Frequency scaling law for nonlinear Compton and Thomson scattering: Relevance of spin and polarization effects

Abstract

The distributions of Compton and Thomson radiation for a shaped laser pulse colliding with a free electron are calculated in the framework of quantum and classical electrodynamics, respectively. We introduce a scaling law for the Compton and the Thomson frequency distributions which universally applies to long and short incident pulses. Thus, we extend the validity of frequency scaling postulated in previous studies comparing nonlinear Compton and Thomson processes. The scaling law introduced in this paper relates the Compton no-spin flipping process to the Thomson process over nearly the entire spectrum of emitted radiation, including its high-energy portion. By applying the frequency scaling, we identify that both spin and polarization effects are responsible for differences between classical and quantum results. The same frequency scaling applies to angular distributions and to temporal power distributions of emitted radiation, which we illustrate numerically.

Supercontinuum in ionization by relativistically intense and short laser pulses: Ionization without interference and its time analysis

“…2 can be estimated from Eq. (28). Namely, using the definition of the laser carrier frequency ω L = N osc ω, we can represent the most probable energy transferred from the pulse to the He + ion as…”

“…In order to evaluate this integral, we perform the Monte Carlo analysis (see, e.g., Refs. [28,77]). To this end, we replace the upper limit of the energy integration by a finite value m e c 2 + E max , with E max being the maximum kinetic energy of ejected electrons.…”

“…In particular, such diverse phenomena have been studied as the vacuum polarization induced Young interference [25], the Kapitza-Dirac effect [26,27], interference effects in Compton and Thomson scattering (see, e.g., [28,29]), and in lasermodified Mott scattering [30,31], the coherent comb structures created by a finite train of short pulses in the Compton [32,33], Breit-Wheeler [34], and ionization [35] processes, which can be used for the diagnostics of relativistically intense laser pulses [36,37].…”

“…Moreover, if the electron supercontinuum is produced by a train of pulses, it will result in the creation of coherent electron energy combs. In analogy to the radiation combs generated in Compton and Thomson scattering [28,29], this may lead to the synthesis of a sequence of very short "electron pulses." The latter could find applications in the "matter-wave" pump and probe electron scattering experiments, very similar to the ones already performed in optics.…”

Theory of radiative electron polarization in strong laser fields

“…Most studies of spinor QED refer to unpolarized electrons where the electron spin is averaged over. More detailed calculations of the non-linear Compton scattering probabilities with regard to the spin and spin polarization have been performed for monochromatic laser fields [24][25][26][27][28], short laser pulses [22,29,30], or constant crossed fields [31,32]. Moreover, in extremely strong fields electrons may polarize without radiating via electromagnetic self-interaction [33].…”