The elastic scattering of positrons from beryllium and magnesium in the low-energy region

The elastic scattering of positrons from beryllium and magnesium is studied by using a simple model potential to represent the interaction between 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 and ground states. An indication of the theoretical uncertainty in the derived phase shifts and cross sections is given by running a series of calculations with slightly different model potentials. The estimated scattering lengths are and for Be and Mg, respectively. The total cross section for positron-magnesium scattering constructed by adding the inelastic cross section computed with many-body perturbation theory to the present elastic cross section is broadly consistent with the experimental data.