Positronium formation from porous silica in backscattering and transmission geometries

The Aarhus positron beam line is utilised to measure the positronium formation fraction from porous silica thin films created by the Glancing Angle Deposition technique. The highest formation fraction found from these studies in a backscattering geometry is (57.7 ± 1.0)% in good agreement with other measurements. In transmission mode, the maximum positronium output is found to be (12.5 ± 0.5)%. These are the first measurements of positronium formation in transmission of a porous silica thin film, a starting point for future attempts to optimise the positronium formation in transmission