Production of Slow Protonium in Vacuum

Abstract

We describe how protonium, the quasi-stable antiproton-proton bound system, has been synthesized following the interaction of antiprotons with the molecular ion H$_2^+$ in a nested Penning trap environment. From a careful analysis of the spatial distributions of antiproton annihilation events in the ATHENA experiment, evidence is presented for protonium production with sub-eV kinetic energies in states around $n$ = 70, with low angular momenta. This work provides a new 2-body system for study using laser spectroscopic techniques.

9 pages with 5 figures and 1 table. Proceedings of the 4th International Conference on Trapped Charged Particles and Fundamental Physics (TCP 06), published in Hyperfine Interactions