Measurements of total cross sections for positron scattering by uracil molecules

We present measurements of total cross sections for 1 to 30 eV positrons scattered by uracil molecules. The measurements are done using a beam transmission technique on a setup adjusted to accommodate the nature of uracil and we discuss possibilities of future experiments studying positron interactions with more complicated targets. These and future investigations of positron interactions with biomolecules have potential relevance to various biomedical applications

Experimental determination of the scattering length for positron scattering from krypton

We report the first experimentally supported determination of the scattering length for positron scattering from krypton. Our result of -10.3 ± 1.5 a.u. compares favourably with that from a convergent close coupling calculation performed as a part of this investigation (-9.5 a.u.), and also with an earlier many body theory calculation of -10.1 a.u. from Gribakin and Ludlow [Phys. Rev. A 70, 032720 (2004)] and a polarized-orbital result of -10.4 a.u. from McEachran et al. [J. Phys. B 13, 1281 (1980)]. The present experimental scattering length supports the existence of a low-lying positron-krypton virtual state (Surko et al. [J. Phys. B 38, R57 (2005)]) at an energy ε = 0.13 eV