Enhancement of positronium formation by trapped electrons in solid n-nonadecane. Light bleaching effect

The increase of positronium formation probability with the time of exposure to positron radiation, observed until now mainly in polymers, is shown for the case of polycrystalline n-nonadecane. Sample illumination by visible light restores the initial low value of positronium intensity owing to elimination of trapped electrons. Slowing down the growth of positronium intensity with prolonged positron irradiation is ascribed to inhibiting action of radicals