Electron–Positron Pair Production by Electromagnetic Pulses

Electron–positron pair production in vacuum by a single focused laser pulse and by two counterpropagating colliding focused pulses is analyzed. A focused laser pulse is described using a realistic threedimensional model based on an exact solution of Maxwell’s equations. In particular, this model reproduces an important property of focused beams, namely, the existence of two types of waves with a transverse electric or magnetic vector ( eor hpolarized wave, respectively). The dependence of the number of produced pairs on the radiation intensity and focusing parameter is studied. It has been shown that the number of pairs produced in the field of a single e -polarized pulse is many orders of magnitude larger than that for an hpolarized pulse. The pulse-intensity dependence of the number of pairs produced by a single pulse is so sharp that the total energy of pairs produced by the epolarized pulse with intensity near the intensity I S = 4.65 × 10 29 W/cm 2 characteristic of QED is comparable with the energy of the pulse itself. This circumstance imposes a natural physical bound on the maximum attainable intensity of a laser pulse. For the case of two colliding circularly polarized pulses, it is shown that pair production becomes experimentally observable when the intensity of each beam is I ~ 10 26 W/cm 2 , which is one to two orders of magnitude lower than that for a single pulse. PACS numbers: 12.20.Ds DOI: 10.1134/S106377610601002X ATOMS, MOLECULES, OPTICS