Abstract
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 γ rays that then create > 108 positrons at intensities of 2 × 1022 Wcm−2. The unique feature of this setup is that the pair creation is primarily driven by the linear Breit-Wheeler process (γγ → 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.
Highlights
Creation of electrons and positrons from light alone is a basic prediction of quantum electrodynamics, but yet to be observed
We show that a structured plasma target irradiated by two laser beams creates an environment where the linear process dominates over the nonlinear and over the Bethe–Heitler process
An overview of the key results of this paper is shown in Fig. 1: we show that a structured target, when irradiated from both sides by intense laser pulses, enables the creation of a large yield of positrons through γ-γ collisions, i.e., the linear Breit–Wheeler process, at intensities well within the reach of existing high-power laser facilities
Summary
Creation of electrons and positrons from light alone is a basic prediction of quantum electrodynamics, but yet to be observed. At intensities exceeding 1023 W cm−2, those energetic particles can drive nonlinear quantum-electrodynamical (QED) processes[2,3] otherwise only found in extreme astrophysical environments[4,5] One such process is the creation of electron-positron pairs from light alone. Achieving the necessary flux requires specialized experimental configurations[13,14] and its possible contribution to in situ electron–positron pair creation has hitherto been neglected in studies of high-intensity laser–matter interactions These interactions create regions of ultrastrong electromagnetic field, and high fluxes of accelerated particles, because relativistic effects mean that even a solid-density target can become transparent to intense laser light[15,16]. These positrons are generated when two high-energy electron beams, accelerated by and copropagating with laser pulses that are guided along a plasma channel, collide head-on, emitting synchrotron photons that collide with each other and the respective oncoming laser
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