Pair production in counter-propagating laser beams

TL;DR

This paper confirms that counter-propagating laser beams at extremely high intensities can generate significant electron-positron pairs, potentially leading to a pair avalanche, through improved modeling of nonlinear Compton scattering.

Contribution

It provides an enhanced analysis of pair production in laser beams, considering various pulse shapes and polarizations, and confirms the possibility of pair avalanche at high intensities.

Findings

Pair production likely occurs at intensities around 10^{24} W/cm^2.

Linearly polarized counter-propagating beams can initiate pair avalanches.

Modeling one beam as a reflected wave yields consistent results.

Abstract

Based on an analysis of a specific electron trajectory in counter-propagating beams, Bell & Kirk (PRL 101, 200403 (2008)) recently suggested that laboratory lasers may shortly be able to produce significant numbers of electron-positron pairs. We confirm their results using an improved treatment of nonlinear Compton scattering in the laser beams. Implementing an algorithm that integrates classical electron trajectories, we then examine a wide range of laser pulse shapes and polarizations. We find that counter-propagating, linearly polarized beams, with either aligned or crossed orientation, are likely to initiate a pair avalanche at intensities of approximately 10^{24} Watts/sq cm per beam. The same result is found by modelling one of the beams as a wave reflected at the surface of an overdense solid.