We report total cross sections (TCS) measurements for positron scattering on N2, Ar, He and three cyclic hydrocarbons. The data have been obtained with a new linear low-energy spectrometer at Trento University. Both nitrogen and argon total cross sections shows a flat part in TCS from few eV up to the positronium formation thresholds. For cyclocarbons he has found very high values of the TCS in low energy range. Modeling using effective range theory is performed for benzene and cyclohexane. In He results we found some resonant structures indicating formation of virtual positronium.
Basic research problems in Atomic Physics with positrons (total cross sections, Ramsauer minima, positronium formation, selective ionization) and some benchmark measurements in Solid State Physics using positron annihilation (He-created nano-voids in Si, Oxygen precipitates in Si, low ε materials) are discussed.
Set-up for positron-molecule scattering measurements in the range of energy 0.1-20 eV is presented. To obtain a positron beam with suitable electron optical parameters apparatus uses brightness enhancement stage.