Electromagnetic cascade in high-energy electron, positron, and photon interactions with intense laser pulses

TLDR

The study investigates how energy loss of an electron beam, requiring a self‑consistent quantum description, provides a clear experimental observable for the transition from the classical to the quantum regime in high‑energy electron–laser interactions. The authors model head‑on collisions of high‑energy electrons, positrons, and photons with intense, broad laser pulses, calculating the resulting particle distributions while assuming negligible transverse three‑dimensional effects. The interaction generates a cascade of photon emission and pair production, but rapid energy loss of charged particles produces an exponentially decaying spectrum that suppresses the electromagnetic avalanche, preventing exponential growth of particles and.

Abstract

The interaction of high-energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high-energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when three-dimensional effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and photons are calculated for the case of a high-energy e-beam interacting with a counterstreaming, short intense laser pulse. The energy loss of the e-beam, which requires a self-consistent quantum description, plays an important role in this process, as well as provides a clear experimental observable for the transition from the classical to quantum regime of interaction.