Creation and uses of positron plasmas*

Abstract

Advances in positron trapping techniques have led to room-temperature plasmas of 107 positrons with lifetimes of 103 s. Improvements in plasma manipulation and diagnostic methods make possible a variety of new experiments, including studies just being initiated of electron–positron plasmas. The large numbers of confined positrons have also opened up a new area of positron annihilation research, in which the annihilation cross sections for positrons with a variety of molecules have been measured, as well as the energy spread of the resulting gamma rays. Such measurements are of interest for fundamental physics and for the modeling of astrophysical plasmas.