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Spin-polarization effects of an ultrarelativistic electron beam in an ultraintense two-color laser pulse
摘要： Spin-polarization effects of an ultrarelativistic electron beam head-on colliding with an ultraintense two-color laser pulse are investigated comprehensively in the quantum radiation-dominated regime. We employ a Monte Carlo method, derived from the recent work of Li et al. [Phys. Rev. Lett. 122, 154801 (2019)], to calculate the spin-resolved electron dynamics and photon emissions in the local constant field approximation. We find that electron radiation probabilities in adjacent half cycles of a two-color laser field are substantially asymmetric due to the asymmetric field strengths and, consequently, after interaction the electron beam can obtain a total polarization of about 11% and a partial polarization of up to about 63% because of radiative spin effects, with currently achievable laser facilities, which may be utilized in high-energy physics and nuclear physics. Moreover, the considered effects are shown to be crucially determined by the relative phase of the two-color laser field and robust with respect to other laser and electron-beam parameters.
关键词： radiative spin effects,Monte Carlo method,quantum radiation-dominated regime,spin-polarization,two-color laser pulse,ultrarelativistic electron beam
更新于2025-09-11 14:15:04
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Polarized Positron Beams via Intense Two-Color Laser Pulses
摘要： The generation of ultrarelativistic polarized positrons during the interaction of an ultrarelativistic electron beam with a counterpropagating two-color petawatt laser pulse is investigated theoretically. Our Monte Carlo simulation, based on a semiclassical model, incorporates photon emissions and pair productions, using spin-resolved quantum probabilities in the local constant field approximation, and describes the polarization of electrons and positrons for the pair production and photon emission processes, as well as the classical spin precession in between. The main reason for the polarization is shown to be the spin asymmetry of the pair production process in strong external fields, combined with the asymmetry of the two-color laser field. Employing a feasible scenario, we show that highly polarized positron beams, with a polarization degree of ζ ≈ 60%, can be produced in a femtosecond timescale, with a small angular divergence, ～74 mrad, and high density, ～1014 cm?3. The laser-driven polarized positron source raises hope for providing an alternative for high-energy physics studies.
关键词： polarized positron beams,ultrarelativistic electron beam,local constant field approximation,spin-resolved quantum probabilities,high-energy physics,Monte Carlo simulation,two-color laser pulses
更新于2025-09-11 14:15:04