Electrostatically Guided Rydberg Positronium

We report experiments in which positronium (Ps) atoms were guided using inhomogeneous electric fields. Ps atoms in Rydberg-Stark states with principal quantum number n = 10 and electric dipole moments up to 610 D were prepared via two-color two-photon optical excitation in the presence of a 670 Vcm(-1) electric field. The Ps atoms were created at the entrance of a 0.4 m long electrostatic quadrupole guide, and were detected at the end of the guide via annihilation gamma radiation. When the lasers were tuned to excite low-field-seeking Stark states, a fivefold increase in the number of atoms reaching the end of the guide was observed, whereas no signal was detected when high-field-seeking states were produced. The data are consistent with the calculated geometrical guide acceptance.