H. Keitel, Baifei Shen, Rashid Shaisultanov, Yueyue Chen
    Abstract:

    Deep understanding of the impact of photon polarization on Pair production is essential for the efficient generation of laser-driven polarized positron beams and demands a complete description of polarization effects in strong-field QED processes. Employing fully polarization-resolved Monte Carlo simulations, we investigate correlated photon and electron (positron) polarization effects in the multiphoton Breit–Wheeler Pair production process during the interaction of an ultrarelativistic electron beam with a counterpropagating elliptically polarized laser pulse. We show that the polarization of e−e+ Pairs is degraded by 35% when the polarization of the intermediate photon is resolved, accompanied by an ∼13% decrease in the Pair yield. Moreover, in this case, the polarization direction of energetic positrons at small deflection angles can even be reversed when high-energy photons with polarization parallel to the laser electric field are involved.

  • High-energy recollision processes of laser-generated Electron-Positron Pairs.
    Physical Review Letters, 2015
    Co-Authors: Sebastian Meuren, Karen Zaven Hatsagortsyan, Christoph H. Keitel, Antonino Di Piazza
    Abstract:

    Two oppositely charged particles created within a microscopic space-time region can be separated, accelerated over a much larger distance, and brought to a recollision by a laser field. Consequently, new reactions become feasible, where the energy absorbed by the particles is efficiently released. By investigating the laser-dressed polarization operator, we identify a new contribution describing high-energy recollisions experienced by an Electron-Positron Pair generated by pure light when a gamma photon impinges on an intense, linearly polarized laser pulse. The energy absorbed in the recollision process over the macroscopic laser wavelength corresponds to a large number of laser photons and can be exploited to prime high-energy reactions. Thus, the recollision contribution to the polarization operator differs qualitatively and quantitatively from the well-known one, describing the annihilation of an Electron-Positron Pair within the microscopic formation region.

  • streaking at high energies with electrons and positrons
    Physics Letters B, 2011
    Co-Authors: Andreas Ipp, Jorg Evers, Christoph H. Keitel, Karen Zaven Hatsagortsyan
    Abstract:

    Abstract A detection scheme for characterizing high-energy γ -ray pulses down to the zeptosecond timescale is proposed. In contrast to existing attosecond metrology techniques, our method is not limited by atomic shell physics and therefore capable of breaking the MeV photon energy and attosecond time-scale barriers. It is inspired by attosecond streak imaging, but builds upon the high-energy process of electron–positron Pair production in vacuum through the collision of a test pulse with an intense laser pulse. We discuss necessary conditions to render the scheme feasible in the upcoming Extreme Light Infrastructure laser facility.

  • ultra strong laser pulses streak camera for gamma rays via Pair production and quantum radiative reaction
    Proceedings of SPIE, 2011
    Co-Authors: Karen Zaven Hatsagortsyan, Jorg Evers, A Di Piazza, Christoph H. Keitel
    Abstract:

    We show that a strong laser pulse combined with a strong x-ray pulse can be employed in a detection scheme for characterizing high-energy γ-ray pulses down to the zeptosecond timescale. The scheme employs streak imaging technique built upon the high-energy process of Electron-Positron Pair production in vacuum through the collision of a test pulse with intense laser pulses. The role of quantum radiation reaction in multiphoton Compton scattering process and limitations imposed by it on the detection scheme are examined.

  • complete qed theory of multiphoton trident Pair production in strong laser fields
    Physical Review Letters, 2010
    Co-Authors: Huayu Hu, Carsten Muller, Christoph H. Keitel
    Abstract:

    Electron-Positron Pair creation by multiphoton absorption in the collision of a relativistic electron with a strong laser beam is calculated within laser-dressed quantum electrodynamics. Total production rates, positron spectra, and relative contributions of different reaction channels are obtained in various interaction regimes. We study the process in a manifestly nonperturbative domain which is shown accessible to future experiments utilizing the electron beam lines at novel x-ray laser facilities or all-optical setups based on laser acceleration. Our theory moreover allows us to add further insights into the experimental data from SLAC [D. Burke et al., Phys. Rev. Lett. 79, 1626 (1997).].

