Development of a high-brightness, energy-tunable positronium beam for surface scattering experiments

Abstract

We have developed an apparatus, which can output a high-quality, energy-tunable positronium (Ps) beam, for fundamental studies on Ps interactions with surfaces. The beam was produced through a two-step process, in which Ps negative ions were efficiently generated by the impact of slow positrons onto a Na-coated W thin-film and were then photodetached by an infrared laser beam. An experimental system for surface scattering experiments was also constructed and tested. The Ps beam was incident on a LiF (100) crystal surface in a grazing-angle geometry and the scattered components were projected onto a position sensitive detector. We show the current status of the Ps beam apparatus and some of the test results of the surface scattering experiment.