Hyperfine splitting in positronium measured through quantum beats in the 3γ decay

Quantum beat oscillations in the 3γ decay of the positronium atom arising from interference between the different spin states have been observed using a simple β-start and γ-stop detection system. Measurements of the beat frequency at different magnetic fields have yielded a value of the 1 1S0-1 3S1 hyperfine interaction of 202.5 ± 3.5 GHz, in good agreement with previous measurements. This novel approach does not require high magnetic fields and the use of microwave radiation to quench the triplet substate of the positronium atom.link_to_subscribed_fulltex