Experimental Observation of Electrons Accelerated in Vacuum to Relativistic Energies by a High-Intensity Laser

Free electrons have been accelerated in vacuum to MeV energies by a high-intensity subpicosecond laser pulse (10{sup 19}W/cm{sup 2}, 300fs). The experimental data are in good agreement with the relativistic motion of electrons in a spatially and temporally finite electromagnetic field, both in terms of maximum energy and scattering angle. {copyright} {ital 1997} {ital The American Physical Society}