Dense Polarized Positrons from Laser-Irradiated Foil Targets in the QED Regime

Abstract

Dense positrons are shown to be effectively generated from laser-solid interactions in the strong-field quantum electrodynamics (QED) regime. Whether these positrons are polarized has not yet been reported, limiting their potential applications. Here, by QED particle-in-cell simulations including electron-positron spin and photon polarization effects, we investigate a typical laser-solid setup that an ultraintense linearly polarized laser irradiates a foil target with $\mu$m-scale-length preplasma. We find that once the positron yield becomes appreciable with the laser intensity exceeding $10^{24}W/\mathrm{c}{\mathrm{m}}^2$, the positrons are obviously polarized. The polarized positrons can acquire $>30\%$ polarization degree and $>30$ nC charge with a flux of $10^{12}{\mathrm{sr}}^{-1}$. The polarization relies on the deflected angles and can reach 60\% at some angles and energies. The angularly-dependent polarization is attributed to the asymmetrical laser fields positrons undergo in the skin layer of overdense plasma, where the radiative spin-flip and radiation reaction play significant roles. The positron polarization is robust and could generally appear in future 100-PW-class laser-solid experiments for various applications.

6 pages, 5 figures, with Supplemental Material

References in corpus (12)

• Physics of Strongly Magnetized Neutron Stars
• Dynamics of spin 1/2 quantum plasmas
• QED cascades induced by circularly polarized laser fields
• Pair Creation in QED-Strong Pulsed Laser Fields Interacting with Electron Beams
• Positrons in Surface Physics
• Spin solitons in magnetized pair plasmas
• Production of highly-polarized positrons using polarized electrons at MeV energies
• Scaling laws for positron production in laser--electron-beam collisions
• Production and dynamics of positrons in ultrahigh intensity laser-foil interactions
• Stable Positron Acceleration in Thin, Warm, Hollow Plasma Channels
• Spin and polarization effects on the nonlinear Breit-Wheeler pair production in laser-plasma interaction
• Radiative polarization dynamics of relativistic electrons in an intense electromagnetic field

Cited by in corpus (9)

• Simulations of laser-driven strong-field QED with Ptarmigan: Resolving wavelength-scale interference and $\gamma$-ray polarization
• Generation of High-Density High-Polarization Positrons via Single-Shot Strong Laser-Foil Interaction
• Laser-driven lepton polarization in the quantum radiation-dominated reflection regime
• Generation of Ultrarelativistic Vortex Leptons with Large Orbital Angular Momenta
• Polarized QED Cascades over Pulsar Polar Caps
• Modeling of axion and electromagnetic fields coupling in a particle-in-cell code
• Coherently Enhanced Axion-Photon Conversion via Seeded Photons for Short-Pulse Axion Detection
• Photon-polarization-resolved linear Breit-Wheeler pair production in a laser-plasma system
• Intrinsic Nonlocality of Spin- and Polarization-Resolved Probabilities in Strong-Field Quantum Electrodynamics