V M Shabaev - One of the best experts on this subject based on the ideXlab platform.

  • locally constant field approximation in studies of electron positron Pair production in strong external fields
    Physical Review D, 2019
    Co-Authors: I A Aleksandrov, G Plunien, V M Shabaev
    Abstract:

    In the present investigation we revisit the widely-used locally-constant field approximation (LCFA) in the context of the Pair-production phenomenon in strong electromagnetic backgrounds. By means of nonperturbative numerical calculations, we assess the validity of the LCFA considering several spatially homogeneous field configurations and a number of space-time-dependent scenarios. By studying the momentum spectra of particles produced, we identify the criteria for the applicability of the LCFA. It is demonstrated that the Keldysh parameter itself does not allow one to judge if the LCFA should perform accurately. In fact, the external field parameters must obey less trivial relations whose form depends on the field configuration. We reveal several generic properties of these relations which can also be applied to a broader class of other Pair-production scenarios.

  • electron positron Pair production in slow collisions of heavy nuclei beyond the monopole approximation
    Physical Review A, 2018
    Co-Authors: I A Maltsev, V M Shabaev, Y S Kozhedub, G Plunien, Th Stohlker, R V Popov, X Y
    Abstract:

    Electron-Positron Pair production in low-energy collisions of heavy nuclei is considered beyond the monopole approximation. The calculation method is based on the numerical solving of the time-dependent Dirac equation with the full two-center potential. Bound-free and free-free Pair-production probabilities as well as the energy spectra of the emitted positrons are calculated for the collisions of bare uranium nuclei. The calculations are performed for collision energy near the Coulomb barrier for different values of the impact parameter. The obtained results are compared with the corresponding values calculated in the monopole approximation.

  • one center calculations of the electron positron Pair creation in low energy collisions of heavy bare nuclei
    European Physical Journal D, 2018
    Co-Authors: I A Maltsev, V M Shabaev, I I Tupitsyn, Y S Kozhedub, R V Popov, A I Bondarev, G Plunien
    Abstract:

    The probabilities of bound-free Electron-Positron Pair creation are calculated for head-on collisions of bare uranium nuclei beyond the monopole approximation. The calculations are based on the numerical solving of the time-dependent Dirac equation in the target reference frame with multipole expansion of the projectile potential. In addition, the energy dependence of the Pair-creation cross section is studied in the monopole approximation.

  • dynamically assisted schwinger effect beyond the spatially uniform field approximation
    Physical Review D, 2018
    Co-Authors: I A Aleksandrov, G Plunien, V M Shabaev
    Abstract:

    We investigate the phenomenon of Electron-Positron Pair production from vacuum in the presence of a strong electric field superimposed by a weak but fast varying pulse which substantially increases the total particle yield. We employ a nonperturbative numerical technique and perform the calculations beyond the spatially-uniform-field approximation, i.e., dipole approximation, taking into account the coordinate dependence of the fast component. The analysis of the main characteristics of the Pair-production process (momentum spectra of particles and total amount of Pairs) reveals a number of important features which are absent within the previously used approximation. In particular, the structure of the momentum distribution is modified both qualitatively and quantitatively, and the total number of Pairs created as well as the enhancement factor due to dynamical assistance become significantly smaller.

  • Pair production in low energy collisions of uranium nuclei beyond the monopole approximation
    Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2017
    Co-Authors: I A Maltsev, V M Shabaev, I I Tupitsyn, Y S Kozhedub, G Plunien, Th Stohlker
    Abstract:

    Abstract A method for calculation of Electron-Positron Pair production in low-energy heavy-ion collisions beyond the monopole approximation is presented. The method is based on the numerical solving of the time-dependent Dirac equation with the full two-center potential. The one-electron wave functions are expanded in the finite basis set constructed on the two-dimensional spatial grid. Employing the developed approach the probabilities of bound-free Pair production are calculated for collisions of bare uranium nuclei at the energy near the Coulomb barrier. The obtained results are compared with the corresponding values calculated in the monopole approximation.

