THE ELASTIC-SCATTERING OF POSITRONS FROM BERYLLIUM AND MAGNESIUM IN THE LOW-ENERGY REGION

The elastic scattering of positrons from beryllium and magnesium is st udied by using a simple model potential to represent the interaction b etween the positron and target atoms. The model is tuned by adjusting the free parameters to reproduce previous predictions of the positron binding energies of the Bee(+) and Mge(+) ground states. An indication of the theoretical uncertainty in the derived phase shifts and cross section's is given by running a series of calculations with slightly d ifferent model potentials. The estimated scattering lengths are 16 a(0 ) and 7 a(0) for Be and Mg, respectively. The total cross section for positron-magnesium scattering constructed by adding the inelastic cros s section computed with many-body perturbation theory to the present e lastic cross section is broadly consistent with the experimental data.