Rydberg-positronium Velocity and Self-Ionization Studies in a 1T Magnetic Field and Cryogenic Environment

We characterized the pulsed Rydberg-positronium production inside the AEgIS(Antimatter Experiment: Gravity, Interferometry, Spectroscopy) apparatus inview of antihydrogen formation by means of a charge exchange reaction betweencold antiprotons and slow Rydberg-positronium atoms. Velocity measurements onpositronium along two axes in a cryogenic environment (10K) and in 1T magneticfield were performed. The velocimetry was done by MCP-imaging of photoionizedpositronium previously excited to the n=3 state. One direction of velocitywas measured via Doppler-scan of this n=3-line, another directionperpendicular to the former by delaying the exciting laser pulses in atime-of-flight measurement. Self-ionization in the magnetic field due tomotional Stark effect was also quantified by using the same MCP-imagingtechnique for Rydberg positronium with an effective principal quantum numbern_eff ranging between 14 and 22. We conclude with a discussion about theoptimization of our experimental parameters for creating Rydberg-positronium inpreparation for an efficient pulsed production of antihydrogen.