Positron Diffusion in Metals

Abstract

From positron lifetime measurements in seven powders of Fe, Co, Ni, and W, the positron diffusion constant in metals at 300°K is found to be $D_{+}=(1.0\mathrm{}\pm 0.5)\times {10}^{-2\mathrm{}}$ ${\mathrm{cm}}^2$/sec. This agrees with a theory based on positron-electron scattering. Evidence is presented that positrons are trapped in metal surface states.