Abstract
Matter can be transferred into energy and the opposite transformation is also possible by use of high-power lasers. A laser pulse in plasma can convert its energy into γ-rays and then e−e+ pairs via the multi-photon Breit-Wheeler process. Production of dense positrons at GeV energies is very challenging since extremely high laser intensity ~1024 Wcm−2 is required. Here we propose an all-optical scheme for ultra-bright γ-ray emission and dense positron production with lasers at intensity of 1022–23 Wcm−2. By irradiating two colliding elliptically-polarized lasers onto two diamondlike carbon foils, electrons in the focal region of one foil are rapidly accelerated by the laser radiation pressure and interact with the other intense laser pulse which penetrates through the second foil due to relativistically induced foil transparency. This symmetric configuration enables efficient Compton back-scattering and results in ultra-bright γ-photon emission with brightness of ~1025 photons/s/mm2/mrad2/0.1%BW at 15 MeV and intensity of 5 × 1023 Wcm−2. Our first three-dimensional simulation with quantum-electrodynamics incorporated shows that a GeV positron beam with density of 2.5 × 1022 cm−3 and flux of 1.6 × 1010/shot is achieved. Collective effects of the pair plasma may be also triggered, offering a window on investigating laboratory astrophysics at PW laser facilities.
Highlights
The rapid development of laser technologies promises substantial growth of peak laser intensities
At extremely high laser intensities, an important mechanism for e−e+ pair production is the multi-photon BW process[7], which enables the laser energy to convert into copious e−e+ pairs via photon-photon annihilation (γ + n ωl → e− + e+)
The laser intensity required is within the capabilities of future multi-PW laser facilities, paving the way to potential applications in nuclear and particle physics for fundamental research, laboratory study of astrophysics, medical imaging and material science[4,5,9,10,11]
Summary
The rapid development of laser technologies promises substantial growth of peak laser intensities. Paid to the first category for overdense e−e+ pair production, which may trigger collective effects or ‘medium-like behavior’, e.g., Debye Shielding, required for modeling astrophysical phenomena in laboratories These studies are limited to either one-dimensional (1D) theory or 2D particle-in-cell (PIC) simulations, and the inherent deficiency, i.e, high laser reflection by the immobile target, results in relatively low laser energy conversion. Due to strong electron heating and foil expansion, relativistic transparency of both foils occurs under certain conditions, such that the laser penetrates through one foil and collide with the counter-propagating compressed layer of electrons accelerated from the other foil This symmetric configuration enables efficient Compton back-scattering and increases equivalent quantum invariants, resulting in ultra-bright γ-ray emission with an unprecedented peak brightness and dense GeV positron beam production. The laser intensity required is within the capabilities of future multi-PW laser facilities, paving the way to potential applications in nuclear and particle physics for fundamental research, laboratory study of astrophysics, medical imaging and material science[4,5,9,10,11]
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