Springer Online Journal Archives 1860-2000
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Abstract The reduction of the thermal positron backdiffusion probability from a dielectric, due to the electrostatic polarization of the surface, has been calculated in the framework of an isothermal diffusion model. Our results show that this reduction can pass from levels of only a few percent (e.g., Si and Ge at room temperature) to almost complete suppression for substances with short positron diffusion length and at low temperatures. It is also shown that the surface polarization effect can be ignored in measurements of the positron diffusion constant with beam techniques if the low-energy part of the backdiffusion probability vs. beam energy curve is not included in the analysis.
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