Polarized Electrons from Photoionization of Polarized Alkali Atoms

Abstract

The process of photoionization of polarized alkali atoms in an atomic beam has been studied for potassium and lithium. Depolarization processes associated with photoionization of alkali molecules and optically excited atoms were discovered. After eliminating these depolarization mechanisms, the measured photoelectron polarization agreed within an accuracy of 3% with the predicted polarization based on the current theory for this electric dipole process. Using a polarized ${\mathrm{Li}}^{6}$ atomic beam and a pulsed uv light source, we have produced an intense and highly polarized electron beam with 2\ifmmode\times\else\texttimes\fi{}${10}^{8}$ electrons in 1.5 \ensuremath{\mu}sec and with a polarization of 0.78, which is a suitable prototype injector source for a high-energy electron accelerator.