Fig. 1. Simulation results for two colliding laser pulses. (a) Schematic setup of the two-pulse collision regime. (b) Energy spectra for γ photons and positrons in both long- and short-pulse cases. (c) and (d) Angular distributions of energy for γ photons and positrons generated in the short-pulse case. (e) and (f) Corresponding results for the long-pulse case.

Fig. 2. Simulation results for a single laser pulse with a plasma mirror. (a) Schematic setup of the regime. (b) Energy spectra for γ photons and positrons in both long- and short-pulse cases. (c) and (d) Angular distributions of energy for γ photons and positrons generated in the short-pulse case. (e) and (f) Corresponding results for the long-pulse case.

Table 1. Main simulation results for all setups: 〈ɛ_γ〉 and 〈εe+〉 are the average energies of the γ photons and positrons; N_γ and Ne+ are the numbers of γ photons and positrons produced in the simulation box; η_γ and ηe+ are the laser energy conversion efficiencies to γ photons and positrons.