Pair Production by Relativistic Electrons from an Intense Laser Focus

A preliminary discussion is given of electron-positron pair production by means of electrons accelerated to relativistic velocities at the focus of a laser beam. First, the pair-production cross section was numerically evaluated near its energy threshold. Then, two methods of relativistic electron production by focused laser light were considered: the coherent oscillation of electrons, and the acceleration of a few high-velocity electrons by plasma waves excited by laser-driven instabilities. It was found that the first method would produce pairs for neodymium-laser light at intensities close to the achievable limit (${10}^{19}$ - ${10}^{20}$ W/${\mathrm{cm}}^2$). The second method, however, may be capable of producing pairs at lower intensities.