Three-Quantum Annihilation of Positrons in Ionic Crystals

Abstract

The three-quantum decay of positrons annihilating in lithium hydride, alkali halides, and alkaline-earth oxides was investigated using a triple-coincidence method. Relative measurements were made by comparing the three-quantum yield in each substance with that in aluminum, taken as a standard. In some cases the three-quantum yield was measured as a function of temperature and employing multicrystalline specimens or single crystals with and without color centers. The results suggest that the essential features of positron decay in alkali halides are connected with the properties of ideal crystals, while this is not true in alkaline earth oxides.