On the Interaction of Positrons with Argon

A semi-phenomenological model of the interaction of positrons with atoms is outlined, and some model properties—enhancement factors, effective mass, and effective charge—are calculated using a local density approximation. These properties are used with a one parameter polarization potential to predict the electric field dependence and the temperature dependence of the positron annihilation rate in argon gas. Comparison of these predictions with experimental data shows good agreement for the electric field dependence, but the predicted temperature dependent effect is less than published experimental results. The model is also applied to helium, with unsatisfactory results, and a prediction of the electric field dependence of the positron annihilation rate in krypton is made.