PW laser-driven bright ɣ-ray emission and dense positron production from diamondlike carbon foils

we propose an all-optical scheme for ultra-bright γ-ray emission and dense positron production with lasers at intensity of 10^22-23 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 γ-photon emission with unprecedented brightness of 10²⁵ photons/s/mm²/mrad²/0.1%BW at 15 MeV and intensity of 5×10²³ Wcm^-2. A GeV positron beam with density of 2.5×10²² cm^-3 and flux of 1.6×10¹⁰/shot is achieved.