Photonuclear fission from high energy electrons from ultraintense laser-solid interactions

A new regime of laser-matter interactions in which the quiver motion of pla sma electrons is fully relativistic, with energies extending well above the threshold for nuclear processes, is studied using a petawatt laser system. In solid target experiments with focused intensities exceeding 10(20) W/cm (2), high energy electron generation, hard bremsstrahlung, and nuclear phen omena have been observed. We report here a quantitative comparison of the h igh energy electrons and the bremsstrahlung spectrum, as measured by photon uclear reaction yields, including the photoinduced fission of U-238.