Singularities of magnetic quenching of positronium in semiconductors

Characteristics of electron-positron annihilation in semiconductors in the presence of an external magnetic field are calculated with account for positronium production. Positronium atoms are supposed to be in two states: delocalized and localized (on defects) and to experience, besides pick-off annihilation, ortho-paraconversion (3S1 reversible 1S0) on free carriers. Numerical calculation results for the field H=15 kGs are presented. The field effect is shown to be sufficiently different for localized and delocalized positronium. For the localized positronium the effect of the field depends greatly on the nature of defects