Observation of positronium annihilation in the 2S state: towards a new measurement of the 1S-2S transition frequency
We report the first observation of the annihilation of positronium from the 2S state. Positronium (Ps) is excited with a two-photon transition from the 1S to the 2S state where its lifetime is increased by a factor of eight compared to the ground state due to the decrease in the overlap of the positron electron wave-function. The yield of delayed annihilation photons detected as a function of laser frequency is used as a new method of detecting laser-excited Ps in the 2S state. This can be considered the first step towards a new high precision measurement of the 1S-2S Ps line.
- Pub Date:
- August 2015
- Bound state QED;
- Physics - Atomic Physics;
- High Energy Physics - Experiment
- 6 pages, 3 Figures, proceedings EXA 2014, accepted for publication in Hyperfine Interactions