Positronium formation reaction of polarized positrons and polarized electrons

Hirade, Tetsuya  ; Kumada, Takayuki   

Positrons injected in molecular solids or polymers will have the positronium formation around a terminal spur of positron track, so-called positron spur, with active species in the positron spur, such as excess electrons. In this case, the electrons are not polarized. At low enough temperatures, long-lived shallowly localized electrons are accumulated by irradiation in darkness, and positrons will have a next chance to form positronium with these long-lived shallowly localized electrons. For these electrons, it is possible to make them to be polarized by applying magnetic field at very low temperatures. We successfully observed the effect of the positronium formation reaction of polarized positron and polarized electrons.