Positron Annihilation in Noble Gas Mixtures

Hara and Massey [1] have investigated the annihilation of positrons in Ar-CO mixtures while the present author studied the behaviour of positrons in the noble gas mixtures (Ne + Ar) [2] and (He-)-Ar) [3]. It has been found that the annihilation decay constant, A, depends quite sensitively on the nature of the gas mixture. Our calculations [3] indicate that it will be quite interesting to explore gaseous mixtures experimentally. We have now extended our previous work to the three component system (He+Ne+Ar). The annihilation decay constant, X, is the quantity which is determined experimentally. Theoretically, it is calculated from the relation