Positron Annihilation in Aqueous Solutions

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Abstract
The angular correlation of 2-quantum emission from the annihilation of positrons in different materials has been measured in an apparatus with 8 photon counters providing coincidences for 16 output channels. As positron targets were chosen indium, water and aqueous solutions of 5 paramagnetic salts and 10 other substances. It was confirmed that the amount of singlet positronium formed is influenced by two processes: a reduction of positronium due to electron capture by oxidizing substances and an increase of the triplet → singlet conversion due to the electron exchange with paramagnetic ions.