  The positron-electron pair annihilation in two photons is known for its
numerous applications using PET scanners. The decay of Positronium (Ps) from a
standard sealed source in more than two photons is less likely but can be
observed with a relatively simple setup. The main goal of this experiment was
to verify momentum and total angular momentum conservation principles at
subatomic level through the Ps annihilation. The two spin configurations of Ps
are produced with a beta+ source. The decay modes are identified using
gamma-ray spectroscopy techniques in a double and triple coincidence setup.
Three germanium detectors (or two HPGe and one NaI(Tl) detectors) and a digital
electronic system are required.
