Target transverse size and laser polarization effects on pair production during ultra-relativistic-intense laser interaction with solid targets

Abstract

Pair production from the Breit-Wheeler process in ultra-intense laser pulse interactions with solid targets are studied by particle-in-cell simulations using the EPOCH code including the quantum electrodynamics module. We find that the pair yield depends on both the target transverse size and the laser pulse duration. For a short laser pulse, the highest pair yield is achieved with a target as wide as the laser spot size. For a long laser pulse, however, the optimal target size for the pair production increases with the pulse duration due to a self-generated cone by the hole-boring process. The effect of laser polarization upon the pair production is also studied. It is found that a circularly polarized laser pulse is more efficient in the ion acceleration rather than in the pair production. With the same laser energy, we find that a linearly polarized laser pulse can generate two times more positrons than the circularly polarized laser pulse does. These findings may benefit the future researches on the laser plasma based electron-positron production.