Bright $\gamma$ rays source and copious nonlinear Breit-Wheeler pairs in the collision of high density particle beams

TL;DR

This paper demonstrates that high-density particle beam collisions can generate intense gamma-ray sources and copious nonlinear Breit-Wheeler pairs, offering a new method to explore quantum electrodynamics at extreme fields.

Contribution

It provides analytical estimates and simulation validation for gamma-ray and pair production in high-density beam collisions, highlighting an alternative to laser-based QED experiments.

Findings

Generation of highly collimated GeV gamma rays with high brilliance

Production of up to 10^5 nonlinear Breit-Wheeler pairs

Agreement between analytical models and 3D simulations including QED effects

Abstract

The collision of ultrashort high-density $e^-$ or $e^-$ and $e^+$ beams at 10s of GeV, to be available at the FACET II and in laser wakefield accelerator experiments, can produce highly collimated $\gamma$ rays (few GeVs) with peak brilliance of $10^{27}~\mathrm{ph/s~mm^2 mrad^2 0.1\% BW}$ and up to $10^5$ nonlinear Breit-Wheeler pairs. We provide analytical estimates of the photon source properties and of the yield of secondary pairs, finding excellent agreement with full-scale 3D self-consistent particle-in-cell simulations that include quantum electrodynamics effects. Our results show that beam-beam collisions can be exploited as secondary sources of $\gamma$ rays and provide an alternative to beam-laser setups to probe quantum electrodynamics effects at the Schwinger limit.