Annihilation of positronium inα-SiO2investigated by combined angular correlation and lifetime measurements

Abstract
By combining angular correlation results of the positron annihilation quanta with lifetime results it is found that a weak but long-lived (599±10 ps) lifetime component can be correlated with the para-positronium peak in angular correlation measurements when taking into account both pickoff annihilation and conversion of positronium. Conversion has not been considered in earlier works.