Enhanced photon emission and pair production in laser-irradiated plasmas

Enhanced photon emission and pair production due to heavy ion mass in the interaction of an ultraintense laser with overdense plasmas is explored by particle-in-cell simulation. It is found that plasmas with heavier ion mass can excite a higher and broader electrostatic field, which causes the enhancement of backward photon emission. The pair yields are then enhanced due to the increase of backwards photons colliding with the incoming laser pulse. By examining the density evolution and angle distribution of each particle species, the origin of pair yield enhancement is clarified.