We describe the experimental production of a beam of 2 3 S 1 positronium (Ps) atoms
obtained from charge-exchange collisions between a positron beam and Xe held in a gas
cell. The angular divergence of the emitted Ps beam was recorded using two position
sensitive detectors located at different distances from the gas cell. The fraction of the Ps
beam produced in the 2 3 S 1 level was measured via the change in the Ps count rate after
driving the 2 3 S 1→ 2 3 P 2 transition with microwave radiation; with optimal experimental …