Published online by Cambridge University Press: 06 November 2014
An ultra-relativistic electron beam propagating through a high-Z solid triggers an electromagnetic cascade, whereby a large number of high-energy photons and electron–positron pairs are produced mainly via the bremsstrahlung and Bethe–Heitler processes, respectively. These mechanisms are routinely used to generate positron beams in conventional accelerators such as the electron–positron collider (LEP). Here we show that the application of similar physical mechanisms to a laser-driven electron source allows for the generation of high-quality positron beams in a much more compact and cheaper configuration. We anticipate that the application of these results to the next generation of lasers might open the pathway for the realization of an all-optical high-energy electron–positron collider.