G Plunien - One of the best experts on this subject based on the ideXlab platform.

  • locally constant field approximation in studies of electron positron Pair production in strong external fields
    Physical Review D, 2019
    Co-Authors: I A Aleksandrov, G Plunien, V M Shabaev
    Abstract:

    In the present investigation we revisit the widely-used locally-constant field approximation (LCFA) in the context of the Pair-production phenomenon in strong electromagnetic backgrounds. By means of nonperturbative numerical calculations, we assess the validity of the LCFA considering several spatially homogeneous field configurations and a number of space-time-dependent scenarios. By studying the momentum spectra of particles produced, we identify the criteria for the applicability of the LCFA. It is demonstrated that the Keldysh parameter itself does not allow one to judge if the LCFA should perform accurately. In fact, the external field parameters must obey less trivial relations whose form depends on the field configuration. We reveal several generic properties of these relations which can also be applied to a broader class of other Pair-production scenarios.

  • electron positron Pair production in slow collisions of heavy nuclei beyond the monopole approximation
    Physical Review A, 2018
    Co-Authors: I A Maltsev, V M Shabaev, Y S Kozhedub, G Plunien, Th Stohlker, R V Popov, X Y
    Abstract:

    Electron-Positron Pair production in low-energy collisions of heavy nuclei is considered beyond the monopole approximation. The calculation method is based on the numerical solving of the time-dependent Dirac equation with the full two-center potential. Bound-free and free-free Pair-production probabilities as well as the energy spectra of the emitted positrons are calculated for the collisions of bare uranium nuclei. The calculations are performed for collision energy near the Coulomb barrier for different values of the impact parameter. The obtained results are compared with the corresponding values calculated in the monopole approximation.

  • one center calculations of the electron positron Pair creation in low energy collisions of heavy bare nuclei
    European Physical Journal D, 2018
    Co-Authors: I A Maltsev, V M Shabaev, I I Tupitsyn, Y S Kozhedub, R V Popov, A I Bondarev, G Plunien
    Abstract:

    The probabilities of bound-free Electron-Positron Pair creation are calculated for head-on collisions of bare uranium nuclei beyond the monopole approximation. The calculations are based on the numerical solving of the time-dependent Dirac equation in the target reference frame with multipole expansion of the projectile potential. In addition, the energy dependence of the Pair-creation cross section is studied in the monopole approximation.

  • dynamically assisted schwinger effect beyond the spatially uniform field approximation
    Physical Review D, 2018
    Co-Authors: I A Aleksandrov, G Plunien, V M Shabaev
    Abstract:

    We investigate the phenomenon of Electron-Positron Pair production from vacuum in the presence of a strong electric field superimposed by a weak but fast varying pulse which substantially increases the total particle yield. We employ a nonperturbative numerical technique and perform the calculations beyond the spatially-uniform-field approximation, i.e., dipole approximation, taking into account the coordinate dependence of the fast component. The analysis of the main characteristics of the Pair-production process (momentum spectra of particles and total amount of Pairs) reveals a number of important features which are absent within the previously used approximation. In particular, the structure of the momentum distribution is modified both qualitatively and quantitatively, and the total number of Pairs created as well as the enhancement factor due to dynamical assistance become significantly smaller.

  • Pair production in low energy collisions of uranium nuclei beyond the monopole approximation
    Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2017
    Co-Authors: I A Maltsev, V M Shabaev, I I Tupitsyn, Y S Kozhedub, G Plunien, Th Stohlker
    Abstract:

    Abstract A method for calculation of Electron-Positron Pair production in low-energy heavy-ion collisions beyond the monopole approximation is presented. The method is based on the numerical solving of the time-dependent Dirac equation with the full two-center potential. The one-electron wave functions are expanded in the finite basis set constructed on the two-dimensional spatial grid. Employing the developed approach the probabilities of bound-free Pair production are calculated for collisions of bare uranium nuclei at the energy near the Coulomb barrier. The obtained results are compared with the corresponding values calculated in the monopole approximation.