Antimatter may soon be living up to its science fiction reputation as a useful commodity. Researchers from Germany's Institut für Nukleare Festörperphysik have developed a scanning positron microscope which is sensitive enough to detect defects in semiconductors.
When a positron meets its antiparticle equivalent, an electron, the two particles annihilate and release energy in the form of a gamma ray photon. Detecting this radiation reveals where in a sample the positron was destroyed. Positrons that enter a sample at vacancy sites (holes) live longer than those that enter elsewhere.
The German team fired positrons emitted by radioactive isotope sodium-22 focused into a 1µm wide beam, which pulsed every 0.2ns, at a GaAs sample.
Werner Triftshäuser, the team leader, said: "Positrons can detect defect concentrations of one part per million. No other method is that sensitive."