Positron annihilation in some organic scintillators: magnetic quenching and three gamma spectroscopy results

We present positron annihilation data in some organic polycrystalline scintillators, obtained through lifetime and three gamma spectroscopies, as well as magnetic quenching measurements. Strong magnetic quenching effects at low fields were discovered, which cannot be explained in terms of simply “swollen” Positronium (qPs): a possible explanation in terms of interactions between the qPs and the magnetic moments of the spur products is proposed.