Bright attosecond gamma-ray pulses from nonlinear Compton scattering with laser-illuminated compound targets

Attosecond light sources have the potential to open up new avenues in ultrafast science. However, the photon energies achieveable using existing generation schemes are limited to the keV range. Here we propose and numerically demonstrate an all-optical mechanism for the generation of bright MeV attosecond γ-photon beams with desirable angular momentum. Using a circularly-polarized Laguerre-Gaussian laser pulse focused onto a cone-foil target, dense attosecond bunches (. 170as) of electrons are produced. The electrons interact with the laser pulse which is reflected by a plasma mirror, producing ultra-brilliant (∼ 1023photons/s/mm2/mrad2/0.1%BW) multi-MeV (Eγ,max > 30MeV) isolated attosecond (. 260as) γ-ray pulse trains. Moreover, the angular momentum is transferred to γ-photon beams via nonlinear Compton scattering of ultra-intense tightly-focused laser pulse by energetic electrons. Such brilliant attosecond γ-photon source would provide new possibilities in the attosecond nuclear science.