Nonlinear Breit-Wheeler pair creation with bremsstrahlung $\gamma$ rays

TL;DR

This paper proposes an experimental setup using bremsstrahlung gamma rays from ultrarelativistic electrons to observe nonlinear Breit-Wheeler pair creation, supported by analytical and simulation results.

Contribution

It introduces a feasible experimental geometry for observing nonlinear Breit-Wheeler pair creation using bremsstrahlung gamma rays and optimizes target parameters for maximum positron yield.

Findings

Optimal target thickness enhances pair production.

Analytical predictions match simulation results.

Experimental parameters are within current laser capabilities.

Abstract

Electron-positron pairs are produced through the Breit-Wheeler process when energetic photons traverse electromagnetic fields of sufficient strength. Here we consider a possible experimental geometry for observation of pair creation in the highly nonlinear regime, in which bremsstrahlung of an ultrarelativistic electron beam in a high-$Z$ target is used to produce $\gamma$ rays that collide with a counterpropagating laser pulse. We show how the target thickness may be chosen to optimize the yield of Breit-Wheeler positrons, and verify our analytical predictions with simulations of the cascade in the material and in the laser pulse. The electron beam energy and laser intensity required are well within the capability of today's high-intensity laser facilities.