Abstract
The new generation of laser facilities is expected to deliver short (10 fs–100 fs) laser pulses with 10–100 PW of peak power. This opens an opportunity to study matter at extreme intensities in the laboratory and provides access to new physics. Here we propose to scatter GeV-class electron beams from laser-plasma accelerators with a multi-PW laser at normal incidence. In this configuration, one can both create and accelerate electron-positron pairs. The new particles are generated in the laser focus and gain relativistic momentum in the direction of laser propagation. Short focal length is an advantage, as it allows the particles to be ejected from the focal region with a net energy gain in vacuum. Electron-positron beams obtained in this setup have a low divergence, are quasi-neutral and spatially separated from the initial electron beam. The pairs attain multi-GeV energies which are not limited by the maximum energy of the initial electron beam. We present an analytical model for the expected energy cutoff, supported by 2D and 3D particle-in-cell simulations. The experimental implications, such as the sensitivity to temporal synchronisation and laser duration is assessed to provide guidance for the future experiments.
Highlights
Generating abundance of antimatter in laboratory is of great importance both for fundamental science and potential applications
Several other laser experiments[5,6,7,8,9,10,11,12,13] use Bethe-Heitler process for pair generation[14]. This is similar to the BW pair production, with one difference: a strong field background is provided by the proximity of a high-Z nucleus instead of a high-power laser pulse
By using more intense laser pulses (I ∼ 1022 W/cm2) or more energetic electron beams, we will soon be able to convert a large fraction of the electron energy into radiation and access the regime of quantum radiation reaction[33,34,35,36,37,38,39,40]
Summary
Generating abundance of antimatter in laboratory is of great importance both for fundamental science and potential applications. This is expected in the few years, as 4 GeV electron beams have already been obtained using a 16 J laser[41] and the generation of facilities is aiming to achieve laser intensities I > 1023 W/cm[2] In such extreme conditions, the energetic photons produced in the scattering can decay into electron-positron pairs[42]. If the created particles are very energetic, they continue emitting hard photons to further feed the pair creation Once their energy is low enough to be trapped, they rapidly develop a momentum component parallel to the laser propagation direction that supresses the quantum interaction. Our theory is supported by full-scale 2D and 3D particle-in-cell (PIC) simulations, where the quantum processes are modelled via an additional Monte-Carlo module We show that this setup produces a neutral electron-positron flow that can reach multi-GeV energies. The pairs and the earlier reflected electrons move in slightly different directions and can be collected separately
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