Dominance of gamma-gamma electron-positron pair creation in a plasma driven by high-intensity lasers

Creation of electrons and positrons from light alone is a basic prediction of quantum electrodynamics, but yet to be observed. Our simulations show that the required conditions are achievable using a high-intensity two-beam laser facility and an advanced target design. Dual laser irradiation of a structured target produces high-density gamma rays that then create > 10(8) positrons at intensities of 2 x 10(22) Wcm(-2). The unique feature of this setup is that the pair creation is primarily driven by the linear Breit-Wheeler process (gamma gamma -> e(+)e(-)), which dominates over the nonlinear Breit-Wheeler and Bethe-Heitler processes. The favorable scaling with laser intensity of the linear process prompts reconsideration of its neglect in simulation studies and also permits positron jet formation at experimentally feasible intensities. Simulations show that the positrons, confined by a quasistatic plasma magnetic field, may be accelerated by the lasers to energies >200 MeV.