Serving up positrons on a table

17 Jun 2002

German physicists have produced rapid bursts of positrons - the antimatter equivalent of electrons - using a table-top femtosecond source.

Unlike previous efforts, which have typically produced only one burst of positrons every few hours, the system developed by Klaus Witte and colleagues at the Max-Planck Institute for Quantum Optics in Munich delivers fewer positrons, but at the rate of ten bursts per second.

The high repetition rate makes the source suitable for applications in materials science and studies of positronium - a short-lived species that consists of a paired electron and positron.

In the set-up, the femtosecond laser pulses excite electrons by accelerating them through a plasma channel. The electrons then produce powerful gamma rays, which in turn create electron-positron pairs.