HYPERFINE SPLITTING IN POSITRONIUM MEASURED THROUGH QUANTUM BEATS IN THE 3-GAMMA DECAY

Quantum beat oscillations in the 3 gamma decay of the positronium atom arising from interference between the different spin states have been observed using a simple beta-start and gamma-stop detection system. M easurements of the beat frequency at different magnetic fields have yi elded a value of the 1 S-1(0)-1 S-3(1) 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 microwav e radiation to quench the triplet substate of the positronium atom.