Simulation of positronium: Toward more realistic models of void spaces in materials

An exact treatment of a positron and electron in a two-chain, Path Integral Monte Carlo (PIMC) simulation is used to calculate both self-annihilation and pick-off rates of Ps at finite temperature. We find the effect of the linear dielectric response of a homogeneous material on the annihilation rate of positrons and Ps in spherical voids. In addition, we find lifetimes and structural information for Ps in cylindrical channels, both with and without adsorbed fluid atoms.