Dense Electron-Positron Plasmas and Ultra-Intense Bursts of Gamma-Rays   from Laser-Irradiated Solids
  In simulations of a 10PW laser striking a solid we demonstrate the possibility of producing a pure electron-positron plasma by the same processes as those thought to operate in high-energy astrophysical environments. A maximum positron density of 10^26/m^3 is achieved, seven orders of magnitude greater than achieved in previous experiments. Additionally, 35% of the laser energy is converted to a burst of gamma-rays of intensity 10^22W/cm^2, potentially the most intense gamma-ray source available in the laboratory. This absorption results in a strong feedback between both pair and gamma-ray production and classical plasma physics in the new `QED-plasma' regime. 
C. P. Ridgers, C. S. Brady, R. Duclous, J. G. Kirk, K. Bennett, T. D.   Arber, A. P. L. Robinson, A. R. Bell
physics.plasm-ph