Positronium in Intense Laser Fields

Henrich, B.; Hatsagortsyan, Karen Z.; Keitel, Christoph H.

doi:10.1103/physrevlett.93.013601

Cited by 37 publications

(44 citation statements)

References 37 publications

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“…Temperatures of about T ∼ 10 MeV, in a laser-generated plasma, would open, furthermore, channels for muon or pion production [11]. While these channels are interesting for their own right (see [12] for another avenue for laser driven particle production), a hot e + e − γ plasma droplet, exploding after the creation process by the enormous thermodynamic pressure, is a source of γ radiation. Such short γ flashes may be of future use in ultra-fast spectroscopic investigations of various kind.…”

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confidence: 99%

Gamma flashes from relativistic electron-positron plasma droplets

Mustafa

Kämpfer

2009

Phys. Rev. A

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Ultra-intense lasers are expected to produce, in near future, relativistic electron-positron plasma droplets. Considering the local photon production rate in complete leading order in quantum electrodynamics (QED), we point out that these droplets are interesting sources of gamma ray flashes. . Electron-positron plasmas are also interesting for astrophysical scenario [10]. Temperatures of about T ∼ 10 MeV, in a laser-generated plasma, would open, furthermore, channels for muon or pion production [11]. While these channels are interesting for their own right (see [12] for another avenue for laser driven particle production), a hot e + e − γ plasma droplet, exploding after the creation process by the enormous thermodynamic pressure, is a source of γ radiation. Such short γ flashes may be of future use in ultra-fast spectroscopic investigations of various kind.In this note, we are going to present estimates of the photon spectrum emerging from a e + e − γ plasma droplet with temperatures in the 10 MeV range. In contrast to often employed particle-in-cell (PIC) simulations (see [3] for a study of the start-up phase of a similarly hot plasma), we base our considerations on results from QED thermo-field theory. The expansion dynamics is treated in a schematic way, as our emphasis is on the photon emission characteristics.The calculation of the local spontaneous photon emission rate from a QED (electron-positron) plasma has been outlined in [13] to complete leading order in elec- * Electronic address: musnhigolam.mustafa@saha.ac.in † Electronic address: b.kaempfer@fzd.de tromagnetic coupling α by including two-loop order. The result, at the heart of our note, may be presented aswhere n F (E γ ) = (exp(E γ /T ) + 1) −1 denotes the Fermi distribution, and the dynamically generated asymptotic mass squared of the electron is m 2 ∞ = 2m 2 th . The thermal mass squared is given by m 2 th = e 2 T 2 /8 with e 2 = 4πα (The considerations apply for T > m e ± which are different from the non-relativistic case where the relevant scales are given by the masses of plasma particles and the temperature [5].) E γ = u · k is a short hand notation for the Lorentz scalar product of the medium's four-velocity u(t, x) and the photon's four-momentum k. This rate includes 2 ↔ 2 processes from one loop [14], viz., Compton scattering and pair annihilation which generate the leading logarithmic contribution (first three terms in (1)). In addition, the rate also includes the inelastic processes [15] from two-loop like bremsstrahlung (fourth term) and offshell pair annihilation (fifth term) with the correct incorporation [13,16] of the Landau-Pomeranchuk-Migdal effect that limits the coherence length of the emitted radiation. A common feature of the latter two processes is that they have off-shell fermion next to the vertex where the photon is emitted, and the virtuality of the fermion becomes very small if the photon is emitted in forward direction. However, contrary to the one-loop diagrams, the singularity is linear instead of logarithmic, and ...

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confidence: 99%

Gamma flashes from relativistic electron-positron plasma droplets

Mustafa

Kämpfer

2009

Phys. Rev. A

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“…Via high-harmonic generation from Ps atoms coherent, hard x-rays well above 1 keV can therefore be produced. For example, a cutoff energy of 50 keV can be reached by interaction with an intense, long-wavelength laser beam (I ≈ 10 13 W/cm 2 , λ ≈ 100 μm) [14]. We note that in view of the latest progress in Ps accumulation mentioned above [12,13], the predictions in Ref.…”

Section: Positronium Atomsmentioning

confidence: 99%

“…Due to a constituent mass ratio of one, Ps atoms are particularly suited for realization of laser-driven recollisions at high field strengths [14]. After ionization (see also [15,16]), the electron and positron oscillate in opposite directions along the laser electric field and experience an identical magnetic drift motion, which largely reduces the detrimental impact of the latter.…”

Section: Positronium Atomsmentioning

confidence: 99%

“…We note that in view of the latest progress in Ps accumulation mentioned above [12,13], the predictions in Ref. [14] regarding achievable x-ray yields may be considered as conservative estimates as they were based on target densities of n ∼ 10 8 cm −3 only. By increasing the laser intensity into the relativistic domain, high-energy e + e − collisions can be obtained by laser-driving Ps atoms which might even lead to particle reactions like muon (μ + μ − ) or pion (π + π − ) pair creation [17,18].…”

Section: Positronium Atomsmentioning

confidence: 99%

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Exotic atoms in superintense laser fields

Müller

Shahbaz

Bürvenich

et al. 2009

Eur. Phys. J. Spec. Top.

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Abstract. The interaction of very strong laser fields with hydrogenlike atomic systems is analyzed theoretically. It is shown that the usual magnetic field-induced limitations for efficient recollisions can be overcome by employing exotic atoms rather than ordinary ones. In this way not only high-harmonic radiation in the MeV regime could be produced, but also laser-induced nuclear effects and particle reactions come into the reach of near-future laser facilities.

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“…These schemes are, therefore, particularly suitable for highly relativistic recollisions. Positronium is an appropriate bound system for relativistic recollisions since both particles drift at the same pace [26,27]. Moreover, standing waves can be applied where the Lorentz drift is circumvented [28][29][30][31] or two consecutive laser pulses, where the drift of the first pulse is compensated by the second one [32,33].…”

Section: Introductionmentioning

confidence: 99%

Laser-driven recollisions generalized to relativistic energies

Verschl

2008

Laser Phys.

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-The important process of laser-driven recollisions, where electrons are accelerated by strong laser fields and return to their parent ions, breaks down if the laser intensities imply relativistic electron dynamics. In this case, the Lorentz force drags the electrons away in the laser propagation direction, which inhibits recollisions. Here, a variety of schemes are discussed and compared which generalize the concept of recollisions to the relativistic regime. Additional static electric fields, antisymmetric initial states, and tailored laser pulses are suitable for weakly to moderately relativistic energies, whereas standing waves, preaccelerated ions, positronium, and counterpropagating consecutive pulses allow for recollisions up to the highly relativistic regime.

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Positronium in Intense Laser Fields

Cited by 37 publications

References 37 publications

Gamma flashes from relativistic electron-positron plasma droplets

Gamma flashes from relativistic electron-positron plasma droplets

Exotic atoms in superintense laser fields

Laser-driven recollisions generalized to relativistic energies

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